FINAL REPORT

European Commission Directorate General XI

Verification of Vulnerable Zones Identified Under the Directive and Sensitive Areas Identified Under the Urban Waste Water Treatment Directive

United Kingdom

March 1999

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European Commission Directorate General XI

Verification of Vulnerable Zones Identified Under the Nitrate Directive and Sensitive Areas Identified Under the Urban Waste Water Treatment Directive

United Kingdom

March 1999

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AN OVERVIEW OF THE IDENTIFICATION PROCESS FOR VULNERABLE ZONES AND SENSITIVE AREAS IN THE UK ENVIRONMENTAL RESOURCES MANAGEMENT I1 1 DIRECTIVE DEFINITIONS AND UK INTERPRETATIONS

1.1 INTRODUCTION

The objectives of the Urban Waste Water Treatment Directive (UWWTD)1 and the Directive2 are to reduce and prevent “pollution”, from urban waste water treatment plants (hereafter ‘sewage treatment works’, STWs, following the UK terminology) and from agricultural nitrates respectively. Some aspects of the Directives are closely defined, others are – to some degree – left open to interpretation by Member States, individually or collectively. This first part of the report reviews the objectives of the two Directives as they relate to estuarine and coastal sites; examines the UK’s operational interpretation of these; and finally reviews the available official UK documentation relating to implementation at specific sites.

1.2 THE URBAN WASTE WATER TREATMENT DIRECTIVE

There are a number objectives and requirements of the UWWTD that relate to the estuarine and coastal environment. The main elements are:

• First, the stated objective, “to protect the environment from the adverse effects” of waste water discharges and “pollution” arising from waste water (Article 1);

• In order to achieve this secondary treatment shall generally be required (Article 4);

• However within ‘Sensitive Areas’ additional action is required, throughout the catchment area, for those treatment plants that contribute to “pollution” (Article 5.5). For estuaries and coastal waters the current or future potential for is a criteria that results in their prescription as a Sensitive Area (Annex II). While Annex II allows some flexibility for “small agglomerations”, the requirement for “large agglomerations” is absolute: phosphorus and/or nitrogen should be removed unless it can be demonstrated that removal will have “no effect” on the “level” of eutrophication – a claim that a contribution will be ‘insignificant’ does not provide a defence for failure to implement.

• In addition an estuarine or coastal water “must be identified” as a Sensitive Area where further treatment than that set out in the UWWT Directive is “necessary to fulfil [other] Council Directives”.

1Council Directive of 21 May 1991 concerning urban waste water treatment (91/271/EEC).

2 Council Directive of 12 December 1991 concerning the protection of waters against pollution caused by nitrates from agricultural sources (91/6765/EEC)

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 1 • The Directive also allows for the creation of ‘Less Sensitive Areas’, LSAs, providing “comprehensive studies” demonstrate that discharges “will not adversely affect the environment” (Article 6.2). Such discharges must receive at least primary treatment. In estuaries this stipulation applies to discharges from “agglomerations” of between 2,000 and a maximum of 10,000 person equivalents, p.e.. Above this size LSA status is not allowed and the provisions of Article 4 regarding secondary treatment apply. In coastal waters the equivalent limit is 150,000 p.e.

• Estuarine discharges under 2,000 in estuaries or under 10,000 p.e. in coastal waters must, by 2005, receive “appropriate” treatment – that necessary to meet the “relevant” aspects of this and other Directives.

• Other Directives relevant to estuaries and coastal waters included those relating to hazardous substances, bathing water, shellfish, and habitats and species protection.

1.2.1 UWWTD: Biochemical oxygen demand and eutrophication

Having allowed for the requirements of other Directives, two aspects of pollution specifically deal with by the UWWTD are the biochemical oxygen demand (BOD) of the decomposing sewage effluent, and eutrophication. BOD, with quantitative criteria set out in the Directive’s annex, is relatively straight-forward, at least in its definition. However that for eutrophication is more complex.

The Directive states (2.11) that “‘eutrophication’ means the enrichment of water by nutrients, especially compounds of nitrogen and/or phosphorus, causing an accelerated growth of algae and higher forms of plant life to produce an undesirable disturbance to the balance of organisms present in the water and to the quality of the water concerned.”

With the exception of the insertion of the value judgement “undesirable” this is fairly close to the standard scientific definition of eutrophication1. One

1 In scientific terms an eutrophic system is, by extention from the origianal medical definition, a ‘well fed’ system. In the literature Nixon (1995) defines eutrophication operationally as: “Eutrophication (noun) – an increase in the rate of supply of organic matter to an ecosytem”. The source of increasing supply of organic matter (‘organic carbon’ is used synonymously) may be from within the system (‘autochthonus’), most familiarly by increased plant growth, or imported into the system from elsewhere (‘allochthonus’). Nixon also proposed a classification scheme for the trophic status of estuarine and coasal ecosystems:

Organic Carbon Supply (g C m-2 y-1) oligotrophic < 100 mesotrophic 100–300 eutrophic 301–500 hypertrophic >500

Nixon continues “The definition has several desirable features. It is short and simple. It is consistent with historical usage. It does not confuse causes or consequences of the phenominon with the phenominon itself. It also focuses on the major process of concern – a change in the metabolic resources and, potentially, the trophic status of an ecosystem. If it can be shown … that the primary production of a bay or estuary is increasing, we can say that the system is undergoing eutrophication. The cause of the eutrophication may be an increase in the input of inorganic nutrients, a decrease in the turbidity, a change in the hydraulic residence time of the water, a decline in grazing pressure, etc.. All of these factors may cause eutrophication, but they are not the phenomena itself. A variety of other changes may be associated with or even caused by the increse in the supply of organic carbon (for example, species changes, , fish kills), but they are not the phenomina itself. It is also clear that ‘eutrophication’ is a process, a change. It is not a trophic state. For

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 2 significant difference is that, in scientific terms, the organic (carbon) burden can also result in eutrophication, entering the food chain via bacteria and certain facultative or obligate heterotrophic microplankton, rather than via ‘plants’, although in taxonomic and functional terms the distinction can become rather indistinct. Although allowed for in the Directive definition, the emphasis is on nitrogen and phosphorus. Another distinction is that ‘eutrophication’, as a process, might be said to have ceased – scientifically speaking – once the situation has stabilised at a new, higher level, although that state would be more eutrophic. Of course, the site would be still be affected by ‘pollution’.

In practice eutrophication has come to be interpreted in a narrower sense than that allowed for in the Directive. Water bodies (particularly estuaries in the context of this report) vary significantly in their natural, background, nutrient concentrations. Anthropogenic nutrient inputs result in a shift along this continuum. Relatively speaking a small input into a nutrient poor (oligotrophic) estuary may have a greater impact on its biodiversity than a larger input to a naturally rich (eutrophic or, in extreme cases, hypertrophic) site. Yet the policy concern, (including other fora such as PARCOM, its successor, OSPAR, and the North Sea Ministerial Conferences) has been almost exclusively at the (more visible) extreme hypertrophic end of the scale – massive algal blooms, algal weed mats and deoxygenationi.

While understandable politically, this represents a major flaw in the implementation of this Directive. Arguably, as sites shift ‘up’ the scale, it is the oligotrophic sites that are at greatest risk of elimination. Certainly the impact upon them should not be ignored, and indeed the Directive does not allow this. This aspect is further explored in the Welsh section of the Nationwide Review (Part III- Section 7 of this report).

For an estuarine or coastal site, if the Directive definition of eutrophication is met, or it has “poor water exchange” (undefined), then it automatically qualifies as a Sensitive Area. ‘Standard’ Article 4 or LSA sites must not, by definition, be eutrophic, or under threat of eutrophication if preventative action is not taken. On this the Directive is absolutely clear. The wording in the annex is that, for those estuaries, bays and other coastal waters “which are found to have a poor water exchange, or which receive large quantities of nutrients, then the removal of phosphorus and/or nitrogen should be included unless it can be demonstrated that the removal will have no effect on the level of eutrophication”.

Thus a high standard of proof is required for lack of action. It is also a stringent requirement – especially so once it is appreciated that eutrophication is a continuum, not just gross effects such as algal mats or exceptional blooms. It also applies to areas which in the “near future” may become eutrophic if protective action is not taken. example, many estuaries that were once mesotrophic may now be classified as eutrophic, but they are not necessarily undergoing further eutrophication. Their increase in organic carbon supply took place some time in the past and they are now fixing carbon at a higher, but relatively constant rate year after year. Many upwelling systems may always have been eutrophic, but they are not experiencing eutrophication.” (Nixon, S. W. (1995), Coastal marine eutrophication: A definition, social causes, and future concerns. Ophelia 41, 199–219).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 3 1.3 THE NITRATES DIRECTIVE

The Nitrates Directive deals explicitly and exclusively with pollution resulting from agricultural activities. The Directive defines pollution as direct or indirect discharges of “nitrogen compounds [sic] from an agricultural source into the aquatic environment” which, (among possibilities irrelevant to estuarine and coastal waters) causes “harm to living resources and to aquatic ecosystems.” The definition of eutrophication is identical to that of the UWWTD except that it is restricted to nitrogen compounds from agriculture. The Directive has a similar dual objective – the reduction of water “pollution caused or induced by nitrates from agricultural sources”, and “preventing further such pollution”. Article 3.1 requires the identification of polluted waters, and those which “could” be affected if action is not taken, according to the criteria set out in Annex I. This Annex simply states that “Waters referred to in Article 3 (1) shall be identified making use, inter alia1, of the following criteria.” Three criteria are set out, of which only the third – where “waters are found to be eutrophic or in the near future may become euthropic [sic] if action … is not taken” – is relevant to estuarine and coastal waters.

1.4 THE UK INTERPRETATION: 1993 CONSULTATION

The UK Government has produced a number of documents elaborating its interpretation and implementation of the UWWT and Nitrates Directives. Of these the most significant are a Consultation paper on the identification of Sensitive Areas and Vulnerable Zonesii, published in March 1993; the Comprehensive Studies for the purposes of Article 6 & 8.5 of Dir. 91/2371 EEC, the Urban Waste Water Treatment Directiveiii – i.e. the UK criteria for establishing LSAs – published in revised form in January 1997; and the new administration’s June 1998 Government Response to the Parliamentary Environment Select Sub-Committee, report on Sewage Treatment and Disposaliv. These are assessed in the following pages.

The 1993 paper on Sensitive Areas and NVZs, (jointly published by the Department of the Environment, the Ministry of Agriculture, Fisheries and Food and the Welsh Office) built on a paper dating from March 1992 which had considered the criteria and procedures for identifying such waters. The March 1993 paper also included a short section on Less Sensitive Areas. This paper was received in 1998 by this author when DETR were approached for their current position, so presumably any responses were not consolidated into a final definitive paper.

The relevant points contained in the 1993 paper were as follows.

1 Oxford English Dictionary definition ‘amongst other things’ – i.e. it implies that this is not to be taken as an exclusive list.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 4 1.4.1 Sensitive Areas

The objectives, standards of treatment required etc. appear to be a straightforward description of the requirements of the UWWT Directive.

• The UK is “required” to identify Sensitive Areas by 1993;

• For estuarine Sensitive Areas the boundaries “will be the downstream and upstream limit of water affected by the relevant discharges of sewage effluent … The freshwater and estuarine limits defined for the purposes of the UWWT Directive may be convenient boundaries in all but the largest estuaries.” (para. 6.1c)1. For coastal waters (6.1d) the “landward boundaries will be estuarine or freshwater limits and the seaward boundaries, lines beyond which algal growth or other symptoms are typical of the sea area”;

• The requirement to define Sensitive Areas where other Directives necessitate more stringent treatment is recognised (2.5). In a response to previous consultation it states (Annex B, para. 5) “In respect of Directives such as those concerning the conservation of the habitats of wild flora and fauna and wild birds, where no numeric standards are set in relation to pollutants, it will be necessary to carefully consider whether a sensitive area should be identified in order to protect a habitat”.

1.4.2 Less Sensitive Areas:

Several points arise from the consultation document’s treatment of LSAs:

• The UWWT Directive (Annex II.B) requires that a LSA has “a good water exchange and not subject to eutrophication or oxygen depletion”. Although the need for good water exchange is mentioned (B.42b) in the introductory description of the Directive’s requirements, it is not listed amongst the specified UK criteria, all of which must be met, for the identification of Less Sensitive estuaries (B.44) or coastal areas (B.45);

• Regarding the transportation of nutrients it notes that there is a requirement (estuaries B.44.3; coastal waters B.45.e), if an area is not to become an LSA, that “there are no or unlikely to be significant detrimental effects attributable to the discharge in adjacent areas including areas in other Member States”. The introduction of the word ‘significant’ is notable. The Directive contains no such limitation.

• Interestingly, given later proposals by the UK, the government unambiguously expresses its understanding and interpretation that “the derogations allowed for in Article 8.5 of the Directive [that, in exceptional circumstances, discharges to coastal waters from agglomerations of more than 150,000 p.e. may be subject only to the requirements of Article 6 for

1 The seaward boundary of an estuary is thus incompletely defined. Note also that the definition breaks down if nutrients from these sources contribute to off-shore eutrophication. The final obscure caveat may have been related the (failed) attempt to define the outer and Severn estuaries as coastal waters.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 5 discharges of between 10,000 and 150,000 p.e.] apply only to Portugal.” (B.46).

• Nitrate Vulnerable Zones: with regard to NVZs the consultation paper state that: The requirements of the Nitrates Directive (3.8) “are in the same spirit as the UWWT Directive’s provisions … whereby additional treatment need not be provided where it can be demonstrated that nutrient removal will have no effect on the level of eutrophication.”1;

• Identifying agricultural land contributing to pollution must not only take into account past and present land uses but also (4.1.h) the “likely effects of future changes, such as those that will be required by changes to the EC’s Common Agricultural Policy”. It is, however, “not possible to predict the effect of these changes.” (Annex B, 39);

• The means of identifying the boundaries of estuarine and coastal NVZs are essentially identical to those for Sensitive Areas (6.3.a);

• The paper notes (Annex B, 16) that [then] current information “suggests that nitrate levels in surface waters have … remained fairly constant in recent years. The halt in the previous rising trend is due at least in part to changes in agricultural practice in recent years.” Subsequently it became apparent that it was in part the result of a run of drought years in the early 1990s which temporarily delaying the transfer of nitrates to the aquatic environment. More recent freshwater borehole measurements do not confirmed that nitrate levels have reached a plateau.

1.4.3 UK interpretation of Eutrophication

Eutrophication is considered (Annex B, 9) to “describe a process rather than a state and … it is controlled by a number of factors [including] nutrients, flow rate of waters, shading and turbidity, depth, temperature and turbulence.” The relationship between these “is not easily quantified”. The “assessment of whether a stretch of water actually or potentially is eutrophic is not possible simply by reference to numeric chemical criteria.” A “judgement” is required; the importance of symptoms will “depend on local circumstances.” This emphasis of the inherent difficulties and judgement is interesting, given the contemporary CSTT LSA guidelines (see below) which placed its weight behind a technical approach, and the later insistence of the UK administration of proof beyond doubt.

1 Note that ‘no effect’ is accepted here, rather than the looser formulation ‘no significant effect’. Given that the necessary information to demonstrate ‘no effect’ is rarely likely to be available, or to be expected, this appears to provide little scope for avoidance of the Directives requirements. Yet UK policy for both Directives appears to have hinged on this. In off-the- record discussions it was several times emphasised with regard to STW discharges – in what appeared to be the ‘party line’ – that while a site might be eutrophic, nutrient removal from STW discharges would have no effect, and this was interpreted as the end of the process. Yet by implication, agricultural nutrients were then likely to be responsible, requiring designation as an NVZ, or at the very least requiring the production of a nutrient budget to back up the (implied) assertion that agriculture was also blameless. Yet nutrient budgets were rarely available. It is also reasonable to ask whether there would be any prospect of the UK accepting an appeal to the ‘spirit’ of a (separate) Directive if it considered that this was against its interests!

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 6 A list of symptoms of eutrophication was developed, following PARCOM guidelines “as closely as possible” (Annex B, 18). While any one may not be indicative of “undesirable eutrophication” they “allow sound judgement taken overall.” Although the precautionary principle (well established by 1993: see also page 13) is not mentioned it is earlier stated (6.1) that the test is “an overall judgement on a balance of probabilities as to whether or not waters are actually or potentially eutrophic”. It is clear from the list that the effects of eutrophication related to extreme (hypertrophic) conditions have been given pre-eminence.

The symptoms are (Annex B, 20):

• Nitrate Concentrations enhanced in winter (February); • Occurrence of exceptional algal blooms. As an indication an upper range of 500,000 cells per litre and 10 mg m-3 chlorophyll-a is considered normal in coastal waters. But it states that this should not be interpreted as a limit (but see also p. 12); • Duration of Algal Blooms where the spring bloom persists through the summer; • Oxygen Deficiency in surface or deeper waters, including areas where sedimentation and/or stratification may occur. No quantitative guidance is given. “Care must be taken … to ensure that consideration is given to oxygen deficiency which is due to the decay of plant material and not caused by organic discharges to the local areas”. However the (UWWT) Directive definition of eutrophication does not rule out problems arising from organic enrichment, and in any case would require action on such pollution, regardless of whether eutrophication was considered to be responsible; • Changes in Fauna. Increases or decreases in biomass, species diversity and death of benthic life or fish; • Changes in macrophyte growth. These may be “minor” (the disappearance of red seaweeds is given as an example, which would not be considered minor in conservation terms), a reduction in photic depth (no examples but seaweeds and Zostera eel-grass are relevant here), or “more significant” effects such as “dense and widespread growth of Enteromorpha”; • Occurrence and magnitude of Paralytic Shellfish Poisoning (PSP) Endemic occurrence may be enhanced by nutrient enrichment; • Algal scum on beaches and offshore caused by, inter alia, Phaeocystis and Chaetoceros. However “The significance of these phenomena should be placed in a historical perspective as such phenomena have been regularly recorded in some UK coastal waters for over 100 years”

As earlier discussed it should be noted that these are only indicators of eutrophication for hypertrophic systems.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 7 1.5 UK CSTT 1997 COMPREHENSIVE STUDIES FOR LSAS

The 1997 Comprehensive Studies Task Team, CSTT, report1 contains the UK’s interpretation of the practical requirements for the ‘comprehensive studies’ that are required to support a claim for LSA status, or the relaxation of standards of treatment for discharges of greater than 150,000 p.e to coastal waters. This document has a bearing on a number of other interpretations, presumptions and requirements concerning the UWWTD.

The most significant general points appear to be that:–

• While it must be “proven” (Section 1.4.b) by comprehensive studies that any such discharge will not adversely affect the environment2, the degree of confidence that a study must provide “should be proportionate to any potential impact a discharge may have” (1.5). This risks leading to a circular argument if it is believed beforehand that the impact will be low;

• It states that the UK policy is justifiable given that the effects of sewage are reversible following cessation of discharge (1.6);

• Article 6 of the Directive “implies [emphasis added] that only the marginal increase in discharge load” from primary compared to secondary treatment need be taken into account (1.9). This is an extension of UWWTD Article 6. The marginal difference, writes the CSTT, will be small, requiring studies “capable of a high degree of discrimination”. This “could be difficult to quantify” (1.14) but, given that most discharges currently receive no treatment, “effects are likely to disappear with primary treatment”3;

• However it is also stated that “Secondary treatment removes up to 90% of BOD from primary (settled only) effluent, an improvement of about one order of magnitude.” (2.5.1). “Suspended solids [SS] loading may be responsible for important effects both in the water column and at the sediment surface. Secondary treatment removed 70 to 80% of SS from primary effluent, but the impact of such a removal will be difficult to assess in the context of an environment receiving substantial particulate input from non-sewage sources.” (2.5.2);

• The degree of confidence believed to be required by the CSTT for ‘Article 6’ LSA studies is contrasted with those for ‘Article 8.5’ discharges (>150,000 p.e. into coastal waters), where it “must be demonstrated that ‘more advanced treatment will not produce any environmental benefits.’ Due to the larger potential impact of such discharges, a high degree of confidence in the results of the study [for an Article 8.5 discharge] is required.” (1.9). Yet, as already noted,

1 Second edition. According to the foreword (dated January 1996) the first edition was issued in February 1994, and the “criteria upon which judgements should be based are unaltered”. According to the title page the original report was dated November 1993, and the second edition released January 1997.

2 Actually the Directive (6.2) says “indicate”, not proven.

3 This is not true for nutrients, for which a separate treatment stage is required.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 8 the UK presumption that the justification required for LSA designation is relatively lax is questionable;

• Studies must have regard to “all potential effects” including effects on adjacent waters (1.10);

• Not all of the techniques proposed to justify Less Sensitive Area status are “fully validated” (1.15) or, in the usual UK parlance, representative of ‘sound science’; this will come only as experience is gained (3.4). “The standards must be regarded as guidelines.” Somewhat contradictory to this, nevertheless the CSTT “is confident that they describe a level of no adverse effect”;

• The differences between coastal and estuarine sites, write the CSTT, need to be recognised. The defining features of estuaries include a “focus for fish migrating between fresh and marine waters and a nursery area for many marine fish species …; the sheltered nature of estuaries encourages a high level of recreational use and intertidal areas have importance for waterside birds” (2.1);

• although fæcal coliform bacterial concentrations “are reduced by at least an order of magnitude during secondary treatment” (therefore another distinguishing feature from primary), the “effect on pathogenic bacteria and viruses is less well understood” (2.3).

• CSTT Definition of an Estuary

• Estuarine LSAs have more stringent conditions than those for coastal waters. The UWWTD does not define an ‘estuary’. Two alternative definitions of an estuary are given in the CSTT report (4.1): That “commonly used in Scotland and Northern Ireland” is “an area receiving freshwater inputs where the waters on a depth averaged basis have a salinity of less than 95% of the adjacent local offshore seawater for 95% of the time.”; That “used in and Wales”: an “inlet of the sea [?] bounded between such topographical features as define the seaward boundary of the estuary”; The boundary between an estuary and its contributory rivers is not defined by the CSTT.

• The report states (4.2) that UK estuaries “are generally dynamic, well aerated areas, many of which have a high dispersive capacity as a result of limited low water retention and a high exchange between estuaries and coastal water on each tidal cycle.” Two exceptions cited are fjordic estuaries, common in western Scotland, and rias in SW Wales and England.

1.5.1 Pollution due to BOD, Suspended Solids & Organic Carbon

The CSTT describe the adverse affects that they consider would prevent the establishment of a LSA for biochemical oxygen demand (BOD), suspended solids and organic carbon. The CSTT regard the distinction between acceptable and unacceptable effects as an arbitrary and difficult judgement. For example they state that “it is clear that there is no well-tested qualitative

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 9 technique for the prediction of change in benthic fauna though inputs of additional organic carbon. Nevertheless a decision must be made in the context of the Directive.” (7.4).

The CSTT also draw a distinction between the requirements for estuarine and coastal LSAs:

For estuaries section 3.2 states that “given the small size of discharge” permitted for an estuarine LSA, only dissolved oxygen “is considered an important parameter”. Examination of the effects of suspended solids and organic carbon are excluded. Regarding dissolved oxygen they conclude that:

• a dissolved oxygen level of 7 mg l-1 will allow the passage of migratory fish and sustain breeding populations of estuarine fish; • a depression of less than 1 mg l-1 is automatically acceptable providing the median level is maintained above 7 mg l-1; • If the level falls below 7 mg l-1 then individual studies will be required, and acceptability considered on a case-by-case basis; • If the difference in dissolved oxygen resulting from applying either primary or secondary treatment is predicted to be 1 mg l-1 or greater, “primary treatment will be inappropriate”.

It is questionable whether the emphasis on dissolved oxygen alone, and of fish only as representatives of the estuarine community, is sufficient to meet the objectives of this and other Directives.

For Coastal Waters dissolved oxygen, suspended sediments and organic carbon are all considered important. Where a reference site is unavailable, and historic data absent, then a post-hoc ‘Infaunal Trophic Index’ may be calculated (3.3.3), which indicates the degree of benthic community change induced by a discharge. Source references for the ITI are given and the method is not further elaborated in the CSTT report. In the section on coastal waters the CSTT state that:

• For BOD a reduction of 0.5 mg l-1 “can be assumed to cause no adverse effect”. This is equivalent to a reduction of BOD >1.5 mg l-1. • For suspended solids and organic carbon only the impact on benthic communities is considered. To be regarded as unacceptable the adverse effects on benthic community structure 100 meters beyond a STW discharge must be greater than a total increase in abundance of 200%; greater than a 50% increase in taxa (the possibility of a reduction in taxa is not mentioned); or a 50% increase in biomass, all compared to a reference station (section 3.3.3). • Additional consideration relating to the assessment of the impact of suspended solids in coastal waters are given in Section 5. For LSAs “there is a responsibility to prove that a given outfall/discharge regime will show no overall environmental disadvantage” for primary treatment compared to secondary (5.1) and “Predictive modelling” will be required (5.1) supported by field

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 10 data (5.2.3). The CSTT conclude that “Predicting the fate of suspended solids discharged from a marine outfall is a highly complex subject. … Given the levels of technical difficulty and uncertainty involved in predicting suspended solids behaviour and the large number of physical and physico-chemical co-efficients which need to be derived locally, we believe that the costs of sophisticated modelling are not justified by the marginal benefits which may be obtained.” (5.3.3.). Instead the benthic community should be studied with two objectives; providing a means for predicting biological changes resulting from discharge changes, and directly assessing the effect of such changes (7.1.1).

The wariness of CSTT towards applying sophisticated modelling techniques to assess the impact of suspended solids is interesting given the approach adopted for eutrophication, described below.

1.5.2 CSTT and Eutrophication

Notwithstanding the 1993 consultation paper’s advice regarding the problems quantifying eutrophication (and indeed the CSTT’s own concerns regarding validation), the CSTT attempted to bring greater precision to the process, with ultimately questionable results. Presumably due to the attraction of the supposedly greater accuracy that its method offers, elements of it have been used in the UK than for more than candidate LSA assessment. Some confusion exists, and at least on occasion the approach has been erroneously applied in inappropriate circumstances.

An understanding of the CSTT approach to eutrophication provides important insights into UK implementation. However it is quite complex, and therefore requires some space to dissect.

Eutrophication is to be assessed by one “main” criteria (in fact the only criteria in the report), water chlorophyll concentration, as a “convenient measure of the abundance of planktonic algae.” (2.5.3). The CSTT recognise that changes in community structure are a legitimate concern, but argues that “Establishing the occurrence of significant changes in the balance of planktonic algal species does not seem feasible in the present context”. It is questionable whether such inability allows this aspect to be ignored.

The other criteria indicative of eutrophication set out in the March 1993 Consultation are not pursued by the CSTT. This surprising omission is (in part) explained by the authors’ presumption that the potential for eutrophication – and hence the need for evaluation – only exists for coastal candidate LSAs. Section 3.2, which deals with estuaries, states that “given the small size of discharge” permitted for an estuarine LSA, only dissolved oxygen “is considered an important parameter”. Yet it is clear, from several sites examined later in this report, that estuarine LSAs did, or do, exist at locations where eutrophication is of concern.

Section 3.3.2 elaborates the steps that the CSTT require to be followed when assessing whether eutrophication exists in a coastal candidate LSA. If

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 11 affirmed, it would result in the rejection of the LSA and establishment of a Sensitive Area.

A distinction is drawn between ‘hypernutrification’1 as a precursor to ‘eutrophication’. Hypernutrification is deemed to exist where winter nutrient concentrations “significantly” exceed 12 mM DAIN m-3 [>12 µM l-1 or 168 µg/l N] in the presence of at least 0.2 mM DAIP m-3 [≥0.2 µM l-1 or 6.2 µg/l P]2. “This could be affected by any difference between primary and secondary treatment. Hypernutrification should not, however, be seen as a problem in itself. It will cause harmful effects only if a substantial proportion of these nutrients is converted into planktonic algae or into seaweed.”;

This CSTT interpretation is not necessarily inconstant with the operational definition of eutrophication in the Directive, although this hinges on the ultimate fate of the nutrients. If these are transported from a ‘hypernutrific’ site where e.g. turbidity prevents significant phytoplankton growth, to another site, possibly remote, which is eutrophic, this would require action. This brings us to the CSTT definition of eutrophication, also contained within Section 3.3.2 as a key but very dense paragraph:

“A region is potentially eutrophic only if the relative rate of light-controlled phytoplankton growth is greater than the relative water exchange rate plus the relative loss rate of phytoplankton by grazing; and the predicted summer maximum chlorophyll concentration is greater than 10 mg chl m-3 [10 µg l-1]. … A region is eutrophic if observed chlorophyll concentrations regularly exceed 10 mg m-3 during summer.” [emphasis added].

This paragraph needs to be looked at in detail: the underlying point regarding the balance between light limitation and water exchange seems to be the following: If the exchange rate is such that water moves through a delimited area around the discharge faster than replacement growth, due to light limitation, then there will be a net loss of phytoplankton, so eutrophication could not occur. This appears to assume that there is a net dilution with less nutrient- and phytoplankton-rich offshore water. This will depend on the degree and boundary of long-shore transportation of possibly nutrient-rich coastal water.

This might be valid for an isolated coastal discharge if it is possible to incorporate tidal factors and the overall effect of repeat discharges into the same water body. But it depends on detailed knowledge of local light regimes, water exchange, the coherence of water bodies, etc., and when attempts have been made to do this (see next paragraph) they have established that such data is rare, and that the calculations on both light and water exchange are extremely sensitive to the methods and data used;

1 A significant elevation of mineral nutrient concentrations. Not to be confused with ‘hypertrophic’ – a site at the extreme end of the eutrophic spectrum.

2 DAIN: Dissolved Available Inorganic Nitrogen (i.e. nitrate + nitrite + ammonia). DAIP: Dissolved Available Inorganic Phosphorus.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 12 These problems become even worse when the techniques are applied to estuaries (which the CSTT did not advise). Attempts to do this in and Essex (see Part III - Section 4 of this report) do not stand up to scrutiny. From off-the-record discussion it seems that this is accepted by at least some parties within the Environment Agency.

A number of other subtle aspects exist, such as the relevant boundary to an area; dealing with multiple inputs and already anthropogenically enhanced ‘background’ levels; the enhancement of inorganic nutrient loads beyond discharge levels due to the mineralisation of organic matter; residual currents; the status of the areas to which the nutrients are then transported etc.. The CSTT report attempts to deal with some of these, and argues that they have applied the precautionary principle to the choice of parameter values “with the aim of minimising environmental impact if the values are wrong” (6.2.11);

Nevertheless many questions remain over methods and the availability of data. It can also be noted that while the CSTT work on the basis of whether an individual discharge will make a ‘significant’ contribution to pollution, (e.g. 10% of eutrophication (3.3.2)) the UWWTD on LSAs (Article 6) requires a absolute demonstration that a discharge “will not adversely affect the environment”;

The CSTT methodology concentrates on typical conditions, whereas for exceptional blooms [or indeed bacterial contamination and other factors] conditions that exist, say, for 5% of the time are also of relevance. The extent of grazing is irrelevant to eutrophication, at least as defined scientifically, and should not be deducted from the total. It is the gross increase in plant growth that defines the degree of eutrophication. However, the guidelines go on to say that grazing rates are usually unknown, so should be assumed to be zero;

However there is now an absolute (cf. p. 12): an area now will be accepted as eutrophic if “observed chlorophyll concentrations regularly exceed 10 mg m-3 during summer.” This makes no allowance for the original nutrient status, and natural chlorophyll level, of the site. Nevertheless, regardless of its validity, it has the merit of allowing an assessment of whether the UK has followed through its own definition of eutrophication, in practice, at individual sites. This complex analysis can be simply summarised. In effect, in the opinion of the author, the CSTT has confused the desirability of a more quantitative approach with the practicality of such an appraisal. The 1993 Consultation Paper’s more qualitative listing appears more justified in a situation where limited information inevitably requires the application of ‘fuzzy’ logic. 1.6 1998 SELECT SUB-COMMITTEE: GOVERNMENT RESPONSE

In February 1998 the Parliamentary Environmental Select Sub-Committee published a report on sewage treatment and disposal. The Labour administration responded to this in July. Both the original report and the response cover a wider range of issues than the estuarine and coastal implementation of the two Directives.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 13 The Sub-Committee report stated that they wished “to see the present Government take a positive attitude to EU Directives: seeking to find ways to implement the regulations with due rigour.” The government responded that it “is taking a much more positive attitude towards the EU water directives than its predecessor [and that] a number of new measures set out in this response, such as the approach to comprehensive studies, Sensitive Areas … continue this more rigorous implementation” (para 44–45).

With regard to Less Sensitive Areas the government has “instructed the Environment Agency to take a rigorous approach to the assessment of comprehensive studies and it has found in many cases that they do not justify allowing primary treatment only.”1 (16). It had accepted the recommendations of the EA that the status of certain other HNDAs should be revoked (17). Moreover the government “wishes to consider very carefully whether, notwithstanding the scientific evidence offered by the comprehensive studies, a precautionary approach should dictate that secondary treatment should always be required for significant coastal discharges.”

The total capital cost of doing this for all significant coastal discharges into HNDAs was estimated by industry at £440–470 million, although the Government believed it could be less. Additional operating costs might amount to £23 million per year. The effect on average bills in areas most affected (e.g. Northumbrian and Southern water companies) would approach £10 per household per year. (19). A survey of water customers conducted for the government indicated that “reducing coastal and river pollution … are among the top priorities for consumers”, and that on average “respondents were prepared to pay £25 a year for their priority improvements” (10).

Pathogen Removal The EA’s bathing water policy is “to ensure compliance with mandatory standards and to endeavour to observe the guideline standards at identified bathing beaches.” The new policy “endorsed by the Government and introduced by the Agency in 1997, to require schemes with secondary treatment but outfalls close to bathing waters to be designed to achieve Guideline standards, will increase the use of UV disinfection” (21).

“A similar approach is being applied” to waters designated under the Shellfish Waters Directive. The government is “currently reviewing the need for additional designations”. Where new waters are designated, disinfection of discharges will be “required, as necessary” (22).

Nutrient Removal The government considers “there is a judgement to be made as to where along the scale of effects it is appropriate to intervene in tackling eutrophication problems, and whether remedial action is likely to be effective.” (23). From this it appears the UK policy of requiring gross effects before action is being maintained. Similarly, if a site is accepted as eutrophic, but STW

1 In this report these changes are documented in sequence in the relevant site accounts.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 14 discharges are ‘insignificant’, this continues to leave open the question of action regarding agricultural inputs. The government conclude that the EA “is currently developing a strategy for tackling eutrophication problems which it intends to issue for consultation.” (24), which implies that there hasn’t been a strategy until now.

Universal Tertiary Treatment to remove pathogens and nutrients had been recommended by the Sub-Committee. The government accepted that this would ensure the highest standard of treatment. But it estimated that the total cost of requiring nutrient stripping for all (inland, estuarine and coastal) discharges of 2000 p.e. or above would be approximately £13 billion; substantially more if it was required for all STW discharges. (28). Requiring UV treatment for the 600 coastal discharges in England and Wales would be a capital cost of ca. £500–600 million, and an annual running cost of £9 million. While the government “is considering the case for more widespread requirement of UV disinfection” and “will be requiring nutrient removal for relevant discharges into the newly designated sensitive areas” it “is not persuaded that the potential environmental benefits from universal application of UV disinfection or nutrient removal is sufficient to justify costs of this magnitude” (29).

Storm Overflows The Sub-Committee had recommended that in future combined sewer overflows (CSOs) should be designed to operate only once in twenty years, with overflow tanks to store storm-water. The government responded that 1,200 of the worst CSOs would be improved by 2000 at a cost of £450 million. A further 4000 had been identified whose performance needs to be brought up to modern standards. The government “considers that bathing waters designated under the Bathing Water Directive and shellfish waters designated under the Shellfish Waters Directive are a priority for improvement … Remedial action proscribed by the Environment Agency varies, depending on the nature of the waters into which the CSO discharges. Thus, for example, design spill frequencies for bathing waters varies between 3 spills per bathing season and 1 spill every five bathing seasons” (42).

Water companies estimate the total cost of improving all 4000 sites at £1.7 billion. These estimates would be scrutinised and the replacement rate decided after consultation. However the government argued that a target of overflows once in 20 years would be impracticable in many urban areas due to the size of storage tanks required and “the Government believes that the environmental benefits would not be sufficient to justify imposing this requirement” (43).

In summary it would appear that the phasing out of LSAs in the UK is now a distinct possibility. There will be increasing use of UV disinfection of discharges that affect Bathing Waters and Shellfish Waters, and action, perhaps more limited and delayed, on CSOs. The least change in policy appears to be for eutrophication, where sewage discharges are still required to make a ‘significant’ contribution for action to be taken, and there are indications of a continuing unwillingness to identify and act on other ‘significant’ sources, which will normally be agriculture. There is no intention to apply universal tertiary treatment to deal with bacteria and nutrients.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 15 1.7 THE BURDEN OF PROOF

During this research the response has frequently been encountered that there was no absolute proof that eutrophication was involved in changes at a particular site, or, where these were acknowledged to exist, that the relative importance of the sources was unproven, thus preventing action. For example the Scottish Office, in rejecting NVZ status for the Ythan during the first round of designations, explained that “whilst the circumstantial evidence was strong, legal advice had been given that the linkage between nitrate concentration and Enteromorpha growth was not established as cause and effect without possible doubt” [emphasis added]v. In the 1998 second round designations NVZ status was once more rejected, despite a Scottish Environmental Protection Agency recommendation, again because ‘existing evidence on whether the is subject to eutrophication … is still not conclusive”. So it would seem that the UK agricultural ministries, unlike DETR, remain consistent despite the change in government.

These are surprising statements. In law the burden of proof is the requirement for a party to produce sufficient evidence to ‘prove’ a case. English and Scots law have long recognised that there is no such thing as “proof without possible doubt”. For this reason it requires that the degree of proof required is varied, depending on the severity of the consequences for the individual. In the most severe – Criminal Law – cases, which threaten the liberty (and once death) of an individual, the standard of proof is ‘beyond all reasonable doubt’vi. For all lesser (Civil Law) cases the standard is ‘on the balance of probabilities’. Indeed the 1993 DoE Consultation paper recognised that this was the appropriate standard for judging eutrophication (see p. 7).

As defined the precautionary principle appears to require a lower standard of proof than even the balance of probabilities. The OSPAR Convention, ratified by and legally binding on Britain, and which applies to all of the seas around it, states that the precautionary principle requires “preventive measures to be taken when there are reasonable grounds [note: not ‘evidence’] for concern”vii. The precautionary principle is part of the Treaty of Union. More generally it is a binding principle of global international lawviii.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 16 2 THE UK DESIGNATION PROCESS - SURFACE WATERS AND

2.1 EC DIRECTIVE ON THE CONTROL OF NITRATE POLLUTION FROM AGRICULTURAL SOURCES (91/676/EEC)

Sixty eight Nitrate Vulnerable Zones (NVZs)were designated in 1996 under the EC Nitrate Directive covering a total of 600,000 ha (Table 2.1). Six are surface water zones, comprising nine river catchments, and the rest are zones. Designation is based on monitoring data collected by the Environment Agency from 750 boreholes, 140 of which are now located within the NVZs.

Table 2.1 Vulnerable Zones (Nitrate Directive) designated by the Government in 1994

Nitrate Vulnerable Zones (NVZ) Nitrate Vulnerable Zones (NVZ)

Bridlington River Leam, Cherwell and Great Ouse Wighton Miligton Spring Great Bircham Springwells Swaffham Cottingham Lyng Forge Brayton Wroxham Carlton Polligton MoultonBury St Edmunds Hatfield Fulbourn North Linton North Nottinghamshire Fowlmere Loncoln Slip End River Witham Weston Husbands Bosworth Great offley Kelsall Kings Walden Swynnerton River Blackwater and Chelmer Telford Old Chalford Bednall Lewknor Shifnal Ogbourne St George Lichfield Compton Oakley Twyford Tom Hill Dorney Hinksford Boxley Kinver Thurnham Wildmoor Minster Astley Egford Haseley Castle Cary Bromsberrow Milbourne Wick Snowshill Beaminster Stow-on-the-wold Otter Valley Garway Duckaller Cheltenham Dyserth The Slaughters Trelech Fairford Balmalcolm

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 17 The NVZs are located mainly in areas of intensive arable farming in the Midlands, and the north east of England. The largest are catchments upstream of surface water abstractions. Smaller areas have been designated as protection for groundwater sources, either individually or in groups where whole aquifer protection is required.

Action programmes to effect a reduction in nitrate runoff and nitrate through changes in agricultural practice within designated zones are to commence in 1998 and a grant aid scheme for improvements to the storage of livestock manure is available to farmers.

Three NVZs in the Anglian Region are also designated as Nitrate Sensitive Areas under the Urban Waste Water Treatment Directive: the catchments of the Waveney, Great Ouse and Blackwater NVZs. Nitrate reduction requirements in the discharge consents of eight large sewage treatment works will come into effect by the end of December 1998.

The Water Resources Act 1991 provides for the establishment of Nitrate Sensitive Areas where groundwater is in excess or at risk of exceeding 50mg/l. Ten NSAs were designated in 1990 and a further 22 in 1994, covering 35,000 has of agricultural land. Farmers within the NSAs are offered compensation for voluntary changes in their activities to reduce nitrate leaching and run off deemed beyond good agricultural practice, including reductions in fertiliser usage. All NSAs are now within the designated Nitrate Vulnerable Zones.

2.2 EC URBAN WASTE WATER TREATMENT DIRECTIVE (UWWTD) (91/271/EEC)

Thirty three Sensitive Areas, as specified under the Urban Waste Water Treatment Directive (UWWTD) have been designated on rivers, lakes or reservoirs in England and Wales (Table 2.2). The eutrophic status of a further forty eight waters were assessed as part of the 1997 review required by the Directive. No data on the location of these sites was available.

UK water companies have allocated a total of £6 billion to a programme of capital investment to upgrade sewage treatment works in response to the requirements of the UWWTD. £1.6 billion of this total is required for sewage treatment works discharging to freshwaters, the remainder for treatment works discharging to estuarine or coastal waters. About fifty sewage treatment works are required to reduce their phosphorus loads by 1998 at an estimated cost of £20 million.

According to the Environment Agency, it is unclear whether this investment will lead to improvements in the chemical quality of rivers because the investment to meet BOD and suspended solids standards has been planned to meet the requirements of the Directive which relate to levels of treatment and effluent quality rather than the needs of rivers. Some of the investment is directed at improvement of sewerage systems, including the frequency with which storm overflows operate to avoid unnecessary flooding to properties

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 18 and environmental problems. This aspect of the overall investment programme is estimated to be £850 million. The Environment Agency is of the view that operational improvements and improved screening of discharges will lead to improvements in the aesthetic quality of rivers and the removal of phosphate in Sensitive Areas will lead to improvements in the nutrient level in rivers and to a reduction in eutrophic state.

Table 2.2 Sensitive Areas (UWWT Directive) designated by the Government on 18.05.94 (Selected on basis of Eutrophication)

EA (NRA) Region Name of Sensitive Area (SA)

North West Bassenthwaite Lake River Eden Leeds-Liverpool Canal Lake Windermere River Douglas

Severn Trent Kingsmill Reservoir River Blythe River Arrow River Avon

Wales River Wye

South West River Creedy

Southern River Test River Stour

Thames River Wey (North) River Ray River Blackwater Langford Brook River Thames

Anglian Hanningfield Reservoir Foxcote Reservoir & Ardleigh Reservoir Hyde Lane Pit Alton Water Pitsford Reservoir River Bure River Nene River Ant Rutland water Cut off and Relief Louth Canal Channel Covenham Reservoir Grafham Water

Northumbria and Yorkshire

The Environment Agency is developing a scheme for describing the trophic status of rivers to assess the impact of eutrophication and to help identify candidates for designation as Sensitive Areas under the Urban Waste Water Treatment Directive. This scheme, the Mean Trophic Rank, is based upon the analyses of macrophyte and diatom populations to which a scoring system is applied to give a direct measure of eutrophic response. The scheme is currently at the preliminary stage of development but the preliminary methodology produces a broad correlation between the Mean Trophic Rank and the proposed classification of phosphate concentrations for rivers.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 19 2.3 IMPLEMENTATION OF OTHER EC DIRECTIVES RELATED TO SURFACE FRESHWATER QUALITY

2.3.1 EC Directive of Water Quality Suitable for Freshwater Fish (78/659/EEC)

Approximately 19,500 km of rivers and canals in the UK are designated as either salmonid waters or cyprinid waters under the EC Freshwater Fish Directive. There number of salmonid waters is highest in the north of England, Wales and the south west. Lowland rivers are generally designated as cyprinid waters.

In 1996, non compliance was recorded for 150 out of a total of 2,288 stretches of designated water, covering 1,220.6 km. A further 28 stretches were given derogations. The non compliances identified during 1996 are attributable to failure to meet the specified standards for five of the determinands: dissolved oxygen ( 44%), total ammonia ( 28%), un-ionised ammonia ( 11%), pH ( 15%) and zinc ( 1%). A few sites failed for more than one determinand

The principal cause of 22% failures was identified as low flow, exacerbated by the 1995 and 1996 drought, leading to low oxygen concentrations and reduced dilution of pollutants. At some sites increased nutrient concentrations and temperatures allowed elevated algal levels to develop, resulting in a pH in excess of the upper limit. Low flow was particularly significant in the Southern, South West and North East Regions. Other failures are attributed to sewage or trade discharges and agricultural pollution. Effluent quality improvements and farm inspections are planned for many affected areas.

2.3.2 EC Directive on the Quality of Surface Water Abstracted for Potable Supply (75/440/EEC)

More than 450 sites have been designated under the EC Surface Water Directive. In 1996, 136 sites failed the standard for one or more substances specified by the Directive, most frequently for dissolved hydrocarbons, colour, copper, dissolved iron, nitrate and polyaromatic hydrocarbons. The Environment Agency does not view this level of failure as a cause for concern, counting poor analytical methodology for dissolved hydrocarbons, low sampling rates and natural sources as reasons why a recorded failure may not warrant corrective action. In addition, all abstracted water undergoes further treatment before entering the public supply to ensure potable water meets the standards of the Drinking Water Directive (80/778/EEC).

2.4 CONCLUSIONS REGARDING THE FIRST ROUND DESIGNATION OF NITRATE VULNERABLE ZONES AND SENSITIVE AREAS

The information provided by the Environment Agency on the first round of designations raises questions concerning implementation of the UWWT and Nitrates Directives in at least the following areas: the quality of information demanded; the level of proof required; the selection process; whether the

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 20 evaluation of NVZ’s was adequately pursued; and whether the requirements of other Directives were taken into account when establishing candidate Sensitive Areas under the UWWT Directive.

In these areas the following points appear relevant when considering whether the UK met its obligations in the first round of designations:

• quality of information • level of proof • the selection process • implementation of the Nitrates Directive • implementation of other Directives

2.4.1 Quality of Information

Member States had two options when implementing the UWWT and the Nitrate Directives. They could either implement the strategies across their entire national territory, or they could evaluate specific areas on a case-by- case basis. The information requirements to implement the latter strategy are obviously considerably higher than the former.

On the basis of the pro-formas prepared for the first round of designations, it does not seem that in 1993 the UK had the necessary information to implement the strategy on a case-by-case basis, at least for the marine sites. Seven criteria were set out by which to judge marine eutrophication, yet on the pro-formas for the candidate areas it was frequently indicated that no information existed. Even at the most basic level of physical effects, the requirement to state background levels of nutrients, this was only stated in two cases (Truro and Tresillian Estuaries and Langstone Harbour). In one of these (Langstone Harbour) the value given appears to be that for the Atlantic, which is of questionable relevance. Information on actual nutrient levels were also very limited, and appeared to be based on very short term and limited sampling. Similarly it was rarely possible to give the requested information on oxygen deficiency duration or cause.

Turning to the biological effects, no advice was given on what should be regarded as an abnormal level of phytoplankton; where this was raised the advice on levels in coastal waters appears to have been used. Where information was given on macroalgal weed mats, this appeared very dated.

Similar problems existed in the section which asked whether action to remove nitrogen or phosphorus would have any effect on the level of eutrophication. In order to make this assessment it would be necessary to have a nutrient budget of point and diffuse sources for the candidate area. No budgets were seen, and none were referred to on the pro-formas. It might be noted in passing that the question may in any case be irrelevant: for “large agglomerations” the removal of phosphorus and/or nitrogen is required “unless it can be demonstrated that the removal will have no effect on the level of eutrophication”. With good data (better that that supplied in the pro-formas) it

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 21 might be possible to demonstrate that the STW had no significant effect on the level of eutrophication, but that is not apparently what the Directive requires.

2.4.2 Level of Proof

For some elements of the UWWT and Nitrates Directives no indication is given of the level of proof required to determine an adverse effect. In the report previously submitted by ERM to the Commission, it was described how, in the specific case of the Ythan, its candidature as an NVZ in the first round of designation was rejected by the Scottish Office on the basis that the linkage between nitrate concentration and Enteromorpha growth was not established as cause and effect “without possible doubt.”.

It is apparent from the English and Welsh pro-formas that this was part of a general strategy during the first round of designations. All of the candidates were rejected on the basis of insufficient evidence. This raises two points:

• the possibility that a Member State, by demanding levels of proof that are impossible to achieve, (or which it may make impossible to achieve, by not providing the funding for the research necessary to reach the standard it has set) may avoid action;

• the extent to which a Member State is governed by other laws and norms when a Directive does not provide guidance. In this case relevant considerations are the civil court standard of proof on the balance of probabilities; wider Community legislation and treaties, the OSPAR North- East Atlantic Convention which requires (to use a short-hand expression) the environment to be given the balance of the doubt, or soft-law commitments such as North Sea Ministerial Declarations dating from 1987.

Tables 2.3 to 2.5 below present further information on sites where designation was rejected on grounds of insufficient evidence.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 22 Table 2.3 Candidate Sensitive Areas (UWWT Directive) and Vulnerable Zones (Nitrates Directive) - Withdrawn by NRA on basis of Insufficient Evidence (eutrophication)

EA (NRA) Region Anglian River Flit Soham Lode River Gipping River Ouzel Great Ouse Swavesey Drain Headwaters of the Great Ouse River Waveney River Ivel River Wensum River Yare Middle Level System Old West River

Severn Trent Bow Brook River Leadon

South-Western Truro and Tresillian Estuaries River Erne River Cobber and Loe Pool

Welsh Cardiff Bay Tywi Estuary

Thames River Mole

Table 2.4 Candidate Sensitive Areas (UWWT Directive) - Rejected by DoE on the grounds of Insufficient Evidence (eutrophication)

EA (NRA) Region Anglian Abberton Reservoir Cam and Ely Ouse Litle Ouse River Stour (including ) River Welland River Witham Southern River Grom (d/s Tunbridge Wells South STW) Rhoden Stream (d/s Paddock Wood STW) Thames River Mole

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 23 Table 2.5 Candidate Sensitive Areas (UWWT Directive) and Vulnerable Zones (Nitrate Directive) - Rejected by the National Panel on the grounds of Insufficient Evidence (eutrophication)

EA (NRA) Region Anglian Colne Estuary Deben Estuary River Wissey Severn Trent Staffordshire and Worcester Canal Shropshire River Severn Gloucester to Sharpness Canal Southern d/s Paddock Wood STW (1) d/s Tunbridge Wells South STW d/s Tunbridge Wells North STW Chichester Harbour (d/s Chichester STW) Chichester Harbour (d/s Thornham STW) Langstone Harbour d/s Ashford STW d/s Andover STW d/s Romsey-Greenhill STW Thames Gran Union Canal d/s - down stream

2.4.3 The Selection Process

The Environment Agency provided information on the stage at which the candidatures failed, and the reason for the failure, but did not supply information on the additional technical evidence that was taken into account so as to over-rule the judgement of the regional offices of the NRA. This makes evaluation of individual cases and of the process as a whole extremely difficult. It has not been possible to gain any further information on this aspect of the designation in the UK.

2.4.4 Implementation of the Nitrates Directive

The UK designation pro-forma makes clear in its title that it supposedly addresses both Sensitive Areas and the Nitrate Vulnerable Zones. Yet the structure is heavily weighted towards the assessment only of Sensitive Area status. Thus it asks for information on the level of sewage treatment, but does not ask for any details relevant to judging NVZ status, such as details on the relative contribution of diffuse and point source nutrients. At least in the case of these marine candidates, reference is only made once to agricultural inputs – the pro-forma on the Deben, for example, answers in the affirmative to the question on whether a reduction of sewage treatment works nutrient inputs will make any difference to the level of eutrophication “provided that diffuse inputs were also reduced”.

(1) STW = sewage treatment works

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 24 2.4.5 Implementation of other Directives

No mention is made of the requirement for Sensitive Areas to be created under the UWWT Directive in order to meet the objectives of other Directives, and no space is provided on the pro-forma. Directives relating to Bathing Water, Shellfish, and Habitats and Species are clearly relevant here. If information on these was taken into consideration, this has not been made available to ERM by the Environment Agency.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 25 3 THE UK DESIGNATION PROCESS - MARINE AND COASTAL WATERS

3.1 INTRODUCTION

The UK government had twice reviewed the status of individual estuaries and coastal waters with regard to the UWWTD and the Nitrates Directive, in 1993–4 and 1997–8iv.

This section attempts to evaluate those reviews. However, for reasons partly alluded to in the introduction, this review has of necessity been significantly constrained. In so far as it has been possible to establish, only one estuarine or coastal site – the Ythan estuary – has been proposed as a candidate by the agencies with regard to possible designation as a Nitrate Vulnerable Zone (NVZ). Moreover, while the title of the pro-formas relating to candidate areas in England and Wales refers to both Sensitive Areas and Nitrate Vulnerable Zones, in practice on all occasions the completed details referred only to Sensitive Areas. There thus appears to have been no systematic nationwide assessment of estuarine or coastal NVZ status (certainly for the first round: see following paragraphs). Thus a systematic evaluation of the UK’s review of NVZ status is impossible. Further discussion of the specific case of the Ythan is deferred for the dedicated section (Part III-Section 1 of this Report).

Turning to the UWWTD, no information was received from the government or its agencies on the assessment underlying the designation, or otherwise, of specific LSAs (in the UK termed Areas of High Natural Dispersion, HNDAs), completed in either 1993–4 or 1997–81. It has therefore been impossible to evaluate these reviews, although information on the location of HNDAs and other details are included in the later sections.

Thus it was only possible to evaluate the process underlying the designation of individual Sensitive Areas. Even this was significantly restricted. No information has been seen on the process underlying the selection of Scottish Sensitive Areas. Moreover, although the Environment Agency had completed its role in the second round of designations in England and Wales2 prior to the start of this research, they indicated that they were unwilling to release related EA documentation. This raises questions as to the requirements of the Directive on the freedom of access to information on the environment3, falling outside the grounds for refusal allowed in Article 3.

The evaluation in this section is therefore limited to an assessment of the 1993, first round designations of Sensitive Areas in England and Wales.

1 although it is known, from the CSTT report, that there is a standard reporting format for candidate estuarine and coastal LSAs.

2 The result of the second round of designations was released on 30 July 1998: Command Paper 4023, ISSN 0101402325.

3 Council Directive 90/313/EEC.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 26 3.2 SENSITIVE AREAS AND NVZS: FIRST ROUND DESIGNATIONS (1993–4)

In England and Wales in 1993 the Regional Offices of the National Rivers Authority, NRA, conducted the first stage of the Sensitive Area review. If they considered that a site fulfilled the requirements for designation as a ‘candidate’ Sensitive Area (or, in principle, a Nitrate Vulnerable Zone), then a pro-forma was completed and submitted to the national headquarters. Additional background material might also be provided. Subsequently these candidate SAs might be rejected either by the NRA at national level, at a subsequent vetting by a ‘National Panel’ of experts, or finally by the then Department of Environment, DoE.

The pro-formas of candidate Sensitive Areas and Nitrate Vulnerable Zones from the 1993 round, received from the Environment Agency, are shown in Table 3.1.

Table 3.1. Summary of 1993 pro-formas received from the Environment Agency.

Region Site — Reason for candidature — Supporting Eutrophic Potentially eutrophic Other documentation UWWTD Nit. Dir.

Welsh Cardiff Bay* 4 Tywi Estuary 44

South- Truro & Tresillian 44 West Estuaries

Southern Langstone 44 Harbour Chichester 4 Harbour†

Anglian Colne Estuary 4 Deben Estuary 4

* may become eutrophic were a tidal barrage to be built † separate pro-formas for Chichester and Thornham Sewage Treatment Works A tick in column ‘Other’ would indicate the nomination of a candidate area in order to fulfil other Directives. A 4 in the final column indicates that additional documentation to the pro- formas was also received from the Environment Agency.

Also included in the Table 3.1 are the three relevant criteria upon which marine or estuarine sites could be proposed, and whether any additional supporting material was supplied by the Environment Agency.

The three criteria by which an estuary or marine area could qualify as a Sensitive Area (or a NVZ) on the 1993 pro-formas were that they were currently eutrophic (with no statement as to which Directive this pertained); that they might become eutrophic if current trends continued (relevant Directive indicated); or where other Directives (e.g. bathing water, shellfish, or those associated with species and habitats) required additional measures.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 27 On this basis seven1 sites (four estuarine and three coastal embayments) were proposed by the NRA Regional Offices. It is apparent that a number of sites over which various (often government-related) bodies had by then raised concerns are missing from the list. These include (with the source of concern in brackets) the Lindisfarne National Nature Reserve in Northumberland (English Natureix), The Wash and its constituent estuaries (OSPARi), the Blackwater estuary in Essex (English Naturex), and Liverpool Bay (Irish Sea Study Group Reportxi)2. The material provided by the Environment Agency does not indicate whether these (and other) sites had been evaluated and rejected as candidates by the Regional Offices.

Of the seven sites proposed, five were on the basis of existing eutrophic conditions and two due to the future potential for eutrophication – both stated to arise from considerations relating to the UWWTD. No sites were nominated as candidates on the basis of the Nitrates Directive or need to fulfil other Directives.

3.2.1 Fate of the Candidate Sites

Ultimately, none of the seven candidate sites were classified as Sensitive Areas or NVZs. Some were rejected by NRA headquarters, and the remainder by the National Panel, all on the basis of ‘insufficient evidence’. A summary of the information provided by the Environment Agency documentation for these candidate sites is given below.

Truro & Tresillian Estuaries on the south coast of Cornwall, was proposed by South West NRA. The pro-forma states that the site was currently eutrophic. The supporting evidence given was that:

• the peak nitrogen levels recorded in the headwaters was 807 µM3 TON

(Total oxidised nitrogen: nitrate, NO3 + nitrite, NO2) in March 1990 and 729 µM TON in 1991. The pro-forma also requires the ‘natural’ background concentration, for which is given the “maximum recorded value” of 198 µM TON in the Fowey estuary headwaters in February 1991. The Regional Office interpreted this as a “significant enhancement”, as required by the DoE/MAFF consultative document on the methodology to be employed to identify Sensitive Areas and NVZs;

• That exceptional algal blooms had occurred, with a maximum chlorophyll- a value of 223 mg m-3. This is well in excess of the coastal waters reference

1 The Truro and Tresillian estuaries are contiguous.

2 Offshore there had already been discussion about the contribution of UK nutrients to eutrophication in the Continental Coastal Zone of the North Sea, and of enhanced nutrient levels in the Irish Sea. However any mechanism for assessing impacts on these sites would appear to lie outside the remit of the regional offices and the pro-forma system.

3 Original values expressed in milligrams. All values in this report standardised as molar units per litre, µmol l-1, abbreviated to µM. This allows direct addition of ammonia/ammonium and TON nitrogen to give Dissolved Available

Inorganic Nitrogen (DAIN), and atomic (elemental) ratios are directly calculable. Note also that because NH4+, NO3, NO2,

PO4 and SiO2 are monovalent compounds of nitrogen, phosphorus and silicon, molar values for N, P and Si on the one hand and ammonia/ammonium, nitrate, nitrite, phosphate and silica are identical.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 28 value of 10 mg m-3. There are no quantitative phytoplankton reference criteria for estuaries.

• That the minimum recorded oxygen level was only 4% of saturation, with a maximum of 128% (the latter indicative of algal blooms). The DoE/MAFF consultation paper says that care should be taken to distinguish between deoxygenation resulting from eutrophication and the subsequent decay of algal blooms, and that due to other causes. No distinction is made in the pro-forma, but this may be irrelevant in the context of the UWWT Directive if it can be assumed that Sewage Treatment Works (STW) discharge(s) are responsible for the deoxygenation.

Thus the regional NRA asserted that three of eight criteria for judging eutrophication in an estuary or coastal water had been met. The pro-forma also illustrated just how scanty the monitoring programme was. No data was given on the bloom species or duration, on the duration or cause of the oxygen deficiency, on changes in fauna, on changes in macrophyte1 growth, on the occurrence and magnitude of Paralytic Shellfish Poisoning – but presumed to be nil – or on the presence of shoreline algal scum.

The pro-forma described Truro (Newham) STW, p.e. 28,000, as having secondary (biological filtration) treatment. No proposal was made for upgrading in the space available on the pro-forma. However the covering letter implies that designation as a Sensitive Area would have implications for the STW, as South West Water were said to be questioning the validity of the candidature on the basis of the relative contribution of the STW. A nutrient budget for the area would be necessary to resolve the relative importance of point and diffuse sources but if it exists, no reference to it was made, and no other documentation was provided by the Environment Agency.

Information independently gathered on these estuaries, (see following chapters) and the related discussion, confirmed that both nitrogen and phosphorus levels were significantly elevated, the latter at least indicating a significant sewage-related component. The candidate site was rejected at the level of the national office on the NRA on the basis of insufficient evidence.

Tywi Estuary, entering Carmarthen Bay on the south Welsh coast, was proposed as a candidate Sensitive Area by NRA Welsh Region, on the grounds that it might become eutrophic in the near future were preventative action not taken under the UWWT Directive. The basis for the candidacy was:

• An elevated nitrate-nitrogen concentration of 100 µM compared to a stated background level of 5.71 µM at a salinity of 27.5‰; • The occurrence of exceptional algal blooms, composed of Phaeocystis, Cytocella and Asterionella japonica at levels up to 50 million cells per litre.

1 literally ‘large plant’; sea weeds (algae) and flowering plants (angiosperms) such as eel-grass.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 29 Levels of chlorophyll-a up to 73 mg m-3 were also cited. These blooms lasted from May to July, with occasional late summer blooms; • Oxygen levels were depleted, to a minimum level of under 2 mg l-1. The causes had not been established, but were believed to be due to a combination of demand from the sediments, from algal respiration, and from organic discharges from STWs; • With regard to changes in fauna, while no mortality of benthos and fish had been recorded, the pro-forma states that “potentially lethal” dissolved oxygen conditions had been observed; • Formation of algal scum on beaches and offshore from Phaeocystis during May to July, occurring in most years. The magnitude and duration were dependent upon wind direction. • Thus, according to the NRA Welsh Office, five of seven criteria were met. Two STW plants discharged into the candidate area, their names illegible. The first, with a p.e. of 20,000 then had primary treatment only: secondary treatment appears to have been tentatively suggested (a question mark was placed by the note). The second STW had a p.e. of 10,000, and secondary treatment was also suggested.

But in answer to the standard question ‘Will removal [of N or P] have any effect on the level of eutrophication?’ the answer was negative in both cases. It is therefore unclear why it was stated at the head of the pro-forma that eutrophication was possible unless action was taken under the UWWTD. Subsequent to this a memorandum was sent from the Welsh Region Office, responding to an (unseen) request for further information from NRA headquarters. This now states that the eutrophication is “thought to result from natural phenomena. It is highly unlikely that reduction of nutrient inputs into the Estuary will make any [their emphasis] difference to the current situation.”. No elaboration was given regarding these ‘natural phenomena’. After raising issues concerning two (unrelated) freshwater sites the memorandum concludes “I should be grateful if you would seek further information on this matter from the DoE. We would wish to see a means of granting derogation from the terms of the Directive if it could be demonstrated that a particular discharge was not contributing to observed symptoms of eutrophication – is there likely to be any scope for this?”.

The candidature was turned down at the national level by the NRA, on the basis of insufficient evidence.

Cardiff Bay, also on the south Welsh coast, was proposed as a candidate Sensitive Area by the NRA Welsh Region. This was on the basis that it might become eutrophic if protective action were not taken under the UWWT Directive, as a result of the construction of the Cardiff Bay Barrage. In such circumstances the affected area of Cardiff Bay would be freshwater, and so is not considered further in this report.

Langstone Harbour was proposed by NRA Southern Region as a currently eutrophic area. The basis for this cited in the pro-forma was:

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 30 • that the historic (term undefined) February nitrate-nitrogen level was elevated, at 17–28 µM N, while “scarce” recent data remained at a similar magnitude, compared to a 1990–92 mean background level of 9.0 µM; • that green algal mats of Enteromorpha and Ulva affected up to 60% of the intertidal area, based on data gathered between 1970–82. A significant area had weed cover over 75% coverage, and a wet weight of 1–2 kg m2 or greater. The information given in the pro-forma implied that the situation remained unchanged; • that invertebrate biomass had increased in sediment covered by algal mats, and the relative abundance of those species present indicative of stressed conditions (presumably a few very common species and the majority represented by only a few individuals). • The one STW listed, Budds Farm, had a p.e. of 378,000, and in 1993 was treated to “tertiary” level (presumably bacteriological treatment, as no nutrient removal occurs).

In addition to the pro-forma, one memorandum and one paper discussing ‘The Extent of Eutrophication in Langstone Harbour’ were included in the papers sent from the EA to ERM, and which raise a number of issues. Further discussion of this site is delayed until the discussion of this area as a case example.

In the event the candidate status of Langstone Harbour was rejected by the National Panel on the grounds of insufficient evidence.

Chichester Harbour adjacent to Langstone and connected with it was also nominated by the Southern Region of the NRA as a currently eutrophic site. The justification in the pro-forma closely followed that for Langstone:

• Changes in macrophyte growth – Enteromorpha and Ulva affected up to 25% of the intertidal area (according to data gathered in 1979). The greatest growth was in sheltered areas. Large accumulations of decaying algae created an odour problem; • This had resulted in an increase of animal biomass under the mats and had distorted species composition.

However no data was provided on nutrient levels in Chichester Harbour, while information on exceptional algal blooms, oxygen deficiency, on PSP, and the formation of algal scums was deemed inapplicable. There were two STWs in the candidate area, Chichester STW with a p.e. of 60,775 and then current treatment to secondary level, and Thornham STW with a p.e. of 29,730, also with secondary treatment. No proposal for enhanced sewage treatment was made on the pro-forma, nor was any prediction made of the effect on nitrogen or phosphorus levels were treatment to be enhanced.

As with Langstone, the National Panel rejected the candidature of Chichester Harbour on the basis of insufficient evidence.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 31 The Colne Estuary in Essex, was put forward as a candidate area by Anglian NRA on the basis that it was currently eutrophic. The reasons were not directly stated but judged by the information provided appear to be as follows:

• That TON levels were elevated. Data appended to the pro-forma for 1992 (only) indicated peak levels of 83.6 µM in April and 280 µM in May; • That there were exceptional algal blooms. The peak chlorophyll-a values recorded in 1992 was 20.1 µg/l in and 37.9 µg/l, both in June. The dominant species recorded in May and June were Skeletonema and Chaetoceros, with total cell counts between 3–5 million per litre; • That oxygen deficiency occurred, to a minimum of 30% of saturation and that the cause was, in part, by Colchester STW.

No data was available on changes in macrophyte growth or changes in fauna, while information on PSP and the formation of algal scum was considered inappropriate. There were three STWs with a capacity over 10,000 p.e. to the candidate area: Colchester (114,836 p.e., secondary treatment), St Osyth (13,726 p.e., secondary treatment) and Colne (10,518 p.e., no information on treatment level). For both Colchester and St Osyth the pro-forma implied that a proposal existed that would result in a significant removal of both nitrogen and phosphate, and that the removal of phosphorus from Colchester STW would have a “significant effect” on the level of eutrophication in the estuary, also affirmed for the other two STWs. No statement was made with regard to the effect on the estuary of nitrogen removal for any of the three STW. The Colne estuary is discussed further in the case example of the Essex and Suffolk estuaries.

The proposal for a candidate sensitive area in the Colne Estuary was rejected by the National Panel on the grounds of insufficient evidence.

Deben Estuary, also in the Anglian Region of NRA, was the final candidate area, and was also proposed on the basis of current eutrophication. The criteria were similar to those for the Colne:

• a peak TON level in 1992 (the only year for which data provided) of 503 µM in April; • A peak chlorophyll-a level of 43.3 µg/l in May; • that algal scums were a frequent occurrence in the estuary.

One STW with a discharge over 10,000 p.e. was listed, that of Woodbridge with a quoted p.e. of 20,798, and current secondary treatment. The proposed level of treatment was estimated to remove 71% of current nitrate, and it was stated that this level of removal would have an effect on the level of eutrophication “provided that diffuse inputs were also reduced”. This presumably refers to concerns about agricultural inputs, but no budget was provided and probably did not exist at that time – later work was commissioned and confirmed the importance of diffuse inputs, as described in a later section.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 32 The Deben estuary candidature was rejected by the National Panel on the grounds of insufficient evidence.

3.2.2 Conclusions regarding the First round designations

The information provided by the Environment Agency on the first round of marine designations raises questions concerning implementation in at least the following areas: the quality of information demanded; the level of proof required; the selection process; whether the evaluation of NVZs was adequately pursued; and whether the requirements of other Directives were taken into account when establishing candidate Sensitive Areas under the UWWT Directive.

In this regard the following points appear relevant when considering whether the UK met its obligations in the first round of designations:

Quality of Information

Member States had two options when implementing the UWWT and the Nitrate Directives. They could either implement the strategies across their entire national territory, or they could evaluate specific sites on a case-by-case basis. The information requirements to implement the latter strategy are obviously considerably greater.

On the basis of the pro-formas it does not seem that in 1993 the UK had the necessary information to implement the strategy on a case-by-case basis, at least for the marine sites. Indeed, judged by the pro-formas it would be fair to say that the quality was abysmal – remarkable, given the frequent emphasis by administration on the importance to them of ‘sound science’ as a basis for decision-making on this issue. Seven criteria were set out by which to evaluate marine eutrophication, yet it was frequently indicated that no information existed. Even at the most basic level, that of physical effects, the requirement to state background levels of nutrients was only given in two cases (Truro and Tresillian Estuaries and Langstone Harbour). In one of these (Langstone Harbour) the value given appears to be that for the Atlantic, which would be inappropriate. Information on current nutrient levels were also very limited, and appeared to be based on very short term and limited sampling. Similarly it was rarely possible to give the requested information on oxygen deficiency duration or cause.

Turning to the biological effects, no central advice was given on what should be regarded as an abnormal level of phytoplankton in estuaries; as a result, where this was an issue, inappropriate guidance on levels in coastal waters appears to have frequently been used. Where information was given on algal weed mats, this appeared very dated.

Similar problems existed in the section which asked whether action to remove nitrogen or phosphorus would have any effect on the level of eutrophication. This requires a nutrient budget of point and diffuse sources. No budgets were seen, and none were referred to on the pro-formas. It can be inferred that few,

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 33 if any, existed at this time. Determining the effectiveness of such action may in any case be irrelevant for UWWTD ‘large agglomerations’, where the removal of phosphorus and/or nitrogen is required “unless it can be demonstrated that the removal will have no effect on the level of eutrophication”. With good data (better that that supplied in the pro-formas) it might be possible to argue that a STW had no significant effect on the level of eutrophication, but that is not apparently what the Directive requires.

Level of Proof

For some elements of the UWWT and Nitrates Directives no indication is given of the level of proof required to determine an adverse effect. As already noted for the Ythan (p. 16) its candidature as an NVZ in the was rejected on the basis that the linkage between nitrate concentration and Enteromorpha growth was not established “without possible doubt”. It is apparent from the English and Welsh pro-formas that the treatment of the Ythan was consistent with a general strategy during the first round of designations. All of the candidates were rejected on the basis of insufficient evidence. This raises two points:

• the possibility that a Member State, by demanding levels of proof that are impossible to achieve, (or which it may make impossible to achieve, by not providing the funding for the research necessary to reach the standard it has set) may avoid action;

• the extent to which a Member State is governed by other laws and norms when a Directive does not provide guidance. In this case relevant considerations are the civil court standard of proof on the balance of probabilities; wider Community legislation and treaties, the OSPAR North- East Atlantic Convention which requires (to use a short-hand expression) the environment to be given the balance of any doubt; or soft-law commitments such as North Sea Ministerial Declarations dating from 1987.

The Selection Process

The Environment Agency provided information on the stage at which the candidatures failed, and the reason for the failure, but did not supply information on the additional technical evidence, if any, that was taken into account to over-rule the judgement of NRA Regional Offices.

Implementation of the Nitrates Directive

The pro-forma makes it clear in its title that it supposedly addresses both Sensitive Areas and the Nitrate Vulnerable Zones. Yet the structure is heavily weighted towards the assessment only of Sensitive Area status. Thus it asks for information on the level of sewage treatment, but does not ask for any details relevant to judging NVZ status, such as details on the relative contribution of diffuse and point source nutrients. At least in the case of these marine candidates, reference is only made once to agricultural inputs – the pro-forma on the Deben answers in the affirmative to the question on whether

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 34 a reduction of STW nutrient inputs will make any difference to the level of eutrophication “provided that diffuse inputs were also reduced”. Implementation of other Directives

No mention is made in the pro-forma of the requirement for Sensitive Areas to be created under the UWWT Directive in order to meet the objectives of other Directives. Those relating to Bathing Water, Shellfish, and Habitats and Species are clearly relevant here. If information on these was taken into consideration, this was not passed on by the Environment Agency.

3.3 SENSITIVE AREAS AND NVZS: SECOND ROUND DESIGNATIONS (1997–8)

The UK Government announced the results of the second review of Sensitive Areas in July 1998. As already described, the Environment Agency felt unable to provide documentation relating to this process. However a few estuarine and coastal sites have now been designated as eutrophic Sensitive areas. These are the Tawe estuary in Wales, the Truro, Tresillian and Taw estuaries in south-west England, Langstone and Chichester Harbour in southern England. With the exception of the Taw estuary, these sites are fully discussed in later sections of this report.

No estuarine or coastal NVZs have yet been designated. The Ythan estuary candidature was once more rejected. Further discussion of this is left until the section on the Ythan estuary.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 35 4 REFERENCES

i Anon. (1993). Eutrophication Symptoms and Problem Areas. Oslo & Paris Commissions. London. 26 pages plus maps. ii Anon. (1993). Methodology for identifying Sensitive Areas (Urban Waste Water Treatment Directive) and methodology for designating Vulnerable Zones (Nitrates Directive) in England and Wales. Department of the Environment / Ministry of Agriculture, Fisheries and Food / Welsh Office. March 1993. iii Marine Pollution Monitoring Management Group. (1997). Comprehensive Studies for the purposes of article 6 & 8.5 of Dir. 91/271 EEC, the Urban Waste Water Treatment Directive. Second Edition. Department of the Environment for Northern Ireland, the Environment Agency, The Scottish Environment Protection Agency and the Water Services Association. January 1997. iv DETR (1998). Select Committee on the Environment, Transport and the Regions. Memorandum of Inquiry by Environment Sub-Committee. Sewage Treatment and Disposal. Government Response. Presented to Parliament by the Deputy Prime Minister and Secretary of State for the Environment, Transport and the Regions. July 1998. Cm. 4023. HMSO, London. v Anon (1997) Nitrates Directive (91/676/EEC) – The Ythan catchment and estuary. Scottish Environmental Protection Agency. Notification to Scottish Office. vi Smith, J. C. & B. Hogan (1983). Criminal Law. Butterworths, London. vii The 1992 Convention for the Protection of the Marine Environment of the North-East Atlantic. viii Cameron, J. (1994). The status of the Precautionary Principle in International Law. p. 262–289 in Interpreting the Precautionary Principle (eds. Tim O’Riodan & James Cameron) Cameron May, London. ix David Witherington, English Nature, pers. com. x Elliot, M., V. N. de Jonge, G.K.L. Burrell, M.W. Johnson, G. L. Phillips & T. M. Turner (undated). Trophic Status of the Ore/Alde, Deben, Stour and Colne Estuaries. Volume 1. Reports in Applied Marine Biology. The University of Hull. 109 pages. Reference on page 49. xi Irish Sea Study Group (1990). The Irish Sea - An Environmental Review: Part 3. Exploitable Living Resources. Liverpool University Press.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI I - 36 PART II

VERIFICATION OF VULNERABLE ZONES AND SENSITIVE AREAS FOR SURFACE FRESHWATERS AND GROUNDWATERS ENVIRONMENTAL RESOURCES MANAGEMENT I1 1. THE CRITERIA USED FOR ASSESSING THE TROPHIC STATUS OF INLAND, ESTUARINE AND MARINE WATERS IN THE UK

1.1 INTRODUCTION

The Urban Waste Water Treatment Directive (UWWTD) and the Nitrates Directive (ND) require Member States to identify ‘polluted’ waters by analysing two rather different kinds of ‘water quality’ measurements:

• measurements of the concentration of a specified nutrient in a sample of water e.g. the concentration of nitrate or nitrate-nitrogen; • measurements that provide an estimate of the trophic status of a particular body of water e.g. the concentration of phytoplankton chlorophyll.

The methods used to measure and report the concentration of nitrate are relatively straightforward, but the measurements required to assess the trophic status of the different systems are more complex and difficult to interpret.

In 1993, the UK Department of the Environment published a Consultation Document that considered some of the practical problems of developing monitoring programmes to meet these reporting requirements. The document outlines the criteria that could be used to assess the trophic status of aquatic systems, and explains the procedures used to define the physical limits of ‘sensitive areas’ and ‘vulnerable zones’ as defined in the Directives. This document was produced after the first round of site designations was completed and was largely based on the experience gained during this exercise. These guidelines have since been used to assess the status of the sites included in the 1997 round of designations and a detailed summary of the results prepared for the Department of Environment, Transport and the Regions.

In this section, we contrast the methods and criteria recommended in this document with those used to identify the ‘sensitive areas’ and ‘vulnerable zones’ in the 1992 round of site designations. The section includes an overview of the relative effectiveness of the different variables and describes some of the data-bases used to identify ‘polluted’ waters in 1992.

1.2 CRITERIA THAT COULD BE USED TO ASSESS THE TROPHIC STATUS OF INLAND, ESTUARINE AND MARINE WATERS IN THE UK

Table 1.1 lists the criteria that could be used to assess the trophic status of the sites covered by the two Directives. The relative effectiveness of the different variables is shown by the number of ‘+’ symbols. A single ‘+’ symbol implies that a particular variable is difficult to interpret whilst three ‘+’ symbols indicate that these measurements provide a more reliable measure of the effects of enrichment.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 1 Table 1.1 The main criteria that could be used to assess the trophic status of the habitats covered by the Directives

Criteria Lakes and rivers Rivers Estuaries Coasts Nitrate concentration + + + + + + + +

Orthophosphate concentration + + + + + + +

Total Phosphorus Concentration + + + + + + +

Oxygen concentration ++ ++ ++

Diel oxygen variation + + + + + + + +

Light Attenuation + + + + + + (e.g. Secchi Disk)

Phytoplankton chlorophyll + + + + + + + +

Microflora (algal mats) + + + + + + + + +

Macroflora + + + + + + + + + +

Faunal change + + + + + + + +

For estuarine and marine habitats the simplest index of ‘pollution’ is the measured concentration of nitrate. The biological productivity of these systems is usually limited by the supply of nitrate but the actual concentrations measured at any location are also influenced by the state of the tide.

Most freshwater systems are limited by the supply of phosphate rather than nitrate, so the best measure of system productivity is the concentration of orthophosphate. Total phosphorus concentrations can also be used as a general measure of system productivity but can sometimes be influenced by ‘local events’ e.g. influx of soil during winter rains.

Individual oxygen measurements are almost impossible to interpret. Very high values can be reported at the end of a sunny day in highly eutrophic systems and relatively low values in small dystrophic bodies of standing water. The diel variation in the concentration of oxygen is a useful index of general productivity but is seldom recorded by the regulatory authorities in the UK. More information of this kind may, however, become available as automatic monitoring systems become more reliable and easy to maintain. Measurements of the attenuation of light in the water column are not often reported and are difficult to interpret since day-to-day changes in the weather can have a major effect on the underwater light climate.

The average concentration of phytoplankton chlorophyll provides a good measure of the productivity of lakes, reservoirs and coastal waters.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 2 Chlorophyll concentrations in running waters and estuaries are, however, very difficult to interpret. Very low chlorophyll concentrations can be recorded in eutrophic rivers that are very turbid and in clearer rivers that have a very short retention time. The appearance of extensive growths of attached algae or submerged macrophytes can, however, provide a useful measure of change in a wide range of flowing, as well as standing waters. They are particularly appropriate in rivers that are too short to sustain significant amounts of phytoplankton, and in estuaries where local concentrations are influenced by tidal movements. Indices based on the relative or absolute change in communities of bottom dwelling animals are widely used for monitoring river sites in the UK, but have yet to be adapted for trophic state assessment. Complex communities of this kind are inherently variably and should be sampled by skilled operators with some experience of local conditions.

1.3 DATA THAT COULD HAVE BEEN USED TO ASSESS THE TROPHIC STATUS OF INLAND, ESTUARINE AND MARINE WATERS IN THE UK

The organisations responsible for aquatic monitoring in the UK maintain a number of long-term data sets that could be used to assess the trophic status of the sites covered by the two directives. These include:

• data acquired under the surface water abstraction directive 75/440/EEC; • data acquired by the harmonised monitoring scheme; • data acquired by the national marine monitoring programme.

All the sites identified as sampling points under the Surface Water Abstraction Directive are freshwater systems that tend to be relatively unpolluted. Water samples are collected at frequent intervals for chemical analysis but very little attention is usually paid to the biological characteristics of the selected sites.

The Harmonised Monitoring Scheme (HMS) was established by the DOE in 1974 (1) to provide a consistent framework within which to monitor river quality in the UK. The two principal aims of the scheme were to estimate the quantities of material discharged to estuaries, in order to fulfil the UK’s international obligations, and to identify any long-term trends in water quality. Over the lifetime of the scheme, 209 sites have been sampled in England and Wales for up to 115 physical, chemical and microbiological determinands. The number of sites included in the network is relatively small, but they cover the whole of the UK and have been sampled using consistent methods for at least twenty years. One disadvantage of the HMS network is the rather limited numbers of determinands measured at many of the selected sampling sites. In the early 1990’s, a biometrician based at IFE Windermere spent some time analysing data acquired by the Harmonised

(1)Methodology for identifying sensitive areas (Urban Waste Water Treatment Directive) and methodology for designating vulnerable zones (Nitrates Directive) in England and Wales. Department of the Environment, Ministry of Agriculture, Fisheries and Food and the Welsh Office (March 1993).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 3 Monitoring Scheme between the mid 1970’s and the early 1990’s (1). Table 1.2 shows the proportion of sites where four key ‘water quality’ variables were monitored at regular intervals between 1974 and 1993. Water samples for nitrate and orthophosphate analyses were typically collected from a large number of sites but phytoplankton chlorophyll measurements were only available at a few locations.

Table 1.2 The data collated by the Harmonised Monitoring Programme between 1974 and 1993

Variable Proportion of sites sampled (%) Proportion of sites sampled at monthly intervals (%) Nitrate 92 60 Orthophosphate 93 67 Total phosphorus 9 0 Chlorophyll 14 10

The quality of estuaries and coastal waters in England and Wales is routinely monitored by the Environment Agency using a small fleet of survey vessels and inshore craft. The most comprehensive spatial distribution studies are the offshore surveys where water samples collected at 15 km intervals are supplemented by airborne remote sensing maps of phytoplankton biomass. The quality of individual estuaries has, in the past, also been classified by the NRA and its predecessors on a scale ranging from A to D (good, fair, poor, bad). This is, however, a very subjective classification system and work is in hand to replace it with a more quantitative system. The results of the chlorophyll distribution surveys have recently been used to highlight coastal eutrophication problems but these concentrations have yet to be related to the measured concentration or the estimated flux of nutrients.

1.4 DATA THAT WAS USED TO ASSESS THE TROPHIC STATUS OF SITES IN 1992

When the first round of site designations was implemented in 1992, the most comprehensive data set available was that already being acquired under the Surface Water Abstraction Directive. This monitoring programme did not, of course, include any estuarine or marine sites but a few coastal sites were included in the review on an ad hoc basis. The main problem with this data set was the limited number of ‘trophic state’ variables included. Table 1.3 shows the key variables selected in a format that allows direct comparison with the ‘ideal’ variables listed in Table 1.1. For most sites, the only measurements reported were the concentration of nitrate and orthophosphate. Such measurements are, of course, only indicative of a potential problem and provide no evidence of an actual biological effect.

(1) Hurley, M.A., Currie, J.E, Gough, J. and Butterwick, C. (1996). A framework for the analysis of Harmonised Monitoring Scheme data for England and Wales. Environmetrics, 7, 379-390.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 4 Table 1.3 The criteria that were used to assess the trophic status of the sites in 1992

Criteria Lakes and Rivers reservoirs

Nitrate concentration üü

Orthophosphate concentration üü

Total Phosphorus Concentration Oxygen concentration

Diel oxygen variation üü

Light Attenuation (e.g. Secchi Disk)

Phytoplankton chlorophyll üü

Microflora (algal mats)

Macroflora

Faunal change

1.5 CONCLUSION

The 1992 round of site designations was almost entirely based on data that was acquired from the Surface Water Abstraction monitoring programme. This data-base includes very little biological data so most ‘trophic state’ designations were based on the potential rather than the actual polluting effect of the specified nutrients. The National Rivers Authority were, however, very much aware of the limitations of these procedures and have now developed a much more rigorous system of assessment which has been implemented in the 1997 round of site designations.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 5 2. THE CONCENTRATION OF NITRATES IN THE SURFACE WATERS SAMPLED IN ENGLAND AND WALES

2.1 INTRODUCTION

In 1991, Member States of the European Community were formally notified of the EC Directive 91 / 676 / EEC (the Nitrates Directive). The Nitrates Directive required Member States to identify waters which were, or could be, affected by the discharge of nitrogen from agricultural sources to the aquatic environment and to designate the catchments that drain into these waters as ‘vulnerable zones’. In this section we review the steps taken in the UK to identify the bodies of freshwater covered by the Directive and the methods used to assess the nutrient status of these lakes and rivers. The impact of nitrates leached from agricultural land on the quality of groundwater supplies in the UK will be considered in Section 3. In this section we compare the number of sites identified in the original round of designations with those identified in a new analysis of raw data provided by the Environment Agency (EA) from measurements collated from a variety of sources.

2.2 THE IDENTIFICATION OF SITES

The criteria used to identify ‘polluted waters’ and ‘vulnerable zones’ are laid down in Annex 1A of the Nitrates Directive and are designed to cover the following three situations:

• Surface freshwaters used for the abstraction of drinking water which contain more than the concentration of nitrate laid down in the EC Directive concerning the quality of surface waters used as a source of drinking water (Directive 75/440/EEC). • Freshwaters which are eutrophic or those which could become eutrophic in the near future if protective measures were not taken. • Groundwaters where the maximum concentration of nitrate exceeds 50mg/l and those where the concentration could reach these levels if protective action is not taken.

The waters identified in the Nitrates Directive differ from those identified in the Urban Waste Water Treatment Directive (Section 4) in three important respects:

• The maximum permissible concentration of a specified nutrient (nitrate) is clearly defined. • The definition of eutrophication is restricted to enrichment caused by compounds of nitrogen. • The definition limits the scope of the directive to pollution caused by nitrogen compounds of agricultural origin.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 6 In the 1992 round of site designations, the Department of the Environment in the UK used data acquired by the National Rivers Authority to assess both the nutrient and trophic status of the short-listed sites. The data set analysed by the NRA was that acquired to meet the criteria laid down by the ‘drinking waters’ Directive (Directive 75 / 440 / EEC). Any sites with an average annual nitrate concentration of 50 mg/l or above were then short-listed for designation. Once these sites had been identified, the National Rivers Authority identified the areas of land draining into the polluted waters and cartographers from the Ministry of Agriculture Fisheries and Food then turned these ‘soft’ hydrological boundaries into ‘hard’ agricultural boundaries using physical features like field perimeters.

2.3 THE SITES DESIGNATED IN 1992.

Table 2.1 summarises the number of catchments designated as Nitrate Vulnerable Zones in 1992. All the surface water designations in this round were based on the measured concentration of nitrate-nitrogen. No site was designated on the basis of its trophic status since it was considered that biological productivity in all UK inland waters was limited by the availability of phosphate-phosphorus rather than nitrate-nitrogen. No sites were identified in Scotland and Northern Ireland and only nine catchments were designated in England and Wales.

Table 2.1 The number of Nitrate Vulnerable Zones established during the 1992 round of site designations

Catchments designated as NVZ’s Number of Sites Monitored

England and Wales 9 503 Scotland 0 563 Northern Ireland 0 56 UK 9 1122

2.4 THE NITRATE CONCENTRATIONS RECORDED IN ENGLAND AND WALES

Table 2.2 shows the results of a re-analysis of all the nitrate data released by the EA from its ‘surface water’ data-base for 1992. No nitrate data has been collated for Northern Ireland and no information has hitherto been provided by SEPA for Scotland. Each EA region in England and Wales was responsible for organising its own reporting procedures so the structure of the data provided varied from region to region. Several grid references were incomplete but only four sites had to be excluded due to a complete lack of any geographic information. The most serious problem with the data was the restricted seasonal coverage. About 27 % of the sites had been sampled on fewer than 12 occasions and were therefore excluded since this sampling frequency did not meet the minimum requirements laid down in the Nitrates Directive (Article 6, 91/676/EEC).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 7 Table 2.2 A summary of the Nitrate concentration data acquired during the 1992 round of site designations

Total number sites sampled 337 Number of sites with incorrect or incomplete grid references 4 Number of sites sampled on fewer than 12 occasions 92 Number of sites included in final analysis 241

The top panel in Figure 2.1 shows the frequency distribution of the average concentration of nitrate measured at all the sites sampled at least twelve times a year. At most sites, the average concentration ranged between 0 and 25mg/l but one site had an average concentration that was greater than 50mg/l. The bottom panel in figure 2.1 shows the frequency distribution of the maximum concentration of nitrate measured at all the sites sampled at least twelve times a year. The maximum concentration of nitrate recorded at most sites also ranged between 0 and 25 mg/l but fourteen sites had concentrations that were greater than 50 mg/l.

Figure 2.1 The average (top panel) and maximum (bottom panel) concentration of nitrate measured at all the surface water sites sampled at least twelve times in 1992.

Mean N conc. (n>=12)

250 200 150 100 50 0 0-25 mg/l >25 - 50 >50 - 100 > 100 mg/l mg/l mg/l

Max. N conc. (n>=12)

200

150

100

50

0 0-25 mg/l >25 - 50 >50 - 100 > 100 mg/l mg/l mg/l

In the next stage of the analysis, a Geographic Information System (GIS) was used to relate the geographic position of these sites to the position of the NVZ’s established in 1993.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 8 The NVZ boundaries were obtained from the EA and imported into an Arcinfo GIS at IFE Edinburgh. The colour coded map in figure 2.2 shows the average nitrate concentrations measured at all sites that were assumed to fall outside these NVZ boundaries. At most sites, the average concentration of nitrate was less than 25 mg/l but one site in the south-west of England had an average nitrate concentration that was greater than 50 mg/l. The colour coded map in figure 2.3 shows the maximum nitrate concentrations measured at all sites that were assumed to fall outside the NVZ boundaries. At most sites, the average concentration of nitrate was less than 25 mg/l but elevated concentrations of nitrate were recorded at fourteen sites that were largely concentrated in the south-east of England.

Table 2.3 lists these ‘problem’ sites arranged in descending order of maximum nitrate concentration. Many of these sites have maximum nitrate concentrations that are very close to the 50 mg/l threshold but there are five sites where the maximum concentration of nitrate exceeded 70 mg/l.

Table 2.3 A list of non-designated sites where the maximum concentration of nitrate exceeded 50 mg/l in 1992.

Region Nitrate concentration (mg l-1) Region Ngr Sample Size Mean Maximum South West ST2660 3600 20 53.164 127.296 Midlands SP33206650 139 49.164 104.887 Southern TQ629473 22 31.121 80.002 Midlands SP51507660 50 37.999 79.215 Southern TQ753570 23 27.227 71.162 North East TA080500 47 30.003 60.996 Thames SU9991075780 23 33.632 60.112 Thames TQ0225071820 23 34.273 57.460 Midlands SO69500425 16 26.078 54.808 Thames TQ0497067900 23 34.065 54.366 South West ST2300 3830 23 14.869 52.598 Thames SP4390006400 27 39.422 51.272 Thames TQ0878066310 20 31.051 50.830 Thames SU5310097200 23 37.897 50.388

2.5 CONCLUSIONS

The results of these analyses suggest that very few surface water sites which should have been designated under the Nitrates Directive were, in fact, overlooked during the 1992 review. Many of the sites identified as having relatively high concentrations of nitrate were associated with the River Thames but the three sites with the highest concentrations of nitrate were located in the South West, Midlands and Southern region. An outline description of these ‘problem’ sites is given in Section 5. Some sites are situated very close to existing NVZ’s but a few are in areas that are quite remote from these designated sites.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 9 Most of the sites listed should also have been considered for designation under the UWW Directive. Since the Thames sites are situated in an area of high population density, it is probably safe to assume that all meet the qualifying discharge criterion. The Southern site with the recorded maximum of 80 mg/l nitrate was also situated below an STW, but the most polluted site in the South West was on a reservoir supplying water to a canal.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 10 Figure 2.2

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 11 Figure 2.3

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 12 3. THE CONCENTRATION OF NITRATE IN THE GROUND WATERS SAMPLED IN ENGLAND AND WALES.

3.1 INTRODUCTION

The requirement to identify groundwaters which are affected by pollution, or could be affected by pollution, relates only to the Nitrates Directive. In 1993, the National Rivers Authority outlined the procedures that were to be used to assess the groundwater data that was then being collated by Water Companies in the UK. The data acquired was analysed using standard procedures that were designed for the following:

• to identify all groundwater sources with nitrate concentrations in excess of 50mg/l or a positive linear trend. • to reject all those sources which, by linear extrapolation were not projected to have a nitrate concentration in excess of 50 mg/l by the year 2010. • to reject all those sources where factors other than agricultural land use play a determining role e.g sources influenced by urban areas.

Any potentially polluted sources identified were then subject to careful scrutiny by the Ministry of Agriculture Fisheries and Food who identified the area of catchment involved and provided an independent estimate of nitrate leaching.

3.2 THE SITES DESIGNATED IN 1992.

Table 3.1 summarises the number of groundwater sources included in Nitrate Vulnerable Zones during the 1992 round of site designations. No groundwater sources were identified in Northern Ireland and there was only one borehole listed in Scotland.

Table 3.1 The number of groundwater sources included in the Nitrate Vulnerable Zones established during the 1992 round of site designations.

Groundwater sources Number of sources included in NVZ’s monitored England and Wales 147 400 Scotland 1 32 Northern Ireland 0 29 UK 148 461

3.3 THE GROUNDWATER NITRATE CONCENTRATIONS RECORDED IN ENGLAND AND WALES

Table 3.2 shows the results of a re-analysis of all the nitrate data collated for all groundwater abstraction points in England and Wales. Note that the data acquired from the EA were the raw values for each borehole i.e. they have not

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 13 been grouped into the sources listed in Table 3.1. Many of the results included in the raw data set were not labelled with a National Grid Reference. We have been told that most of these values are for mixed outputs from groups of boreholes and were therefore not included in the 1992 round of site designations. The most serious problem with the remaining data was the restricted coverage with over 45 % of the boreholes being sampled on fewer than twelve occasions.

Table 3.2 A summary of the groundwater nitrate data acquired during the 1992 round of site designations.

Total number of boreholes sampled 1608 Number of boreholes with missing or incomplete Grid References 518 Number of boreholes sampled on fewer than 12 occasions 719 Number of boreholes included in the final analysis 358

The top panel in Fig. 3.1 shows the frequency distribution of the average concentrations of nitrate measured at all the ‘boreholes’ sampled at least twelve times a year. Note that the term ‘borehole’ is used in a general sense since the raw data included measurements on wells and springs as well as drilled boreholes. At most boreholes the average concentration of nitrate ranged between 25 and 50 mg/l, but 23 % of the boreholes contained concentrations in excess of 50 mg/l. The lower panel in Fig. 3.1 shows the frequency distribution of the maximum concentration of nitrate measured at all the boreholes sampled at least twelve times a year. The maximum concentration of nitrate recorded in the majority of boreholes also ranged between 25 and 50/l, but 43 % had maximum concentrations that exceeded 50 mg/l.

In the next stage of the analysis, a GIS system was used to exclude all boreholes that were located within the NVZ’s designated in 1993. The colour coded map in Figure 3.2 shows the average nitrate concentrations measured at boreholes that were assumed to fall outside these NVZ’s. The map shows that 18 sites had elevated nitrate concentrations but several of these sites were located very close to the boundaries of the NVZ’s. The colour coded map in Figure 3.3 shows the maximum nitrate concentrations measured at all locations that were assumed to fall outside these NVZ’s. The map shows that 50 boreholes located outside these limits had maximum concentrations of nitrate that were greater than 50 mg / litre but many were again positioned very near to the boundaries of the designated areas.

Table 3.3 lists these ‘high nitrate’ sites arranged in descending order of maximum nitrate concentration. Some of the sites are situated very close to the NVZ’s but two sites in the south west of England are located well away from these designated areas.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 14 3.4 CONCLUSIONS

The results of our analyses suggest that most of the groundwater sites which should have been included in NVZ’s were identified during the 1992 round of site designations. Many of the non-designated sites identified as having elevated nitrate were, however, very close to the boundaries of designated NVZ’s. The methods used to transfer polygons between GIS systems are subject to some degree of error so some of the ‘problem’ sites identified may in fact lie within the boundary of these NVZ’s. At least four of the ‘high nitrate’ sites identified were, however, situated well away from the NVZ’s. A more detailed description of these four sites is given in section 6 which also includes some time-series plots of the nitrate concentrations reported at these sites in the late 1980’s and early 1990’s.

Table 3.3 A list of non-designated ‘boreholes’ where the maximum concentration of nitrate exceeded 50 mg / l in 1992.

Nitrate Concentration (mgL-1) Local ID / Borehole MAFF ID Sample Size Mean_N Max_N Drove Lane 1 16 45 57.98 92.11 Barton 1 5 41 74.96 82.82 Waneham Bridge 2 39 42 69.88 82.82 Barton 3 5 40 72.17 77.06 Waneham Bridge 1 39 54 70.67 75.73 Crescent Rd. Well No.R5 596 31 49.87 74.00 Ulceby 2 38 28 60.02 73.52 Seven Springs 177 207 33.39 73.05 Ulceby 3 38 23 56.34 71.74 Haseley Gathering Grounds B/H 769 52 47.08 71.60 Aldeburgh Hall 2 25 48.44 70.70 Aldeburgh Raw 2 42 48.57 70.70 Ulceby 1 38 24 54.80 70.42 Barrow 1 4 20 65.59 69.97 Thorpe Bh 1 265 30 60.76 65.99 Lord Of Manor 70 50 56.47 63.31 Chew Hill Head (Monthly Data) 896 12 53.16 60.10 Egford Sub 79 215 40.42 58.70 Little London 3 27 18 55.28 58.46 Lower Swell 173 105 33.77 58.43 Southwold Quay Lane 34 85 44.69 56.90 Aswarby 2 3 22 35.33 56.69 Little London 1 27 13 53.55 56.69 Egford Main 79 215 37.42 56.40 Habrough 1 22 17 50.85 55.80 Bowthorpe 11 36 52.06 55.36 Healing Bore 2 23 14 50.41 54.03 Southwold Raw 34 26 46.65 53.80 Aswarby 1 3 24 35.04 53.59 Healing Bore 5 23 14 50.00 53.59 Habrough 2 22 26 50.24 53.14 Blockley Mill 134 67 45.10 52.68 Thornton 1 36 31 40.08 50.04

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 15 Figure 3.1 The average (top panel) and maximum (bottom panel) concentration of nitrate measured at all the groundwater sites sampled at least twelve times in 1992.

Mean N conc. (n>=12)

250 200

150 100 50

0 0-25 mg/l >25 - 50 >50 - 100 > 100 mg/l mg/l mg/l

Max. N conc. (n>=12)

200

150

100

50

0 0-25 mg/l >25 - 50 >50 - 100 > 100 mg/l mg/l mg/l

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 16 Figure 3.2

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 17 Figure 3.3

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 18 4. THE CONCENTRATION OF ORTHOPHOSPHATE IN THE SURFACE WATERS SAMPLED IN ENGLAND AND WALES

4.1 INTRODUCTION

In 1991, the European Community produced a Directive that laid down minimum standards for the provision of sewerage systems and sewage treatment facilities in all member states. This Directive, commonly known as the Urban Waste Water Treatment Directive, required member states to identify all waters that were either affected by pollution or were likely to be affected by pollution by the end of 1993. In this section we review the steps taken in the UK to identify the bodies of freshwater covered by the Directive and the methods used to assess their trophic status. The section compares the number of sites identified in the original round of designations with those identified in a new analysis of raw data provided by the Environment Agency.

4.2 THE IDENTIFICATION OF SITES

The criteria used to identify ‘sensitive areas’ are laid down in Annex 11A of the UWWT Directive and are designed to cover the following situations:

• surface freshwaters used for the abstraction of drinking water which contain more than the concentration of nitrate laid down in the EC Directive concerning the quality of surface waters used as a source of drinking water (Directive 75/440/EEC); • freshwaters which are eutrophic or those which could become eutrophic in the near future if protective measures were not taken; • situations where treatment more stringent than secondary treatment is required in order to fulfil other Community Directives.

Some of the criteria used to identify ‘sensitive areas’ under the UWWT Directive are very similar to those used for identifying polluted waters under the Nitrates Directive (Directive 91/676/EEC), but the sites selected under the UWWT Directive must also be subject to a defined anthropogenic load. The Directive defines this critical load as a ‘population equivalent’ (p.e.) greater than 10,000, where a p.e. of 1 is defined as the organic biodegradable load having a five-day biochemical oxygen demand (BOD) of 60g oxygen per day. In the 1992 round of designations, the Department of the Environment in the UK used these p.e. values as the first test criterion and then acquired data from the National Rivers Authority to assess both the nutrient and trophic status of the short-listed sites. The data set analysed by the NRA was that acquired to meet the criteria laid down by the ‘drinking waters’ Directive (Directive 75/440/EEC).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 19 Any sites with an average annual nitrate concentration of 50 mg/l or above were immediately designated and the trophic status of the remaining sites assessed by referring to the measured value of three specific variables:

• the average annual phosphorus concentrations measured either as total phosphorus (standing waters) or orthophosphate (running waters); • the diurnal variation in the concentration of dissolved oxygen; • the average annual concentration of the phytoplankton chlorophyll.

If no information on these three attributes was available for the short-listed sites, the sites were excluded from any further analysis.

4.3 THE SITES DESIGNATED IN 1992.

Table 4.1 shows the number of freshwater sites designated as sensitive areas under the UWWT Directive in 1992. The sites are listed according to the regions that were then administered by the National Rivers Authority. Several regions only designated one or two sites, presumably because no information was available on the chlorophyll content and/or the diurnal oxygen variation of the selected sites.

Table 4.1 The number of ‘sensitive areas’ established during the 1992 round of site designations.

Administrative Region Number of Sites Designated

North West 6 Severn Trent 4 Welsh 1 South Western 1 Southern 2 Thames 5 Anglian 13 Northumbria and Yorkshire 1 England and Wales 33

Table 4.2 shows the results of a re-analysis of the orthophosphate data provided by the EA from the 1992 round of site designations. No data has yet been received from Scotland and the results from Northern Ireland have been analysed in tabular form since these results were geo-referenced on the Irish rather than the UK National Grid. The most serious problem with the data was again the restricted seasonal coverage. Over 50 % of the sites included in the survey had been sampled on fewer than 12 occasions and were therefore excluded from any further analysis.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 20 Table 4.2 A summary of the orthophosphate concentration data acquired from the EA for 1992.

Total number of sites sampled 337 Number of sites with incorrect or incomplete Grid References 4 Number of sites sampled on fewer than 12 occasions 182 Number of sites included in final analysis 145

The upper panel in Fig. 4.1 shows the frequency distribution of the average concentrations of orthophosphate measured at the sites sampled at least twelve times a year. The distribution of orthophosphate is decidedly bi- modal with 38 % of the sites having average concentrations below 25ug/l and 35 % having concentrations in excess of 100 ug/l. The lower panel in Fig. 4.1 shows the frequency distribution of the maximum concentrations of orthophosphate measured at the sites sampled at least twelve times a year. More than 60 % of the sites had maximum orthophosphate concentrations that were greater than 100 ug/l, a value that is known to be associated with ‘significant plant growth related problems’ in a number of UK rivers (DOE, 1993).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 21 Figure 4.1 The average (top panel) and maximum (bottom panel) concentration of orthophosphate measured at all the surface water sites sampled at least twelve times in 1992.

Mean OP conc. (n>=12)

60 50 40 30 20 10 0 0-25 µg/l >25 - 50 >50 - 100 > 100 µg/l µg/l µg/l

Max. OP conc. (n>=12)

100 80 60 40 20

0 0-25 µg/l >25 - 50 >50 - 100 > 100 µg/l µg/l µg/l

In the next stage of the analysis, a GIS system was used to map the geographical distribution of all the sites sampled in England and Wales. The colour coded map in Figure 4.2 shows the average orthophosphate concentrations recorded at all sites that were sampled at least twelve times a year and which were not subsequently designates as Sensitive Areas. Many of the sites with elevated orthophosphate concentrations were located in the South East of England but there were also a number of sites with high orthophosphate concentrations in the north-west and the south-west.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 22 Figure 4.2

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 23 Figure 4.3

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 24 The colour coded map in Figure 4.3 shows the maximum orthophosphate concentrations recorded at all sites that were sampled at least twelve times a year and which were not subsequently designated as Sensitive Areas. Only a small number of sites in Wales and the south-west of England have maximum orthophosphate concentrations that fall below 100 ug/l empirical threshold and the vast majority have maximum concentrations that are very much greater than this empirical threshold.

Table 4.3 lists all the sites where the maximum concentration of orthophosphate exceeded 500 ug/l (0.5 mg/l). The sites have been arranged in descending order of maximum concentration and the average concentration of orthophosphate included for comparative purposes.

Table 4.3 A list of sites where the maximum concentration of orthophosphate exceeded 0.50 mg /l in 1992.

OP concentration (mg l-1) Region NGR Sample size Mean Maximum

Southern TQ629473 22 1.562 7.200 North West NY342200501800 12 0.569 6.300 Thames SP4510006400 26 0.709 4.200 North West SD352600447900 12 0.293 2.640 Southern TQ497461 23 1.397 2.000 Thames TQ3550088300 20 1.445 1.870 Thames SU7030071200 30 0.285 1.400 Southern TQ753570 23 0.822 1.300 North West SD353200448200 12 0.185 1.250 North West SD388200431700 15 0.198 1.200 South West ST5780 1390 21 0.591 1.200 South West ST1870 2480 20 0.379 1.100 Southern TQ379345 22 0.327 0.980 South West ST2660 3600 20 0.340 0.820 North West NY352400514700 12 0.119 0.780 Southern TQ49304740 12 0.343 0.700 Thames SP3020010700 30 0.100 0.640 North West SD369400426000 16 0.101 0.600 South West SY0732 8418 12 0.159 0.600 North West SJ362100355300 20 0.117 0.580 South West SY2618 9532 13 0.355 0.570 South West SZ0650 9730 46 0.311 0.550 North West NY308900515300 81 0.028 0.520 North West NY326700532600 69 0.024 0.520 North West SD390100436400 15 0.092 0.520 Thames SP4612042320 26 0.188 0.510 North East TA080500 47 0.203 0.500

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 25 At most sites, these average concentrations are closely correlated with the recorded maximum concentrations but there are a few sites where the maxima reported are very much higher than the seasonal average. Some of the rural sites shown could well not be covered by the UWWT Directive but there was no simple way of relating the measured concentrations to the p.e. values calculated for the different catchments. A more detailed description of six of these sites is given in Section 7. The examples selected are taken from a number of EA regions and include a few cases where the p.e. value was below the stipulated threshold.

4.4 CONCLUSIONS

The results of these analyses suggest that a very large number of potentially eutrophic sites were not identified during the 1992 round of site designations. It is, however, important to emphasise that this re-appraisal is based solely on the measured concentration of a key driving variable (orthophosphate) not the biological response of the systems to the implied nutrient load. A more detailed analysis of the raw data also shows that many of the high orthophosphate values reported were extreme values that could well have been produced by sample contamination. The method recommended for identifying ‘polluted’ sites in the Directives places too much emphasis on these extreme values. A method based on the upper confidence limit of the collated measurements would be much more appropriate and would reduce the risk of selecting sites that were biased by a single high measurement. Reliable methods have been developed to assess the trophic status of standing waters from their phosphorus content (OECD, 1982) but comparable techniques have yet to be developed for running waters. In this study, we have used a maximum concentration of 100 ug orthophosphate / litre as an empirical index of potential productivity. It is clear from discussions with staff from the EA that they recognise the practical difficulties of defining the ‘trophic’ status of sites from such simple chemical measurements. Their decision to exclude all sites that did not have any supporting biological data in the first round of site designations is scientifically valid, but the resulting list of designated sites gives a very biased view of the ‘state of the environment.’

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 26 5. THE SURFACE WATER SITES WITH ELEVATED NITRATE CONCENTRATIONS THAT WERE NOT DESIGNATED IN 1992.

A list of surface water abstraction sites (SWAD) at which the maximum

measured nitrate concentration exceeded 50 mg NO3/l (11.3 mg NO3-N/l) limit imposed by the Nitrates Directive has been given in Table 2.3. In this section we describe five of these sites in greater detail by referring to published sources and information contained in the catchment management plans originally produced by the National Rivers Authority and now updated by the Environment Agency (LEAPS). All the site maps included in the Case Studies are photocopies of originals published by the NRA and the EA. A list of all the LEAPS documents consulted is included in the text together with any scientific papers identified in a preliminary literature review.

5.1 SOUTH-WEST REGION

Durleigh Reservoir

The maximum nitrate concentration measured in Durleigh reservoir in 1992

was 127.2 mg NO3 /l. The reservoir is situated in the catchment of the river Parrett approximately 3 km west of Bridgewater (ST26603600) and serves as an impoundment reservoir from the Taunton and (see figure 5.1). The abstraction licence (to Wessex Water Services Ltd) is held by the Board. The daily licence allows abstraction of 30 ML/day subject to an annual total of 8000 ML. The canal is fed by water from the (1) and this abstraction is exempt from regulation as the water is required for 'navigation purposes'.

The Local Environment Action Plan (LEAP) consultation report was published in March 1997 (2). The canal marginally failed to comply with its River Quality 0bjective (RQO) of RE4 (generally poor water quality) due to low oxygen levels. The LEAP stated that the poorest water quality was found downstream of the intake to Durleigh reservoir but the quality of the pumped water must also be low. The data from 1992 showed that nitrate concentrations at the Durleigh SWAD site exceeded the 50 mg/l limit in late October and, with one exception, all the samples taken in November. It is not clear if the SWAD site is on an inflow to the reservoir (in which case water quality would reflect land-use in the catchment) or in the reservoir (in which case it would be a blend of abstracted and inflowing water).

A review of existing designations in this region was due for completion in 1997 but first indications were that no new zones would be designated in the South-West Region. There was no supporting information available in the scientific literature.

(1) National Rivers Authority (1995) River Tone Catchment Management Plan: Consultation Report. National Rivers Authority (South-Western Region) (2) Environment Agency (1997) River Parrett Consultation Report. Local Environment Agency Plan.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 27 The Ashford Reservoir (ST23003830) also failed the nitrate compliance

(maximum NO3 concentration 52.598 mg/l) and, like Durleigh, is situated in the catchment of the river Parrett (Figure 5.1). However, the raw data indicate only the failure of one sample in November.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 28 Figure 5.1

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 29 5.2 SOUTHERN REGION

River Medway downstream of Tonbridge

This site (TQ629473) had a maximum nitrate concentration of 80 mg/l in 1992 and is situated on the river Medway approximately 4 km downstream of Tonbridge (Figure 5.2). The licence for abstraction was granted post 1963 and the volume of abstraction has been designed to protect the environment, protect existing lawful interests and balance the resources in the aquifer. The maximum abstraction permitted is < 1 Ml/day. The discharge from Tonbridge STW enters the river approximately 1 km upstream. A survey of available literature from 1981 to present provided no additional information on the nitrate chemistry of the river Medway.

The Medway Catchment Management Plan (1), stated that diffuse pollution caused by surface run-off from agricultural land is a cause for concern in the catchment and that nitrate concentrations can exceed the maximum admissible concentration permitted (by the EC Nitrate Directive) at the Springfield abstraction intake.

Another site in this catchment is also identified in Table 2.3 (NGR TQ753570) since it had a maximum nitrate concentration 71.1 mg/l in 1992. This site is situated downstream (see Figure 5.2), near the tidal limit at Maidstone and is operated by Southern Water Services. The water is pumped from the Medway to Bewl Water which serves not only as the water supply but also as the main regulating reservoir for the river Medway scheme. The catchment management for the area stated that elevated nitrate concentrations are usually associated with the first rains of Autumn but the database for 1992

revealed nitrate (NO3) concentrations of 80 and 70 mg/l in April and May at Tonbridge and 71 mg/l at Maidstone in February. These were the only time nitrate concentrations exceeded the acceptable limit for either site. It would seem the sites are only intermittently associated with unacceptable concentrations of nitrate. Moreover, the management plan stated that the excedence of the nitrate limit is a major issue within the catchment but also that intakes were not used during periods of high nitrate concentrations. The nutrient status of these waters have recently been reviewed and information collated for the 1997 round of site designations.

(1) National Rivers Authority (1993). River Medway Catchment Management

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 30 Figure 5.2

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 31 5.3 THAMES REGION

River Thames

Table 2.3 lists six sites within the Thames region which fail the nitrate compliance. All these sites are associated with abstraction from the river Thames. There is a general trend for the maximum concentration of nitrate to decrease with distance downstream which could indicate assimilation of nitrate or progressive denitrification. A more detailed analysis of the data showed that the highest concentrations of nitrate were usually recorded in January and December. The nitrate concentrations recorded during this period were all greater than 50 mg / l but the position of the sampling stations were not clearly indicated and may include sites on the reservoir intake. The river Thames, and associated impoundment reservoirs, have been important sites for the development of mathematical models to describe the behaviour of nitrate in surface waters (1) (2) . However, these descriptions utilise long-term data sets obtained before the 1992 round of designations and cannot be used to assess the sites current status. More recent modelling studies, in which maximum nitrate concentrations are predicted from annual nitrate loads (3) , also refer to these historical data sets and therefore provide little additional information on recent trends.

5.4 NORTH-EAST REGION

This site (TA 080500) is situated on the River Hull at , approximately 30 km north of Kingston-upon-Hull and had a maximum concentration of 60.9 mg / l nitrate in 1992. The site area it is flanked by three nitrate vulnerable zones collectively known as the River Hull NVZ. (see Figure 5.3). When this map is compared with the NVZ boundaries supplied by the EA (Figure 2.2) it appears that this was provisionally designated and was then excluded after further consultation. The average nitrate concentrations recorded at the site were, however, relatively low. A more detailed analysis of the data showed that, of the 47 samples from this site only two (October

(61mg/l) and January (57.9 mg/l) exceeded the 50 mg NO3/l limit.

Information within the River Hull Catchment Management Plan (4) indicated there were extensive reaches of the river, including the abstraction site, which failed to meet water quality targets. Indeed this failure in addition to the failure of EC Directive drinking water standards were seen as major issues of concern within the catchment. The LEAPS document perused show that the abstraction at Helpholme also had elevated nitrate concentrations and noted

(1) Whitehead, P. G. (1990) Modelling nitrate from agriculture into public water supplies Philosophical Transactions of the Royal Society of London Series B 329, 307 - 410 (2) Whitehead, P. G. and I. P. Toms (1993) Dynamic modelling of nitrate in reservoirs and lakes Water Research 27, 8, 1377 - 1384 (3) Scolefield, D., E. I. Lord, H. J. E. Rodda and B. Webb (1996) Estimating peak nitrate concentrations from annual nitrate loads. Journal of Hydrology 186, 355 - 374. (4) National Rivers Authority (1994) River Hull and Coast Catchment Management Plan: Action Plan. National Rivers Authority (Northumbria and Yorkshire Region)

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 32 that this area would, almost certainly, be included in an NVZ in the next round of site designations.

The flow regime in the river Hull is dominated by the groundwater level in the surrounding chalk aquifer and therefore the concentration of nitrate in the abstracted water is dependent upon protection of the chalk aquifer from nitrate pollution. This is a major objective stated as major issue 3 in the Catchment Management Action Plan (1) . The proximity of this SWAD site to designated nitrate sensitive areas would make it an ideal site to examine the effectiveness of the implementation of good agricultural practise. Unfortunately although there are many studies on the river Hull in the scientific literature (2) there are no independent reports of nitrate concentrations. Moreover, the river was not included in the sampling regime for the LOIS study. Therefore the lack of data prevents what would have been a useful comparative study.

(1) National Rivers Authority (1995) River Hull and Coast Catchment Management Plan: Action Plan. National Rivers Authority (Northumbria and Yorkshire Region) (2) Yamakanamardi, S. M. and R. Goulder (1995) Activity and abundance of bacterioplankton in three diverse lowland water courses. Regulated Rivers Research and Management 10, 51 - 67

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 33 Figure 5.3

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 34 6. THE GROUND WATER SITES WITH ELEVATED NITRATE CONCENTRATIONS THAT WERE NOT DESIGNATED IN 1992.

A list of ground water sites at which the maximum measured nitrate

concentration exceeded 50 mg NO3/l (11.3 mg NO3-N/l) limit imposed by the Nitrates Directive has been given in Table 3.3. In this section of the report we describe the long-term changes recorded in five of these sites in greater detail and present selected results from other boreholes situated in the same area.

6.1 ALDEBURGH

This site (NGR TM 45405680; Fig. 6.2) includes two of the boreholes listed as having elevated concentrations of nitrate in Table 3.3 (Aldeburgh Raw and Aldeburgh Hall, MAFF ID 2). Both had similar mean and maximum nitrate concentrations in 1992 although this seems rather fortuitous as the data from Aldeburgh Hall was very variable. The time-series in Fig. 6.1 show the longer- term variations in nitrate recorded at the two sites. There was no consistent trend in the series but many of the individual measurements were above the permitted concentrations. The most recent data collated for the two sites nevertheless suggests that there has been a recent upward trend in the concentration of nitrate. There was no supporting data available from the literature and the only source of additional information was the East Suffolk Consultation Report (1) . This report confirmed there had been no designations of Nitrate Vulnerable Zones in the East Suffolk Catchment (Figure 6.2).

The Aldeburgh borehole is situated close to the coast at the northern end of a geological area known locally as the sandlings. The Environment Agency acknowledge there was evidence for elevated concentrations of nitrate in this area (issue A1) which is confirmed by a plot of average nitrate concentrations (summarised by Parish) in private wells and boreholes (Figure 6.3). All sites show average nitrate concentrations at, or above, the acceptable concentration. This independent evidence suggests nitrate concentrations in the groundwater now consistently exceed the permitted levels and should be included in an NVZ.

It is also of interest to note that Southwold Raw and Southwold Quay Lane, groundwater sources which are listed in Table 3.3 (MAFF ID 34) are also located in this catchment The trend of nitrate concentrations pre-1992 for these sources (Figure 6.4) also shows values very close to the acceptable limit, in addition to a clear upward trend post 1992. This site does not appear to be associated with the sandlings area which would indicate a general upward trend of the nitrate concentration in the groundwater of the area.

(1) Environment Agency (1997) East Suffolk Consultation Report June 1997. Local Environment Agency Plan.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 35 Figure 6.1

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 36 Figure 6.2

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 37 Figure 6.3

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 38 Figure 6.4

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 39 6.2 DROVE LANE

This site (TF 0552 4623) is associated with two sources (Drove Lane 1 and Drove Lane 2) situated to the west of Sleaford (Figure 6.6). Only Drove Lane 1 (MAFF ID 16) was identified from the raw data but both sites are included here for the sake of completeness. Figure 6.5 shows the long-term variations in the concentration of nitrate recorded in the two boreholes. The individual measurements are highly variable but the 50 mg/l level was regularly exceeded in the late 1980’s and early 1990’s (Figures 6.5). A search of the literature detected no corroborative evidence for these observations and additional information was sought from the Lower Witham Catchment Management Plan (1) . Thin soils, particularly to the west (see Figure 6.6) provide little protection for the aquifer from diffuse sources of pollution and the management plan provided numerous references to the EC Nitrate Directive. The problem of diffuse sources of pollution in this area is now attracting a considerable amount of scientific interest. The Lincolnshire Limestone Aquifer (LLA) has now become a ‘flagship’ site for the development of mathematical models that simulate the transfer of chemicals through groundwater aquifers. The EA catchment management plan recognised that the nitrate limit is regularly exceeded and the central and southern LLA is being considered as a candidate for designation as a nitrate vulnerable zone (Figure 6.6). Extension of the boundary of the NVZ designations within this area has been reviewed using sophisticated mathematical modelling techniques (2) and it is likely the existing NVZ will extend to the west of Sleaford thereby including the Drove Lane boreholes.

(1) National Rivers Authority (1995) Lower Witham Catchment Management Plan: Consultation Report.

(2) National Rivers Authority (1995) Lower Witham Catchment Management Plan: Consultation Report.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 40 Figure 6.5

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 41 Figure 6.6

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 42 6.3 EGFORD

The Egford groundwater source (ST 7559 4819; Figure 6.9) is situated to the west of the Frome in the catchment of the lower Bristol Avon. The source draws water from two boreholes (Egford Main and Egford Sub) which are identified by the same MAFF ID (79) in Table 3.3. The time-series in Fig. 6.7 shows the variations in the concentration of nitrate recorded in the two boreholes in the 1980’s and 1990’s. In the 1980’s, the concentrations recorded at measurements at Egford Main were always below 50 ug / litre but elevated nitrate concentrations were periodically recorded in Egford Sub. Much higher nitrate concentrations were recorded at both sites in the 1990’s and a number of more extreme events have been recorded during the winter months.

The Chew Hill (ST 5970 5330) borehole (MAFF ID 896) also lies within this catchment but is recorded as a surface water abstraction (see Figure 6.10). The long term trend of nitrate concentration in this borehole is shown in figure 6.8. Pre-1992 the nitrate concentrations increased during 1988/89 after which the 50 mg/l limit was regularly exceeded. Post 1992 the trend was reversed but this seemed a transient phase as during 1995 the concentration increased to

over 75 mg NO3/l.

A survey of literature revealed no additional information and, as with the other sites, the only corroborative information had to be obtained from the local catchment management plan (1) and the annual review (1997). These management plans contained very few references to the Nitrate Directive and there were no cross-references in the section describing the general implementation of EC Directives. The EA have, however, produced a number of publications that review the diffuse pollution of groundwater (Policy and Practise for the Protection of Groundwater) but copies of these documents have yet to be obtained.

(1) National Rivers Authority (1995) Lower Bristol Avon Catchment management Plan: Consultation report.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 43 Figure 6.7

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 44 Figure 6.8

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 45 Figure 6.9

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 46 Figure 6.10

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 47 7. THE SURFACE WATER SITES WITH ELEVATED ORTHOPHOSPHATE CONCENTRATIONS THAT MIGHT BE CONSIDERED ‘EUTROPHIC’ ACCORDING TO THE CRITERIA DEFINED IN THE UWWT DIRECTIVE.

The list of surface water abstraction sites (SWAD) at which the maximum measured orthophosphate concentration exceeded 500 ug per litre has been given in Table 4.3. In this section of the report we describe six of these sites in greater detail by referring to published sources and the EA catchment management plans. No attempt has been made to check the p.e. status of the different sites since this information is not readily available. Some sites that appear near the top of the list in Table 4.3 are, however, located in rural areas where the p.e values must be below the critical threshold. Some of these sites have, nevertheless, been included as ‘case studies’ since they illustrate the problems that can arise when too much emphasis is placed on individual measurements.

7.1 NORTH-WEST REGION

Dubbs Tarn (NY422018)

This is an upland reservoir known as Dubbs Tarn in the catchment of lake Windermere (Cumbria). The surrounding land is primarily upland grazing and the failure of this site (maximum orthophosphate concentration of 0.63 mg/l) was surprising. The reservoir is leased as a put and take rainbow trout fishery by the Windermere, Ambleside and District Angling Association. A wind driven mixing device is installed in the Tarn so it is possible that algal blooms have been a problem in the past. A search of the literature revealed little additional information for this site. The records for the site contained only 12 determinations of orthophosphate and six of these were at the limit of detection. The high average value for the whole data set was biased by one reading of 6.3 mg P/l which could well have been due to contamination or careless sample collection.

Barnacre Reservoir (SD5260044790).

Barnacre reservoir is situated approximately 4 km north-east of Garstang (Lancashire) and is also used as a source of water by North-West Water. This site is recorded as having a maximum concentration 2.64 mg/l orthophosphate in Table 4.3 but nothing is known of its p.e. status. Four of the 12 analyses reported were again at the limit of detection and the single extreme value (2.64 mg P/l) was recorded in November.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 48 7.2 SOUTHERN REGION

River Medway (TQ629473)

This site is on the river Medway approximately 4 km downstream of Tonbridge and lies on the western boundary of the Mid-Kent Water Company (see Figure 7.1). The licence for abstraction was granted post 1963 and the maximum abstraction permitted is < 1 Ml/day. The discharge from Tonbridge STW enters the river approximately 1 km upstream. The site heads the list of concentrations recorded in Table 4.3 with maximum and mean concentrations of OP as 7.2 and 1.562 respectively. A survey of available literature from 1981 to 1998 provided no corroborative data for this site. However, some publications highlighted poor water quality in the upper Medway estuary (1) which was due in part to localised effluent discharge. The Local Environment Action Plan for the Medway catchment (2) was the only readily available source of additional information. The river water quality objective for the river the Medway is1B (good) which had been achieved for 70% (219.6 km) of the river. However, there were local failures, particularly in summer when low flows, high temperature and high concentrations of nutrient caused excessive algal (or weed) growth. The attached map (Figure 7.2) showed the areas most frequently affected but this does not include the station analysed here. A key issue identified in the management plan was the control of taste and odour problems in potable supplies. This suggests that the abstracted water contained relatively high concentrations of algae but there is no reference to any supporting biological studies. The Local Environment Action Plan also stated that low flow and high population densities in the upper catchment led to ‘water quality’ problems and there was a proposal to extend the designation of appropriate river reaches in line with EC Directives.

River Eden (TQ497461)

A site on the river Eden (a tributary of the Medway) was also identified as a ‘high phosphate’ water in Table 4.3. This site is situated near Chiddington approximately 3 km downstream of Edenbridge (Figure 7.1). The Chiddingstone input is managed by the East Surrey Water Company which is licensed to abstract >5Ml/day. The water is pumped to Bough Beech reservoir and used to supply the Reigate area. This represents the export of water from the Medway to the Thames catchment. The discharge of effluent from Edenbridge STW no doubt affects water quality and although the general quality is regarded as 1B (Figure 7.2) this reach of river is frequently affected by intermittent pollution. The evidence suggests both these sites would qualify for designation under the UWWT directive and this was recognised in the catchment management plan. However, there was no indication of the time scale over which designation issues would be decided.

(1) Wharfe, J.R., A. Dines and L. A. Bird (1986) The environmental impact of paper mill discharges to the upper Medway estuary, Kent, England. Environmental Pollution (Series A) 40, 4, 345 - 358 (2) National Rivers Authority (1993) River Medway Catchment management Plan. Final Report. NRA (Southern Region)

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 49 Figure 7.1

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 50 Figure 7.2

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 51 7.3 THAMES REGION

Farmoor Reservoir

Farmoor is a complex of two reservoirs (SP4510006400) acting as pumped storage for water abstracted from the river Thames approximately 6 km west of Oxford. Farmoor 1 was constructed in 1965 and was designed with draw off valves situated at either end of 0.49 km2 lake (1) . A diagram of Farmoor 1 is presented in the attached Figure 7.3. The reservoir has a maximum depth of 11m and frequently becomes thermally stratified during the summer. In 1973/4 the highest concentration of orthophosphate was 0.55 mg /l (2) but the maximum concentration recorded in 1992 was 4.20. In the early days of the reservoir, the maximum concentrations of chlorophyll recorded in the surface water was 36.8 mg/l but no biological data is available for 1992. There is little doubt that Farmoor has been regarded as a eutrophic reservoir since construction and, as judged by concentrations of orthophosphate recorded in 1992 should still be so. In 1976, the complex was extended by excavating the adjacent gravel pits to form Farmoor 2. Although this is approximately twice the size of Farmoor 1 the biology should be very similar to the smaller reservoir.

Another site in this system (SP4390006400) is also listed in Table 4.3. This site was located on the inflow to the reservoir and had a much lower concentration of orthophosphate (0.76 mg /l ) than the stored water. The reservoir maximum of 4.2 mg P/l seemed outstanding and could possibly be regarded as an outlier. Analysis of the data without this value provided a mean of 0.569 with a maximum of 0.7 mg P/l which could be reconciled with the intake water. There is no discharge of sewage effluent directly to the reservoir and therefore the issue of whether this site qualifies for UWWT designation is problematical.

River Lee

Site TQ3550088300 is situated on the river Lee (Fig. 7.4) and had a recorded maximum orthophosphate concentration of 1.87 mg/l in 1992. Most of the published information on this site is contained information in the Lower Lee Catchment Management Plan published by the NRA in November 1995 (3) . A high proportion of the water flowing down the river is used for public supply and most of this volume abstracted at Chingford upstream of this monitored site. The Chingford site has not been listed so it is either already designated or fails to meet the designation criteria. The plans imply that the quality of water in the river declines downstream of Tottenham which is very close to the

(1) Youngman, R. E. (1975) Observations in Farmoor, a eutrophic reservoir in the upper Thames valley, during 1965 - 1973. Proceedings Symposium, The effects of storage on Water Quality. Reading University (organised by WRC, Medmenham, Bucks.) (2) Youngman, R. E. (1975) Observations in Farmoor, a eutrophic reservoir in the upper Thames valley, during 1965 - 1973. Proceedings Symposium, The effects of storage on Water Quality. Reading University (organised by WRC, Medmenham, Bucks.) (3) National Rivers Authority (1995) Lower Lee Catchment Management Plan: Action Plan. NRA (Thames Region) November 1995.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 52 SWAD site identified in Table 4.3. It is not therefore surprising that water quality problems are associated with this site. In the management plan River Quality Objectives (RQO's) have been developed only for river ecology (RE) and RQO's for potable abstractions are still being developed. Around the Walthamstow/Tottenham area the river is allocated RE5 which describes poor water quality likely to limit fish populations. The plan recognises that with current projected investment the maintenance of this RQO is short term ie not likely to improve within ten years. The plan also states that a review due to be completed in by December 1997 will re-examine the data available to determine if more reaches should be designated under the UWWT Directive.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 53 Figure 7.3

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 54 Figure 7.4

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 55 7.4 ADDITIONAL REFERENCES

Lack. T. J. (1971) Quantitative studies on the phytoplankton of the river Thames and Kennet at Reading Freshwater Biology 1, 213 - 224 Neal, C., M. Harrow and R. J. Williams (1998) Dissolved carbon dioxide and oxygen in the river Thames Spring/Summer 1997. The Science of the Total Environment 210/211, 205 - 217 Robertson, A. L. (1990) The population dynamics of Chydoridae and Macrothricidae (Cladocera:Crustaceae) from the river Thames, UK. Freshwater Biology 24, 375 - 389 Duncan, A. and L. C. Dos Santos (1989) Plankton interactions in the London Reservoirs. Ergebnisse der Limnologie 33, 475 - 478.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 56 8. CONCLUSIONS

8.1 INTRODUCTION

This report has been compiled from information collated by the National Rivers Authority (NRA) during the first (1992) round of site designations. All the data analysed was collected by the regulatory authorities or the responsible Water Company. The UK Government is satisfied that such organisations operate to the highest professional standards and considers NRA and Water Company data should be the only basis for designation (MAFF, 1995). Many of the procedures used to identify ‘problem’ sites have since been modified and a document explaining the EA’s current management strategy for aquatic systems in England and Wales has now been published as a Consultative Report (EA, 1998). In this chapter, we review the methods used to identify Sensitive Areas and Vulnerable Zones in 1992 and comment on some recent documents received from the Environment Agency.

8.2 THE NITRATES DIRECTIVE

8.2.1 Surface Waters.

All the surface water designations in 1992 were based on the measured concentration of nitrate nitrogen. No site was designated on the basis of its trophic status since it was considered that biological productivity was limited by the supply of phosphorus rather than nitrogen. The EA acknowledge that the concentrations of nitrate in the rivers and lakes of southern and eastern England are high (European Environment Agency, 1998) and are now addressing these problems on a catchment by catchment basis. Over the last twenty years, monitoring data for England and Wales suggests that there has been no significant changes in river nitrate levels, although there may have been marked changes in specific catchments (DoE, 1996).

As regards sources, the UK use of nitrogenous fertilisers increased by around fifty percent from 1970 to the early 1990s (Environment Agency, 1996). Trends in inputs of nitrogen from Sewage Treatment Works are not known (Environment Agency, 1998) but are assumed to be relatively unimportant in winter when the concentration of nitrate typically reaches its annual maximum. The following paragraph taken from the MAFF document issued in 1995 explains how the impact of point sources was largely ignored when the NVZ’ s were originally designated:

“With a large network of river sampling points it is inevitable that many are sited downstream of sewage treatment works. However, the GQA (General Quality Assessment) points are so sited so as to be typical of the river reach and not to be influenced by point discharges (our italics). Furthermore, such

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 57 sampling points tend to show the impact of sewage-derived nitrate in summer when effluent nitrate concentrations are high and dilution in the receiving river is low. In the autumn / winter when river flows (and hence dilution of effluents) are high the nitrate load from sewage works is typically a very small part of the total. It is at these times that the rivers fail the nitrate parameter.”

This statement first implies that the sites sampled were not influenced by STW’s and then suggests that these loadings were not particularly important. Comments such as ‘tend to show’ and ‘is typically a very small part ’ are general statements that shed little light on the procedures used to quantify the sources of nitrate at any particular location. The identification of nitrate sensitive areas is further complicated by the methods used to delineate the land to be included in the NVZ. This procedure is clearly stated in a MAFF document issued in 1994:

“ The lower extremity of a polluted water is determined by an abstraction point which exceeds the 50 mg/l limit using the methodology of Directive 75/440/EEC. The upper point is either the first upstream sampling point which complies with the 50 mg/l limit on a 95 percentile approach using five year’s data, or the source of the headwaters, if all the sampling points fail. The vulnerable zone is the land draining into this polluted water. This land is defined by delineating the boundary of the natural catchment, upstream of the abstraction, and reducing this catchment, as appropriate, to exclude land draining the first upstream passing point.”

When the boundaries of the existing NVZ’s were defined, the process required much consultation and argument at local level. In some cases, the position of man-made drains was also considered and the boundaries changed to take account of additional hydrometric information. As third parties, we cannot possibly define the areas that ‘should have been included’ on a site by site basis. Only 14 high nitrate sites were identified in our re- analysis of the surface water data and 7 of these sites had concentrations that were less than 60 mg/l.

8.2.2 Ground Waters

When the nitrate in ground waters chapter was compiled in July 1998 we were very impressed with the information provided with the Midlands Region of the EA. In contrast to the information gathered from other sources, this data had already been assembled into a ‘spreadsheet’ format and included detailed annotations such as Grid References and site ID’s. The results of this first analysis suggested that the procedures used to identify ‘problem’ sites in 1992 had proved very effective and only 33 ‘rogue’ boreholes were located from a total of 358.

The document on the maximum concentration of nitrate recorded in a number of English boreholes recently supplied by the Commission

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 58 (Water UK, 1998) raises a number of questions that have yet to be resolved. Only a small proportion of the boreholes that we identified as having nitrate levels in excess of 50 mg / l in 1992 appear in the new list. At first sight, this is quite understandable since the new list is based on a much longer time series of observations. It is not, however, clear why most of the boreholes that contained high levels of nitrate in 1992 have now disappeared from the 25-50 mg as well as the > 59 mg list of the sampling sites in Anglian Region. Another question that needs to be resolved in the anomalous 99999999 grid references entered in the final column. The site listings provided are of little use without these grid references. When we telephoned Steve Fletcher (the EA database manager) to discuss these results, he suggested that Anglia may simply not have bothered to check these references when they compiled the list.

The Water UK document also provides a brief synopsis of recent trends in the UK. It concludes that there have, in general, been few problems but notes that some boreholes have been abandoned and that there is some evidence of rising nitrate trends. No illustrative examples are provided, but it is generally critical of the methods used to predict future nitrate levels. They suggest that nitrate concentrations can only be predicted with any degree of confidence when sites have been monitored for a period of 10 years. In this respect, the apparent mismatch between the high nitrate sites identified in 1992 and the high nitrate sites listed for the Anglian region in the attached table give some cause for concern. Only 17 of the sites identified in the 1992 survey appear in the list compiled over the last 10 years. The most puzzling aspect is the apparent improvement of the sites that were only listed in 1992. Water samples collected from river systems are frequently influenced by episodic events but we would expect ‘integrated’ groundwater samples to be relatively immune to such effects.

8.3 THE URBAN WASTE WATER DIRECTIVE

The first attribute considered in the choice of site was the p.e. (population equivalent) value defined in the Directive (> 10,000 in 1992). The collated data from these sites was then reviewed and those with sufficient data short- listed for designation. Three variables were considered essential for any meaningful classification: the average annual concentration of phosphorus, the diurnal variation in dissolved oxygen and the average concentration of phytoplankton chlorophyll. If no information was available on these three attributes the sites were excluded from further consideration. In practice, very few sites monitored by the NRA in 1992 had information on the diurnal variation in dissolved oxygen or the concentration of phytoplankton chlorophyll so the number of sites designated was inevitably small.

In 1994, the UK Government designated 33 Sensitive Areas in England and Wales and most of these sites were situated in central and south-eastern England. In Section 3, we ranked the sites sampled in 1992 according to one

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 59 key determinand (the maximum concentration of orthophosphate) and found very high concentrations at 26 sites distributed throughout England and Wales. The concentration threshold for the maximum concentration recorded at these ‘worst case’ sites was arbitrarily set at 0.5 mg l-1. and the average concentration at the same sites was around 0.4 mg/l. In their 1998 report, the EA suggest that an average concentrations of 0.2 mg l-1 could be considered indicative of eutrophic running waters but no precise limit is defined in the UWWT Directive.

In 1998 the UK Government designated a further 47 waters (mostly rivers) on the basis of advice from the Agency, and a total of 2,540 km of 62 rivers/canals has now been designated. In this new round of designations, waters receiving discharges from large Sewage Treatment Works were assessed for the effects of eutrophication using chemical, biological and use-related criteria. Excessive weed growth and changes to macrophyte communities were the main ecological impacts detected, although benthic and floating mats of blue-green algae are also reported to have caused problems in slow-flowing rivers.

The approach adopted to identify ‘problem’ sites in 1992 was clearly inadequate but the decision to consider the combined response of a physical, chemical and biological variable is scientifically sound. Some of the problems associated with quantifying the trophic status of flowing waters have already been discussed in Chapter 1. Although we have not been able examine any recent results, the approach adopted in 1997 is again sound since it pays particular attention to the structure of the attached vegetation not the transient characteristics of the flowing water. We also strongly endorse the integrated approach to catchment management that is now being adopted by the Environment Agency. The Agency estimates that some 51 STWs currently require some phosphorus stripping and a further 90 or so may need to install this technology by 2005. The output of phosphorus from many STWs fell steeply in the early 1990’s and has been matched by a parallel fall in the concentration of river phosphate concentrations (environment Agency, 1998). In geographic terms, the rivers in the south and east have been slowest to recover whilst the rivers in Wales and the west of England now have much lower concentrations of phosphate. The following paragraph, taken from the1998 Consultation paper, sets out the Agency view on the current state of the environment:

“Regarding the ecological and use-related impacts of eutrophication, no discernible national trends are evident. This is due partly to difficulties in determining the influence of factors such as the weather, and also to a lack of biological data and long-term records of use-related problems. There are some notable exceptions where extensive, historic data-sets have been collected in relation to well-studied waters such as the Norfolk Broads and the Lake District. In a European context, the eutrophication problems in England and Wales nationally are arguably moderate in extent. A comprehensive pan-European assessment has yet to be undertaken.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 60 However, a preliminary review by Chiaundani and Premazzi (1988) indicated that the extent of the problem was greatest in , , , Italy and the , and moderate in Greece, Ireland, Luxembourg and Spain. In France the position varied across the country. It is anticipated that the European Environment Agency will address the need for more reliable information across Europe.”

Other sections in the same document explain how the EA has recently adopted an integrated approach to the management of aquatic systems. Waters will be identified for potential action on the basis of information contained in the Local Environment Agency Plans (LEAPS). In this report, the outline descriptions of ‘problem’ sites listed in the Appendix are largely based on these LEAPS documents. In future, more attention will be given to the use of airborne remote sensing and Geographic Information Systems in catchment management. This is an area of particular research interest to the IFE who have recently published several papers on the aquatic applications of these new technologies (George, 1997; May et al, 1996).

8.4 CONCLUSIONS

When we started this project, we anticipated receiving summary data sets from the regulatory authorities quite soon and in a form that could be easily manipulated. In the event, some data sets (e.g. those for Scotland) were never provided whilst others (e.g. Northern Ireland) could not be georeferenced to the UK (Ordinance Survey) grid. Much of our time was spent ‘editing’ raw data by identifying duplicates, cross checking internal codes and correcting grid references. Despite these problems, we were eventually able to analyse ca 95 % of the raw data received. The first problem identified was the general lack of information that could be used for ‘trophic state’ assessments. All the sites identified as requiring further investigation in this report have been selected on the basis of the measured nitrate or phosphorus concentration since very little biological data was available in 1992.

The most comprehensive data set analysed was that provided by the EA groundwater unit. Only 33 ‘high nitrate’ boreholes were located outside the NVZ’s but some of these were very close to existing boundaries. With the surface water data, only 14 ‘rogue’ sites were identified and only 7 had maximum nitrate concentrations greater than 60 mg/l. If we assume that 25 % of the nitrates entering these waters was of non-agricultural origin we are left with only 5 sites that merit further investigation.

A much stronger case could, however, be made for the designation of more Sensitive Areas. Our analysis identified 60 sites where the average concentration of orthophosphate was greater than 100 ug/l. Very little biological data was, however, available for these sites in 1992 and we have no simple way of relating these extreme values to the critical population equivalent values identified in the directive.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 61 All the ground and surface water sites that we have identified as requiring the most urgent investigation are reviewed in the Case Studies. Most of this information has been gleaned from the regional LEAPS documents, which provide the most up to date view of the ‘state of the environment’ in the different areas.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 62 9. REFERENCES

______

i. Chiaudani, G. and Premazzi (1988). Appraisal of the possible methods of combating threats of eutrophication in Community waters. Commission of The European Community, Brussels. ii. Department of the Environment (1996). Indicators of sustainable development for the United Kingdom, HMSO, London. iii. Duncan, A. and L. C. Dos Santos (1989) Plankton interactions in the London Reservoirs. Ergebnisse der Limnologie 33, 475 - 478 iv. Environment Agency (1997) River Parrot Consultation Report. Local Environment Agency Plan. v. Environment Agency (1997) East Suffolk Consultation Report June 1997. Local Environment Agency Plan. vi. Environment Agency (1998). Aquatic eutrophication in England and Wales. Consultative Report, 36 pp. vii. European Environment Agency (1998). Europe’s Environment: The Second Assessment. European Environment Agency, Copenhagen, Denmark. viii. George, D.G. (1997). The airborne remote sensing of phytoplankton chlorophyll in the lakes and tarns of the English Lake District. International Journal of Remote Sensing, 18, 1961-1975. ix. Lack. T. J. (1971) Quantitative studies on the phytoplankton of the river Thames and Kennet at Reading Freshwater Biology 1, 213 - 224 x. MAFF (1994). Designation of vulnerable zones in England and Wales under the EC Nitrate Directive (91/676). xi. MAFF (1995). Government response to the consultation on the designation of nitrate vulnerable zones in England and Wales. xii. May, L., Place, C.J. and George, D.G. (1996). Estimating total phosphorus losses from diffuse sources within the catchment of Bassenthwaite Lake. Diffuse Pollution Conference Proceedings, 247- 250. xiii. National Rivers Authority (1993) River Medway Catchment Management Plan. Final Report. National Rivers authority (Southern Region) xiv. National Rivers Authority (1993) River Medway Catchment management Plan. Final Report. NRA (Southern Region) xv. National Rivers Authority (1994) River Hull and Coast Catchment Management Plan: Consultation Report . National Rivers Authority (Northumbria and Yorkshire Region) xvi. National Rivers Authority (1995) Lower Bristol Avon Catchment management Plan: Consultation report. xvii. National Rivers Authority (1995) Lower Lee Catchment Management Plan: Action Plan. NRA (Thames Region) November 1995. xviii. National Rivers Authority (1995) Lower Witham Catchment Management Plan: Consultation Report. xix. National Rivers Authority (1995) River Hull and Coast Catchment

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 63 Management Plan: Action Plan. National Rivers Authority (Northumbria and Yorkshire Region) xx. National Rivers Authority (1995) River Tone Catchment Management Plan: Consultation Report. National Rivers Authority (South-Western Region) xxi. Neal, C., M. Harrow and R. J. Williams (1998) Dissolved carbon dioxide and oxygen in the river Thames Spring/Summer 1997. The Science of the Total Environment 210/211, 205 - 217 xxii. Robertson, A. L. (1990) The population dynamics of Chydoridae and Macrothricidae (Cladocera:Crustaceae) from the river Thames, UK. Freshwater Biology 24, 375 - 389 xxiii. Scolefield, D., E. I. Lord, H. J. E. Rodda and B. Webb (1996) Estimating peak nitrate concentrations from annual nitrate loads. Journal of Hydrology 186, 355 - 374. xxiv. Water UK (1998). Nitrates and groundwater in the UK. (Full reference not provided). xxv. Wharfe, J.R., A. Dines and L. A. Bird (1986) The environmental impact of paper mill discharges to the upper Medway estuary, Kent, England. Environmental Pollution (Series A) 40, 4, 345 - 358 xxvi. Whitehead, P. G. (1990) Modelling nitrate from agriculture into public water supplies. Philosophical Transactions of the Royal Society of London Series B 329, 307 - 410 xxvii. Whitehead, P. G. and I. P. Toms (1993) Dynamic modelling of nitrate in reservoirs and lakes. Water Research 27, 8, 1377 - 1384 xxviii. Yamakanamardi, S. M. and R. Goulder (1995) Activity and abundance of bacterioplankton in three diverse lowland water courses. Regulated Rivers Research and Management 10, 51 - 67 xxix. Youngman, R. E. (1975) Observations in Farmoor, a eutrophic reservoir in the upper Thames valley, during 1965 - 1973. Proceedings Symposium, The effects of storage on Water Quality. Reading University (organised by WRC, Medmenham, Bucks.)

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI II - 64 CONTENTS

1. THE CRITERIA USED FOR ASSESSING THE TROPHIC STATUS OF INLAND, ESTUARINE AND MARINE WATERS IN THE UK 1

1.1 Introduction 1 1.2 Criteria That Could Be Used to Assess the Trophic Status of Inland, Estuarine and Marine Waters in the UK 1 1.3 Data That Could Have Been Used to Assess the Trophic Status of Inland, Estuarine and Marine Waters in the UK 3 1.4 Data That Was Used to Assess the Trophic Status of Sites in 1992 4 1.5 Conclusion 5

2. THE CONCENTRATION OF NITRATES IN THE SURFACE WATERS SAMPLED IN ENGLAND AND WALES 6

2.1 Introduction 6 2.2 The Identification of Sites 6 2.3 The Sites Designated in 1992. 7 2.4 The Nitrate Concentrations Recorded in England and Wales 7 2.5 Conclusions 9

3. THE CONCENTRATION OF NITRATE IN THE GROUND WATERS SAMPLED IN ENGLAND AND WALES. 13

3.1 Introduction 13 3.2 The Sites Designated in 1992. 13 3.3 The Groundwater Nitrate Concentrations Recorded in England and Wales 13 3.4 Conclusions 15

4. THE CONCENTRATION OF ORTHOPHOSPHATE IN THE SURFACE WATERS SAMPLED IN ENGLAND AND WALES 19

4.1 Introduction 19 4.2 The Identification of Sites 19 4.3 The Sites Designated in 1992. 20 4.4 Conclusions 26

5. THE SURFACE WATER SITES WITH ELEVATED NITRATE CONCENTRATIONS THAT WERE NOT DESIGNATED IN 1992. 27

5.1 South-West Region 27 5.2 Southern Region 30 5.3 Thames Region 32 5.4 North-East Region 32 6. THE GROUND WATER SITES WITH ELEVATED NITRATE CONCENTRATIONS THAT WERE NOT DESIGNATED IN 1992. 35

6.1 Aldeburgh 35 6.2 Drove lane 40 6.3 Egford 43

7. THE SURFACE WATER SITES WITH ELEVATED ORTHOPHOSPHATE CONCENTRATIONS THAT MIGHT BE CONSIDERED ‘EUTROPHIC’ ACCORDING TO THE CRITERIA DEFINED IN THE UWWT DIRECTIVE. 48

7.1 North-West Region 48 7.2 Southern Region 49 7.3 Thames Region 52 7.4 Additional References 56

8. CONCLUSIONS 57

8.1 Introduction 57 8.2 The Nitrates Directive 57 8.3 The Urban Waste Water Directive 59 8.4 Conclusions 61 PART III

VERIFICATION OF VULNERABLE ZONES AND SENSITIVE AREAS FOR ESTUARIES, MARINE AND COASTAL WATERS ENVIRONMENTAL RESOURCES MANAGEMENT I1 1 THE YTHAN ESTUARY

The information available on the Ythan is relatively good. A University field station has been present on the estuary since 1958, and detailed information is available on both physical and biological parameters. The North East River Purification Board’s 1993 assessment of the status of the estuary for the UWWTD and Nitrates Directive was made publicly available. The 1997 second round assessment, by its statutory successor, the Scottish Environment Protection Agency, SEPA, has also been publishedi and is available via SEPA’s web-siteii. On both occasions NVZ status was recommended, due to enhanced nitrate levels, and the formation of algal weed mats, but on both occasions this has been rejected by the Scottish Office.

1.1 SITE LOCATION & DESCRIPTION

1.1.1 Nature of Catchment

The Ythan’s catchment of 689 km2 is located in , in the north east of Scotland (see Maps A and B). The river rises at an altitude of 200 m and flows 60 km through low-lying land to an estuary 8 km long and 2.76 km2 in area; the largest in north-east Scotlandiii. The geology is glacial till overlying granite and metamorphic rock1. Woodland and hedgerows are scarce or absent, and field boundaries tend to extend to the edges of watercourses (pers. obs.), although there has been a recent increase in tree-planting programmes within the catchment.

1.1.2 Nature of Land-use

Ninety percent of the catchment area is devoted to agricultural activity, an important industryi. This includes arable and improved grassland. Animal production is important: some 25% of all pigs reared in Scotland come from within the Ythan catchment, although the bankruptcy of the major operator in 1998 may affect this. There have been major changes in agricultural land use between 1960 and 1990iv (Table 1.1). Wheat, barley, oil-seed rape (all with high nitrogen demandv), and pigs, increased at the expense of oats and sheep, while cattle also slightly declined.

1 Research on marine eutrophication in Brittany has indicated that rock formations, particularly the degree of permeability, will have an impact on patterns of eutrophication and abatement strategies. While this aspect is not pursued in this report, relevant aspects of geology of catchment areas has been included to assist any future assessment.

Ménesguen, A. & J-Y Piriou (1995). Nitrogen loadings and macroalgal (Ulva sp.) mass accumulation in Brittany (France). Ophelia 41, 227–237.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 1 Table 1.1 Changing land use in the Ythan catchment. Scottish Office statistics.

barley (ha) wheat, ha rape (ha) oats (ha) pigs sheep cattle

1960 4,000 1,000 0 10,000 15,000 75,000 44,000

1975 15,000 800 0 500 50,000 35,000 48,000

1990 12,000 6,500 4,100 1,000 80,000 50,000 40,000

Source: Raffaelli (1998).

Many people in the scattered settlements commute to work in Aberdeen. The largest town within the catchment is Ellon, just above the estuary, which has a sewage treatment works of 15,000 p.e. capacity. The estuary is a National Nature Reserve, a candidate Special Protected Area (SPA) and a Site of Special Scientific Interest (SSSI). It holds internationally important numbers of breeding Sandwich tern and wintering pink-foot goose, and nationally (UK) important numbers of breeding eider, common tern, little tern, as well as wintering eider and redshank.

1.2 CHEMICAL PROFILE

The data in this section come from Balls et al. (1995)vi, Anon. (1997)i and from Pugh (1998)iii unless otherwise stated.

1.2.1 Nitrogen

TON In the estuary, TON versus salinity profiles are available since the 1960svi. There is a strong negative linear relationship between the two (r2 varying between 83.2–96.2%). The intercept of the fitted regression in 1967 had a value of 125.1 µM TON at 0‰ (of which nitrite is known to be insignificant) since when TON levels have consistently increased, reaching 525.3 µM in 1991–92. The range about the 91–92 mean is shown in section 7.1.2, which also gives values for the mid- and lower estuary.

Table 1.2 Time series of nutrient concentrations in the Ythan estuary at 0‰ salinity

TON, µM PO4, µM SiO2, µM N:P N:Si

1967 125 0.363 94.7 344:1 1.32:1

1981–85 381 0.551 111 691:1 3.43:1

1986–1990 418 0.874 108 478:1 3.87:1

1991–92 525 0.901 99.8 583:1 5..26:1 Notes: Based on regression analysis of data gathered the length of the estuary. NB note that the

headings for PO4, SiO2, NH4 etc. in all the tables in this report are synonymous with PO4

phosphorus, SiO2 silicon. etc. Source: Balls et al. (1995).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 2 Ammonia makes up only a small proportion of the total dissolved inorganic nitrogen in the estuaryvi. The nitrogen levels recorded in the Ythan are by far the highest recorded in any Scottish estuary. They are of the same order as the most polluted English estuaries encountered in this study (Humber, Wash estuaries, and the Ore/Alde, Deben and Colne,), and are significantly higher than those of the Southern English embayments such as Langstone, where algal mats are also a problem.

1.2.2 Phosphorus and Silicon

Phosphorus levels in the river show ambiguous evidence for a rising trend. Generally levels between 1982–1991 lay between 0.02–0.08 µM P, with occasional peaks of 0.25 µM or moreiii. Judged by eye, those in the upper catchment suggested a distinct rising trend, while those in the lower river, at Ellon, show greater scatter. Similarly, in the estuary the phosphorus vs. salinity profiles are more variable than those for TON (r2 varying between <0.1% in 1981–85 (unusually weak), and a maximum of 57.3% in 1991/92. These also suggest a rising trend. Ellon STW has increased with the growth of the town (from 6,600 in 1981 to 8,670 in 1991). The STW may therefore be associated with this increasevi. However sewage accounts for just half of the phosphorus entering the catchment, with intensive animal husbandry presumably making up a significant fraction.

Silicon, which is less affected by anthropogenic activities, shows no signs of change in either the river or the estuary. At 0‰ it ranged between 201.4 µM in 1967 and 236.5 µM in 1981–85 with a strong negative linear relationship with salinity (r2 varying between 77.1–93.9%).

1.2.3 Nutrient Ratios

Based on the above figures the N:P ratio1 in the estuary at 0‰ varied between 344:1 in 1967 to 583:1 in 1991/92. Nitrogen is thus vastly in excess of the Redfield ratio. The N:Si ratio varied between 1.32:1 in 1967 to 5.26:1 in 1991/92.

At the estuary’s mouthvii, using a different measure, that of the “ratio of the extrapolated nitrate:phosphate ratios at 34.5 salinity … to those normally observed in coastal waters” gave a ratio for the Ythan ranging from ca. 17:1 in February 1992 to 0.5:1 in July (September appears on the graph as zero, assumed to be unrecorded). The Ythan (and the adjacent Don) had ratios much higher than the other east coast estuaries.

1.2.4 Nutrient Trends

The trends in the estuary for nitrogen, phosphorus and silicon have already been described. There is a longer time series for the river Ythan at Ellon, just above the estuary, when annual average TON concentrations have increased

1 Atomic ratios are used throughout this report.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 3 from ca. 100–150 µM in the late 1950s to ca. 500–550 µM (i.e. 31–34 mg/l nitrate) in the early 1990svi. The same data show no obvious trends in phosphorus or silicon, although phosphorus is highly variable.

1.2.5 Biological Oxygen Demand

In 1991–92, of nine Scottish east-coast estuaries1 the Ythan, at one metre depth, had marginally the highest oxygen saturation at 0‰ of ca. 130% through spring to autumn, and 90% in Februaryvii. This upper estuary supersaturation is associated with significant phytoplankton growth. The winter value was typical of most of the estuaries. There was no sign of an oxygen sag as displayed by the Forth. This level of saturation at 0‰ decreased in an approximately linear fashion to ca. 110% at 34‰.

No data has been seen on water BOD immediately above the sediments. However, sediment deoxygenation (revealed by black discoloured sediments) under the algal weed mats is clearly apparentviii.

1.3 BIOLOGICAL EFFECTS

1.3.1 Nutrient Related Effects

Algal weed mats

The Ythan estuary’s ecology is amongst the best understood anywhere in the worldiv. There are a number of studies examining nutrient levels, the smothering growth of Enteromorpha spp., Ulva and Chaetomorpha, and the biological effectsix,x. This summary is based on Raffaelli (1998)iv, with some additional information from Raffaelli (in press axi,bv), Raffaelli et al. (in press)xii and Raffaelli et al. (submitted)xiii,

In some of the areas now worst affected by algal mats the 1960s–1970s typical wet weight biomass was of the order 150–1,500 g m2. Currently algal biomass often exceeds 1 kg m2 and “in many areas” exceeds 3 kg m2. Typically, between May and September, about 30% of the intertidal mud-flats are carpeted by the dense weed growth, although coverage varies markedly from one year to the next. This is partly dependent on the initial over-wintering biomass. 1998 saw notably high peak biomass totals (Raffaelli, pers. com.). Generally, these biomass levels are greater than those reported for Langstone Harbour (Section 5), now accepted by the UK administration as resulting from eutrophication. Weed mats greater than 1 kg m2 have “a dramatic impact on the underlying mudflat invertebrate communities”. The small shrimp-like amphipod Corophium is known to be severely affected, disappearing completely from weed covered areas. Corophium is documented to be extremely important in the diet of both birds and fish, 55% of the annual production being eaten by redshank, shelduck and flounder alone. Corophium density in the estuary, measured in

1 Tweed, Forth, Tay, Dee, Don, Ythan, Beauly/Inverness Firth, Cromarty Firth and Dornoch Firth.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 4 1964 before the weed became a problem, was again assessed in 1990. It had decreased in those parts of the estuary regularly affected by weed, while in unaffected parts the density had increased, in common with other invertebrate species.

There is no specific data of the impact of this change upon the main fish species that feed on Corophium, but there is good data on winter bird densities since 1963. Oystercatcher, curlew, bar-tailed godwit, redshank and dunlin have all increased substantially. Mute swan and widgeon (which feed on the algae) have also increased. Shelduck have declined. Raffaelli (1998) concluded:

“The increases in Corophium [in areas unaffected by weed] and in several species of shorebirds are consistent with an overall enhancement of the Ythan’s productivity through nutrient enrichment. The decrease in shelduck is probably due to interference by the weed with the bird’s feeding behaviour, and it is noteworthy that the centre of shelduck distribution (and several other shorebirds) have shifted to unweeded areas … It would appear then at the time of writing there remains sufficient unaffected intertidal area … which, together with areas between large weed patches, has an enhanced productivity, allowing the estuary as a whole to support more shorebirds now than in the mid-1960s. As long as these areas remain weed-free, numbers of shorebirds (and fish) will probably be maintained. However, if weed mats continue to spread upstream and if patches become contiguous then the conservation status of the Ythan may be seriously affected.”

International Comparisons with biogeographically similar sites indicate that eutrophication in Ythan lies towards the higher end of observed effects. Thus a study of Waquit Bay, Massachusettsxiv (which is a model example of a research programme and assessment, given adequate funding) Cladophora weed mats became a major problem in part of the Bay (Childs Estuary) where nitrate N quadrupled (based on currently less affected sites within the Bay); from perhaps less than 10 µM to ca. 40 µM at 0‰, with proportional changes further downstream. In Brittany, France, Ulva weed mats have become a problemxv. At the most eutrophic site, the Bay of Saint-Brieuc, algal biomass was similar to that in the Ythan. Nutrient levels in the 14 km2 Bay were not published, but in the lower reaches of the River Gouessant nitrate varied between 80–1,130 µM N [i.e. between 5 and 70 mg l-1], strongly correlated with flow rate. Moreover there was an extremely tight positive correlation between daily June nitrogen loading to the Bay and total Ulva biomass, which ranged between 5,000 and 25,000 tonnes wet weight between 1986–92. Other examples can be found in the review by Raffaelli et al. (in press). Such evidence makes it implausible to argue that the proliferation of algal mats in the presence of sharply increased nutrient levels are derived via another mechanism, unless convincing evidence for that mechanism can be demonstrated. No such evidence is available for the Ythan.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 5 Phytoplankton

Chlorophyll-a1 concentrations were surveyed in the Ythan estuary in 1993 and compared with results from 1967. The peak phytoplankton growth was between May and August in both years. Although the highest value recorded was in May 1993, (6.5 µg l-1) generally there did not appear to be a significant increase in chlorophyll concentrationvi. A wider range of data would be required to draw firm conclusions.

As already mentioned, significant phytoplankton blooms are known to occur in the upper estuary, but no measures of chlorophyll have been seen.

1.3.2 Sewage-specific Effects

None identified. The apparent elevation of phosphorus loadings from Ellon STW may be of some concern, given the very high N:P ratio.

1.4 NITRATE DIRECTIVE: SHOULD THE ESTUARY BE DESIGNATED?

This section is based on the 1997 Scottish Environmental Protection Agency report to the Secretary of State for Scotland on the NVZ status of the Ythan estuaryi, unless otherwise stated.

1.4.1 Nutrient Sources and Quantities

A nutrient budget for the Ythan catchment and estuary is availablexvi. In 1992, of the water entering the estuary, 2% of the nitrogen and 48% of the phosphorus were attributable to inputs from sewage treatment plants. In 1967 these values were 1 and 10% respectively. The Ellon STW was responsible, for 83% of the nitrogen and 81% of the phosphorus of a STW origin. However nitrogen inputs were dominated by diffuse sources, namely terrestrial (primarily agricultural) at 8,708 tonnes per year and atmospheric, at 434–2,000 tonnes per year. There will be some error associated with these estimates. But it is highly improbable that these would be sufficient to overturn, for example, the relative ranking of the contributions of sewage and agriculture to the nitrates budget. Certainly any credible challenge to this conclusion would have to be accompanied by substantial evidence.

1.4.2 The 1993 NERPB Assessment

Nitrate limit

No samples of surface or groundwater abstracted under the terms of the Drinking Water Directive (75/44/EEC) to public potable water supplies in north-east Scotland exceeded the 50 mg l-1 (806 µM N) limit. “By this criteria, there were no nitrate polluted waters”i.

1 ‘Chlorophyll-a’ or ‘chlorophyll’ is used in this report following the style of the original reference. The CSTT report questions the validity of the use of ‘chlorophyll-a’ and suggests that this should more accurately be reported as ‘chlorophyll’ or ‘chlorophyll-a and associated pigments’ unless a specific analysis has been done.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 6 However as no water is abstracted into public potable supply in the Ythan catchment under the terms of that Directive, “there were no qualifying supplies requiring to be sampled and analysed”. Nonetheless, an “extensive monitoring programme” in the Ythan catchment meant that “it was known that nitrate concentrations in the waters of the main river and its tributaries were high (30–40 mg l-1) and occasionally some of the tributaries exceeded 50 mg l-1”. At the time of the 1993 assessment it was also known that groundwater samples from wells were up to 55 mg l-1. Subsequently it was learn that some shallow wells supplying private properties “contained nitrate in concentrations excess of 200 mg l-1”.

Eutrophication

The eight criteria for assessing eutrophication in the 1993 Consultation paper, were adopted by the Scottish Office. “If one or more of the criteria were met by a water then it would be considered to be eutrophic, and if the eutrophication was due to the effect of nitrogen from agricultural activities then the area draining to the eutrophic water would qualify for designation as a Nitrate Vulnerable Zone.”

For the Ythan, attention was centred on the estuary. The 1993 report concluded that three of the criteria for an NVZ were met:

• Changes in macrophyte growth (the algal weed mats); • Changes in fauna; • The “threefold” increase in nitrate concentrations in the river over thirty years; “a feature not restricted to the Ythan but exhibited by many rivers nation- wide, reflecting the three or fourfold increase in inorganic nitrogen fertiliser usage since 1960, and the increased disposal of animal wastes and slurries by spreading on land.”

It continued “On the basis of this assessment where there are three very clear and marked qualifying criteria – and where several of the other criteria are not applicable because of the hydrography of the estuary – it has to be concluded that the Ythan estuary is eutrophic [and] that the nutrient enrichment is due to nitrogen and that that nitrogen arises from agriculture”. The report concluded “As such, under the terms of the Nitrates Directive and the implementation guidelines, the estuary falls due for identification as a ‘polluted water’ and subsequent administrative action.”

1.4.3 Response to the 1993 NERPB Assessment

The recommendation of NERPB was controversial, especially with farmers. According to the 1997 SEPA report there was a “reluctance to accept the possibility of an NVZ designation” and a number of alternate explanations were advanced or other remedial measures proposed. Several are highlighted in the SEPA report. One theory was that siltation in the estuary, since the suspension of dredging, had reduced the depth of the water, increased light penetration to the sediment surface, and thus allowed the proliferation of the weed. Linked to this it was proposed that dredging or scraping the mudflats could remove the problem, and hence the need for agricultural action.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 7 Another proposal was the elimination of weed mats with herbicide, again with the intention of avoiding agricultural measures.

The Secretary of State, in January 1996, concluded that “Since a final link between higher levels of nitrate and the increase growth of the algae Enteromorpha1, has yet to be determined scientifically, the Government has decided not to designate the catchment of the river Ythan as a NVZ on this occasion.”xvii

In the words of the SEPA report “It was explained that whilst the circumstantial evidence was strong, legal advice had been given that the linkage between nitrate concentration and Enteromorpha growth was not established as cause and effect without possible doubt.” This is an extremely severe requirement which conflicts with the UK’s 1993 Consultation paper’s “balance of probabilities” approach, and undertakings made by the UK in OSPAR and successive North Sea Conferences. The Nitrates Directive also unambiguously indicates that ‘without possible doubt’ is an excessive test, as it requires the identification of water bodies that may (not will) become eutrophic if action is not taken (Annex I, A.3).

1.4.4 The 1997 SEPA Report

The SEPA report reviewed the research carried out since the 1993 NERPB paper. According to the report new research on the physiology and nutrient requirements of Enteromorpha had shown its growth to be “promoted by nitrogen”2 and that the variant present in the Ythan is highly resistant to a wide range of stress, including anoxia and darkness, allowing it to over- winter and propagate from a small standing stock. The natural isotopes present in the plants were also being examined to try and demonstrate the sources of carbon and nitrogen they exploited.

New bathymetry and hydrography work “indicate little change over the past 30 years and probably for longer … it is now clear that dredging was infrequent, [and] highly localised … It would therefore be difficult to argue that the observed high biomass of opportunistic benthic macroalgae are due to historic changes in the Ythan’s hydrodynamic environment.”

1 Although many of the parties involved refer exclusively to Enteromorpha it is likely that species such as Ulva make up at least a significant part of the weed mat composition

2 Raven, J. (1995). The effects of elevated nutrients on macroalgae. p. 12–16 in The impact of nutrients in estuaries – Proceedings of a Workshop on 23 May 1995 (ed. D. B. Nedwell) English Nature/National Rivers Authority. University of Essex R&D Interim Report 639/1/A. Raven has argued that ‘Enteromorpha’ is more likely to now be limited by carbon or phosphate than by nitrogen. The very high N:P ratio provides some evidence for (current) phosphate limitation, but note the earlier cautionary footnote regarding the difficulties surrounding such measures. The argument for carbon limitation may be more difficult to sustain. If a change in carbon availability was said to be responsible for the increase, on the one hand one would need to provide a plausible increased source of carbon since the 1950s, and it also has to be noted that the weed spends

much time exposed to the atmosphere, and that atmospheric CO2 is sufficient to support very high (terrestrial) plant biomass. This minority view also has to contend with work from many sites (not just the Ythan) correlating increased algal weed mats with increased nitrogen concentrations. If it is only argued that carbon limitation now prevents further algal growth then, while interesting, it is irrelevant to the matter at hand. Academic iconoclasm is an essential part of the research ethos: but Governments have different responsibilities and, in these circumstances, cannot reasonably justify the suspension of action on the basis of such speculative work.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 8 Research had also continued examining the historic and contemporary nutrient status of the Ythan estuary. Previous work had only investigated the delivery of nutrients to the estuary, not through it, and this had been seen as a weakness in the case put forward by NERPB, “since the nitrate criteria for eutrophication applied to nitrate concentrations of estuaries, not of rivers”. According to SEPA “this and associated work removes the weakness”.

The fate of fertiliser inputs had also been modelled. Data gathered on a farm- by-farm basis allowed accurate hindcasting, and the projection of future scenarios. As a result “there is a comprehensive understanding of the spatial distribution of farm types and land use within the catchment, the changes in cropping patterns, fertiliser use, and manure and slurry production and application. The nitrogen and phosphorus budgets associated with the different activities and, perhaps more importantly, their changes during the past 30 years are understood”. It was clear that “there has been a three-fold increase in nitrogen inputs to the catchment in the period 1960–1990, tonnages increasing from 2,562 to 7,626 (passing through a maximum on 8,030 in 1980). The corresponding uptake from the catchment (to crops) … increased … from 1,392 tonnes … to 3,475 in 1990, and therefore the surpluses (lost into the watercourses) has increased from 1,170 to 4,151 tonnes per annum - the latter equates to 67 kg1 of nitrogen per hectare. … the largest surpluses … are associated with pig and poultry units and the farms growing winter cereals and oilseed rape. Winter cereals receive higher applications of nitrogen that their spring sown counterparts, and this is applied in the autumn at the time of greatest potential for loss. There has been a marked movement towards the growing of winter cereals, especially barley, since about 1990”.

SEPA concluded in its 1997 report that “The position remains unchanged since the report … in April 1993. Still three of the eight Guideline criteria for eutrophication are met in a clearly outstanding manner” (emphasis added). Whilst the nitrate concentration entering the estuary in the winter of 1996/97 was the lowest since 1989/90, that for 1995/96 was the highest ever recorded2. “Research has shown that the nitrogen entering from the river does move through the estuary depending on river flow conditions and tidal influences, that the high nitrate concentration freshwater overlays the advancing salt water intrusion into the estuary at every tide and bathes the mudflats where Enteromorpha proliferates.”

Siltation has been shown not to be a factor, whilst scraping the Enteromorpha and/or treating with herbicide is unlikely to eradicate the problem, or address the requirements of the Nitrates Directive. “There is a growing weight of evidence that the nitrogen impacting the Ythan estuary is derived from agricultural activities in the catchment. Research confirms that in line with national trends nitrogen use in this intensely farmed catchment has increased and that there has been a move towards more nitrogen demanding crops. Soil fertility and the reserves of bound-up nitrogen

1 Which suggests that the 7,626 tonnes of nitrogen applied in the catchment in 1990 equates to an average 123 kg per hectare.

2 A likely explanation for this difference may be variation in rainfall and river flow, rather than in annual inputs.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 9 have been built up over many decades of intensive agricultural activity to leave a precarious legacy for future years.”

SEPA therefore argue that the case for designation has increased. “It is expected that [isotope] trace research … will establish the issue beyond scientific doubt1. There may still be argument for delay until that clinching evidence is available. However delayed designation may not be possible” because the October 1997 Report of the Commission to the Council and European Parliament “appears likely to induce infraction proceedings against the UK government by the European Community”. SEPA echoes the Commission’s view that the 50 mg/l level is not the defined limit with regard to eutrophication in the Directive; indeed it is likely to be significantly too high to reduce eutrophication. In any case, for the purposes of the Directive, there is no need to set a concentration. The intention is to “reduce water pollution … by nitrate from agricultural sources and prevent further such pollution”. It does not require the eradication of Enteromorpha; “merely infer that it should not be present as a dense and widespread growth”.

Finally in its assessment of evidence, SEPA concluded that previously discounted criteria also require designation of the catchment. “Instructions were issued (emphasis added) indicating that only those waters which were abstracted into public potable supply should be considered against a nitrate concentration limit. Had all waters been considered it is most probable that several of the small watercourses in the catchment and much of the groundwater would have been caught exceeding the 50 mg/l nitrate standard, and the subjective aspects and debate over the interpretation of the eutrophication criteria (including the linkage between nitrate and Enteromorpha) would not have arisen. It is clearly the Commission’s intention that all waters should be considered”.

1.4.5 The 1997 SEPA Recommendation

SEPA concluded that this report, and the reports from the research projects undertaken since the 1993 NERPB Recommendation, be forwarded to the Secretary of State for Scotland “to draw attention to the fact that the Ythan estuary in the North East of Scotland meets three of the criteria for the eutrophic condition, that the eutrophication arises as a result of the impact of nitrogen entering the aquatic system from agricultural sources in the catchment, and that under the terms of the Nitrates Directive the Ythan catchment qualifies for designation as a Nitrate Vulnerable Zone.”

The response from the Secretary of State was initially expected in December 1997. However, after several delays the decision was announced in September 1998. It was to again reject NVZ status, Lord Sewel (Scottish Office Minister for Agriculture and Environment) stating in his press releasexviii that “existing evidence on whether the Ythan estuary is subject to eutrophication (the enrichment of

1 In fact it didn’t – according to Raffaelli (in press a), the results were contradictory, apparently due to inherent variability of isotope ratios in the Ythan Enteromorpha.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 10 water by nitrogen compounds) is still not conclusive, so I have decided, for the moment, not to designate the Ythan catchment as a Nitrate Vulnerable Zone”. He continues “We are continuing with our research effort to find out whether the estuary is subject to eutrophication in terms of the Nitrates Directive, and whether this is having an adverse effect on the environment. We hope to have firm evidence on this soon.”

1.4.6 Conclusions

The Ythan estuary is clearly eutrophic by any standard scientific assessment, and there has been no dissent in the peer-reviewed scientific literature as to that conclusion. Rather it is regarded as a text-book example. The Scottish Office has repeatedly been advised both by its scientific advisors, Scottish Office scientists, and SEPA that the Ythan is eutrophic, judged by the criteria of the Nitrates Directive. Scottish Office scientists have even co-authored papers documenting the effect, including one submitted in July 1998 entitled “Eutrophication-related trends in the ecology of the Ythan estuary, Aberdeenshire, Scotland”xiii.

In a meeting of Scottish Office officials with Scottish Wildlife Link (the umbrella group of major environmental NGOs in Scotland, including the RSPB and WWF), subsequent to the September rejection, it appeared to be conceded by the SO that nitrate had increased; that the source was agriculture; and that this was having a biological effect. However it was being argued that it had not yet been demonstrated to be an ‘undesirable’ effect, c.f. the Nitrates Directive definition of eutrophication – even though it meets UK criteria for judging this set out in the 1993 Consultative paper. In the course of the discussion it was also conceded by the SO that there was also an economic element: and that they were concerned that the farmers in the Ythan catchment would force a judicial review if a decision was made to designate. Yet there has already been an UWWTD judicial review with regard to the redefinition of estuary boundaries where it was ruled that this was primarily an economics-driven decision, and therefore an inadmissible reason for not implementing the Directive. Indeed the UK would now appear to be vulnerable to both a judicial review regarding the failure to designate the estuary as a NVZ, and to a Complaint to the European Commission. Moreover, with the designation, in July 1998, of Langstone and Chichester Harbours, on the south coast of England, as eutrophic Sensitive Areas under the UWWT Directive, even though algal biomass and nutrient loadings are reportedly lower than the Ythan, and sources more poorly characterised, policy is now clearly being applied inconsistently across the UK.

1.5 UWWT DIRECTIVE: SHOULD THE ESTUARY BE DESIGNATED?

There is no prospect that the Ythan estuary could qualify for LSA status. With regard to Sensitive Area status the issue is slightly more complex. The information in this section is taken from Pugh (1998)iii.

The anthropogenic BOD loading of water in the estuary can be expected to be low. There are no direct discharges from sewage treatment plants into the

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 11 Ythan estuary. The BOD at the Ellon Car Park sampling point on the River Ythan, above but close to the tidal limit, from 1982 to 1991 typically ranged from around 0.1 to 2.0 mg/l with a mean of perhaps 1 mg/l (visual inspection of graphic data). By this standard the quality of the Ythan is considered very good, Class 1 (The upper limit of BOD for Class 1 status is 3 mg/l). During this period the three greatest isolated BOD peak demands recorded at the Ellon Car park sampling site were of ca. 6, 4 and 3 mg/l, confined to a period between 1986-88. The ecological implications of such extreme events possibly require evaluation, although there are no obvious trends in the BMWP (Biological Monitoring Working Party) biological index for the Ythan between 1982 and 1991. The site downstream of Ellon sewage treatment works typically scored between 4 and 5, a score less than 5 indicating progressively higher pollution. This is part of a “slight reduction in water quality with the passage downstream, a reflection of the general inputs (point source and diffuse) as the catchment area increase.” Thus estuary BOD would not appear to be an issue with regard to the Directive.

With regard to nutrients, as already discussed the discharge of nitrogen from STWs into the Ythan catchment is small in comparison to that from agriculture, coming mainly from Ellon STW close to the head of the estuary. SEPA appear confident that the phosphorus load to the estuary from STWs is irrelevant. But given the very high N:P ratio it should perhaps be highlighted as of some concern. Generally in European policy (c.f. OSPAR and the North Sea Conferences) it has been regarded as necessary to reduce both nitrogen and phosphorus where problems exist.

Taking these factors into account it might be argued (with little credibility) that nitrogen inputs make an insignificant contribution to eutrophication in the Ythan, given that ‘insignificant’ is not defined, but it cannot be demonstrated to have no effect on the level of eutrophication, as required by the Directive. Given the high N:P ratio, it may also be considered necessary to strip phosphorus, although it should be borne in mind there are other significant sources of phosphorus to the Ythan catchment.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 12 2 THE HUMBER ESTUARY

The Humber is a major source of UK pollutants entering the North Sea. Historically information on UWWTD and Nitrates Directive ‘pollutants’ have been in short supply. For nutrients this has begun to change with significant publications on concentrations and fluxes passing through the Humber system. However information on nutrient budgets and anthropogenic contributions remain either unavailable or poor. Efforts to assess the biological impact also lags behind the quantification of physical parameters. Some relatively accessible information exists on other pollutants, such as sewage related bacterial contamination, via the publication of periodic Humber ‘Quality Reports’. While imperfect, this situation is better than at any other UK sites.

2.1 SITE LOCATION & DESCRIPTION

2.1.1 Nature of Catchment

The catchment of the rivers feeding the Humber – the ‘Humber Basin’ in the words of the NRA’s 1980–90 reviewxix, has an area of 24,240 km2, occupying much of the English Midlands and Yorkshire (see Maps C and D). The terrain varies from the high moorland and the North Yorkshire Moors, through the arable chalk uplands of the Wolds, to fertile plains such as the Vale of York, Holderness and the Trent valley. Permeable rocks and alluvium predominate. The major tidal rivers are the Yorkshire Ouse, Wharfe, Aire, Don, Trent and Hull. The total length of tidal waters is 313 km and the longest tidal run is 147 km from Head to Cromwell Weir on the Trent.

The Humber estuary, as defined in the NRA review, runs from the confluence of the Ouse and Trent at Trent Falls to the estuary’s mouth between Spurn Head on the north bank and Donna Nook on the south. The same limits are used in the Sea Vigil nutrient monitoring reportsxx,xxi,xxii. By this measure the centre line of the Humber has a length of 62 km. However saline penetration extends beyond Trent Falls, and the Humber Estuary Environment Quality Reportsxxiii,xxiv,xxv extend to the tidal limits of the rivers. Where available the data used here also extends to the tidal limits.

The estuary has a very large, 7 m, tidal range, hence the large tidal penetration. The average tidal ‘excursion’ with each tidal cycle is 15 km. “This is several times greater than the seaward displacement due to the freshwater input during the tidal cycle. Thus effluents which discharge to the estuary are held there for a considerable length of time, being progressively diluted as they edge there way gradually into the North Sea. This residence period allows the full polluting effect of discharges to be exerted within the estuary”xix. In other words the Humber is a low natural dispersing area.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 13 The Humber is also naturally turbid. According to the 1980–90 Report most of the sediments are derived from the North Sea, due to the asymmetric tidal flow. It is argued that although sediments also enter via the rivers, most pass through to the North Sea without being deposited, partly because the less dense freshwater floats on the surface. There is a turbidity maximum in the vicinity of Trent Falls. Also, according to the 1980–1990 report, there is a tendency for incoming seawater to enter the estuary via the northern bank and for freshwater to keep to the southern bank as it moves towards the sea.

2.1.2 Nature of Land-use

In 1990 some 11 million people lived within the Humber Basin, notably in major conurbations such as Birmingham, Leeds, Sheffield, Bradford, Leicester, Nottingham, Stoke upon Trent and . This population represents 6.7% of the total population of 164 million estimated to live in the entire European North Sea catchment areaxxvi. Also located within the catchment is (or was) much of England’s coal industry, electricity generating capacity and manufacturing industryxix.

The immediate environs of the estuary are predominantly rural with localised industrial areas While the majority of industrial and municipal pollution originates in the non-tidal catchments, that from Humberside “is not inconsiderable, and the direct discharges of sewage from Hull, Grimsby and other Humberside towns have appreciable, albeit relatively local, significance”.

2.2 CHEMICAL PROFILE

2.2.1 Nitrogen

Before the 1990s the data on nutrients for the Humber Basin and estuary was poor, particularly for nitrogen. This has since improved, at least for contemporary concentrations, through initiatives such as the Sea Vigil vessel- based survey work, much of it for LOIS (Land Ocean Interaction Study) and JoNuS (Joint Nutrient Study).

1960–90

Data gathered between 1960 and 1980 (not seen) includes ammonia, but not other nitrogen nutrientsxxvii. Between 1980 – 1990 annual average nitrate N concentrations were 407 µM in the tidal Ouse at (just above Trent Falls) and 628 µM in the tidal Trent at Keadby (Table ). Values in the estuary ranged from 421 µM at Brough (furthest inland) to 121 µM at Spurn, at the estuary mouth. Ammoniacal N ranged from 35.7 µM (Blacktoft), through 3.16 (Keadby & Brough) to 7.14 µM at Spurn.

1990s – Tidal Rivers

The nutrient fluxes to and through the Humber estuary have recently been analysed by Sanders et al. (1997)xxviii. The inputs to the Humber from the six

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 14 major rivers at the tidal limit, and in their tidal reaches, vary considerably (Table ). The Trent has by far the largest flow, followed by the Ouse. The Trent also has very high concentrations of nitrate. Over 1990–93 the Trent tidal limit mean was 680 µM, but this hides considerable seasonal and annual variation. During 1990–93 winter concentrations frequently exceeded the 50 mg l-1 Nitrates Directive limit (i.e. 806 µM N) in the upper part of the tidal river, with a maximum of ca. 980 µM (See Sanders et al. 1997, particularly their Figs. 6 & 10). The significant urban influence in the catchments of the Aire and Don is also clear from their elevated concentration of ammonia, the largest input to the system.

1990s – The Humber

The North Sea Quality Status Reportxxvi presents nitrate (and phosphate) plots against salinity for the major North Sea river estuaries. This shows virtually identical nitrate plots for the Humber and Rhine/Meuse (the two systems with the highest levels), with a peak at 6‰ of ca. 650 µM, declining steadily as salinity increases. However the volume transported by the Humber is very much lowerxxix – long term flow rates are 246 m3 s-1 as against 2,200 m3 s-1.

Table 2.1 Nutrient concentrations and flow rate in Humber tidal rivers and estuary

period NH4 µM NO3 µM P µM flow m3s-1

1980–1990 tidal Ouse – Blacktoft annual 35.7 407 3.16 - tidal Trent – Keadby annual 21.4 628 10.5 - inner estuary – Brough annual 21.4 421 2.10 - estuary mouth – Spurn annual 7.14 121 0.631 -

1990–1993 tidal limit – Wharfe 4 yr mean 5 150 1.5 17.5 tidal limit – Ouse 4 yr mean 20 280 3.5 45 tidal limit – R. Hull 4 yr mean 35 250 3.0 < 5 tidal limit – Aire 4 yr mean 105 330 18 30 tidal limit – Don 4 yr mean 165 530 28 15 tidal limit – Trent 4 yr mean 25 680 43 80

Trent, 0–2‰ 4 yr range 8–42 460–980 2–67 Trent, 2–16‰ 4 yr range 1–7 350–550 2.5–40

Ouse, 0–2‰ 4 yr range 3–52 150–575 0.3–14 Ouse, 2–16‰ 4 yr range 0.5–9 320–560 1.5–7.5

Humber, 0–10‰ 4 yr range 0.5–37 280–850 1–10.5 Humber, 10–20‰ 4 yr range <0.5–12.5 150–550 0.3–7.5 Humber, 20–34‰ 4 yr range <0.5–7.5 <10–450 <0.2–6.25

Note: The tidal limit represents the freshwater inputs to the Humber system. The six rivers account for 85% of freshwater flow to the estuary. Note the significant range about the mean values. For seasonal nutrient levels, and for silicon, see text. Source: Anon., 1993, Sanders et al. (1997).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 15 However these comparisons have to be treated with caution, as the Rhine data is for February 1990, while that for the Humber is for January 1991. The flux of nitrate transported (in particular) is sensitive to annual variation in rainfall. Increased river flow generally result in an increase, per unit volume, in nitrogen. 1989, 1990, 1991 were dry years and the Humber tributaries had low flowsxxiii, 1993 had flows close to normalxxiv, higher in 1994 (although the summer was dry), and dryer once more in 1995xxv.

Such variation shows clearly in Sea Vigil data for the Humber during the 1990s, which is the source, directly or indirectly, for much of this section. The range in Humber nitrogen concentrations between 1990–1993 are shown in Table . During this period the annual total mean flow was 190 m3 s-1, significantly lower than the long term mean. The mean nutrient concentrations were typically ‘well behaved’, lying approximately mid-way within the ranges shown. Nitrate nitrogen is among the highest encountered in the study (e.g. from 280–860 µM in the upper estuary), along with those from the Deben and Ythan. The Humber flux is, of course, much the greatest.

This confirms that nitrite concentrations were insignificant in comparisons with nitrate1 .

1990s – Humber seasonal variation

The Sea Vigil reports provide information on inter and intra-annual differences between 1992–95.

First quarter values (January–March) from the plotted nitrate/salinity gradients in the reports varied from an observed intercept value at 0‰ of ca. 860 µM in January 1992; an extrapolated value2 of 680 µM in February 1992; an observed value of 500 µM in January 1993 and an extrapolated value of 780 µM; two extrapolated values of 500 µM in January 1994, of 540 µM in February, and one observed value of 430 µM and one extrapolated value of 500 µM in March. There were no winter surveys covering a wide range of salinity in 1995.

During the second quarter (when phytoplankton growth might be expected to increase) the majority of transects covered only a small range of salinity in the outer estuary. Of those extending into lower salinity, that in June 1992, had an observed intercept at 0‰ of ca. 430 µM, that for April 1993 an observed intercept of ca. 570 µM; and a highly variable transect from June 1993 indicated a tentative value of ca. 510 µM. In 1994 there was an estimated May value of possibly 430 µM. The May 1995 transect recorded very high nitrogen values, rising linearly to 360 µM at a salinity of 17‰ (half way between fresh

1 Nitrate and nitrite values were separately recorded for the Sea Vigil data between January–June 1992. From then on merged values, presented as TON, were cited. For the Humber data these can be taken to be virtually identical.

2 Care has to be taken when extrapolating data because the maximum values may (but not always) occur at the turbidity maximum, typically a few points above 0‰. This may produce (minor) inaccuracies; this has been taken into account when providing these estimates. Where transects did not enter low salinity water no extrapolation has been attempted. These figures are provided as guidance: for any detailed assessment the original sources should be consulted.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 16 and sea-water, at the Humber Bridge) but was not extended further up the estuary.

Third quarter work was limited. There were no transects covering a wide range of salinity in the summer months. Visual inspection of the graphs do not suggest any obvious differences in nitrogen concentrations from other times of the year.

Fourth quarter values are similar to those earlier in the year. In autumn 1993 one October transect suggests a tentative estimated value at 0‰ of 430 µM, a second two weeks later gives a more confident observed value of 625 µM, with a November observed value of 640 µM. A December 1995 transect gives an extrapolated value of 610 µM nitrogen.

Fluxes and Sources

The estimated annual average inputs of nitrogen between 1980-90 were, for nitrate N, 9.01 MM d-1 (i.e. 126.2 tonnes per day1) from the Ouse plus the Trent, 214 kM from Hull and Grimsby sewage discharges combined, and 107 kM from fertiliser production discharge into the estuary. The total was therefore 9.14 MM d-1. The ammoniacal N load was put at 1.56 MM from the rivers 486 kM from Hull and Grimsby sewage, and 350 kM from fertiliser manufacture; a total of 2.4 MM per day.

Currently, given acknowledged trends in the UK, as in adjacent countries, it can be assumed that a significant part of the river borne nitrate comes from agriculturexxvi,xxx,xxxi. Surprisingly, the Sea Vigil Reports (including that published in January 1998) quote sewage and industrial discharges as the major sources.

Table 2.2 Nutrient fluxes through the Humber estuary.

— input, kM d-1 — output, net change tidal limits “anthropogenic” total kM d-1

phosphate P 431 70 510 75 - 85% nitrate N 9,552 130 9,682 10,574 + 9% ammonium N 845 700 1,545 221 - 86%

Note: the term “anthropogenic” (following the data source’s usage) is potentially misleading – it only includes sewage and industrial discharges to the estuary; and that the river inputs at the tidal limits also include substantial diffuse (agricultural and atmospheric) anthropogenic inputs. Source: Saunders et al. (1997)

Unfortunately Saunders et al. 1997 compiled what at best has to be described as a poorly drafted table of the nutrient fluxes into and out of the Humber estuary which may add to the confusion (their Table 4; Table 2.2 here). The column marked “anthropogenic inputs” reports improbably low values,

1 Original units in tonnes, converted here to megamoles [millions of moles].

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 17 particularly for nitrate. This is because what they classify as anthropogenic are only “those which can be unequivocally traced to anthropogenic processes, either industrial or sewage”. It turns out that these are simply the old figures for 1980– 90, converted to molar units – presumably the only data available. While the inputs from sewage may not have significantly changed, those from the fertiliser industry may have done.

Anthropogenic inputs to the river catchments, including what are certain to be significant agricultural and anthropogenic atmospheric nitrogen loads are included in the – by implication, non-anthropogenic – ‘tidal limit inputs’ column. There will also be diffuse anthropogenic inputs directly into the estuary. Nowhere in the text is this clarification made. It remains to be seen if these statistics now appear as the total anthropogenic component for the Humber in official documentation.

Setting aside the source of the nutrients, the flux calculations indicated that 86% of ammonium inputs to the estuary were removed, much of it by conversion to nitrate, with the result that nitrate flux entering the North Sea is actually increased, to 109% of the total nitrate inputs to the estuary. Three broad points can be drawn from the nitrogen data. The levels of nitrate are very high. There are no signs of major phytoplankton-induced nitrogen depletion in the second and third quarters. Third, if the fate of the vast bulk of the nitrogen is to enter the North Sea, its destination will be of importance when calculating regional effects.

2.2.2 Phosphorus and Silicon

Phosphorus

Sea Vigil and other data suggests that that the processes affecting phosphorus are complex, in common with other estuariesxxxii. Between 1980 – 1990 annual average orthophosphate ranged from 10.5 µM in the Trent (Keadby) through 3.16 (Blacktoft), 2.10 (Brough) to 0.63 µM at Spurnxix. Data from 1990–93 demonstrate the Trent’s dominance of phosphorus inputs to the estuary (76% of total flux), as for nitrogen.

In the North Sea 1993 Quality Status Report’s international comparison of major estuaries, the January 1991 Humber phosphate concentrations was the lowest; stable through most of the salinity range at ca. 2.5 µM. When the entire data-set for 1990–93 is examined the QSR values appear on the lower edge of a very variable data-set. On a national basis, the overall levels are significant. While apparently less than the Thames (Section 6), the north east England Wear and the Essex Colne, they were similar to polluted estuaries such as the north east Scotland Don, the Inner Clyde, the Tyne and Tees, the Axe and Exe in south west England, and some of the Welsh estuaries entering the outer Severn. They are greater than most sites reviewed in this report.

No obvious intra-seasonal traits show through the general variation in the Sea Vigil reports. In January 1992 concentrations ranged from 6.4 µM P at 0‰, dropping sharply to 3.2 µM at 1‰, and then generally declining to ca. 0.8 µM

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 18 at 33‰, whereas in June 1992 it declined more steadily over the same range. The steepest of the Sea Vigil transects was for November 1993, from 11.3 µM at 2‰ to 0.97 µM at 29‰. On other occasions, such as October 1993, the concentration was virtually constant at ca. 2.4 µM through a salinity range of 1.5–27‰. Data from 1994 and 1995 showed similar patterns. From this data- set alone one might conclude values in the QSR appear to be at the higher end of the range – again indicating the need for caution when making comparisons.

Silicon

Silicon levels were not reported in the 1980–90 compilation, or in the 1990–93 analysis of Saunders et al. Measurements by Sea Vigil at 0‰ in June, October and November 1993 all produced values of 150 µM Si, (i.e. 9000 µg l-1 SiO2), declining more or less monotonically seawards. This was typical of other surveys, where silicon was measured, between 1992 and 1995 and the molarity was usually a quarter of that for TON. Thus in December 1995 it declined from 110 µM at 6‰ to 8 µM at 33‰ (equivalent TON values were 460 and 35 µM respectively)1. However on occasion, notably December 1992 and March and April 1993, silicon was markedly reduced through part of the salinity range. This possibly (but not conclusively) is indicative of diatom blooms, as stated in the Sea Vigil reportxxi.

Generally data on silicon is less often reported, restricting comparisons with other sites. These levels are very similar to those of the Wash estuaries and the Ythan and Don in north east Scotland, and very much greater than most other east Scottish estuaries. It is difficult to make comparisons with the data from north-east England which were limited in extent and date only from summer.

Silicon is usually thought of as mineral unaffected by human activities. This is incorrect. Of these UK sites, those with relatively high silicon concentrations are marked out by their intense agricultural activity, which is known to enhance the rate of weathering processesxxxiii, increase turbidity (itself a form of pollution with biological consequencesxxxii) and to accelerate the release of silica. It has long been argued that marine diatoms – an important component of the phytoplankton community – are limited by silica availability, which they require for their test, the outer ‘shell’. The levels recorded here appear to be significant enhancements. Thus it is possible that intensive agriculture results in silicon eutrophication (at least as scientifically defined) even if the magnitude and consequences are rather less understood than those resulting from nitrogen or phosphorus.

However this issue is too complex, and the data too limited, to be profitably pursued further for the purposes this evaluation.

1 So typical ranges, combining surveys, might be 100–150 at 0–10‰; 60–100 at 10–20‰; and 8–60 at 20–33‰

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 19 2.2.3 Nutrient Ratios

In December 1995 Sea Vigil was used to gather continuous data in a profile running from Spurn Point to Trent Falls and then back to Hull. TON declined linearly from 500 µM at 7‰ to 54 µM at 33‰ as did silicon, from 117 µM to 12.5 µM1. Phosphate P declined from 8.7 µM to 1.3 µM in a slightly concave manner. From this it was possible to produce detailed nutrient ratios. That for N:P rose steadily from 60:1 at 7‰ to 90:1 at 25‰, and then fell rapidly to 40:1 at 33‰. That for N:Si was ca. 4.2:1 throughout the salinity range.

It might incorrectly be thought (indeed sometimes argued) that the influence of the rivers, and their anthropogenic burden, on nutrient levels near the mouth of an estuary would be small, given the massive dilution by seawater. But this fails to appreciate just how high the initial nutrient concentrations are in the rivers compared to the sea. This is well illustrated by Saunders et al., who plot the N:P ratio at Spurn Point (at the estuary’s mouth; salinity 33.4‰ in low flow conditions) against the mean river flow over the previous two weeks. There is a strong correlation, resulting in a N:P ratio as low as 10:1 during low river flow to the estuary (100 m3 s-1), rising to 90:1 during a spate (750 m3 s-1). They argue that the adjacent offshore area may by nitrogen limited at low flows, and that higher discharges, and higher nitrogen levels, may progressively stimulate plant growth providing turbidity is low.

Moreover, their flux analysis provides strong supporting for the existence of a buffering mechanism for phosphorus: as phosphorus is withdrawn from solution, for example by plant growth, it will be compensated for by particulate phosphorus entering into solution, with the result that available phosphorus – and the potential for plant growth – is much higher than the water concentration (and Redfield ratio) suggests. Indeed, as the principle source of phosphorus is marine, at least for the lower Humber, very significant reserves are available.

2.2.4 Nutrient Trends

No paleoecology studies relating to the Humber have been encountered (See The Wash, p. 29), and the data seen for recent decades are insufficient to examine trends. For the future one important issue is whether measures taken to reduce the significant BOD demand above Trent Falls will reduced denitrification processes, resulting in an increase in nitrate loadings to the lower estuary, c.f. the example of the Scheldtxxxiv.

2.2.5 Biological Oxygen Demand

Between 1980 and 1990 the average BOD at the tidal limits of the rivers was 5.9 mg l-1 for the Aire, 4.0 mg l-1 for the Trent and 2.4 for the Ouse. Although there are defects with the data the sewage derived BOD load to the entire

1 Original data in terms of weight rather than molarity or atomic ratios

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 20 Humber system apparently rose from 78 to 132 tonnes per day, while the industrial BOD load fell from 97 to 68 tonnes per dayxix.

Tidal Rivers

Data from the 1990s highlighted a continuing problem with deoxygenation in the tidal rivers (particularly the Ouse) and upper estuary (references xxiii– xxv). Suspended sediments play a major part in creating a significant stretch of the tidal Ouse having modelled dissolved oxygen levels in 1995 that still fall to just 0–20% of saturation. Although there has been a significant improvement since the 1970s, this is acknowledged to remain a serious problem. However no quantitative data on the contribution of STW discharges to this problem were seen.

Estuary

Moving below Trent Falls, in July and August 1993 dissolved oxygen levels at Blacktoft, were typically under 5 mg l-1 and there were two periods when it fell to under 1 mg l-1 at its lowest point during each tidal cycle. Only marginally better results were recorded in 1993 further down the estuary at Upper Whitton, and at Hull’s Corporation Pier, in the mid-estuary. In 1994, oxygen saturation at Blacktoft steadily declined through June and July until by late July it oscillated from ca. 50% to zero over each cycle. Data presented for all of 1995, which smoothed out short term extremes (which nonetheless represent important biological events), still showed oxygen levels at Blacktoft to repeatedly drop to 20% of saturation between August and November. The text of the 1995 report refers to well oxygenated seawater at Hull Corporation Pier in June, but this may be an error – the graph is labelled, and appears typical of, late November.

Dissolved oxygen, as a percentage of saturation, is presented in the 1995 Sea Vigil Report for a series of transects (at one metre depth) across the Humber from the Humber Bridge to Spurn Point. The May Humber Bridge transect gave values of 64–75% saturation, while that from Spurn ranged from 85–97%. A continuous sampling transect from Trent Falls to Spurn in December 1995 returned values ranging from 72–80% saturation below Trent Falls to 95–98% in the outer estuary.

Sources

Between 1980–1990 the BOD of sewage discharges to the tidal rivers was put at 5.9 tonnes per day, while that from industry was a nominal 47.1 tonnes1. The effect of such discharges is disproportionate to their size because of the lack of dilution and long retention timexix. That for the estuary was 126.4 tonnes per day from sewage (principally Hull (84.3) and Grimsby (37.1)) and from industry, a nominal 20.5 tonnes BOD per day.

1 The industrial values for BOD are nominal because of the toxic contaminants that inhibit biological activity – that from the Killingholm/Grimsby area had a nominal BOD of just 9 but a COD of 125 tonnes per day.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 21 The conclusion is that – while improvements have taken place – in the early and mid 1990s there were still significant problems from oxygen depletion especially in the upper estuary and tidal rivers.

2.3 BIOLOGICAL EFFECTS

2.3.1 Nutrient Related Effects

Phytoplankton

It is generally assumed that Humber phytoplankton production is insignificant. Thus the 1994 Sea Vigil report says (p. 8) “Due to the high turbidity of the Humber Estuary, it was not felt necessary to sample for chlorophyll” The absence of nutrient depletion in the summer months can be taken as evidence to support that view. Indeed this belief was so strongly held, that it is only the last few years that chlorophyll levels have begun to be assessed, and there appears to be little information on phytoplankton (or zooplankton) community structure, even at a crude level.

However the assumption should be regarded with caution. First, it is now clear that there can be unexpectedly high levels of phytoplankton growth in turbid estuaries, such as the Great Ouse in the Washxxxv. Second, as the Sea Vigil reports show, there is evidence that silicon at least can be depleted in the Humber, and this has been taken as indirect evidence for diatom bloomsxxi. Third, Sea Vigil Humber data for 1995 showed that turbidity is quite variable. Fourth the same Sea Vigil data revealed a significant range of phytoplankton activity (measured as chlorophyll-a) in both May and in December.

Unfortunately the measurements are in arbitrary units so production levels are unknown, and turbidity may conceivably interfere with these measurementsxxxvi. However the interesting feature of the December chlorophyll measurements was that the highest values were in the upper estuary, just below Trent Falls, where the turbidity was low. Nevertheless it would be remarkable if phytoplankton blooms turned out to be anything other than sporadic and localised. The issue, within the estuary at least, is perhaps more one of the impact on natural community structure, rather than absolute phytoplankton levels.

Some light on the upper estuary peak is shed by a paper currently in pressxxxvii. This records a range in chlorophyll-a concentrations in 1994–95 from 60 µg l-1 to less than 13 µg l-1 along a transect from the non-tidal to the tidal Yorkshire Ouse in summer. In the estuary itself two significant areas of phytoplankton abundance were noted.

First, a peak was present at the inner estuary turbidity maximum, from February to high summer. Maximum levels, between June and July, reached 13–14 µg l-1. High concentrations of phæopigments1 (up to 65 µg l-1 in June

1 phytoplankton post-mortum degradation products

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 22 and July) indicated to the authors that these were freshwater phytoplankton with short survival times, predominantly being accumulated by the same physical processes that created the turbidity maximum, rather than by active growth of brackish water species (but c.f. the Tamar). Second, significant phytoplankton growth occurred in the third quarter of the year in the outer estuary. This peaked in August 1994 at ca. 10 µg l-1. This was not accompanied by phæopigments. This appeared to be the estuary end- phase of a surge in phytoplankton growth which, starting off-shore in late spring, proceeds up the North Sea Humber plume as turbidity levels decline and light limitation ceasesxxxviii.

It should be noted that toxic contaminants can suppress plant growth, and that growth may increase as pollution controls are implemented After more stringent controls of industrial discharges on the south side of the estuary Fucus seaweed growth increased in the vicinityxxxvi. The section on north-east England estuaries discusses increases in seaweed growth following reductions in pollution; reductions in algal growth in bioassays presumed to result from toxic inhibition; and concerns relating to herbicide effects.

As already noted, no information was encountered on phytoplankton community structure, and possible changes, which may be the chief area of concern regarding phytoplankton within the Humber (c.f. Welsh estuaries, Section 7).

Finally, given that the estuarine uptake and elimination of nitrogen is low, the fate of nutrients beyond the estuary is also relevant to the Directives’ requirements.

Macrophyte Growth

Intertidal algal mats are far less affected by turbidity than phytoplankton, and the Humber’s extensive mud flats and relatively sheltered conditions provide an ideal habitat. Yet algal mats are not mentioned in any of the Humber reports. This is surprising. CASI spectral images of aerial photographs available for part of the lower Humber estuary reveal ‘dense algae’ cover over most of the mudflats surveyed (the 25 km2 embayment to the west of Spurn Point, and those to either side of Grimsby)xxxix. For Spurn Point, at least, it was confirmed that this was due to extensive Enteromorpha weed matsxl. Work on the image analysis of Enteromorpha weed mats in the Ythan have revealed that only biomasses “in excess of 1 mg m-2 are apparent on aerial photographs [and that] other studies have shown that invertebrate abundances are most affected by macro-algal biomasses of 1 kg m-2 or more”. It is important to note that both TON and phosphorus in the outer Humber, where (known) mats proliferate, are much higher that those affecting algal mat sites in the Ythan (TON <10–450 vs. 0–180 on the Ythan: PO4 <0.2–6.25 vs. 0.1–1.5: salinity range 20–34‰ for both estuaries). Nutrient levels are also higher than those associated with algal mats in Langstone Harbour Sensitive Area. Thus there is prima face evidence for significant eutrophication in at least part of the Humber.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 23 Anecdotal accounts exist of the historical presence of eel-grass (Zostera) beds in the Humber, which are apparently no longer present. As described in later sections, eel-grass is vulnerable to eutrophication due to smothering by algal mats or epiphytic algal growths.

In summary, the Humber is clearly hypernutrific, but turbidity prevents widespread active phytoplankton growth in the inner and mid-estuary. The outer estuary is clearer, and phytoplankton levels approach 10 µg l-1, hinting at the extensive coastal blooms that develop in the Humber estuary’s nutrient rich plume. There is now clear evidence of algal mats at biomasses likely to cause adverse effects, but there appears to have been little regulatory interest in this dimension. There are also suggestions that eel-grass beds have declined or disappeared: these could not be confirmed in this study but in principle should be easy to resolve via the vice-county plant recorder.

2.3.2 Sewage-specific Effects

The impact of sewage is monitored by faunal surveys of intertidal and sub- tidal invertebrate community structure and organic carbonxxiii,xxiv,xxv. A fish survey is also carried out. The most recent compilation seen is for 1995. Because the ecology is poorly understood, it can be difficult to distinguish between inherent biological variability; that due to natural changes in the physical environment (such as sediment changes); and those due to human activities. However certain species are considered indicative of organic enrichment, such as from sewage.

The intertidal sampling for 1995 revealed a general increase of oligochaete worms, which was particularly evident on the north shore of the inner estuary. The relevant reportxxv concludes “This may reflect a change in water quality but is equally likely to be a result of natural population fluctuations”. Elsewhere there were reductions in organic carbon, and changes in biodiversity that the authors believed were best explained by improvements to sewage discharges.

For the subtidal samples there was a decline in species diversity in the upper estuary in 1995. This was considered to be within the normal bounds of variation, and were attributed to changes in the sediments rather than a decline in water quality. Mid-estuary tidal sites were dominated by Capitella which “indicates generally poor environmental conditions and an ongoing state of organic enrichment” from sewage. The lower and outer estuaries generally showed a slight increase in diversity, and this was taken as an improvement in environmental conditions.

The 1995 fish surveys were consistent with previous years. Sand goby, whiting, Dover sole, place, flounder and dab were all caught. Variations in the numbers caught were attributed to changes in migration patterns and spawning activity rather than of the environmental quality of the estuary. Microbiological surveys performed in 1995 included tests for Clostridium perfringens, which produces spores that have a long survival time, and are therefore used as a long-term indicator of sewage contamination. Clostridium

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 24 was found throughout the estuary, including the outer estuary. This “indicates that sewage is contaminating mud-flats further down the Estuary than would otherwise have been expected”. Tests were also performed for Escherichia coli and Streptococcus species which have lower survival times in saline water. All were ubiquitous throughout the estuary, although showing peaks in the vicinity of Hull and Grimsby sewage works, and the confluence between the Ouse and Trent.

2.4 NITRATES DIRECTIVE: SHOULD THE AREA BE DESIGNATED?

In 1997 the Environment Agency reviewed the Humber’s status for the purposes of the Nitrates and UWWT Directives but, unlike SEPA’s report on the Ythan, these results have not been made available.

2.4.1 Nutrient Sources & Quantities

Unfortunately, although requested, a breakdown of the sources for nitrate entering the Humber estuary has not been received. As already reported, Saunders et al., and earlier crude accounts, do not distinguish the agricultural component of their flux calculations. However agriculture will be a significant source of nitrate in the Humber catchment. Nitrate occasionally exceeds the 50 mg l-1 standard in the upper estuary, and regularly does so in the lower tidal Trent. Thus one condition for the application of the Nitrates Directive applies to the catchment of this major UK river. However until now the UK has only evaluated NVZ status against waters abstracted into a public potable supply.

Based on the UK interpretation, nitrate levels have lead to the establishment of NVZs in parts of the catchment of the Humber Basin, including North Nottinghamshire, North Lincolnshire, the River Hull, scattered sites on the Yorkshire Wolds chalk, and sites in the vicinity of Birmingham. Whether these will have a significant effect on the nitrate concentrations in tidal Trent and upper Humber appears unlikely. Any claim to the contrary would need to be backed up with a detailed nutrient budget.

2.4.2 Evidence for Eutrophication

Checking the information compiled here against the UK 1993 Consultation leads to the following conclusions:

• Nitrate Concentrations As just described, frequently exceeds 50 mg l-1 in the tidal Trent and approaches this in some surveys of upper Humber. If the low oxygen conditions in the tidal Ouse are improved, and other factors remain unchanged, denitrification may be reduced, resulting in increased nitrate levels in the lower tidal river and upper estuary; • Occurrence of exceptional algal blooms The absence of historical records make it difficult to define an ‘exceptional bloom’ in the Humber context. Blooms are not expected on the scale seen, for example, in the Wash Great Ouse estuary. Significant chlorophyll concentrations in the inner estuary have been interpreted as moribund freshwater phytoplankton

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 25 accumulations, but not unequivocally demonstrated as such. Blooms occur in outer estuary which (on the basis of limited sampling) approach 10 µg/l. Major offshore blooms occur in the North Sea Humber plume; • Duration of algal blooms through summer Peak annual abundance occurs in summer in both inner and outer estuary; • Oxygen deficiency Known to occur in tidal rivers and inner and mid- estuary. Believed to be primarily due to sewage BOD. Sediment oxygen deficiencies associated with algal weed mats not directly assessed; analogies with other sites suggests that it could be significant; • Changes in fauna Have been identified in intertidal and subtidal fauna but believed to be due to sewage BOD, with good supporting evidence, in the estuary and tidal rivers. Effects associated with algal mats unmeasured, likely to be significant; • Changes in macrophyte growth Sea-grass (Zostera) apparently declined, possibly extinct. Changes in seaweed growth difficult to establish because of lack of historical data, confounded by known toxic effects. But dense algal growth occurs on mud-flats, at least in the outer estuary. Apparent absence of historical data. • Occurrence and magnitude of PSP Believed to be absent. • Formation of algal scums on beaches and offshore Anecdotal accounts, but apparently of minor significance.

In addition to the Nitrates Directive guidelines, the outer Humber estuary also significantly exceeds CSTT guidelines regarding nutrient levels and chlorophyll concentrations for defining hypernutrific eutrophic coastal waters. It is accepted that the estuary is hypernutrificxxii, the Sea Vigil Humber reports use these CSTT definitions.

The UK interpretation represents only an extreme form of eutrophication. The Nitrates Directive, in conjunction with the Habitats and Species Directive, may require a more strict interpretation such that the natural species composition and abundance are maintained or restored.

Finally the Directive requires that the nitrogen does not contribute to eutrophication problems elsewhere. Denitrification may account for perhaps 10% of the estuary’s nitrogenxli, although Saunders et al. revise this down to just 4%. The majority of the nutrient load is transferred to coastal waters where represents ca. 20% of the UK’s nitrogen inputs to the North Sea.

2.4.3 Conclusions

The contribution from agricultural nutrients has apparently not be quantified, although the information necessary to do this exists, and has been applied elsewhere (see Essex & Suffolk estuaries, Section 4). It is nevertheless implausible to argue that agriculture does not make a major contribution to total Humber inputs. While some NVZs within the catchment have been agreed, they cover a relatively small area, and it is dubious whether action here, even if successfully implemented, will have significant implications for the estuary.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 26 On this basis, judged by nitrate levels and eutrophication, there is a strong case that the entire catchment of the waters contributing to the Humber estuary should have been designated as an NVZ.

2.5 UWWT DIRECTIVE: SENSITIVE, LESS SENSITIVE OR THE NORM?

The history of the Humber estuary in relation to the UWWT Directive has been highly controversial, both with regard to the distinction between a coastal and an estuarine water, and for the UK’s operational implementation of LSAs via the concept of HNDAs.

2.5.1 Less Sensitive Area status

The UK Government initially sought to redefine the boundaries of the Humber estuary, for the purposes of the UWWT Directive, such that the coastal waters were deemed to start at the Humber Bridge. Yet salinity levels under the Humber Bridge are typically 15‰xxii, and the outer limit of the estuary had previously been regarded by regulators as defined by a line between Spurn Point and Donna Nook, many miles downstream. However the establishment of a coastal HNDA would have had major cost-saving implications with regard to sewage disposal from Hull, Grimsby and other smaller sites. However the Local Authorities took the case to Judicial Review, where the re-definition was rejected in 1996, it being judged that it was indeed driven by financial considerations rather than scientifically justifiable criteriaxlii. Since that time the boundary of the estuary has once more been considered to lie between Spurn and Donna Nook.

The justification given for estuarine HNDAs in the CSTT Report is that “Estuaries around the United Kingdom are generally dynamic, well aerated areas, many of which have a high dispersive capacity as a result of limited low water retention and a high exchange between estuarine and coastal water on each tidal cycle.” [para. 4.2].

Given that the Humber clearly does not fit this description, the greater length of the estuary (down to Pyewipe, beyond Grimsby) was designated as an estuarine HNDA and LSA after the court case. The tension this causes is clear in the Environment Agency 1995 Humber Estuary Report, published in January 1998. Immediately after describing the situation with regard to HNDAs it states “The tidal excursion of the Humber is several times greater than the displacement of seawater by freshwater input during the tidal cycle. This asymmetrical tidal flow results in an extended residence period of effluents discharged to the estuary whilst they are progressively diluted and edged towards the North Sea.”

The UWWT Directive allows designation as an LSA “if the discharge of waste water does not adversely affect the environment”, but requires that issues such as oxygen depletion or eutrophication “should be taken into consideration”.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 27 Taking all of these factors into account it was questionable whether LSA status for the Humber Estuary can be justified. Following on from the court case, Yorkshire Water agreed that it would install secondary and bacteriological treatment to its Hull STW.

Finally, in the June 1998 Government statement, it was announced that HNDA status was being withdrawn for the Humber STW discharges, “which will now require secondary treatment”. These range in size from (p.e. 3,490) to Hull (p.e. 510,000).

2.5.2 Sensitive Area Status for the Humber?

The Humber was not put forward as a candidate Sensitive Area in the first round of designations. From the data quoted in Sanders et al., re-quoting 1980- 90 data (see Table), and if these estimates are still regarded as valid, it would appear that Hull and Grimsby STW contribute ca. 5% of the combined nitrate and ammonium inputs to the Humber. Assuming that all the ammonium reported for the tidal limit inputs comes from freshwater sewage1, and that

their NO3:NH4 ratio is the same as those to the estuary, this gives an overall STW input of dissolved inorganic nitrogen that is 12% of the total. This might reasonably be regarded as a significant input to the eutrophic estuary, especially as ammonium (which makes up the bulk of the STW inputs) is the favoured form for marine plants.

In the words of the UWWTD Annex II, as the Humber estuary both has “poor water exchange”, and receives “large quantities of nutrients”, and it cannot be demonstrated that removal will have “no effect on the level of eutrophication” it would seem the Humber should have been designated as a Sensitive Area.

1 reasonable, given that the other major source of ammonia is also a diffuse agricultural input, from livestock, explicitly excluded from Sanders et al.’s “anthropogenic” column.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 28 3 THE WASH

The Wash, with its extensive mudflats and sandbanks, and its low-lying intensively farmed hinterland, bears many similarities to the Wadden Sea and the Dutch landscape, with its well established vulnerability to eutrophication. Rainfall in the Wash catchment is low by UK standards, and significant amounts of water are withdrawn for irrigation. That which remains slowly passes via dikes and enchannelled rivers with negligible gradients to the estuaries and the sea. In these aspects the catchment is the most extreme in the UK. One would therefore anticipate that it would be especially vulnerable to agricultural eutrophication, while STW nutrients, oxygen demand and associated problems can also be expected to have a marked effect.

3.1 SITE LOCATION & DESCRIPTION

The description of catchment and land-use is mainly derived from the Wash Zone Report, published in 1994xliii, the source of the unattributed quotations throughout this section.

3.1.1 Nature of The Wash and its Catchment

The Wash, with a surface area of 700 km2, is the largest estuarine complex in Britain, particularly apparent as such when viewed at low tide. Located in Eastern England, it has four main estuaries (see Maps E and F). From the north these are the Witham (estuary length 25 km, maximum flow to tide in 1990 55 m3 s-1), the Welland (estuary length 22 km, maximum flow 90 m3 s-1), the Nene (estuary length 40 km, maximum flow 23 m3 s-1) and the Great Ouse (estuary length 60 km, maximum flow 220 m3 s-1) which collectively have a catchment area of 15,650 km2, some 12% of the land area of England.

For 20–40 km or more of the Wash’s hinterland, the terrain is mostly low- lying, a few metres above sea level, with there result that there is virtually no gradient for the lower fenland sections of the rivers. The resulting long residence time thus allows the build-up of pollutants.

The entire Wash is a designated Special Protected Area and a designated Ramsar site. Part of it is a National Nature Reserve. It is “one of the most important areas of estuarine mudflats, sandbanks and saltmarsh in the United Kingdom” xliv. Prominent invertebrates include mussels, cockles and shrimps, and it is also an important nursery area for flatfish, including plaice, dab and sole. It holds the largest breeding colony of common seals in Europe (greater than 6000 individuals), and supports internationally important numbers of 13 wintering wildfowl species, nationally important numbers of seven others, as well as a large number of breeding waterfowl.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 29 3.1.2 Nature of Land-use

The land is predominantly agricultural and intensively used. Water abstraction for irrigation is substantial with the result that there are “often little or no freshwater flows to tide in summer.” Despite this there is one STW discharge to each of the rivers, except the Nene, which has three. In 1994 the level of treatment varies from primary only (e.g. King’s Lynn, on the Great Ouse estuary) to secondary (e.g. Spalding, on the Welland estuary). There were then some limits to ammonia discharges (e.g. West Walton, on the Nene). In some cases, such as the discharge from Peterborough, also on the Nene, conditions in 1994 were truly shocking: “The effluent is discharged into the counter-drain [i.e. drainage dike], where it causes chronic water quality problems (the flow in the drain comprises almost 100% sewage effluent) before it is pumped into the Nene estuary just downstream of the Dog-in-a-doublet Sluice. [The high ammonia] concentrations downstream of the Dog-in-a-doublet are polluting the estuary and give much cause for concern. There are no plans for any improvements to be carried out at the works.”

In addition to STW there are also food processing, chemical and timber industry discharges (which have been upgraded during the 1990s, according to the Wash Zone Report although the extent of this is not described).

3.2 THE ESTUARIES

The Wash Zone Report provides data from 1987 to 1992. In addition there are two Sea Vigil reports for The Wash, for 1992–1993xlv and 1994xlvi. Data covering the four major estuaries from these reports are shown in Table. The first three rows of data for each estuary, giving values for upper, mid and lower salinity ranges, come from the JoNuS programme which included five to seven sampling trips along each estuary between July 1990 and February 1992. The Wash Zone Report also includes data collected over a longer period for the lower estuaries. These are summarised in the final two rows for each estuary.

3.2.1 Nitrogen

Nitrite

Nitrogen,NO2, was infrequently sampled and is not included in the table. It appeared to be responsible for up to 5% of TON for the Nene and Great Ouse estuaries, and considerably less for the Welland and Witham. The data is insufficient for further examination.

TON

The Witham showed astonishing concentrations of TON, virtually all nitrate. Between 0–10‰ this ranged up to ca. 2000 µM (23 mg l-1 N, equivalent to 102 mg l-1 nitrate), measured in both January 1991 and 1992 at 0‰. From this, concentrations declined monotonically towards the sea, so these were not spurious data points. Unfortunately TON was only sampled on two other occasions, in July 1990 and April 1991, when sampling extended from only

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 30 15‰ to the estuary mouth. These indicated values under 35 µM throughout their length. The reasons for this dichotomy are pursued shortly.

Table 3.1 Wash estuaries’ nutrients, dissolved oxygen and chlorophyll

NH4 TON P04 Si02 O2 chloro- µM µM µM µM % sat. phyll, µg

Witham estuary, 0–10‰ annual 16–52 1400-2000 0.40–8.0 37–155 82–87 - estuary, 10–20‰ annual 1–34 <35–1600 2,1–10 1.6–122 85–120 - estuary, 20–34‰ annual 1–27 <35–780 1.3–5.1 <1–77 70–130 -

lower estuary winter 16.0–24.5 140–786 0.79–3.71 - 78–96 - lower estuary summer 3.01–21.5 47.6–378 0.34–3.03 - 82–107 -

Welland estuary, 0–10‰ annual 1.4–130 30–1200 1.0–16 0–136 75–180 - estuary, 10–20‰ annual 0–54 15–910 1.0–5.1 0–117 65–115 - estuary, 20–34‰ annual 0–36 <15–610 0.64–9.0 0.16–47 75–90 -

lower estuary winter 13.7–61.8 275–774 1.84–5.66 - 72–97 - lower estuary summer 5.56–46.5 52.1–542 1,23–4.34 - 72–107 -

Nene estuary, 0–10‰ annual 0–470 300–1200 2.4–66 0–132 7–95 - estuary, 10–20‰ annual 0–160 140–1000 2.4–35 0–99 33–80 - estuary, 20–34‰ annual 0–130 <10–857 <1.5–19 1.60–68 65–95 -

lower estuary winter 16.0–78.5 235–558 5.11–9.68 - 54–82 - lower estuary summer 14.1–59.0 86.3–449 1.58–8.92 - 47–84 -

Great Ouse estuary, 0–10‰ annual 0–68 0–930 1.3–50 0.80– 65–115 - 136 estuary, 10–20‰ annual 2.1–27 71–790 6.4–34 6.6–136 65–85 - estuary, 20–34‰ annual 1.4–39 0–410 0.64–18 <1–68 75–90 -

lower estuary winter 9.26–22.4 128–589 3.82–7.76 - 76–92 9.63–41.5 lower estuary summer 14.8–35.4 52.7–450 1.78–8.82 - 62–88 12.0–66.7

Source of raw data: Wash Zone Report: A Monitoring Review (1994).

The first three rows for each estuary are from a series of JoNuS estuary-length surveys between 1990 and 1992, covering all four seasons. They show the range of individual data points for upper, mid and lower salinities. The last two rows are means of all the lowest, and all the highest, values taken from each quarter-year during winter (first and fourth quarter) and summer (second and third quarter). These come from a separate data set of near- continuous monitoring between 1987 and 1992.

Note that no chemical units for JoNuS surveys given in source document. (e.g. phosphate mg/l or phosphate-phosphorus mg/l). Other JoNuS Wash

documentation cites mass of N for ammonia, P for phosphorus but SiO2 for silicon, and this is assumed to be the case here when making molar

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 31 conversions. Continuous sampling graphs are marked ‘ammonia’ and ‘phosphorus’, so molar values of 18 and 95 assumed in conversion from mg l-1 original units.

However it should first be noted that these winter Witham TON values were the highest encountered at any UK site examined as part of this evaluation with the possible exception of the Blackwater estuary (see p.82). Moreover those for the Welland and the Nene, ranging over 30–1200 and 300–1200 µM respectively at 0–10‰, were not much lower than the Witham. Those for the Great Ouse (0–930 µM) were also very high, of the same order as the tidal Trent at 0–2‰ and the Humber at 0–10‰, and greater than severely eutrophic sites such as the Ythan.

The JoNuS values used here are the maximum range of individual values sampled on relatively few occasions. It might be argued that, by chance, rare events are being over-emphasised. It is possible to test this, as the Wash Zone Report also provides graphs of (near) continuous monitoring between 1987– 1992 for the lowest sampling point on each estuary. From these graphs the lowest and highest nutrient values for each year-quarter were extracted for this report. From these in turn the mean of both the lowest and the highest values were calculated for winter (year quarters 1 and 4) and for summer (quarters 2 and 3). This provides a balance, ameliorating the influence of any extreme values, while not discounting them entirely.

In fact the correspondence with the values from the JoNuS surveys is good. For the Witham the lowest summer value was 47.6 µM, the highest winter value was 786 µM. The equivalent range for the JoNuS survey at 20–34‰ was <35–780 µM. There was a relatively good match for the other estuaries as well, bearing in mind that the range of years was different. In particular there was no evidence that the JoNuS values represented unusual high extremes of nutrients.

Inspection of the Witham lower estuary graph also shed some light on the high winter but low summer TON values for the Witham and other estuaries. As for the JoNuS data they also show that in some years TON was very low in quarters 2–4 (1989 and 1990) or quarter 3 (1991). These include the periods of low JoNuS values at 0‰. In other years (1987–88), TON values stayed high for much of the year. There was also a (low tide) peak of 2000 µM TON at this lower estuary site in November 1992. This at first seems particularly extraordinary until the salinity data is examined. This shows that the salinity was then only 1.5‰. Salinity also helps account for the low summer TON values. Inspection of the data shows that these corresponded to very high salinities even at low tide (when maximum dilution by freshwater normally occurs). Thus what appears to happen in the Witham are periods of high flow/high freshwater TON, and low flow/lower TON levels, further exaggerated by extreme ranges in saltwater penetration along the virtually gradient-less estuary.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 32 The TON data for the lowest sampled point on the other three rivers display similar patterns.

Ammonium concentrations were greatest in the Nene, where individual values ranged between 0–470 µM at 0–10‰, while a mean value at the lower estuary site would appear to be ca 35–50 µM. Thus the Nene has the same magnitude of ammonium pollution as other heavily contaminated sites such as the tidal Yorkshire Don and Aire and the Essex Colne. It also corresponds to ammonium levels in Portsmouth Harbour in the mid-1970s, prior to the diversion of what were accepted as polluting sewage discharges. The Welland also has very significant concentrations of ammonia throughout its length, comparable to those in the Clyde estuary at 0‰ and the Yorkshire Don, and greater than sewage-polluted south west England estuaries such as the Truro and Tresillian. The Witham and Great Ouse appear to have ammonium concentrations of the same order as that of the Truro, greater than the Tresillian, and greater than sites such as Southampton Water, where ammonia is established an important factor in the dynamics of red tides.

3.2.2 Phosphorus and Silicon

Phosphorus

Phosphorus concentrations are highest in the Nene (2.4–66 µM at 0–10‰, and mean levels of 5–10 µM in the lower estuary) and the Great Ouse (1.3–50 µM at 0–10‰; mean levels in lower estuary 4–8 µM) with the Witham and Welland having lower estuary means of approximately half this value. The Wash estuaries thus carry significant phosphorus burdens compared to other UK sites. The concentrations place the Nene and Great Ouse at approximately the same magnitude as phosphate-polluted Humber tidal rivers such as the Trent, Don and Aire; and greater than sites such as the Essex Colne, the Clyde estuary, or the north east England Wear. The Welland, although lower, has similar levels to the Clyde and Colne, with the Witham only slightly below.

All four estuaries showed similar behaviour over the year, declining to minimum and relatively constant levels in April (typically ca. 6 µM for the Nene and Great Ouse, 2 µM for the Witham (recorded over 15–32‰) and 1 µM for the Welland).

Silicon

The JoNuS transects also recorded silicate. All four estuaries had concentrations similar to those in the Humber and Ythan (see Humber section, p. 19, for discussion re. anthropogenic influences). All four showed similar patterns: at their highest in January, showing depletion by February, low levels in April and very low in July, then recovering through autumn. There was also consistent variation in concentrations between the years: For all four rivers silicate at 0‰ in January 1991 was ca. 67 µM, but ca. 150 µM in January 1992, apparently correlated with the significantly higher January flow in 1992.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 33 3.2.3 Nutrient ratios, trends, budgets and sources

Information on estuarine nutrient ratios is included with that for the Wash. Accessible information on nutrient trends are apparently unavailable for any of the estuaries, the information contained in the Wash Zone Report dating back only to the late 1980s.

Table 3.2. Great Ouse estuary 1992 dissolved nutrient budget

River Removal by Estuary Estuarine export to inputs algae conversion inputs The Wash

TON MM 372 --7– -8.71 1.57–5.21 280–285 651

phosphorus MM 9.71 -0.419– -0.548 -2.700 – -2.721 5.42–5.64 12.1

silicon MM 72.8 -1.43– -1.79 0.321– 1.11 82.5–83.6 157

Note: Units in megamoles (multiply by molar values to derive tonnage). Estuarine inputs are “agricultural drains, tributaries, sewage works”. Estuarine conversion is, for TON, addition via water column nitrification of ammonia; for phosphorus additions from sediment release (100– 119 kM) minus substantial inorganic removal (2.71–2.84 MM); and for silicon, addition by biogenic opal dissolution. Source: Rendell et al. (1997)

Nutrient budgets and sources

Nutrient budgetand sources been approximated for the Great Ouse in a recent paper by Rendell et al. (1997)xlvii. The fluxes for 1992 are shown in Table 3.2. They indicate substantial transfers of dissolved nitrogen and silicon through the estuary into the Wash, while ca. 20% of dissolved phosphorus inputs to the estuary from all sources are adsorbed onto suspended particles – although much of this will subsequently be transferred to the Wash and presumably available for subsequent desorption.

However there are a number of aspects to this analysis that have to be taken into account.

First, the uncertainties are considerable. The estimated river inputs of nitrogen and phosphorus are believed relatively accurate. But – according to the authors – silicon river inputs, all estuarine conversions, and the final exports to the Wash are subject to an error of perhaps ± 20%.

Second, Rendell et al. confirm that fluxes are substantially affected by freshwater flow. A comparison of January – August 1992 with the same period in 1993 demonstrated that an increase in freshwater flow of 124% was associated with an increase of the flux to sea of TON by 160% (from 220 to 580 MM) and of silicon by 40% (from 58.2 to 80.3 MM); but with what Rendell et al. judge to be little change in the phosphorus flux, nominally reduced by 14% (from 7.10 to 6.13 MM). They earlier explain that “lowland areas of intense agriculture such as the Great Ouse catchment present a large and diffuse source of nitrate which is readily leached into water courses when it rains … during small or

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 34 moderate rainfall events, nitrate leaching increases markedly with rainfall amounts, but then levels off as rainfall amount continues to increase. While nitrate may have a diffuse source, the dominant sources of phosphate are sewage works. These point discharges are subject to dilution by the receiving river as a function of freshwater flow, and thus … show the inverse relationship with flow [NB not total flux] observed”. Variable fluxes may also account for the differences with another analysis of nutrient cycling in the estuary, for summer 1994xlviii. It was a then minor sink for TON (-8% of inputs – thus destruction of nitrates via denitrification, although greater, still remained trivial), a large source for ammonium (95%) and therefore a minor sink for dissolved inorganic nitrogen overall (-2%). It was also a modest sink for phosphate, (-22%) and silicon (- 12%). The relative insignificance of estuarine denitrification is confirmed in other publications as equivalent to ≈1% of the TON load of the Great Ousexlix.

The third consideration is that Table 3.2 might be taken to imply that algae remove very little of the nutrients, and are not nutrient limited. However annual budgets have to be treated with caution. During the two week peak of algal growth in June 1992, 27% of TON, 43% of phosphorus and 31% of silicon inputs were removed by algae. In 1993 uptake was even greater (despite the increased flux), periodically exhausting silicon in the lower estuary. Rendell et al. suggest that this growth, when nutrient inputs to the sea are at their annual minimum “may therefore exert an important control over the likelihood of coastal eutrophication events during this period”. Nevertheless nutrients exported as dead plant material (or other organic forms) will be available to the environment, even if this is delayed to some degree.

Finally, anthropogenic contributions form a major part of what are termed ‘estuarine inputs’ in Table 3.2. Unfortunately “in the absence of sufficient data to calculate it directly [estuarine input] was taken to be the residual quantity” and is thus “very poorly constrained”. Nor were they able to quantify the anthropogenic component of the river inputs.

Thus, even for one of the better studied UK estuaries, nutrient budgets and estimates of anthropogenic sources have to be regarded as provisional. Nevertheless the information can only be interpreted as providing strong supporting evidence for the importance of agricultural inputs. The other Wash estuaries are unlikely to be substantially different.

3.2.4 Oxygen

The 1987–92 lower estuary data for the Witham showed surface dissolved oxygen to vary between extremes of ca. 70–130% saturation; that for the Welland between 30–175%; for the Nene between 30–140%; and 50–110% saturation for the Great Ouse. Mean values for the quarterly lower and upper extremes are shown in Table. This also shows the oxygen saturation levels encountered in the JoNuS transects, which show several superimposed traits:

• A tendency for oxygen saturation to increase with increasing salinity. The Nene showed the greatest depression at 0‰, with the other three rivers roughly on a par;

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 35 • A tendency for oxygen depletion to be least in the winter. The Nene showed the greatest range (75% saturation in January 1992, 5% in July 1990), followed by the Witham, and the Great Ouse. The Welland had the least seasonal variation. However there are exceptions, for example the February saturation for the Nene was low; • Superimposed upon these trends occasional peaks of oxygen (super)saturation in all four rivers over part of the salinity range, all in July 1990. These were 130% at 22‰ for the Welland, 185% at 3‰ for the Welland, 95% for the Nene at 7‰ and 120% at 2‰ for the Great Ouse. These are indicative of major blooms.

Rendell et al. add some detail for the Great Ouse. Oxygen levels became supersaturated (up to 133%) at salinities of 0–2‰, associated with a substantial and active spring bloom, with chlorophyll-a concentrations typically 20–75 µg l-1. This effect persisted, at lower levels, throughout the summer. Below this point between May and October oxygen fell (to a minimum of 69%) at 3–6‰. This was linked with “the trapping and cyclic resuspension of organic-rich particles” (i.e. sewage, see below). Oxygen recovered at lower salinities.

These two counteracting tendencies of deoxygenation due to the decomposition of organic pollutants, and supersaturation due to eutrophication, are clearly common to all four estuaries. It should be noted that supersaturation in daylight hours due to photosynthesis will not be maintained at night, when deoxygenation can occur as a result of plant respiration.

3.2.5 Biological Effects

Eutrophication

In the 1994 Wash Report data on chlorophyll -a is presented for the Great Ouse from 1987 to 1992. Levels were typically above 10 µg l-1 throughout this period with peaks ranging between 100–200 µg l-1. Raw data is also presented on phytoplankton species and numbers for the four estuaries. This shows vastly greater numbers in the Great Ouse compared to the other estuaries, but there are problems with the data. The Wash Report notes that “Without comparing samples taken at the same time of year it is not possible to estimate to what extent the findings reflect natural seasonal variation.”

The data on oxygen supersaturation and nutrient depletion in all four estuaries provides strong evidence of significant blooms.

The low salinity chlorophyll-a peaks of up to 189 µg l-1 in the Great Ouse estuary, surveyed by Rendell et al., and already mentioned, were seeded by freshwater blooms of up to 151 µg l-1. They averaged between 20–75 µg l-1 from March to early autumn1 (their Fig. 4). Significantly, in addition to this

1 i.e. well in excess of the UK 1993 Consultation Paper criteria for freshwater eutrophication, of annual chlorophyll-a concentrations above 25 µg l-7

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 36 upper estuary peak Rendell et al. also note that “relatively high chlorophyll-a concentrations (16–57 µg l-1) were also observed in the vicinity of Kings Lynn [lower estuary] between late May and late August 1992, peaking in late June. This suggests that high levels of primary production may have been occurring in the Wash during this period”.

This significant phytoplankton activity took place in the Great Ouse estuary despite high levels of turbidity. Chlorophyll maxima of 36 µg l-1 in March 1992 and 55 and 114 µg l-1 in July occurred in association with suspended particulate loads of 254, 520 and 216 mg l-1. According to Rendell et al. loads greater than 100 mg l-1 in the Great Ouse reduce ‘light penetration’ to less that 20 cm (this was unquantified). Thus significant growth occurred at turbidity levels previously assumed impossible even in an earlier paperl devoted to this issue1.

Although UK policy does not define an estuarine value of chlorophyll indicative of eutrophication, the estuary is eutrophic in scientific terms, as the earlier description of nutrient depletion makes clear.

Sewage-specific effects

The upper reaches of the estuaries of all four rivers have similar characteristics; dominated by oligochaete worms, often of high density and low diversityxliii. The Nene’s low dissolved oxygen concentrations in the summer months further depressed diversity compared to the other estuaries. The characteristics of all four estuaries are typical of high organic inputs, and various STWs were implicated. Lower down the estuaries the harsh physical environment (changing salinity and canalised beds resulting in tidal scour) resulted in low diversity and biomass. The exception was the mouth of the Great Ouse where an order of magnitude increase in abundance of species such as Tubificoides benedeni indicated problems with sewage pollution from the King’s Lynn STW, coupled with low freshwater flow.

As already described, in summer oxygen levels in surface water can be supersaturated due to algal blooms. No data on oxygen demand in water close to the sediment surface has been seen.

3.3 THE WASH

The general characteristics of nutrients and phytoplankton growth in The Wash itself are apparent from the synoptic summary given in Table 3.1. Dividing The Wash diagonally into four quadrants, water typically enters the north, and flows successively through west, south and east quarters. Nitrogen, phosphorus and silicon all build up as water passes through the west and south sectors, recipients of successive major estuarine discharges,

1 The assumption (see also Essex & Suffolk Estuaries) that turbidity de-facto rules out significant phytoplankton growth is surprising given that phytoplankton physiologists and ecologists have long since documented the evolutionary importance of circumventing light and nutrient limitation, with various species acquiring various stratagems for ensuring that they spend at least part of the time in favourable conditions.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 37 before falling back slightly in the east quadrant. This is matched by the phytoplankton which reached a peak mean summer abundance of 14.9 µg l-1 in the southern quadrant, adjacent to the Great Ouse.

Table 3.3 The Wash nutrient, oxygen and chlorophyll concentrations.

NH4 TON PO4 SiO2 O2 chloro- µM µM µM µM % phyll, µg saturation

North winter 2.4–4.7 33–56 0.80–0.98 7.3–10 90–93 1.8–3.9 summer 2.0–4.7 6.0–15 0.27–0.48 1.6–3.2 96–105 1.2–7.6

West winter 3.3–6.1 43–75 0.87–1.1 8.9–14 81–87 1.5–3.8 summer 3.1–5.1 7.8–21 0.36–0.59 2.1–4.6 93–101 1.7–6.0

South winter 4.7–11.4 55–142 0.83–1.9 12–28 80–90 1.2–6.8 summer 3.4–7.7 9–39 0.44–0.98 2.7–6.6 90–103 1.9–14.9

East winter 2.4–9.2 32–91 0.84–1.6 7.5–16 90–98 1.7–9.4 summer 1.9–6.3 7–28 0.28–0.62 1.5–4.4 91–111 1.6–8.0

Notes: Summary of JoNuS surveys 1992–94. The Wash, roughly square and set at 45°, was divided into four equal quadrants by diagonals running NW–SE and NE–SW*. Values are the means of the lowest and highest values recorded in each quadrant on each survey. There were four winter (1st and 4th quarter) and seven summer surveys, except for chlorophyll, which was only recorded on one ‘winter’ survey (October 1994), and five summer surveys. * This division was made using the JoNuS sampling grid such that West and North quadrants were separated from South and East by a line bisecting stations 21 and 35, which were included in West and North respectively (Station 33, which fell on the line, was included in North). West and South were separated from North and East by a line bisecting stations 7 and 54, which were included in West and South respectively. Sources: Sea Vigil Water Quality Monitoring The Wash: 1992-1993 & The Wash: 1994.

The detail underlying these patterns is pursued below.

3.3.1 Chemical Profile

TON

Monitoring took place between 1987–92 within the southern quadrant of the Wash (at ‘Cork Hole’). TON was then typically under 70 µM, but in winter 1992–93 rose to a level remarkable for a coastal water – 500 µM [equivalent to 31 mg l-1 nitrate] – with ammonia up to 18 µM. Between 1992–1993 extensive sampling of a grid of sites in the Wash was repeatedly carried out. Late autumn (November 1992) and winter (February 1993) showed nitrate levels typically of the order of 50–75 µM along the inner, south-western margin, increasing to a maximum of ca. 175 µM in the southern quadrant. During summer these levels were reduced to a fraction of winter levels, c.f. a maximum value of 0.33 µM in August 1992, of 1.6 µM in June 1993, of 0.33 µM

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 38 in August 1993, recovering to 2.3 µM in September. Nevertheless the same relative pattern, of highest concentrations along the inner south-western shore, and particularly the south-eastern shore, were maintained. These were confirmed by the 1994 survey series.

Ammonium

Ammonium levels were significantly elevated in the Wash, with those in the southern quadrant the highest in both winter and summer. Compared to other coastal sites these were greater than those encountered in the outer Thames equivalent to the most elevated sites in the Solent (closest to Southampton Water) and indeed equal to those in Langstone Harbour, although less than the inner parts of Southampton Water and Chichester Harbour. The Wash levels were also typically higher than those in the Humber (at salinity range 20–34‰) and those off the Lincolnshire coast; and usually higher than those of the East Anglia coast. They were greater than any western UK coastal site reviewed in this report.

Thus, with the possible exception of Southampton Water (if this is considered a coastal site rather than an estuary), and its equivalent ranking to parts of the Solent and the East Anglian coast, this southern quadrant was otherwise the most highly ammonium-polluted coastal site encountered in this review. As can be seen from inspection of the table, the other quadrants also rank highly in comparison with other sites.

Phosphorus

The relative distribution patterns in the Wash grid sampling programme in 1992–93 for phosphorus followed those for nitrogen, with maxima along the inner south-western and particularly the south-eastern margins. In November 1992 and February 1993 peak values in the southern quadrant were above 1.6 µM P, declining to peaks of ca. 0.6 µM in June/August, largely recovering by September. The 1994 series confirmed the pattern although June values were lower – a maximum of 0.18 µM.

These values, including the southern quadrant with the highest values, were less than those for the Solent, the outer Thames estuary and mid-channel of the outer Severn estuary, but greater than those for other south-western and north-western English coastal sites, and the Lincolnshire and East Anglian coasts.

Silicon

Silicon also followed the distribution pattern of nitrogen, with maximum concentrations of 34 µM Si in November 1992 and 40 µM in January 1993, falling to a maximum of 6.7 µM in June, of 2.9 µM in August, recovering to a maximum of ca. 15 µM by September. Again, the 1994 survey confirmed the earlier patterns, although again reaching a lower maximum value, this time of 1.4 µM in August.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 39 3.3.2 Nutrient Ratios

Nutrient ratios are available for 1995 from continuous sampling transects. In January the N:P ratio in the outer Wash ranged from 20:1 to 30:1, while the N:Si ratio was approximately 1.75:1. In July the N:P ratio ranged from ca. 40:1 in the outer Wash to less than 7.5:1 in the Great Ouse estuary. At the same time the N:Si ratio varied within a (maximum) range of 0.32:1 to 5.6:1 in the Wash but was over 40:1 in the Great Ouse (c.f. the comments on silicon limitation regarding the Wash estuaries)

3.3.3 Trends

In favourable circumstances very long term records of nutrient trends, and their effect, can be established. In sediment cores taken from Chesapeake Bay, on the US East Coast, the silica tests of identifiable individual diatom species are preserved and long-term nitrogen (and other) trends are recoverableli. These show detectable effects of eutrophication – including phytoplankton species changes – when European settlers cleared the land for agriculture in the 1760s, and rapidly accelerating trends over the last 100 years). It can be expected that similar changes would have taken place in NW European waters. However conditions are apparently much less favourable for undisturbed preservation in the Wash. Biogenic opal (the degenerate remains of the tests) in Wash sediments apparently do show an increasing trend with depth, possibly indicative of increased diatom biomass over time, but the physical characteristics of the Wash mean that the prospects for detailed information do not appear goodlii. The data series since 1987 is too short and varied to allow a trend analysis for more recent years.

3.3.4 Denitrification

As already described, denitrification in the Wash estuaries is apparently insignificantxlix. However it has been argued by Trimmer et al. (1998)liii that denitrification in the sediments of the southern quadrant of The Wash accounts for up to 56% of the riverine inputs of the Great Ouse. However this statistic requires cautious interpretation.

One of many qualifications is that this maximum rate occurred in July 1992 (only), when TON inputs fell to a minimum 10 MM per month. Denitrification fell to only 1% in winter, when the monthly flow was estimated to be 57 MM. By visual inspection of Trimmer et al.’s Fig 9, the annual mean in 1992–93 might be ca. 15%.

Another qualification is that the inner half of the southern quadrant of The Wash (which Trimmer et al. refer to as the ‘lower part’ of the Great Ouse estuary) also receives TON from other estuaries and the sea. Indeed, a point often made by the UK Government inappropriately with regard to eutrophication – that the greatest contribution to any site comes from the open sea – is for once relevant, as these calculations refer to the total water column

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 40 TON load, rather than that available and relevant to plants (see p. 71 (Langstone Harbour, Chemical Profile) for further discussion of this aspect). A third issue is that the calculations are very approximate, with different methods use by Trimmer et al. giving very different answers; for example a range of 21–79% for the proportion of sediment nitrogen denitrified. Note also that Rendell et al.’s calculation of annual Great Ouse TON inputs to The Wash (651 MM) is very much greater than that implied here by Trimmer et al., and the proportion denitrified correspondingly less.

Finally, Trimmer et al. argue that the maximum percentage denitrification is at its greatest in summer, when “N demand would have been maximal”. The implication is presumably that this denitrification will then limit the potential for plant growth. But phytoplankton data published elsewhere demonstrate that any such depletion was evidently insufficient to prevent eutrophication (even were this an acceptable practice), as summer chlorophyll-a in this southern quadrant exceeds the levels indicative of coastal eutrophication (see below).

It can also be noted in passing that Trimmer et al. also estimate the amount of dissolved ammonia (re)generated in the sediments and released into the water column. This was put at 128 MM yr-1, equivalent, they estimate, to 22% of plant production in the Wash.

3.3.5 Oxygen

In 1992–93 surface water oxygen saturation tended to be lower in the western and southern quadrants, and highest in that for the east, albeit with greater variability than for nutrients. Values for August 1992 ranged from 91% to 126%; those for November were 61–75%; for February 1993 between 92–101; for June between 84 and 117%; in August 91–113%; and in September between 96–100%. In 1994 the trend was a more definite one of lower oxygen saturations in the inner, western and southern, quadrants. The lowest saturation was 77% in February in the southern quadrant; the highest was 111.5% in June, in the northern quadrant.

3.4 BIOLOGICAL EFFECTS

3.4.1 Phytoplankton

Mean winter and summer chlorophyll levels are shown in Table. The Wash Zone Report also provides data for chlorophyll-a between 1987–1992 at Cork Hole in the southern quadrant. The annual averages recorded were 16.4 µg l-1 (1987), 7.7 (1988), 3.8 (1989), 25.4 (1990), 11.7 (1991) and 10.2 µg l-1 (1992). On three occasions values exceeded 40 µg l-1, the maximum being 100 µg l-1 in November 1990. These indicate prolonged periods substantially in excess of the levels considered demonstrative of coastal eutrophication by the UK CSTT. Remarkably the Wash Zone Report concluded that “these results would suggest that there is no significant algal activity within the Wash”. As might be expected from the nutrient distribution, the JoNuS 1992–1993 grid survey shows a tendency for the greatest chlorophyll-a concentrations to be in the

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 41 southern quadrant. Chlorophyll was not measured as frequently as the physical chemical parameters. In June 1993 chlorophyll-a peak values in this area were 9–11 µg l-1. In September the peak value was 33 µg l-1, but with another peak of 23 µg l-1 in the western quadrant. In 1994 the maximum April values of 4.6–6.9 µg l-1 were in the southern quadrant. In June maximum values lay between 10–15.1 µg l-1, concentrated in the eastern quadrant, between 5–9.7 in August with the same distribution, and again in October (3.9–9.4 µg l-1).

In August 1994 continuous sampling transect extending from the Great Ouse to the outer Wash showed the same pattern of greater chlorophyll-a in the inner coastal waters which were closely and positively correlated with the measure of turbidity. The range was up to 7 arbitrary units in the Great Ouse, down to 1.1 units in the Outer Wash.

In 1995 the Wash was included in continuous sampling programme extending between the mouths of the Humber and Thames (See also sections on Outer Thames and the Humber to the Thames). These used the same arbitrary units. In January 1995 fluorescence in the Outer Wash lay between 0–8 units, similar to the Norfolk coast, but lower than the majority of the transect, including sites off the Lincolnshire coast and Suffolk down to the Thames estuary. The same broad pattern was true in March, when outer Wash fluorescence was mostly between 7–14 units. By May the range in the outer Wash was much greater, 0– 200 units, equivalent to the highest levels recorded elsewhere, notably the South Lincolnshire coast and off Great Yarmouth. The contiguous high values with those from South Lincolnshire suggest that nutrients from the Humber plume could be partially responsible for the elevated chlorophyll levels in the Outer Wash. In August 1995 the levels were 5–10 units (i.e. apparently higher than those reported for 1994) in the northern quadrant (only), while in September levels were recorded between 3–6 units in the northern quadrant, and up to 15 in the eastern quadrant. This was high for the transect as a whole, and extended into the most elevated sector, along the adjacent north Norfolk coast.

These peak values – at least for chlorophyll – along with the mean values, can be set in the context of the southern North Sealiv. There, by the end of April 1989, roughly equivalent phytoplankton biomasses (although not necessarily at the same time of year) was found in Belgium and Dutch coastal waters, extending into the German Bight, with chlorophyll concentrations of more than 8 µg l-1, with a peak of 56 µg l-1. These “very high chlorophyll concentrations were associated with extensive blooms of Phaeocystis sp.” By the end of May “the extremely high chlorophyll concentrations were no longer present, although biomass did remain high [> 4 µg l-1] along the European coast. At that time there was evidence of the effect of the UK estuarine plumes, with higher chlorophyll concentrations being present close to the estuary of the river Humber and in the Wash”. These were 4–8 µg l-1. Note that the only Wash-specific site for which equivalent 1989 data has been encountered was Cork Hole, in the southern, inner, quadrant. Here the annual mean was then 3.8 µg l-1, the lowest recorded between 1987–92.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 42 Taking all of this data into account it appears that the Wash would be considered eutrophic by any normal standards.

3.4.2 Macrophytes in the Wash

Zostera spp. eel-grass beds were once present in the Wash but have been declining for many years. What are believed to have been the last, at Mare’s Tail, east of the Welland’s entrance to the Wash, were last seen in the late 1970s or 1980slv. It is likely that land reclamation will have been partly to blame. But in Denmarklvi,lvii recent declines in Zostera have been associated with increased turbidity reducing the photic depth, and the growth of epiphytic algae, both explicitly linked to eutrophication (see discussion regarding Langstone). In the German Wadden Sea Zostera beds have been smothered by Enteromorpha. It is therefore perfectly reasonable to assume that eutrophication may have been one factor, but in the absence of detailed records it will be impossible to establish the cause of the final decline of Zostera in the Wash.

Other prima face evidence for eutrophication comes from the presence of weed mats. Although no systematic ground surveys appear to have been carried out, these are extensive in parts of the Wash. Dense beds were accidentally encountered in 1997 during the course of other work along an old river channel of the Wellandlviii. These stretched “as far as the eye could see”. In terms this meant “hundreds of metres extending away from the channel, and kilometres along it”. While this was a discovery for the scientists, the fishers accompanying them were well aware of ‘The Weed’. It is believed that the Environment Agency has spectral images of the Wash (c.f. The Humber) which would indicate the degree of coverage, but these have not been seen. As with Zostera it is likely that any conclusions made with regard to eutrophication will have to rely, to a significant extent, on knowledge gained elsewhere.

3.4.3 Sewage-specific Effects

Benthic Life in the Wash

The Wash seabed has been surveyed several times since the 1970s. Statistical analysis suggests two broad community types, above and below 10 m, of which that below 10 m was numerically more abundant per unit area and had the greater species diversity. Again there was evidence of “disturbance of the fauna” at sites close to the Great Ouse, but it was “not possible to be sure” whether this was the result of pollution.

Fish surveys

A variety of fish are found in the Wash but it does not support major commercial fin-fisheries. However there are significant fisheries for brown and pink shrimps and for mussels and cockles. There have been problems with cockles and mussels which were assumed to be due to over-fishing. But

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 43 although cockles apparently responded to protection, mussels did not. The reason(s) for poor recruitment thus appear unknown.

Surveys of fin-fish in the Great Ouse found two-thirds of the species in the Wash; while the Nene, Witham and Welland were “generally poor” in species. No speculation is made regarding this inter-estuarine variation.

Bacteriological conditions

In 1991 a subtidal benthic survey found E. coli at their highest levels in the southern quadrant of the Wash (maximum > 2000 per l-1 sediment sample at two sites). This was attributed to the King’s Lynn STW. In the Great Ouse estuary levels reached 10 million per litre sediment just downstream of the STW, and 1.2 million per litre at the entrance to the Wash. These results had “obvious implications for the shellfish beds in this area”. Clostridia, which has the greatest survival time in saline water, was mapped in the Wash in 1991. It was found throughout the area, with the greatest densities found in the east (range 160–4800 per 100 ml).

The Shellfish beds in the Wash were not covered by the Shellfish Waters Directive (79/923/EEC) but the commercial fisheries for mussels and cockles within the Wash (18 sites, all but one in the inner Wash) had all (in 1994) been proposed as harvesting areas under the Shellfish Hygiene Directive. The results of hygiene monitoring tests showed a general decline in quality from west to the east of the inner Wash. There was also a decline (or random fluctuation?) in overall quality between 1990 and 1992 such that those at the western end typically shifted from A (Good, no treatment required) to B (Shellfish need treatment). At the eastern end (i.e. adjacent to the Nene and Great Ouse) the shift was generally from C (Shellfish need extensive treatment) to C/D (D represents a ban on human consumption). “Kings Lynn STW is clearly implicated in these results”.

These were the most recent figures in the information provided.

3.5 NITRATES DIRECTIVE: SHOULD THE AREA BE DESIGNATED ?

3.5.1 Nutrient Sources & Quantities

A budget for the sources of nitrogen entering the Wash was requested but not received; it is doubted whether this exists. Certainly it is apparent from Rendell et al. (1997) that a budget did not exist for the Great Ouse at the time that paper was written. Nevertheless they considered it self-evident that agriculture was a major source. Similarly for the Witham estuary the Wash Report states that the results “seem to indicate that the main source of TON to the estuary is from the surrounding agricultural land.” This can be assumed to be true for the other estuaries. They, and the Wash, are hypernutrific. Thus these precondition for the application of the Nitrates Directive clearly apply.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 44 3.5.2 Evidence for Eutrophication

Checking the information compiled here against the UK Guidelines for the interpretation of the Nitrates Directive would suggest the following;

• Nitrate Concentrations Massively elevated in the river estuaries, with JoNuS peak levels at 0‰ of ca. 2000 µM TON for the Witham, 1200 µM for the Welland and Nene and 930 µM for the Great Ouse. Generally, the nitrogen levels of Witham, Welland and Nene were the highest encountered in this UK review, while that for the Great Ouse was also very high. The range of Wash levels were also significantly elevated, with a maximum observed value of 500 µM TON in the southern quadrant, and summer levels in all four significantly exceeding the 12 µM DAIN standard for hypernutrific coastal waters set by the CSTT. Apparently no catchment budget has been calculated, but agriculture is accepted as a major source;

• Occurrence of exceptional algal blooms Yes. Major blooms in the estuaries resulting in oxygen supersaturation: up to 175% saturation recorded. Detailed data on phytoplankton only available for the Great Ouse when levels were typically above 10µg l-1 throughout 1987–1992, with a peak of 200 µg l-1. Typical the 1992 summer biomass in the upper estuary ranged between 20–75 µg l-1, when that in the lower estuary ranged between 16–57 µg l-1. These were regarded as high and remarkable given the turbidity of the estuary;

• For The Wash annual mean chlorophyll-a was above 10 µg l-1 in 1987, 1990, 1991 and 1992 with a peak observed value of 100 µg l-1. Wide-scale surveys of The Wash in 1993 and 1994 also revealed summer values significantly and regularly in excess of 10 µg l-1 regarded as the defining criteria for coastal eutrophication by the UK’s CSTT;

• Duration of algal blooms through summer Yes;

• Oxygen deficiency Surface waters in both estuaries and Wash can be supersaturated. Values above the sediments, and night-time values, unknown. Contribution from the decay of blooms, if any, unknown. Oxygen deficiencies, if any, associated with algal mats unstudied;

• Changes in fauna Major disturbances in river estuaries and altered subtidal fauna, but believed to be due to sewage-derived BOD, with good supporting evidence. Changes associated with algal mats, if any, unstudied;

• Changes in macrophyte growth Sea-grass (Zostera) apparently lost since the 1970s. Dense ‘Enteromorpha’ algal mats in some areas of the Wash. Apparent absence of historical data;

• Occurrence and magnitude of PSP Unknown;

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 45 • Formation of algal scums on beaches and offshore Anecdotal accounts of foam on beaches. Phaeocystis certainly present.

As discussed in the first part of this report, the CSTT guidelines only represent an extreme form of eutrophication. The Nitrates Directive, in conjunction with e.g. the Habitats and Species Directive, can be interpreted as requiring a stricter interpretation such that the natural species composition and abundance is maintained or restored.

Finally the Directive requires that the nitrogen does not contribute to eutrophication problems elsewhere. The Wash catchment was estimated to deliver in excess of 4,000 tonnes total nitrogen to the sea in 1990 and 1991xliii, 3–4% of England and Wales’s total load to coastal waters. Claims in the literature regarding elimination of nitrogen via denitrification in The Wash appear over-inflated. The transfer of nutrients from the Humber and Wash to the wider North Sea are discussed later.

3.5.3 Conclusions

There are clearly major problems with nitrates in the catchments of all four major river estuaries that enter the Wash. It is not questioned that agriculture is a major source.

While NVZs within the catchment have been agreed, they cover a relatively small and peripheral area. In order to address the problem it will be necessary to define a substantial part, or even all, of the Wash’s catchment as an NVZ. In 1997 the Environment Agency concluded its review of NVZ status for the Wash for the second round of designations. This was not made available. It is understood that no change was proposed for the NVZ status of the Wash.

3.6 UWWT DIRECTIVE: SENSITIVE, LESS SENSITIVE OR THE NORM?

The river estuaries and the Wash are clearly not Less Sensitive Areas. With regard to Sensitive Area status, at the time the data reviewed was gathered ammonium and phosphorus levels in the four estuaries were amongst the worst encountered in the UK review, and much of this would have come from STWs on the lower rivers and/or estuaries. This adds to the agricultural nitrogen burden. As already described, there was clear evidence of eutrophication both in the estuaries and in The Wash. It thus appears inescapable that the catchments qualify as eutrophic Sensitive Areas under the UWWTD, requiring nutrient stripping. The community structure at some sites indicated that measures to deal with organic enrichment and BOD would also be required.

In 1997 the Environment Agency reviewed the status of Wash and its contributory estuaries for the purposes of the UWWT Directive. Its conclusions were not made available. The rivers Great Ouse and Witham were announced as eutrophic Sensitive Areas in the July 1998 Government Response to the Parliamentary Sub-Committee. With regard to nitrogen

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 46 renewal, an environmental report released by Anglian Water in 1998 refers to the “completion of nine phosphorus removal schemes in the Broads” with work underway three more in the Wash catchment (, Corby and Towcester) and planed for Flag Fen, Peterboroughlix.

There are also Annex III industries within the catchment area, and these may require action under Article 13. Moreover, given the low flow rates and poor water exchange, it may also be necessary to reduce water abstraction (ideally by more efficient irrigation methods) so as to increase water flow. However this lies outside the scope of the UWWTD.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 47 4 ESSEX & SUFFOLK ESTUARIES

In the early 1990s the then NRA Anglian Region surveyed 13 estuaries in its area for signs of nutrient enrichment. This data has not been seen but the NRA judged four to show “clear signs of nutrient enrichment”lx – the Ore/Alde, the Deben, the Stour and the Colne, and these were further investigated1. The evaluation below is largely derived from three reports arising out of that investigation. These are Elliot et al. (1994)lx on the trophic status of the four estuaries; that of Johnes (1994) reconstructing the changes in the nutrient loading of the Ore/Alde and Deben catchments between 1930 and 1990lxi; and that of Sage et al. (1997) on sediment, water quality and phytobenthic interactions in the Debenlxii.

The Environment Agency, in response to the approach by ERM provided only the 1993 pro-formas for the Colne and the Deben. The three reports were provided by the Environment Agency to the author as part of on-going work for WWF-UK, on the clear understanding that in doing so they were being placed in the public domain.

4.1 SITE LOCATION & DESCRIPTION

Suffolk is located on the east coast of England, making up the southern part of the East Anglian ‘bulge’ between the Wash and the Thames estuary (see Maps G and H). Essex lies to the south. Two of the four estuarine systems considered to be vulnerable to eutrophication by the NRA are in Suffolk: the Ore/Alde and the Deben. The Stour is on the Suffolk/Essex border and the Colne is in Essex.

4.1.1 Nature of Catchment

The gently rolling catchment area of the four estuaries is low-lying, typically under 100 m in elevation. Permeable chalk rock is overlain in the east of the area by permeable ‘Crag’ deposits from one vast estuary (sourced by Thames, the Rhine and other rivers) which once discharged to the north prior to the rise in sea level following the last ice-age. Much of the area is in turn overlaid by glacially derived clay, loam, sand and gravel.

The Ore/Alde2 estuary (note: not the river) has a catchment of 1,820 ha, a length ca. 25 km, and an average freshwater flow of 0.66 m3s-1. It has a human population of 1,500. The Butley estuary joins the Ore before the Ore finally enters the sea at Hollesley Bay. The water quality of the Ore/Alde, as defined by the NRA in the early 1990s, was grade A. There is one estuarine treated sewage input, at Orford. The estuary is important for wildlifexliv. It is in part a

1 Although only two, the Colne and the Deben, were advanced as candidate Sensitive Areas/NVZs by Anglian NRA in the first designation round – see page Error! Bookmark not defined..

2 The Alde changes its name to the Ore at Orford, approximately half way down the estuary.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 48 NNR (National Nature Reserve), a designated SPA (Special Protection Area1), a candidate Ramsar site2, a SSSI (Site of Special Scientific Interest) and an AONB (Area of Outstanding Natural Beauty), and includes the RSPB (Royal Society for the Protection of Birds) reserve of Havergate Island, which holds the largest UK colony of avocets. The area is important for wintering wildfowl and waders, and breeding birds. Recreational use, including water contact sports, is high.

The Deben estuary catchment is 1,007 ha, the estuary is 12 km long, and has an average freshwater flow of 0.87 m3s-1. It has a population of over 20,000. Water quality was classified in the early 1990s as B in the upper estuary and A for the remainder. The two largest treated sewage inputs are at Melton and Woodbridge, and sewage pollution has been noted as an issue of concernxliv. The estuary holds 40% of Suffolk’s saltmarsh and includes extensive mudflats on the inner estuary. It is an AONB and an SSSI (Site of Special Scientific Interest), the latter due to both the saltmarsh and extensive population of over-wintering birds, including average peak counts, 1985–90, of 1490 dark- bellied brent geese, 1080 shelduck, 150 black-tailed godwit and 1740 redshank. It is a candidate SPA and Ramsar sitexliv. Recreational use, including water contact sports, is high.

The Stour estuary has a catchment of 2,531, a length of 19 km, and an average freshwater flow of 3.6 m3s-1. There is a population of 17,000. The estuary has three treated sewage discharges, at Manningtree, Mistley and Holbrook. In the early 1990s the water quality was classed as A, except below the Mistley discharge, where it was B. There are extensive mudflats and 2150 ha of the estuary is an SSSI, and there is an RSPB reserve at Copperas Bay, primarily due to the over-wintering birds.

The Stour joins at its mouth, Harwich, with the Orwell estuary. Both estuaries combined are a candidate SPA and Ramsar site, and the extensive mudflats of both have glasswort species (Salicornia), dwarf eel-grass (Zostera noltii), eel- grass (Z. marina), cord-grass (Spartina) and Enteromorpha algae. The Orwell is a long and narrow estuary, supporting a sandy, calcareous saltmarsh. Combined, the site is a wetland of international importance3 by virtue of regularly supporting the standard of over 20,000 waterbirdsxliv. The basis for the exclusion of the Orwell from eutrophication studies is not known. Sewage pollution is apparently of concern in the upper Orwell estuaryxliv.

1 SPAs are part of EC Directive 79/409 on the Conservation of Wild Birds

2 Under the Ramsar Convention. For a SPA or Ramsar sites the government is first required to notify them as (in the UK) SSSIs before their international status can be formalised by SPA or Ramsar classification, in part explaining the very slow progress in the UK compared to the leading countriesxliv.

3 Following the Ramsar Convention, the number of birds is considered of international or national importance if it is 1% of the biogeographical or national population. Note that the SPA or Ramsar status may have changed since the publication of the source reference in 1992.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 49 There are recreational uses of the estuary, it is important for container and ferry vessel use, and there are commercial fisheries, including those for bass and mullet.

The Colne estuary has a catchment of 2,335 ha and a complex shape of five tidal arms entering one main channel. The average freshwater flow is 1.7 m3s- 1. Land-use is predominantly urban and arable. The human population is ca. 107,000. Again there are extensive mudflats and saltmarsh. There are sewage discharges at Jaywick, Brightlingsea, St Oysth and Colchester, and these affect the water quality of the upper estuary, which was classified as B in the early 1990s. The lower estuary was then classified as A. The estuary is important for wildlife, 2,915 ha having been designated as an SSSI, and it is also part of the Mid-Essex Coast candidate SPA and Ramsar site. The Mersea flats are an internationally important over-wintering site for Brent Geese. It is also important for recreational use, including water contact sports.

4.1.2 Nature of Land-use

The land use of the estuarine catchments are similar, predominantly cereal, pig and poultry with some forestry in some catchments and urban land use notably on the Deben estuary and especially Colchester, on the Colne.

Ore/Alde & Deben trends 1930–1990

In the UK full agricultural and human population censuses are taken in the first year of every decade, with the most recent exception of 1941. A significant amount of information also exists on fertiliser use. In principle this allows the construction of nutrient budgets and trends, and this has been done for the Ore/Alde and the Debenlxi.

In the 1930s these catchments were predominantly arable in the upper regions, with pig rearing a secondary industry. The lower half of both catchments were predominantly mixed farming, with significant areas of heathland, forestry, and with dairy herds along the river corridors. A common trend was apparent in both catchments to 1990; of cereal growing increasing at the expense of permanent grassland in the headwaters, and also at the expense of heathland rough grazing downstream. The pig population increased from ca. 30,000 to ca. 150,000, while poultry increased from ca. 0.25 to 1.25 million. The upper catchments of the two rivers are now the most important for pig production in England & Wales (c.f. the similar situation regarding the Ythan in Scotland). Cattle production had declined but was still important, while sheep production had virtually disappeared.

Nitrogen fertiliser use increased dramatically for permanent grass (54 to 175 kg ha-1), temporary grass (34 to 225), cereals (24 to 186) and other arable crops (95 to 175) but not for rough grazing (10) or woodland (20). Phosphorus fertiliser applications also increased for permanent grass (9.5 to 13 kg ha-1) temporary grass (9.5 to 16), cereals (6.8 to 24) and other arable (13.3 to 61). No fertiliser application of phosphorus are recorded for rough grazing or woodland.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 50 There were no significant urban centres in either catchment in 1930 when the population was ca. 30,000. This had doubled by the early 1990s mainly adjacent to the estuaries, especially for the Deben.

Stour & Colne

No equivalent compilation has been carried out for the other estuaries, although there is no reason, in principle, why it should not have been. The land use is likely to be similar, although without the extremes of pig and poultry.

4.2 CHEMICAL PROFILE

The data used by Elliot et al. 1994 was gathered between March 1992 and September 1993. Inter-annual variability is likely to be considerable, and this sampling period is too short to allow this to be taken into account. No indication is given of how the river flows during this period compared to the long term means. Just to the north of this area, the Wash Zone Report records low water flows in the contributory estuaries from March 1990 to September 1992, with levels recovering towards the end of 1992lxiii. The flow of the Trent (and other Humber Rivers) was reported to have returned to levels close to normal in 1993lxiv. Increased precipitation and river flow is commonly thought to result in an increase, per unit volume, of nitrogen, but not of phosphorus.

4.2.1 Nitrogen

Elliot et al. give nitrogen data for the four estuaries as seasonal means of Total Inorganic Nitrogen, TIN (nitrate + nitrite + ammonia, synonymous with DAIN), in µM per litre.

If nitrite and ammonia were negligible, then 806 µM TIN would be equivalent -1 to 50 mg l NO3. This may be the case for nitrite, and from the loading calculations appears to be the case for ammonium for the Ore/Alde, Deben and Stour, but not for the Colne where ammonium loadings can be roughly calculated to be 15% (1992) and 25% (1993) of the combined total1. However the 50 mg l-1 nitrate standard is of little relevance to estuaries, other than to indicate quite remarkable levels of hypertrophication. Elliot et al. instead make reference to the CSTT (1994) determination that areas should be regarded as hypernutrified where DAIN ‘significantly’ exceeds 12 mM m-3 [i.e. 12 µM l-1 or 168 µg l-1 N] in the summer months, in the presence of sufficient phosphate (at least 0.2 mM DAIP m-3 according to CSTT [i.e. 0.2 µM l-1]). However CSTT intended these values for coastal waters, not estuaries. As already described there are no specific guidance values in the UK for estuaries, and the CSTT coastal water value tends to be used “in the absence of anything better”, as one contact put it. In practice the concentrations are too

1 Unfortunately the data is not presented in a form that can be systematically dis-aggregated into ammonia and TON, necessary for a fuller assessment and comparison with other sites.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 51 low to give a credible assessment of eutrophication in an estuary or embayment with restricted water exchange with the open sea.

Table 4.1 Total Inorganic nitrogen and phosphorus for Suffolk and Essex estuaries

period N mean, µM N peak P mean, µM P peak inner outer inner outer estuary estuary estuary estuary

Ore/Alde summer 92 150 10 500 0.5 0.5 1.5 summer 93 100 20 450 0.5 0.25 1.5 winter 92-3 390 20 600 1.5 1.0 2.5

Deben summer 92 100* 10 500 1.5* 0.5 3.75 summer 93 125 20 500 2.0 1.0 3.5 winter 92-3 500* 30 825 3.0* 1.0 5.0

Stour summer 92 30 10 125 1.0 0.5 2.25 summer 93 50 20 200 1.5 0.75 2.5 winter 92-3 190 30 250 2.0 1.5 4.0

Colne summer 92 120* 20 650 11.0* 1.0 39.0 summer 93 280 25 350 15.0 1.0 20.0? winter 92-3 260* 50 450 8.5* 2.0 30.0?

Note: An * indicates no upper estuary measurement; value taken from nearest mid-estuary site. A ? indicates peak value off the scale of the graph, but linking lines shown in part allowing derivation by extrapolation to the first or last unploted value. Peak values typically in inner estuary. Source: Figs. 11–15 of Elliot et al. 1994

Remarkably – given the dilution by seawater – the data in Elliot et al., summarised here in Table 4.1, suggests that the peak winter nitrogen levels in the inner estuaries may indeed approach or occasionally exceed the 50 mg/l nitrate limit.. Average levels in the upper estuary of the Deben are close those observed at the saline limit of the Ythan (525 µM TON at 0‰ in 1991–2) and between 0–10‰ in the Ythan estuary (625 µM), with the other estuaries not far below. The outer estuary levels are usually well in excess of the CSTT guideline value for hypernutrific coastal waters.

4.2.2 Phosphorus and Silicon

No values for silicon are given for these estuaries in Elliot et al. 1994. Phosphate data was reviewed, recorded as soluble reactive phosphate (SRP), and reference is made in their evaluation to the CSTT guidance value for hypernutrific coastal waters of 0.2 µM DAIP l-1.

As can be seen from Table, the phosphorus levels are significantly higher than the CSTT guideline, even for the outer estuary sites, for all estuaries. The levels are probably of the same order or higher than those of the Ythan (2.7 µM at 0‰ in 1991–92, 0.8–5.5 µM between 0–10‰). Note that Ythan’s largest STW discharge – at Ellon, just above the head of the estuary – is for 15,000

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 52 p.e.; slightly less than the population in the Deben estuary catchment and much smaller than that for the Colne.

Table 4.2 N:P atomic (elemental) ratios for Suffolk and Essex estuaries

N:P period mean range ratio inner outer inner estuary estuary estuary

Ore/Alde summer 92 300 20 <25 – 550† summer 93 200 80 <25 – >1000† winter 92-3 260 20 33 – >600†

Deben summer 92 66.7* 20 ≈ 0 – 300† summer 93 62.5 20 ≈ 0 – 550† winter 92-3 167* 30 50 – 200†

Stour summer 92 30 20 ≈ 0 – 75† summer 93 33.3 26.7 ≈ 0 – 50† winter 92-3 95 20 50 – 120†

Colne summer 92 10.9* 20 ≈ 0 – 20† summer 93 18.7 25 ≈ 0 – 50† winter 92-3 30.6* 25 ≈ 0 – 50†

Notes: An * indicates no upper estuary measurement, value taken from nearest mid-estuary site. A † indicates that some mid-estuary N:P ratios were higher than those of the inner estuary. This was particularly marked for the Ore/Alde. Outer estuary N:P ratios were always much lower than those from the inner estuary. Source: Elliot et al. 1994. Fig 11–14 (means) and Fig 18 (range)

4.2.3 Nutrient Ratios

N:P elemental nutrient ratios are shown in Table 4.2. What the table does not emphasise is the extreme and rapid fluctuation in the ratio, particularly for the Ore/Alde, where the ratio could change from 100 to ca 1000:1 over one or two fortnightly sampling intervals. The classic marine pattern is for the ratio to decrease in the summer months as ambient nitrogen levels are reduced. However here, with the exception of the Deben in 1992 there were no obvious seasonal trends.

It is difficult to draw any conclusions about nutrient limitation from these figures. It is received wisdom that marine and estuarine plant growth is limited by low nitrogen levels. But phosphorus limitation is possible, and some phytoplankton can capture sufficient nitrogen to grow at their maximum rate even though dissolved nitrogen is apparently zerolxv.

4.2.4 Nutrient Trends

No nutrient trends can be derived from actual estuarine measurements in the three reports that have been seen. But the purpose of Johnes’ (1994) report which evaluated changes in catchment land use between 1930–1990 was to

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 53 model changes in annual nitrogen and phosphorus loadings in the catchments of the Ore/Alde and Deben.

The resulting hindcasts (which were validated against actual 1988 data) depict average catchment nitrogen loadings accelerating throughout this period for both catchments. In the case of the Ore/Alde catchment (note, not just the estuary catchment) the average loading in 1930 was calculated to be 9 kg ha-1, rising to 17.5 kg ha-1 in 1990. For the Deben the equivalent change was modelled to be from 9 kg to 23 kg ha-1. Phosphorus also rose, from 0.6 to 1.2 in the Ore/Alde catchment, and from 0.75 to 1.6 in the Deben over the same period. The greatest increase in Deben catchment phosphorus was predicted to have occurred within the estuary catchment, as a result of human population increase.

4.2.5 Biological Oxygen Demand

Elliot et al. (1994) present data on dissolved oxygen levels at various positions along each of the four estuaries, for summer 1992, winter 1992 and summer 1993. The data, presented as percentage saturation, is unexceptional. Oxygen saturation is typically between 90 to 100%, on occasions with an inner estuary dip to ca 80%. The only slight exception in the Colne, where levels perhaps lay between 80–90%, with larger variation about the mean that the other estuaries.

However these samples were taken at approximately one metre depth. The major site for organic matter decay, from whatever source, is likely to be the bottom sediments. A more detailed survey was carried out by Sage et al. (1997). Unfortunately the page displaying the results is missing from the report, but they concluded that there was no significant water column oxygen sag. Dissolve oxygen levels were higher in winter at all sites.

Nevertheless, this does not tell the entire story. Both of these surveys were at spaced intervals down the estuaries. Dissolved oxygen levels will be lower in the vicinity of STW discharges. Thus the Colne pro-forma reports a minimum of 30% saturation due “in part” to Colchester STW. No data on oxygen levels were given in the Deben pro-forma, and the other two estuaries were not candidate sites.

4.3 BIOLOGICAL EFFECTS

4.3.1 Nutrient Related Effects

Phytoplankton

Data in Elliot et al. (1994) show all four estuaries to have extended phytoplankton peaks from spring through to early autumn, that for the Stour being the least well defined. The Deben had the highest chlorophyll-a levels, peaking at 86.6 µg l-1 in 1992 and 339 µg l-1 in 1993. This was followed by the Colne, with peaks of 30–40 µg l-1 in 1992 and 20–30 in 1993. The Ore/Alde had

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 54 peaks between 10–20 µg l-1 in both years, while the Stour’s summer levels were typically around 10µg l-1. Again it is necessary to emphasise that two year’s data are insufficient to indicate the full range of inter-annual variability.

Elliot et al. review the data available for other estuaries, noting the difficulty in making comparisons when so many variables were involved. A range of Spanish estuaries generally had lower nitrogen and turbidity but higher phosphorus and chlorophyll-a. As already noted here, nitrogen levels of the Colne, Deben and Ore/Alde were of the same order as those of the Ythan estuary, but only the Colne had higher phosphorus concentrations, while the Ythan was at least as turbid as the Suffolk estuaries – although this may be due to phytoplankton blooms. Compared to the Dutch Wadden Sea and the Ems estuary, chlorophyll-a levels were higher in the Colne and Deben, but lower in the Ore/Alde and Stour. Phosphorus levels at the Dutch sites ranged between 0.6–6.7, and nitrogen between 0.7–2.5, of the Suffolk estuaries.

A comparison can also be made to Roskilde Fjord, in Denmark, which is regarded as “highly eutrophic” with spring blooms up to 100 µg l-1 chlorophyll- a, and summer levels of ca. 10µg l-1. Nitrogen levels (measured in March and June) appear to be lower that those of the Suffolk estuaries with the possible exception of the Stour, although phosphorus appears higher with the exception of the Colnelxvi1.

Algal cell counts were also made by Elliot et al. at a site on the Deben. A peak value of ca. 47.5 million cells l-1 was measured in late August 1992. The correlation between cell numbers and chlorophyll-a was poor, because of the range in phytoplankton cell size. The late spring/early summer community was dominated by species of Skeletonema, Chaetoceros and Thalassiosira, while in late summer the large centric diatom Coscinodiscus and Rhodomonas could become common. In late summer benthic diatom colonies of Chaetoceros and Nitzchia could break up to form floating mats which caused a “significant æsthetic problem”.

On the basis of observed nutrient, chlorophyll-a levels, and also by comparison with other sites, Elliot et al. therefore provide the data to establish that there is a prima-face case to consider the Deben, the Colne and the Ore/Alde (in order of diminishing chlorophyll-a levels) as eutrophic. This leaves open the question as to whether this eutrophication is, as defined in the Directives, “undesirable”.

Nevertheless in other sections of their report Elliot et al. argue the case against considering these estuaries to be eutrophic. Part of this is based on what are considered to be relatively high turbidity levels, which they consider restrict the potential for phytoplankton growth (but c.f. The Wash). And partly it is based on an attempt to apply the UK CSTT methodology for determining Less

1 Roskilde March 1992 mean levels: NH4 2.1 µM, NO3 48µM, and total P 11 µM; June mean levels 0.6, 17 and 18 µM respectively.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 55 Sensitive Areas. When this is done the calculation suggests that phytoplankton cannot grow to eutrophic levels. But, apart from the fact that the CSTT model is intended be coastal waters, in reality this seems to say more about the inherent weaknesses of the CSTT advice (particularly its sensitivity to assumption about water exchange-rates and light levels, as discussed by Elliot et al.) than it does about phytoplankton levels in the Suffolk estuaries.

To argue otherwise come dangerously close to rejecting real data because they do not match the theory. But this is what Elliot et al. seem to do, stating in their summary (at variance with the data presented in the report) that “The chlorophyll-a levels were mostly low to moderate” and also that “the existing numerical models did not conclusively indicate potential eutrophic conditions in the estuaries” before going on to suggest that the turbidity of these areas was preventing such eutrophication.

Subsequently, additional information on phytoplankton in the Deben estuary is provided by Sage et al. (1997), which states in the introduction that the estuary is “one of the more eutrophic of the Suffolk and Essex estuaries”. Turbidity in the study year (1996) was found to be extremely variable and dependent on weather conditions, with the middle sections having relatively low levels. The maximum average chlorophyll-a levels were in the inner estuary, 20 µg l-1 in May and 23 µg l-1 in August. Measurements of turbidity and light showed that incident light levels were sufficient to maximise phytoplankton growth from April to October, and that the phytoplankton were also able to adapt to lower light intensities. The depth at which maximum plant growth could be maintained fell from zero in mid March to a maximum depth of 0.4 metres in August and September, before rapidly falling during October. The lower limiting depth, beyond which the light levels were too low to sustain net plant growth, varied between 1.5–2.5 metres during the summer months, although it should be remembered that turbulence and/or self-propulsion may mean that individual phytoplankton experience better light regimes than this suggests. There was also evidence that turbidity was partially due to the phytoplankton itself. Interestingly, experiments indicated that only the addition of ammonium resulted in an increase of chlorophyll-a; adding nitrate had no effect, while the addition of phosphate actually inhibited algal growth. Sage et al. also point out that the maintenance of characteristic brackish water species of phytoplankton in the upper Deben estuary indicated either that the flushing rate was not great enough to remove the cells, and/or that the growth rate exceeded the flushing rate.

Interpretation of these results is complex; however the authors indicated that, where light limitation was absent, ammonium appeared to be the primary limiting factor. They estimated the total annual production, using the average light conditions for each month, the average volume of the estuary, the average monthly growth rate for the phytoplankton in the water column. This suggested that the amount of nitrogen consumed by the phytoplankton was equivalent to 96% of the total annual input of TON to the estuary (estimated to be 7 megamoles TON in 1996).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 56 Care has to be taken in interpreting this figure – a significant amount of these TON inputs would not have been intercepted, for instance in winter months, while a proportion of nitrogen would be recycled between living organisms. Some of the nitrogen entering the estuary will be denitrified in the sediments – based on experimental, work the report calculates that this accounts for 6% of the total nitrogen load. There is also other plant growth to take into account, such as benthic diatoms. Nevertheless, as Sage et al. point out, Johnes’s work – already referred to – indicates that there has been a 100% increase in nitrogen inputs between the 1930s and the 1990s, and it is difficult to conclude that current levels of phytoplankton production could be sustained were nitrogen inputs at 1930s levels.

Regarding the Colne, Sage at al. make the comment in their discussion that it has higher ammonium concentration than the Deben, due to the “poorer quality effluent” from the Colchester sewage treatment plant. “As a result of this and other factors the standing crop of phytoplankton in the Colne is considerably higher than in the Deben. The River Colne may be viewed as an example of the changes that may take place if ammonium concentrations were allowed to increase in the ”.

Benthic diatoms

Some relatives of the single-celled phytoplankton have adapted to a life on the substrate surface. There has been some debate about the relative importance of their contribution to total plant growth, for example in the Wadden Sea. On the intertidal flats of the Deben there were five dominant genera: Navicula, Nitzchia, Gyrosigma, Pleurosigma and Cylindrotheca. However, compared to the phytoplankton, they were relatively unimportant, their uptake of nitrogen calculated to be equivalent to just 5.5% of the TON inputs, compared to the 96.2% removed by phytoplankton. However, as indicated by Elliot et al., the break up of the algal mats can result in substantial and problematic rafts appearing on the surface.

Macrophytes

Sage et al. surveyed the intertidal coverage by algal weed mats concentrating their efforts in the middle estuary, “where extensive macro-algal growth has been known to occur”. Their method was to take random sightings along transects, using a telescope with a cross-hair sight and record ‘hits’ or ‘misses’. This was done on a number of occasions between June and December 1996. The average number of hits for the entire estuary peaked at just under 50% in July, and declined through to December. The maximum annual average number of hits at any one site was just under 60%, at an upper estuary site. The general distribution was also confirmed by aerial photography. Unfortunately, as no measurement of biomass were made it is difficult to compare these results with those from sites such as the Ythan and the Solent embayments, although their appearance on aerial photographs suggest that the growth was substantial (c.f. The Ythan and The Humber) It also has to be remembered that

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 57 these results are for a single season, and that biomass can vary markedly from one year to the next, as illustrated by the Ythan research.

Fauna

Elliot et al. surveyed the fauna in the four estuaries to establish whether there was any general evidence of deoxygenation or organic enrichment resulting from eutrophication (as opposed to localised effects from STW discharges). They saw no evidence of a dissolved oxygen sag in the Ore/Alde or Stour, but the Deben and Colne were recorded as having “slight” summer dissolved oxygen decreases in the vicinity of sewage treatment plant discharges, an effect “exacerbated by the low flows, shallow depths and high temperatures”. The work was not of sufficient detail to directly reveal any transient but biologically significant deoxygenation phenomena. All the measurements of water column dissolved oxygen were in excess of 7 mg l-1, considered by the CSTT to be a safe standard allowing the passage of migratory fish through estuaries.

The benthic fauna of all four estuaries was “characteristic of muddy estuaries with some small patches of hard substratum”. There were no “large populations of opportunist or pollution tolerant organisms” and the communities “do not show features of severe organic enrichment”.

Elliot et al. conclude that “nutrients in general were not having an effect within the estuaries” but left open the possibility that they were contributing, along with the (much larger) inputs from the Thames and the Humber, to coastal effects in the southern North Sea.

4.3.2 Sewage-specific Effects

Neither Elliot et al. or Sage et al. assessed the localised effects of sewage treatment plant discharges to the estuaries, nor are their measurements of bacteriological criteria. Nor did the Environment Agency provide data on these aspects. The only indication seen of possible effects is the reference to dissolved oxygen levels falling to 30% of saturation in the Colne estuary due “in part, to Colchester STW” in the 1993 Colne pro-forma.

4.4 NITRATES DIRECTIVE: SHOULD THE SUFFOLK ESTUARIES BE DESIGNATED?

4.4.1 Nutrient Sources & Quantities

The relative importance of nutrient sources was directly addressed in the report by Johnes for the Ore/Alde and Deben estuaries. In both estuaries the nutrient loadings from the freshwater catchments had increased by over 100% over the past sixty years.

The influence of the agricultural changes already described resulted in a marked increase in nutrient levels in the headwaters of both catchments, and

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 58 were an important component of the increase in downstream parishes. The key elements that contributed to the increased diffuse pollution, according to Johnes, were the conversion of permanent grassland and heathland rough grazing to cereal production, and the intensification of pig and poultry production in factory farming units.

4.4.2 Evidence for Eutrophication

There is clear evidence of hypertrophication and resultant eutrophication in the Deben (peak chlorophyll-a levels of 86.6 µg l-1 in 1992 and 339 µg l-1) and the Colne (20–30 µg l-1 in 1993). The Ore/Alde showed a peak of between 10– 20 µg l-1 when surveyed by Elliot et al. in 1992–93, while the Stour’s summer levels were also typically around 10 µg l-1. These levels, at least for the Stour, might be considered marginal in terms of extreme hypertrophic eutrophication. However it has been emphasised that the impact of increased nutrient loadings on naturally oligotrophic (low-nutrient) or mesotrophic estuarine systems should not be ignored. In this context the doubling of agricultural nutrient inputs in the Ore/Alde catchment, and in all probability a significant increase in the Stour, can be expected to have increased phytoplankton growth in these estuaries as well.

4.4.3 Conclusions

Declaration of the Deben catchment as a Nitrate Vulnerable Zone can be justified on the basis of hypertrophication and eutrophication. The significant contribution of agricultural nutrients to this problem has been established beyond reasonable doubt. The Anglian NRA 1993 Deben pro-forma acknowledges the need to act on diffuse sources in conjunction with measures on STW nitrogen levels.

There has clearly been a major increase in agricultural nutrient inputs to the Ore/Alde estuary over the last 60 years. The evidence suggests that the estuary in the early 1990s would be a candidate site using the UK guidelines regarding hypertrophication and extreme eutrophication. It is not unreasonable to conclude that the changes in nutrient status over the decades will have resulted in increased production and changes in the species composition of phytoplankton and other components of the Ore/Alde estuary. Whether this aspect of eutrophication is seen as ‘undesirable’ will depend on the interpretation of the Nitrates Directive, and those Directives concerned with the protection of Habitats and Species.

The Colne is clearly eutrophic, but the relative contribution of agriculture within the catchment has not been studied. Designation at this point as an NVZ would depend upon whether general evidence for increases in the agricultural nitrogen and phosphorus in the UK, coupled with detailed budgets for adjacent catchments, were considered sufficient to require designation.

The Stour has the lowest nutrient and phytoplankton estuaries of the four estuaries reviewed. There is no nutrient budget for the river catchment.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 59 Nevertheless, according to Elliot et al. it is one of four estuaries regarded as showing “clear signs of nutrient enrichment”.

4.5 UWWT DIRECTIVE: SENSITIVE, LESS SENSITIVE OR THE NORM?

Elliot et al. concluded that the Colne and the Deben received most of their ammonium load and phosphorus from estuarine sewage treatment plants and would benefit the most from greater controls. They also noted that the Colne (only) had significant inputs of nutrients from freshwater STW discharges. Sage et al. concluded for the Deben that when light is not the limiting factor (i.e. spring – autumn) nitrogen was the primary limiting nutrient and that ammonium (from STWs) was the limiting form of nitrogen. They cited other work as having drawn the same conclusions for the Colne. They continue “The Colne however, has higher ammonium concentrations than the Deben, resulting from a poorer quality effluent from Colchester STW. As a result of this the standing crop of phytoplankton in the Colne is considerably higher than in the Deben.” Sage et al. add that “improving the effluent quality from the STWs by ensuring a well nitrified effluent might help to alleviate the potential for planktonic algal blooms. In the absence of ammonium algae may switch to growth utilising nitrate, which is abundant. However, algal growth on nitrate is usually slower than on ammonium, reducing the probability of algal blooms in the estuary, and also leading to greater export of inorganic nitrogen to the sea before it can be assimilated by algae during growth” They conclude “… it would appear there may be little immediate gain in nitrate stripping at Woodbridge STW, but in the longer term any reduction in nitrogen load would help to alleviate adverse biological effects. Ensuring a well- nitrified effluent, with low ammonium concentrations, may have a more immediate effect on algal production in the estuary.” This would nevertheless still allow the export of nitrogen to offshore waters in an area where problems are apparent

It should be recalled that the Deben and Colne estuaries were put forward as candidate Sensitive Areas by Anglian NRA. On this basis it appears reasonable to expect that the Deben and Colne should be designated as Sensitive Areas. It should also be noted that no data has been seen on sewage- derived bacteriological levels in these estuaries.

Insufficient information has been provided in order to make site-specific assessments for the Ore/Alde and the Stour estuaries. However, the following comments are offered:

• The Ore/Alde, according to Elliot et al. has only one treated sewage input entering it at Orford. The population in the estuarine catchment is approximately 1,500. But, while it may be true that sewage-derived nutrients may make up a small part of the overall nutrient budget, it would be difficult to assert that it has no effect on eutrophication. • The Stour estuary catchment has a population of 17,000. At the time when Elliot et al. wrote their report there were three sewage treatment works. It is understood that the discharges have since at least in part been diverted to Copperas Bay. This bay incorporates an RSPB reserve for the nationally important numbers of over-wintering birds.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 60 LSA status for all four estuaries would be clearly inappropriate.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 61 5 SOLENT & SOUTH COAST EMBAYMENTS

The 1993 Oslo and Paris Commissions’ report on Eutrophication Symptoms and Problem Areas included the embayment of Langstone Harbour, on the central south coast of England, as one of just two UK “eutrophication problem areas” in the Convention Waters (the other being the Ythan). But Langstone is just one of a complex of adjacent embayments which run for some twenty-five kilometres along the margin of the Solent – a stretch of water that runs between the Isle of Wight and the mainland – where concerns exist regarding eutrophication, These embayments are, running from west to east, Southampton Water, Portsmouth Harbour, Langstone Harbour and Chichester Harbour1.

5.1 SITE LOCATION & DESCRIPTION

5.1.1 Nature of Catchment

The mainland catchment to the Solent is the Hampshire Basin (see Maps I, J and K); rimmed by higher (permeable) chalk to the north, covered mainly with Tertiary sand and clay running down to the sea. The main rivers draining the Basin are the Test and the Itchen which enter Southampton Water, and the Meon which enters the Solent between the mouths of Southampton Water and Portsmouth Harbour. The embayments of Portsmouth, Langstone and Chichester Harbours are backed by chalk rises (Ports Down and the western end of the South Downs) which restrict their catchment area and hence the diffuse inputs from agriculture. The land to the north of these are drained by the Meon, and the Rother which runs to the east and, after joining the Arun, discharges at Littlehampton 25 km east of Chichester Harbour. Thus water currents will have a crucial influence upon the speed and direction of the transport of nutrients once they reach the coastal sea. But the currents are complex. On the large scale there is a current ‘watershed’ in the English Channel running from the Isle of Wight south to France. To the west the current, on average, runs west: to the east it runs east. But in the Solent from Southampton Water eastwards, and the coastal waters off the Harbours, the prevailing current is from east to west, at least judged by sediment transport. The tidal regime is also complex, due to the Isle of Wight: consequently Southampton Water has a double high tide.

The Solent embayments are a key wildlife site for the UK. Southampton Water is fringed with mud-flats with extensive growths of Enteromorpha and eel- grass. It, with other intertidal areas of the Solent, are in part a NNR, a candidate SPA and a candidate Ramsar site. The area supports internationally important numbers of wintering dark-bellied brent geese and nationally important numbers of teal, ringed plover, grey plover, dunlin, ruff, black-

1 Smaller sites which may also be affected by eutrophication, but which are not evaluated here, include those in the vicinity of Lymington, and the Beaulieu estuary (both in the western Solent) and Pagham Harbour to the east.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 62 tailed godwit and greenshank, and breeding black-headed gull, Sandwich tern, common tern and little ternxliv. Portsmouth, Langstone and Chichester Harbours are interconnected, and the scarcity of freshwater inputs and restricted access to the sea gives them an unusual hydrology. Portsmouth Harbour is in part an SSSI and candidate SPA. There are beds of narrow- leaved and dwarf eel-grass, as well as extensive areas of Enteromorpha and Ulva, although a Spartina cord-grass marsh has been degraded. Portsmouth Harbour holds internationally important numbers of wintering dark-bellied brent geese, and nationally important numbers of grey plover, dunlin and black tailed godwit. Langstone and Chichester Harbours together form a designated SPA and Ramsar site, and part of Langstone is an RSPB reserve. They form “the largest area of estuarine mudflats on the south coast of Britain, of exceptional importance to wintering waders and wildfowl”.lxvii Bird concentrations of international importance are those of wintering dark-bellied brent geese (6% of the world total), shelduck, ringed plover, grey plover, dunlin, black- tailed godwit and redshank, and nationally important numbers of wintering black-necked grebe, pintail, shoveler, red-breasted merganser, golden plover, grey plover, sanderling, bar-tailed godwit and curlew, and breeding little and common terns.

5.1.2 Nature of Land-use

With regard to agriculture, it can be expected that there has been some transition from grassland to cereal growing over the last forty years on the chalk margin of the basin, although race-horse grazing remains one unusual but locally significant feature on these alkaline soils. On the lower sands and clays, soil quality varies from very good to poor, and mixed farming co-exists with woodland and other land-uses, such as gravel extraction in the river valleys. The New Forest lies on poor soil to the west of Southampton Water. The Test, the Itchen and the Meon, with their chalk-stream headwaters, are naturally highly productive, and are famous salmonid fishing rivers.

Increased nitrate levels, compounded by decreased flows in these rivers and headwaters are prominent issues, seen as one contributory factor in the decline in catches. No data has been seen for nitrate trends in the Hampshire Basin, but are known to have increased, for example, by 50% (from 645 µM to 968 µM) between 1966 and 1986 in the Bere chalk-stream in Dorsetlxviii. As fishing purchase values on these rivers are measured in hundreds of pounds per foot of river-bank, as are the single-rod daily permits, the economic valuation placed on this aspect of biodiversity should not be overlookedlxix.

The headwaters of a significant number of UK chalk-streams have been converted to water-cress farmslxx, where phosphorus is added; agriculture in general and fish-farming are other nutrient sources. It is usually assumed that majority of phosphorus entering lowland rivers in this part of the UK comes from domestic sewage. A range of 20–95% of the load from this source was quoted in the mid-1970slxxi. Nevertheless it will always be prudent to evaluate the specific status of a catchment by the construction of a nutrient budget – c.f. the considerable anthropogenic component to the phosphorus budget, other than sewage, in the Ythan.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 63 Apart from agriculture the major change in land use affecting nutrient inputs from the catchment has been the increase in urban development and population along the coastal strip, with a almost continuous conurbation stretching from Southampton in the west to Chichester in the east.

5.2 SOUTHAMPTON WATER

The most prominent issue in Southampton Water relevant to eutrophication is that of red tides. These, caused by the ciliate Mesodinium rubrum, were first reported in the scientific literature in 1980lxxii. In a paper written in 1996 and published the following year, Crawford et al.lxxiii reported that they occurred during most summers, and sometimes in autumn. After an absence for a number of years they reappeared in 19981. M rubrum has an extremely high rate of growth and has high nutrient demands. It is not thought to be directly toxic, and Crawford et al. reported no evidence for toxic effects in Southampton Water. However it can be responsible for other adverse effects, for example deoxygenation or the possible competitive exclusion, via nutrient depletion, of other species.

Crawford et al. does not include the comprehensive details necessary to construct, for example, a nutrient budget for the area, or nutrient ratios. Nevertheless they includes sufficient detail to make a prima-face case for the designation of Southampton Water as a Sensitive Area and/or Nitrate Vulnerable Zone.

5.2.1 Chemical Profile

Nitrogen

Table 5.1 provides details of nutrients in Southampton Water.

Winter levels for nitrogen are not given. In the first study period of Crawford et al., in 1985, nitrogen levels were not measured until mid-May, by which time the authors expected that M rubrum would have already partially depleted the available nitrogen. Salinity at the three sites when measured in spring and summer 1995, and based on samples taken from 1 to 8 m depth, ranged from 27–33‰ – i.e. approaching that of seawater.

1 D. Lowthion, EA Southern Region, pers. comm.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 64 Table 5.1 Nutrients in Southampton Water

Site Year period NH4 NO3 NO2 PO4 N:P µM µM µM µM

Southampton Water Upper estuary, 3 sites 1985 mid-May 4–12 22.4–50 - - bloom peak < 2.5 10–20 - 0.3–0.5 25-75:1 August 12–16 25–50 - -

Upper estuary, 1 site 1986 June 18 60 - -

Note: Range at three sites, at Princess Alexandra Dock, Cracknore Buoy and NW Netley Buoy, all located in the upper estuary. Source: Crawford et al. (1997)

Given that these are summer measurements, and that there is a large sea- water component, the nitrogen levels are remarkably high. Surface ammonium concentrations at the three sites (ranged over a total distance of ca. 5 km) were 12, 7,5 and 4 µM. They then declined to less than 2.5 µM at all sites until the beginning of August, when the bloom ended. In some occasions ammonium was depleted to unmeasurable levels. Peak values subsequently measured during August were 16, 12 and 13 µM. Dissolved ammonium concentrations below the surface followed the same trends but were typically lower. Various explanations are possible for this difference.

Nitrate levels at the three sites in mid-May were 50, 37.5 and 22.4 µM. They fell to minima of 20, 18, and 10 µM during the bloom, and then recovered to August maxima of 50, 40 and 25 µM. Nitrate levels in deeper water were also typically lower than those at the surface.

Combining the two, this means that DAIN levels were 26–62 µM in mid–May, and between 38 and 66 µM in August. This vastly exceeds the winter qualifying level of 12 µM l-1 DAIN in the UK guidance for coastal waters – possibly a more valid comparison than for more confined sites such as the Suffolk and Essex estuaries.

Additional, more detailed, vertical profiles were measured in June 1986. This again showed high levels of ammonium and nitrate before the bloom at the surface (maxima of 18 µM ammonium N and 60 µM nitrate N), falling off with depth. As the bloom developed it resulted in an “almost complete removal” of ammonium below 2 metres, although it was still detectable at the surface. Nitrate also “declined markedly” but was not depleted to less than 5 µM. Their calculations indicated that while proportionally less nitrate was used than ammonium, in absolute terms nitrate was more important.

Phosphorus

Phosphorus was not measured as part of the research of Crawford et al. Citing other work they comment that phosphorus levels generally remain high in Southampton Water in winter, and is not severely depleted by the spring

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 65 diatom bloom. They do not consider phosphorus to be likely to limit the red bloom. They cite other work as indicating that “inorganic phosphate generally declines to about 0.3–0.5 µM during the bloom”. So the UK winter coastal water guideline for hypernutrification of at least 0.2 µM l-1 DAIP is also exceeded.

Silicon

Silicon data was not included or referred to.

Salinity

Salinity profiles with depth during the spring and summer of 1998 at the three sites consistently showed salinity to increase with depth. The less saline water therefore had the higher nitrogen concentrations – thus a freshwater source was implicated.

Oxygen

The depth distribution of dissolved oxygen reflected the distribution of the bloom. In daylight in 1985 it reached a maximum of 175% of saturation in late May. Night-time sampling was apparently not undertaken. Plant respiration, without the oxygen production resulting from photosynthesis, would then have resulted in lower oxygen saturation levels. At the three sites in June 1996 oxygen levels did not fall below 70% saturation in bottom waters (i.e. below the bloom). But a general decline in dissolved oxygen occurred in July 1987, from ca 90% to ca. 20% over eight days. The paper also refers to severe depletion (dissolved oxygen 20% of saturation) at a site further up the Test estuary, and comment that this resulted from bloom respiration, rather than from sedimentation and decay. They also comment that the relatively long intervals between sampling may have resulted in greater oxygen depletion events being missed.

Nutrient trends and ratios

Given the absence of specific data on phosphorus and silicon it is not possible to calculate nutrient ratios. Nor was there any discussion of nutrient trends in Southampton Water.

5.2.2 Biological Effects

In 1985 cell numbers of M. rubrum grew from ca. 1,000 l-1 in mid-April to 1,000,000 l-1 in summer in the surface layer. Numbers at greater depths were usually lower. Chlorophyll-a peaked at ca. 100 µg l-1, and was linearly correlated with cell numbers. Similar peak cell counts of over one million per litre were observed in the June 1986. Cell numbers at the one site studied in 1987 peaked at 3.2 million per litre. Once established, the blooms tend to persist for ca. two months. M. rubrum “actively maintains itself within the estuary”. The UK guidance suggests that levels significantly greater than 0.5 million cells per litre and chlorophyll-a concentrations regularly exceeding 10 µg l-1 during summer should be taken as evidence for eutrophication

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 66 Crawford et al. concluded that the blooms at their maximum were limited by light and self-shading: calculations indicated that they were intercepting all available light, and that photosynthesis for much of the population was only just sufficient to cover respiratory requirements.

Comparison of cell numbers and the typical chlorophyll-a concentrations within individual cells on the one hand with total chlorophyll-a in the water “strongly suggest that during the blooms Southampton water is dominated by M. rubrum”. Whether other phytoplankton existing at normal densities would have shown up in this calculation is questionable, but it would have indicated the presence of other bloom species such as Phaeocystis. Crawford et al. conclude that the interception of light and reduction of nutrients “must have and impact upon the other photosynthetic plankton within the estuary”. Nevertheless, other species occurred, of which the most prominent was the dinoflagellate Scrippsiella trochoidea. Phaeocystis and diatoms are known to occur in the period before the red tides.

Macrozooplankton declined during the bloom period when measured in 1985, and showed an inverse relationship with M. rubrum abundance, although they remained present under the bloom. As the bloom died away the surface layers were re-occupied by macrozooplankton.

No direct toxic effects of M. rubrum were observed. And although mass mortalities have been associated with depleted or total deoxygenation resulting from M. rubrum blooms, for example in South Africa, this was not observed in Southampton Water, although the authors warn that monitoring was not continuous. At the opposite extreme, oxygen supersaturation can also cause problems such as ‘gas-bubble’ disease in fish. However a study of post- larval gobies during blooms revealed no adverse affects.

5.2.3 Sewage-specific Effects

The paper by Crawford et al. is specifically about the red tides, so contains no general information on sewage-related effects. However they cite other work which states that red tides increase the abundance of bacteria in Southampton Water, presumed to be via the release of dissolved organic matter from M. rubrum which provides bacterial food. They note that there is evidence that these bacteria are flushed out of the estuary, possibly provoking an immunological response in oysters in the Solent. They also comment that there is evidence from Spain that Vibro shellfish and human pathogens increase in abundance in the presence of M rubrum.

5.2.4 Designation under the Directives

Nitrogen levels, at 26–62 µM DAIN in mid–May, and between 38 and 66 µM DAIN in August are in excess of winter qualifying level of 12 µM l-1 DAIN in the UK guidance levels for hypernutrification in coastal waters. By comparison to the Suffolk Estuaries (see Table 4.1) the total nitrogen levels are greater than those of the inner Stour estuary, and typically half those of the other three inner estuaries. This is remarkable, because the red-tide sites

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 67 are more outer- than inner-estuary on the basis of salinity – indeed Southampton Water might be considered to be sufficiently large. and the salinity sufficiently low, to verge on being a coastal water (albeit one with poor natural dispersion, as indicated by the persistence of the red tides, and thus ruling out LSA status). The summer levels are far higher than those reported for the Wash in June and August, when TON ranged from 4.64–22.8 µM, with ammonium very much lower.

The UK CSTT Comprehensive Studies Manual regard a coastal region as eutrophic if observed chlorophyll concentrates regularly exceed 10 µg l-1. The UK general guidelines on Sensitive Areas and NVZs repeat this advice, in conjunction with the observation that normal blooms reach densities of 0.5 million per litre. The blooms are also of regular occurrence, and last through the summer months. There is also evidence of oxygen deficiency directly caused by the bloom. They cause displacement of the (zooplankton) fauna, and Crawford et al. make it clear that the lack of continuous monitoring mean that other faunal effects cannot be ruled out.

Red tides in Southampton Water have “subjectively been observed to occur after heavy rainfall in some years”, and with reduced tidal mixing, such as at neap tides. Both of these factors will increase the stability of the water column, but increased rainfall is also known to increase nitrogen concentrations.

On this evidence five of the seven criteria indicating Sensitive Area or Nitrate Vulnerable Zone status are met:

• nitrate concentrations; • occurrence of exceptional algal blooms; • duration of algal blooms; • oxygen deficiency; • changes in fauna.

Moreover, while changes in macrophyte growth were irrelevant to this study, it is known that Enteromorpha occurs extensively on the mudflats fringing Southampton Water. Similarly, while information was not provided on algal scums, Crawford et al. stated that Phaeocystis blooms occurred. The sheltered conditions that allow the persistence of red tides also reduce the likelihood that algal scums will be whipped up, even in the presence of major blooms of scum-producing species.

As to the source of the problem, and which Directive applies, ammonium levels are very high (June levels typically over 10 µM and with a peak value of 18 µM, compared to winter values in the Deben of 15–20 µM (Sage et al.). This indicates that sewage treatment plants are an important source of this preferred source of nitrogen. But high nitrate levels, between 25–50 µM (compared with winter Deben nitrate concentrations at comparable salinities of ca. 40 µM and 130 µM on two dates in January 1996, (Sage et al.) suggest that diffuse agricultural inputs may also be important). On this basis it would seem that both Sensitive Area and Nitrate Vulnerable Zones could be

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 68 justified, requiring measures for both sewage treatment and agriculture. Although the lower reaches of the River Test was designated a Sensitive Area in the first round, the requirement was for phosphorus removal only.

Less Sensitive Area status is clearly inappropriate for Southampton Water, and it was not so designated in the first round of 1994.

5.3 PORTSMOUTH HARBOUR

Portsmouth Harbour lies to the east of Southampton Water. While most of the attention, and literature, regarding eutrophication has focused on the adjacent embayment of Langstone Harbour, Portsmouth Harbour provides significant insights.

The “eutrophication problem” – the then Southern Water Authority had no problems with the term in the mid-1980s – dates back to the 1960s when increasing STW discharges were associated with an increase in algal weed mats of Enteromorpha with some Ulva in both embayments, as recorded by Soulsby et al.lxxiv. But in 1980 the discharges into Portsmouth Harbour were diverted directly into the Solent, while that into Langstone Harbour continued. The fate of the weed mats in the two embayments were seen to test the hypothesis that the sewage discharges were responsible for the increased weed cover. If the weed declined in Portsmouth Harbour, but not in Langstone, this would indicate that the nutrients from the STW were responsible for the eutrophication.

The outcome in Portsmouth Harbour may have come as a surprise to those working for the Water Authority who in 1980 thought that nutrient removal from the sewage might be necessarylxxv. Despite the cessation of sewage discharges, the weed mats continued to be prolific. In 1974 and 75, before the sewage was diverted, 156 and 137 hectares had weed cover over 75%1, but in 1981–83 the figures were 376, 186 and 359 ha respectivelylxxiv.

Soulsby et al. argued that both nitrogen and phosphorus were present in excess in Enteromorpha tissues throughout the growing season when they measured this in 1982–83, noting levels over 2%, “which are found throughout the growing season”2 as representing a situation “only found in nutrient rich areas.” according to other research. These high concentrations in the absence of sewage nutrient inputs to Portsmouth Harbour (and therefore presumably from some other source) was taken as evidence that nutrient removal from sewage discharges to Langstone Harbour would have no impact on the weed mats. Table 5.2 provides data on nutrients in the Solent Embayments.

1 typically equivalent to between 1–3 kg wet weight, based on data for Langstone Harbour.

2 actually only true in the northern (innermost) parts of both Harbours according to their Fig. 2

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 69 Table 5.2 Nutrients in the Solent embayments

Site year period NH4 NO3 NO2 PO4 N:P µM µM µM µM

Portsmouth Harbour Fleetlands 75-76 winter 50 49.3 - - 81-82 winter 5.5 55.1 - -

Hardways 75-76 winter 10 30 - - 81-82 winter 3.71 21.1 - - 1982 annual 2.86 60.7 2.14 1.29 51:1 1990 annual 6.86 13.5 0.71 0.93 22.6:1 1991 annual 8.14 15.5 0.97 3.06 8.0:1 1992 annual 7.14 14.4 0.71 1.03 21.6:1

Langstone Harbour northern site 73-81 winter 4.28- 8.07- - 1.77- 10.3 27.7 4.29 summer 1.64- 3.21- - 1.03- 4.86 6.21 2.26 southern sites 73-81 winter 3.0-6.5 6.14- - 1.39- 19.7 4.06 summer 0.57- 1.07- - 0.51- 3.07 4.71 2.10 1982 annual 3.94- 14.6- 0.70 1.13- 16-17:1 4.24 18.0 1.43 1990 annual 9.29- 14.9- 0.7-0.8 1.83- 18-20:1 17.5 28.6 1.93 1991 annual 7.32- 14.0- 0.7-2.01 1.88- 12-13:1 9.52 14.9 1.93 1992 annual 5.71- 9.75- 0.5-0.7 1.31- 14-16:1 12.9 12.0 1.45

Chichester 13 sites 1991 2,3 qtrs 10-27.6 7.14- -- 23.6 1992 2,3 qtrs - 4.5-41.1 - - 1993 2,3 qtrs 2.5-8.57 4.6-74.1 - - one value 1985 annual - - - 3.16/9. 68 1990 annual - - - 0.42/1. 29

Note: See text for additional information. Source: Soulsby et al. 1985, Montgomery et al. 1985, NRA Southern Region memorandum 1993, WS Atkins English Nature Report 1994.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 70 5.3.1 Chemical Profile

Nitrogen

However, examination of the nitrogen data warns against simple conclusions. Ammonium levels apparently dropped dramatically after the diversion of STW discharge. At the closest sampling point, Fleetlands, mean ammonium N winter levels fell from 50 µM in 1975-76 to 5.5 µM in 1981/82. But nitrate levels at this site, which were considerable, did not fall (mean nitrate N winter levels 49.3 µM in 1975-76 to 55.1 µM in 1981/82). It is stated that the nitrates come from the adjacent River Wallington, which receives no sewage-based discharges, and – if typical of other rivers – can be assumed to come primarily from agricultural sources; its catchment certainly includes agricultural land. Data was also presented for a west bank site (Hardways), mid-way between the River Wallington and the embayment mouth. Winter ammonium levels in 1975–76 were 10 µM, but only 3.71 µM in the winter of 1981–82, seemingly confirming the changes nearer to the discharge. But a 1993 NRA Southern Region memorandumlxxvi, supplied by the EA with the 1993 pro-formas, complicates the story. It gives the ‘mean’ ammonium N level (i.e. including lower summer levels) in 1982 as 2.86 µM1, but 6.86 µM in 1990, 8.14 µM in 1991 and 7.14 µM in 1992.

The winter nitrate N levels at Hardways reported by Soulsby et al. (1985) were 30 µM in 1975–76 and 21.1 µM in 1981–82. The mean nitrate levels at Hardways reported in the 1993 memorandum were 60.7 µM in 1982 and 13.5,

15.5 and 14.4 µg/l in 1990–92. The memorandum confirmed that nitrite, NO2, levels were low (2.14 µM in 1982, and 0.7–1 µM in 1990–92).

Thus it appears that the effect of the initial diversion of sewage effluent out of Portsmouth harbour was less than initially thought. Moreover there has been no obvious reduction in ammonium or nitrate resulting from the subsequent diversion, in 1991, of a 70 Ml.day-12 crude sewage discharge, from the southern end of Langstone Harbour to an outfall 6.4 km offshorelxxvii. So it seems that one of the few conclusions that can be drawn is that a significant source of ammonium remains in or close to Portsmouth Harbour. The same is true of nitrate. Inter-annual variation is high. The contribution of any historical burden from the sediments is unknown. On the basis of this data, at least, it is difficult to see any obvious decline in overall nitrogen levels, so the persistence of algal weed mats is not surprising, even if the reasons are less certain.

Phosphorus

The memorandum also gives mean phosphorus values for Hardways, of 1.29 µM in 1982, and of 0.93, 3.06 and 1.03 µM in 1990–92. Again, on the basis of

1 No units given in the memorandum, assumed to be micrograms per litre and converted here.

2 Ml: million litre

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 71 this (limited) information, no obvious trends are apparent. It does not included data from the period when there was a direct STW discharge into the Harbour. No data has been seen on silicon.

Nutrient Ratios

On the basis of the data in the memorandum the mean annual atomic N:P nutrient ratio at Hardways varied from 8:1 in 1991 to 51:1 in 1982. These ratios may be of limited use for the reasons given in earlier sections.

5.3.2 Biological effects

No biological effects resulting from the weed-mats were reported for Portsmouth Harbour, but see the section on Langstone. Nor did the documentation seen discuss other sewage related effects such as deoxygenation and bacteriological criteria.

5.3.3 Designation under the Directives

Portsmouth Harbour no longer has sewage discharges directly entering it. It was not designated as a Sensitive Area, Less Sensitive Area or Nitrate Vulnerable Zone in either the 1993 or 1997 rounds. See the concluding discussion for Solent for further discussion.

5.4 LANGSTONE HARBOUR

Langstone Harbour is immediately to the east of Portsmouth Harbour. Portsmouth is on an island (Portsea) between the two, although the 2.5 km connection between the two embayments at the top, northern, end is little more than a channel.

There is a STW, Budds Farm, on the northern shore of Langstone Harbour. According to a NRA document prepared at the time of the first round of designations “The volume of effluent discharged from Budds Farm increased from about 7 Ml/day in 1955 to 40 Ml/day in 1980 and a corresponding rapid increase in the amount of macro-algae Enteromorpha and Ulva spp. occurred at the same time.”lxxvii It continues “Excessive growth of such macro-algae in enclosed estuarine and marine waters have been attributed to the stimulating effect of nutrients in domestic sewage effluent in a wide range of locations”. According to the 1993 candidate Sensitive Area pro-forma Budds Farm had a discharge of 378,000 p.e. and tertiary treatment.

There was a second sewage effluent discharge – Eastney – during this period, with a 70 Ml/day of crude sewage discharge, from the southern end of Langstone Harbour. In May 1991 this was diverted to an outfall 6.4 km offshore.

The same document tabulates the intertidal area covered by algal weed-mats during the latter part of this period, 1973–82, when it varied significantly

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 72 between years but without obvious trend. Up to 60% of the intertidal area was affected during this periodlxxvi. The minimum area recorded during this period with over 75% cover was 68 ha in 1976, the maximum was 377 ha in 1979. Although found throughout the Harbour, the algal mats form consistently high cover in the north, particularly to the west of the Budds Farm outfall. Cover was also high on the western side of the embayment during the latter part of the period (1977–82). Cover elsewhere varies to a greater extent, but can equal that found in the northern part – the highest mean wet weight recorded during this latter period was 3318 g m-2, in the south-west of the Harbour1.

The macro-algal cover was re-surveyed in 1993 as part of the designation process when there “was no evidence of any decline in macro-algal cover in the north, south-east and west of the harbour on those mudflats adjacent to the shoreline” and which were accessible to the survey.

5.4.1 Chemical Profile

According to Soulsby et al. (1985) Langstone Harbour is “a fully saline tidal inlet”. Nevertheless there will be a freshwater component and an associated vertical salinity gradient (c.f. Southampton Water). As the nutrient concentration in the freshwater can be expected to be very much higher that that of seawater, small difference in salinity may make a significant difference to nutrient exposure of macroalgae. In calm conditions it is possible that intertidal algal weed-mats will be bathed in relatively fresh – and relatively nutrient rich – water. Both Enteromorpha and Ulva are able to absorb and store large amounts of nutrients during brief exposure.

It is therefore unfortunate that salinity levels and depths of sampling are not given in any of the published material, not least because it makes comparison of nutrient levels with those of other sites more difficult. Moreover it is clear that variability is high and that the sampling regime – at least on the basis of the figures presented – is inadequate to deal with this. Finally the 1993 Technical Report warns against comparing the more recent measurements with those of 1977–81 because recent surveys were relatively infrequent and not standardised with regard to the state of the tide (c.f. the Wash estuaries).

The result is a very confused mass of data. Although summarised in the following pages for both nitrogen and phosphorus, it would be unprofitable to spend too much effort attempting to extract trends, and questionable to place too much reliance on any trends that might appear.

Nitrogen

As with Portsmouth Harbour there are no obvious changes in nitrogen levels in the waters of Langstone. Turning to ammonium first, between 1973 and 1981

1 it should be noted that the observed weights are the net result of two processes – growth and attrition (by grazing, physical processes, etc.) and the rate of attrition is not known.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 73 winter ammonium-nitrogen levels at the northernmost sampling point1 (i.e. nearest to Budds Farm STW) varied between extremes of 4.28 µM in 1978 to 10.3 µM in 1980lxxviii. Further south in the embayment2, the lowest during this period was 3.0 µM in 1978, the highest 6.5 µM in 1980. Summer values over the same period in the north of the Harbour ranged between 1.64 µM in 1981 and 4.86 µM in 1977. Those further south ranged from 0.57 µM in 1981 to 3.07 µM in 1977. These data, at least, appear to display a concentration gradient declining from the north (inner Harbour) towards the south.

The 1993 memorandum gives mean annual levels for two southern sites3 in 1982 of 3.92–4.21 µM. Between 1990-92 these varied between 5.71 and 17.5 µM at Hayling Ferry, at the mouth of Langstone, while that for ‘The Deeps’ ranged between 9.29–12.9 µM. The Hayling Ferry maximum occurred in 1990, before the commissioning of the long sea outfall, but this is insufficient to assume cause and effect. Levels in 1990 at the Deeps were not higher than those of 1991–92.

Winter nitrate N levels between 1973–81 at the northern-most site ranged between 8.07 and 27.7 µM. At the two more southerly sites the range was between 6.14 and 19.7 µM. Summer levels ranged between 3.21–6.21 µM at the northernmost site, and between 1.07–4.71 µM at the other two sites. As for ammonium, this implies that an inner nitrogen source was being diluted by seawater. In the 1993 memorandum, mean nitrate N levels in 1982 of 14.6 and 18.0 µM are given for the southern sites only. In the 1990s, these levels were 14.9 and 28.6 (1990), 14.1 and 14.9 (1991), and 12.0 and 9.75 µM (1992).

As with ammonium there are no conclusive temporal trends. Montgomery et al. (1985) confirm this, while noting that there are statistically significant differences between individual years, which were larger, they argued, than could be accounted for by any variation in the input of nutrients. Although any spatial trend would most likely appear to be that of a reduction from inner to outer sites, they attribute the spatial pattern to the variable composition of the sea water, and to incomplete mixing and variable biological and chemical processes within the embayment.

Nitrite levels are low compared to nitrate and ammonium. The 1993 memorandum records a maximum annual average of 2.01 µM in 1991 at Hayling Ferry, and a minimum of 0.5 µM in 1992 at The Deeps.

Finally it is interesting to make a comparison with the TON levels in the mid- reach of the Ythan estuary most affected by Enteromorpha in the early 1990s. Raffaellilxxxix indicates a salinity range of ca 32–34‰ for this part of the Ythan which in turn suggests a mean TON of perhaps 50 µM in 1991–92, judged from the regression in Balls et al.lxxix Taking the 1990–92 data, the TON

1 site identifier “pile C/E”

2 site identifiers “Rafts” and “Ferry”

3 site identifiers ‘Hayling Ferry’ and ‘The Deeps’

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 74 (nitrate+nitrite) concentrations at Langstone are lower than this; between 27– 80% of those in the Ythan.

Phosphorus

Between 1973 and 1981 winter mean phosphate levels at the northernmost site varied between a low of 1.77 µM averaged from the winters of 1973–74 and the first part of 74–75, and a high of 4.29 µM recorded in November 1977. At the two more southerly sites the minimum and maximum values occurred at the same time as the northernmost site, and were of 1.39 and 4.06 µM respectively. The lowest summer value at the northern site was 1.03 µM in 1979, and the highest 2.26 µM in 1978. The range at the southern sites was 0.51–2.10 µM, on the same dates.

The 1993 memorandum reports mean annual phosphate values of 1.13 and 1.43 µM for Hayling Ferry and The Deeps in 1982, and 1.13–1.93 µM for the two sites between 1990–92. Any changes over the entire period are therefore not apparent at this very crude level of analysis, and the warning concerning different methodology in the 1993 memorandum should be kept in mind. Using the same calculation as for TON, the area of the Ythan most affected by Enteromorpha has a mean phosphate level of perhaps 1 µM phosphate in 1991– 92, lower than that for Langstone.

Silicon

No data on silicon have been seen.

Nutrient ratios

In Montgomery et al.’s study winter nitrogen:phosphorus ratios in 1973–4 and 1981 were similar: between 13.2:1 and 16.2:1 at the three sites in 73–74 and between 11.1:1 and 13.2:1 in 1981. Summer values were much lower than in winter at 3.62–4.58: 1 in 1973–4, and 2.01–2.90:1 in 1981

From these the average annual ratio would be ca. 7–9:1. Compared to this the 1993 memorandum annual mean values are much higher; in 1982 17.3:1 and 15.8:1, in 1990–92 between 12.1:1 and 20.0:1. The internal consistency within the two data sets, and the considerable difference between the early 1980s values, suggest that the apparent change may be a methodological artefact.

Benthic nutrients

Montgomery et al. examined nitrogen and phosphorus concentrations in sediments from high and low weed sites in Langstone. They concluded there was no significant difference in nutrient content, nor any seasonal trends. They estimated the total N and P present in the top 165 cm of Langstone Harbour sediments (6000 tonnes nitrogen and 2200 tonnes phosphorus). But presence does not necessarily indicate availability to the overlying water or weed. No data was presented on exchange rates between the sediments and overlying water over the annual cycle.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 75 Source of Nitrogen and implications for remedial action

For nitrogen Montgomery et al. estimated daily inputs of 0.7–1.8 tonnes nitrogen entering Langstone from Budds Farm STW, and 0.3 tonnes from the Eastney discharge. Fresh water inputs were, at the extreme, estimated to be under 0.5 tonnes per day, which assumes that agricultural inputs from the hinterland were indeed relatively unimportant. However an important budget term, the (winter and summer) input from the Solent, was not directly measured. Instead an approximation of total nitrogen present in Langstone at high tide is estimated from the average concentration in the Harbour – of 12.6 tonnes nitrogen in winter and 3.3 tonnes in summer, and the input from the sea calculated by subtraction – a slightly dubious if understandable procedure.

Nevertheless it seems likely that inputs from the Solent will be a significant component in winter. Assessing the contribution in summer is only possible in crude terms, because the water concentration is the result of a dynamic process, with nitrogen being removed by weed-mats and other plants. Montgomery et al. estimated that the weed-mats could be removing up to 1.7 tonnes nitrogen per day at the peak of the growing season, suggesting a combined input to the Harbour of some 5 tonnes per day, although this does not take account of possible sediment interactions, or uptake by other plants. For phosphorus an input of 0.3 tonnes per day was calculated for Budds Farm STW and 90 kg per day from Eastney, with all other sources (except the sea) considered negligible. Total P in the embayment water body at high tide was estimated to be 2.9 tonnes in winter, and 1.9 tonnes in summer. Phosphorus limitation was apparently considered implausible, although the reasons for this are not stated. Soulsby et al. recorded a mean plant tissue N:P ratio over the growing season, in Portsmouth and Langstone Harbours, of 31:1 and that the ratio never fell below 9:1. This is interpreted as ‘luxury uptake’ and storage of nitrogen rather than possible phosphorus limitation.

Conclusions

Montgomery et al. state that “At the time an earlier paper was written … it was still thought that partial removal of nutrients from the Budds Farm effluent might be necessary. The following discussion shows that such a conclusion is incorrect.” Actually their discussion was more equivocal. They state that “… the supply of N from the Solent is well in excess of the 1 tonne a day derived from Budds Farm, and that the Solent alone could supply the N requirement of the crops of Enteromorpha observed in 1973–83. On the other hand, the excess N derived from Budds Farm, coupled with the growth promoting factors thought to be present in the sewage effluent, may well be increasing the growth rate to a point where the gains and losses of Enteromorpha equilibrate to give the observed [crop].”1

1 Soulsby et al. having noted the continuing presence of algal weed mats in Portsmouth Harbour, cite this passage as supporting evidence “which suggest that the nitrogen contained in the sea water entering the harbour each day could support the present standing crop without the presence of the sewage effluent” They go on to suggest “The waters of the Solent, which dominates the harbour waters, are supplied by two nutrient rich chalk based rivers and it is possible, therefore, that they have always been able on their own to satisfy the nutrient demand of the macroalgae”. This leaves the recent expansion of the weed-mats unexplained.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 76 The statement that “the Solent alone could supply the N requirement of the … Enteromorpha” in any case needs to be treated with some caution. Overall budgets for water bodies can be misleading. Even for the German Bight, where anthropogenic eutrophication increased dramatically between the 1960s and 1980s, the vast majority of the nutrients in the water column budget still come from the Atlantic, rather than from human sourceslxxx. The solution to this apparent paradox is that the phytoplankton are concentrated in the surface layer, and this narrow, fresher, surface layer largely contains the anthropogenic component. The column of marine water, stretching down to the sea bed, contains far more nutrients in total (although at a lower concentration per unit volume), but is largely irrelevant to the budget of the plants. Similar considerations may apply for algal weed mats, including those at Langstone1.

Montgomery et al. went on to consider the impact of a projected further increase (ca 50%) in Budds Farm nutrient discharges. They concluded that there were no trends in weed-mat cover between 1973–83 “despite the fact that, during this period, there was an increase in volume of the effluent discharged from Budds Farm of approximately 55% which is equivalent to the increase in the 1950s and 1960s to which the rapid expansion of macroalgal production at the time was attributed”. But, had nutrients became present to excess during this first period, so that other factors became limiting, no further change would be expected. In any case Montgomery et al. go on to say “The conclusion of this discussion is that it is impossible to predict the effect of a further 50% increase in the load of effluents from Budds Farm with complete certainty”. But “even a slight risk of environmental damage should be avoided if that can be done without excessive expenditure”, and the continuation of denitrification (conversion of ammonium to nitrate) was recommended, as was the continued control of other sources2.

But it is clear from the Ythan that Enteromorpha can thrive on nitrate. In the event, according to the 1993 memorandum, a less denitrified effluent was apparently being produced by 1990–92 than in the early 1980s.

5.4.2 Biological Effects

The biological consequences of the algal mats are straightforward. Those species that feed upon it benefit; those that are displaced by the weed, and the species that feed upon them, do not.

Most of the observations on the biological impact concentrate on the birdlife. Dealing briefly with other effects first, Soulsby et al. note that the increase in

1 Apparently a recent internal report on Langstone, (not made available) from S. Malcolm’s research group at the MAFF Labs at Lowestoft repeats the argument that the main source of nutrients is from the Solent, so that there may be little benefit from controlling nutrients from Budds Farm (D. Lowthion, EA Southern Region, pers. comm.)

2 The same team are more assertive in the final paragraph of Soulsby et al.:”… the distribution and biomass of macroalgae in the harbours are controlled almost entirely by the availability of habitat, by physical and climatic factors and by grazing, and that the effect of a further increase in sewage derived nutrient concentration in the water column would be undetectable.”

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 77 algal mats “coincided with a period of rapid decline in the areas of Spartina marsh, which once dominated the harbour.” Montgomery et al. assert that this was “a result of natural die back of Spartina” but in support of this only cite an obscure reference in a local field club publicationlxxxi. In the Netherlands it is suspected that increasing nutrient levels have affected the species composition of salt marsheslxxxii, while the 1993 Quality Status Report for the Wadden Sea notes that late summer storms break up the algal mats and drive them into the open sea or to salt marshes and beaches where they “constitute a considerable burden for the ecosystem”lxxxiii, although it doesn’t specifically state that it causes die- back and decline.

Green algae at Sylt, in the German Wadden Sea, also smother eel-grass bedslxxxiv, while Valiela et al. correlated declining eel-grass with increasing nutrients, increasing algal mats and increasing phytoplankton in Waquoit Bay, Massachusettslxxxv. While lacking experimental evidence they also associated the decline in eel-grass with algae growing on the surface of the leaves, in common with effects observed elsewherelxxxvi.

Annual surveys between 1979 and 1982 might be taken as giving no evidence for a decline in Zostera at Langstonelxxvii. However three points have to be borne in mind. The surveys are were over too short a period to expect to detect all but a very rapid decline; there was significant variation between each year which, given Zostera’s perennial form, suggests considerable sampling error; and third, the Langstone observations were for intertidal beds, whereas adverse effects often become apparent in a reduction in the maximum depth of eel-grasses in the sub-tidal zone, due to epiphytes growing on the foliage that intercept the light.

According to a 1993 NRA memorandum “Zostera appears to be thriving in Langstone which one would not expect to be the case if the harbour was becoming more eutrophic”lxxxvii. In the event research published the following year provided direct evidence that the intertidal Zostera beds in Langstone were indeed being smothered by Enteromorphalxxxviii.

Montgomery et al., in the mid 1980s, placed a positive emphasis on the impact of the algae. They state that “the present effects of the mats of algae upon the benthic ecology … are measurable, but not detrimental, consisting of a large increase in the resident population of Hydrobia [a small grazing snail] and a slight change in the numbers and species of polychaetes. The algae are beneficial insofar as they provide part of the diet … of Brent Geese (Branta bernicla bernicla) and probably some species of fish. Although adverse effects of the mats … have been alleged (Tubbs & Tubbs 1983), such allegations have been shown to be doubtful (Soulsby et al., 1983).”

Since then more has been learnt about the actual and potential effects of algal weed mats. The major vertebrate predators of Hydrobia (at least in the Ythan) are flounder, shelduck, eider and redshank, but even so it is not a particularly important diet item. The invertebrate predators of Hydrobia in the Ythan have also been documented, but there is less information on the quantitative importance of these links. It is clear that the algal weed mats are eaten by

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 78 grazing birds, including widgeon and mute swan. The major negative impact is via the shrimp-like invertebrate Corophium, which is not mentioned by Montgomery et al.. Corophium cannot survive under dense weed mats’ while at lower algal densities the weed physically impedes the ability of predators to extract Corophium from the mud. In the Ythan 55% of Corophium production is cropped annually by redshank, shelduck and flounder, and it features in the diet of many other specieslxxxix.

Later research, described in a NRA reportlxxvii, apparently confirmed that certain large deep burrowing polychaete worms are restricted by the Langstone algae, and also that the algal mats inhibited the feeding of all eight species of wading birds and shelduck studied, although “none of the birds had difficulty in obtaining food during a ‘normal winter”.

Some might argue that what was some species loss was another species gain – in this case the Brent Geese and other grazers. But at the national and international scale it is the species that do not benefit from eutrophication that are under the greater threat from habitat loss. As nutrients are reduced it can also be expected that the original food sources for grazers (such as eel-grass) will recover.

So on this basis the original conclusion of Montgomery et al. of minimal impact may be more questionable than they assumed.

5.4.3 Designation under the Directives

Langstone Harbour could not be considered a Less Sensitive Area. Arguments have centred on whether it is a Sensitive Area. That was in part settled in July when the government announced its designation as a Sensitive Area, along with Chichester Harbour, on the grounds of eutrophication. No discussion has been seen of whether the discharge fulfils the requirements of other Directives, for example regarding bacteriological standards.

The research upon which the arguments centred was largely conducted in the early 1980s, and was inconclusive due to the absence of historical data, and insufficient resources to answer the questions posed1. The twists and turns in policy appear to have been largely based on interpretation and re- interpretation of this inconclusive body of information.

In the early 1980s the then Southern Water Authority appeared to accept that that Langstone was eutrophic, and were considering nutrient removal. By the mid-1980s this view had changed. The conclusions from the research now emphasised that any future increase in discharges (which were anticipated) would not result in any further increase in algal mats – a different issue from whether it was currently eutrophic.

1 More research, funded by the EU, has been carried out in the last few years at the University of Portsmouth, but the results have yet to be published (B. Fletcher, pers. comm.).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 79 However, in the 1993 first round of Sensitive Area designations, the regional authority once more proposed this as a candidate site, citing its current eutrophic status, algal weed mats and “stressed” invertebrate community. But in a subsequent memorandum dated 24 March 1993, from the then NRA Southern Region to NRA’s head office, “discussions” were referred to, and the nomination for Sensitive Area Status was withdrawn. In justification this document refers to the continuing presence of weed mats in Portsmouth Harbour, despite the cessation of sewage discharges. It also states that the sewage discharges in Langstone were not believed to be the “only major source”. It acknowledges that there are no (direct) agricultural inputs to Langstone, and so concludes that “Levels in tissues probably reflect elevated levels in the Solent”.

The implications of accepting such a widespread source of eutrophication were passed over. In any case, it was accepted that the sewage discharges were one “major” source, and the Directive’s Annex II requires the removal of nutrients “unless it can be demonstrated that the removal will have no effect on the level of eutrophication”. Either this cannot be demonstrated, or, if Portsmouth Harbour is cited as supporting evidence for the claim, this implies that the entire Solent region would indeed require designation as a Sensitive Area and/or a Nutrient Vulnerable Zone.

The memorandum revived the questionable assertions that the algal weed mats represent a successional stage to the Spartina salt marsh, and also that “The Eel Grass, Zostera, appears to be thriving in Langstone which one would not expect to be the case if the harbour were becoming more eutrophic.”

Now, with the second round, the regional authority once more has asserted that Langstone was eutrophic. On this occasion the head office of the Environment Agency, the Review Panel and the Department of Environment, Transport and the Regions concurred.

The outstanding issue is how the change in policy will be implemented – whether by the removal of nutrients from Budds Farm STW discharge, or by re-routing to an offshore discharge.

5.5 CHICHESTER HARBOUR

Chichester Harbour is immediately to the east of Langstone and interconnected via a wide channel. No major rivers discharge into the embayment. The catchment of the embayment is more agricultural than Langstone or Portsmouth. This is reflected in the smaller size of the two sewage treatment plants.

The documentation for Chichester Harbour appears to be subsidiary to Langstone and limited in extent. The 1993 pro-forma records Enteromorpha and Ulva as affecting up to 25% of the intertidal area, mentioning the extremely sheltered creek of Bosham Channel and the less sheltered Emsworth Channel by name. However this data is from 1979.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 80 5.5.1 Chemical Profile

Limited data on nitrogen levels comes from a report prepared for English Nature by Environmental Consultants WS Atkinsxc on 27 proposed Important Marine Areas, IMAs, in England1. These were of nitrate and ammonium from 13 sites in Chichester Harbour sampled in the second and third quarters between 1991 and 1993. This indicates ammonium values for Chichester that are substantially higher that those for Langstone. The nitrate values indicate levels possibly higher than for Langstone or Portsmouth at that time. Compared to the other harbours, many of the Chichester sampling points were around the edge of the more indented embayment – in some cases within enclosed creeks.

The only values for phosphorus in Chichester Harbour that has been encountered also came via English Naturexci. The two mean values cited, of orthophosphate, did not make it clear whether phosphate or phosphorus was being given. Depending on this, the values were of 3.16 or 9.68 µM P in 1985 and 0.42 or 1.29 µM in 1990. Compared to the mean 1990–92 values for Langstone, the 1985 value is very high, while that for 1990 Is far lower, indeed at the very lowest end of the range for 1979–1981, taken from the most seaward Langstone site. It would not be prudent to place too much emphasis on this data.

5.5.2 Biological Effects

The 1993 pro-forma repeats, word perfect, the statement regarding stressed invertebrate communities found in the Langstone submission. The March 1993 memorandum notes that “Chichester Harbour was included … which is not unreasonable as the two Harbours have similar problems. Aerial photography undertaken during the 1970s and 1980s showed areas of excessive algal growth. Spartina has died back and been replaced by Enteromorpha and Ulva in the long creeks in the Harbour. However, Chichester Harbour tends to be more erosive than Langstone which may contribute.”

5.5.3 Designation under the Directives

Chichester Harbour was designated as an eutrophic Sensitive Area in the second round of designations this July. No evidence has been seen to suggest that a nutrient budget has been calculated to quantify the relative input of agricultural nutrients – see the general conclusions regarding the Solent area for NVZ status.

1 In principle these ‘Special Marine Areas’ (as IMAs became) are still an active concept, but work on establishing Special Areas of Conservation, SACs, and Special Protected Areas, SPAs, is currently receiving priority.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 81 5.6 THE SOLENT

The Solent is one of the 27 IMA sites proposed by English Nature in 1993. The site includes the embayments, and stretches the full length of the Solent. A report produced by consultants WS Atkins (referred to in the section on Chichester Harbour) documented the chemical characteristics, including nutrients, in so far as the information allowed. The report describes the Solent as a “sheltered channel characterised by a two way fast flow of water” based on chalk bedrock. The overall site is “a complex set of ecosystems and there will be complex interactions between these systems … The area is of international importance with respect to birds and wildlife”.

5.6.1 Circulation

The reversible flow in the Solent raises two inter-related issues with regard to the implementation of the Directives. Are the circulation patterns in the Solent such that contamination from the off-shore discharge from Eastney can still reach the embayments? If not, if the flow is a rectilinear oscillation that keeps water from the discharge offshore, does this imply that there is a narrow band of coastal water that might transport nutrients (and bacterial contamination) from either Southampton Water or from sites to the east? The UK authorities have carried out modelling, which they argue supports the case for a rectilinear flow in the vicinity of the off-shore discharge (without apparently considering the inshore implications). Documentation relating to this modelling has not been seen. However the issue has been discussed, off the record, with a representative of the Environment Agency. From this, the salient points appear to be that:

• The discharge of Eastney sewage effluent into the Solent is continual – in other words it doesn’t attempt to exploit certain tidal states to achieve a particular dispersion pattern. There will also be significant nutrient inputs from the coast, including Southampton Water. Thus nutrient (and other) inputs from Eastney are only one component of the total Solent burden.

• It is argued that the Eastney discharge, at the eastern end of the Solent, would typically be carried westward; that it might be detectable at least to the mouth of Portsmouth Harbour and Southampton Water; and would ultimately be discharged from the western end of the Solent. A minor part will be carried directly out of the Solent on the east flowing part of the tidal cycle. Residual currents – those remaining after reversible tidal currents are taken into account – are small. Whichever route the water takes out of the Solent, the authorities believe that it is probable that it is then carried in an easterly direction eventually to enter the North Sea;

The typical route of any individual discharge, such as Eastney, may in any case be of secondary importance. More important would be to establish the general pattern, including the possibility of ‘repeat’ discharges into the same body of oscillating water, from whatever source. If the typical pattern is rectilinear, and if water from the centre of the Solent channel infrequently reach inshore waters, then this also implies that inshore waters are usually

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 82 trapped against the shore. This water body can be expected to contain nutrient sources derived from sewage and from other major south-coasts inputs such as agriculture. This may be derived either from the coast to the east of the Solent, or possibly from Southampton Water and other sites to the west. If true, this might help explain why algal weed mats have persisted in Portsmouth Harbour despite the diversion of sewage effluent. If nutrient inputs to the embayments from the harbour mouths are now the major source, this may be visible as a nutrient gradient from the outer to inner embayments.

The only data relevant to this, that from Langstone described earlier, tentatively indicate the opposite, of higher nutrient concentrations in the inner reaches. However these date from the late 1970s and early 1980s when sewage discharges to the inner embayment still occurred.

Another consideration is that water from the Solent, and perhaps to the south of the Isle of Wight, may be at a ‘dead’ point, allowing the accumulation nutrients in the general areas, or the recirculation of water around the Isle of Wight. The position of the Isle of Wight at a current ‘watershed’ in the English Channel was noted at the opening of this section.

It would be necessary to make a detailed evaluation of circulation patterns to carry this aspect any further. However some indirect indication may be gleaned from the nutrient distribution throughout the Solent.

5.6.2 Chemical Profile

The WS Atkins report includes (limited) Solent data on nitrate and ammonia between 1991–93. The coverage in the four quarters of the year varies from year to year. The range between the maximum and minimum levels measured in the first quarter of the year between 1991–93 are given for sites in the Solent ranging from East Brambles, off the entrance to Southampton Water, to a site off Selsey Bill in the east. The annual mean is also given, but this is less reliable because sampling intensity varied markedly across the seasons from one year to the next. Table shows these values, together with earlier Solent data from Montgomery et al., and also from other comparative sites.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 83 Table 5.3 Nitrogen concentrations in the Solent compared to other sites

Sites — Ammonium N µM — — Nitrate N µM — Winter Annual Winter Annual minimum maximum mean minimum maximum mean

Solent 77–80 East Brambles 1.43 16.4 3.86 2.14 31.4 11.2 Nab Tower 1.43 7.86 2.21 0.17 12.1 5.57

Solent 91–93 East Brambles 1.50 5.00 4.07 7.14 37.9 11.9 Calshot 2.07 20.0 12.1 27.6 75.3 32.3 Nab Tower 0.14 5.00 2.43 16.6 17.4 7 Selsey Bill 0.36 6.29 4.71 18.9 22.3 5.93

Comparative sites W. English ---1.0711- Channel 74–87 Beachy Head 0.43 4.86 2.43 8.78 9.64 3.14 East Anglian coast < 0.36 3.57 - 21.4 42.8 - 95 outer Thames < 0.36 1.43 - 21.4 71.4 - estuary 95 Wash 93–94 1.57 3.93 - 30 157 - outer Wash 95 < 0.36 4.64 - 35.7 107 - Lincolnshire coast 0.36 6.43 - 39.3 72.8 - 95

S Wadden Sea 78– < 0.36 1.93 - 15 100 - 91 N Wadden Sea < 0.36 4.23 - 25 140 - 78–91

Note: Ammonium and nitrate N, winter minimum and maximum levels, and annual mean where available. The sources are varied, so the different sampling and analytical methods, depths, frequency and reliability all have to be taken into account, and comparisons only made at the broadest level. Skegness was taken as the boundary between the Lincolnshire coast and the Wash, Wells as the boundary between the Wash and the East Anglian coast, and Clacton as the boundary between the East Anglian coast and the outer Thames estuary. S. Wadden Sea is the Dutch section, N Wadden Sea is the German and Danish Section. Sources: Solent 1977–80: Montgomery et al. 1985lxxv. Solent 91–93, Beachy Head: WS Atkins Reportxc. W. English Channel: Jordan & Joint 1998xcii. Lincolnshire coast, outer Wash (95), East Anglian coast and outer Thames Estuary: Sea Vigil Lincolnshire Coast reportxcvii The Wash 1993–94: Sea Vigil Wash Reportsxciii, xciv . Wadden Sea: Wadden Sea sub-regional reportlxxxiii.

There are no obvious trends in the Solent concentrations over time. Those in the 1990s appear very much higher than those from the western English Channel, which are the closest to ‘natural’ Atlantic Water. There is a suggestion that they are also higher than those off Beachy Head, 100 km to the east of the Solent. With regard to the English east coast and the Wadden Sea, the Solent measurements fall in the lower half of the range. However such comparisons should be regarded as tentative, given the limited nature of the data on the Solent.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 84 Ammonia nitrogen levels show no dramatic change in the Solent between 1977–81 and 1991–93. The WS Atkins report also comments (their section 5 p. 4) that these ammonia levels are high for coastal waters.

There is no Solent data on phosphorus in the WS Atkins Report. Montgomery et al. reported winter phosphate between 1977–80 of 0.64–3.22 µM P at East Brambles and 0.32–2.58 µM at Nab Tower. This compares with 0.40–0.81 µM in the western English Channel, and is of the same order as peak winter values of 1.61 µM in the Wash in 1992–23, but substantially less than the 4.84– 9.68 µM in the southern Wadden Sea, 9.68–30.6 µM in the central and 0.40– 14.5 µM in the northern Wadden Sea recorded between 1978–1991. On the basis of these figures the Solent would be classified as hypernutrific using the UK definition. There is, however, insufficient information to make any judgement about circulation patterns and nutrient sources affecting the Solent.

5.6.3 Biological Effects

The UK administration has argued that phytoplankton assessments were carried out for the second designation round between 1994–1996, and that evidence of algal blooms was found for only four of 200 samples, and that these occurred in late spring or early summer when naturally occurring algal blooms would be expected. Subsequent enquiry to EA Southern Region established that these occasions were when chlorophyll-a levels exceeded the 10 µg l-1 eutrophication criteria for coastal waters. Circumstantial evidence suggested that Phaeocystis was responsible.

The suggestion that blooms are rare is however contradicted by the EA’s web- site pagexcv on the 1993–96 Baseline Survey of spring chlorophyll-a which states that the Solent is one of only three sites in England and Wales where elevated levels of algal blooms persist through summer (the others were Liverpool Bay and the north-east coast)

The UK also assert that there is no evidence that such blooms are increasing in intensity – but nor do they appear to have evidence to rebut such an assertion. It seems that the UK are in no position to assert that these were associated with a naturally occurring bloom offshore. The species was natural, of course, but there is apparently no data to assess the anthropogenic component of the extent, intensity or duration of the bloom.

It is understood that a Solent Nutrient Study, SoNuS, based on the model of the Wash JoNuS project is now underway, but that resources are limited. No results are currently available.

5.6.4 Designation under the Directives

From the information provided by the Environment Agency it appears that the Solent has been largely ignored with regard to implementing the two Directives, despite its nomination by English Nature in 1993 as an IMA. The policy to date regarding sewage nutrients in the area has been one of moving

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 85 discharges from the embayments to the Solent, rather than nutrient removal. The onus rests on the UK authorities to demonstrate that current and future discharges will have no unacceptable effects in the Solent, taking into account future long sea outfall diversions and projected population growth in the area.

Until a nutrient budget is constructed for the Solent catchment, and of the balance of transfers from adjacent areas, it is impossible to state the contribution of agricultural nitrogen or of possible NVZ status.

5.7 CONCLUSIONS – SOLENT & SOUTH COAST EMBAYMENTS

The Solent has been treated in an apparently inconsistent manner in implementing the two directives. Algal weed mats in the embayments are blamed on nutrients from the Solent. Yet assessments of the Solent argue that there no evidence for hypernutrification or eutrophication. Future plans for one site seem to take no account of the impact on another. Southampton Water’s red tides meet the UK’s criteria for eutrophication, yet no designation has been made. The contribution of agriculture nutrients appears never to have been assessed. It is thus questionable whether the UK has yet taken all the necessary steps to identify sensitive areas or NVZs in this area.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 86 6 OUTER THAMES ESTUARY

This area is influenced not only the Thames, with its large urban and agricultural catchment, but the Essex sites running along the north bank to Suffolk including, from west to east, Benfleet and Southend Marshes, the Roach, Crouch, Blackwater and Colne1 estuaries, and ending at Hamford Water (see Maps L). The Kent bank includes the estuary and marshes of the Thames (in a strict sense), The Swale, the Medway estuary and marshes, ending at the Isle of Thanet.

The geology of the area is primarily permeable chalk and clay.

6.1 OFFSHORE NUTRIENTS AND PHYTOPLANKTON

The data published on the Thames for example in the UK’s sub-regional North Sea Quality Status Reportxcvi, has historically been poor compared to other sites in the UK Published data is often old, interpolated from sparse data, and absent from shallower water.

6.1.1 Chemical profile

The situation has improved with the publication of the Sea Vigil-based research in 1995, nominally on the Lincolnshire Coast, which includes a significant number of transects extended down the east coast from to the Thames estuaryxcvii. The results from these are summarised in Table. Winter DAIN and DAIP were vastly in excess of the levels given in the UK definition of hypernutrification. The nitrogen:phosphorus ratio in winter (January) varied from 18:1 to 33:1, suggesting that – were this underlying ratio to be maintained during the spring bloom and beyond – that phosphate was likely to become limiting first. But in addition to the normal cautions about interpreting such data, phytoplankton were already present in January, and this may significantly affect the ratio.

The nitrogen:silicon January ratio varied from 2:1 to 3.1:1. For diatoms, silica is used to form the outer shell, and is required in far greater amounts than nitrogen, cf. 1:15xcviii This suggests that silicon would be the most likely nutrient to limit diatom growth, which would be normal. Unfortunately data on nutrients for March, when the spring diatom bloom may be expected, was not published in the report. In May plant growth was considerable (see below), and silicon was depleted but still present. Silica is much less important for most other phytoplankton.

It is notable that the July water temperature – an approximate indicator of residence time in shallow coastal waters – ranged from 20°C off Harwich to

1 Note that the Colne is dealt with, out of sequence, in the section on the Essex/Suffolk estuaries because of the large amount of comparative work between it and the other three sites.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 87 22°C in the mid-estuary point, universally higher than any other point of the transect stretching north to the Humber. This suggests that the water in the Thames ‘embayment’ is not rapidly flushed to the southern North Sea.

Table 6.1 1995 nutrients, salinity, turbidity and chlorophyll in the outer Thames estuary

Date NH4 TON PO4 SiO2 O2 salinity turbid. plant N:P N:Si µM µM µM µM % ‰ % trans pigs.

Jan. 0.36– 21.4– 1.29– 10–29 94.5– 31–34.5 20–90 6–12.5 18–33 2–3.5 3.2 71.4 4.03 96.2

March????89.5–32.5– 75–97 7.5–33 - - 94 33.7

May 0.36– 0– 0– 0– 97– 33–33.7 91.5– 10–190 - - 7.1 21.4 0.32 0.33 140 99.5

July 0–7.1 0.36– 0.48– 0– 92– 33.2– 84–97 12–48 7–22 2–16 25 2,90 4.16 130 34.4

Sept. 0.5–5 7.14– 0.97– 5.83– 94–96 33.5– 35–95 4–10.5 - - 17.9 1.93 10 34.9

Note:Continuous sampling from Sea Vigil, taken from 1 metre depth. The data extracted here was from Harwich in the north to a mid-estuary point approximately between Shoeburyness and Sheerness except in September, when it continued along the south side of the estuary to Margate. Data was read off from small-scale graphs, so should be treated as approximate. Oxygen is percentage saturation, salinity is parts per thousand, turbidity is percentage transmission, ‘plant pigs.’ are uncalibrated fluorescence units of solvent-extracted plant pigments, predominantly chlorophyll and phaeophytin, and represent an approximate index of plant abundance. N:P and N:Si are atomic ratios, converted from the mass ratios given in the source. These are for individual samples and cannot be calculated for the nutrient ranges given here because e.g. a minimum N and minimum P value may come from two different sites. Source: Anon. (1997). Sea Vigil Water Quality Monitoring. The Lincolnshire Coast 1995. Environment Agency, Anglian Region. Peterborough.

Overall the important point is that although N, P and Si values were occasion close to zero at a few sites, during most of the year, for most of the Thames outer estuary, all three nutrients were still detectable.

6.1.2 Biological effects

The units used to measure phytoplankton abundance (fluorescence) are arbitrary and are not a direct measure of chlorophyll-a. It is therefore not possible to compare these measurements directly with the UK definition of eutrophication.

However it is possible to make relative comparisons with the remainder of the transects extending to the mouth of the Humber. In January the phytoplankton pigments in the outer Thames estuary was equal to that along the East Anglian coast, although with less variation about the mean. It was higher than the levels recorded further north. In March the Thames pigments

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 88 were the highest recorded by a considerable margin, the levels then falling rapidly between Harwich and the Ore/Alde. In May the peak level recorded anywhere on the transect was again in the Thames estuary, although typically the pigment levels were lower than those between the Norfolk and the Wash. But in July the general levels in the Thames were once more the highest along the transect. By September these had fallen such that the levels from the Thames to Great Yarmouth were lower than those from Yarmouth to the Wash, but similar to those from the Wash to the Humber.

Although unquantified it is indisputable that these include major blooms. In May the extremely high dissolved oxygen levels (peaking at 140% of saturation) were exactly correlated with the peak in plant pigments, and the maximum turbidity of 91% transmission. It is possible that this was a Phaeocystis bloom, as these certainly occur in the area. The same correlation between peak plant pigments and peak oxygen supersaturation was true in July, although light transmission remained high. However in March there was no supersaturation in the Thames, although oxygen levels were positively correlated with plant pigments in the southern part of the transect. In September levels were unremarkable for all three factors.

Winter turbidity (January and March), which was due to sediments less influenced by the complicating factor of phytoplankton, was lower in the Thames than the Lincolnshire coast (presumably affected by Humber sediments) and the eastern East Anglian coast. It was roughly equivalent to the outer Wash and north East Anglian coast.

6.1.3 Designation under the Directives

On the basis of these measurements it would appear that the open water of the outer Thames is likely to be eutrophic, using the UK’s definition. While the results are only for one year it is unlikely that inter-annual variation would reduce nutrient levels below their hypernutrific status. Nutrients (in either inorganic or transformed organic form) will also subsequently be transported towards the Continental Coastal Zone.

Nutrient budgets have not been encountered for the Thames. However given the nature of the large catchment it can be assumed that both urban and agricultural inputs are important. It is likely that the outer Thames, at least, would qualify as both a Sensitive Area and a Nitrate Vulnerable Zone. However it appears not to have been considered as a candidate for either.

6.2 THE COASTAL MARGIN

The margin of the outer Thames estuary is lined with sites of international and national conservation importance. Starting at the northernmost point, Hamford Water is a designated SPA and Ramsar site, and part of it is a National Nature Reserve. It is a large shallow estuarine embayment, with extensive tidal creeks and islands, intertidal mud- and sandflats and saltmarshes. The saltmarsh includes several plant species uncommon in the

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 89 UK, while the mud-flats include small-cord grass, narrow-leafed and dwarf eel-grass.

It supports internationally important numbers of wintering dark-bellied brent geese, black-tailed godwit and redshank, and nationally important numbers of wintering shelduck, teal, avocet and grey plover, as well as breeding little tern.

The Mid-Essex Coast includes the Blackwater and Colne estuaries and Dengie saltmarshes, Foulness and Maplin Sands, the River Crouch Marshes and Sandbeach Meadows. It is a candidate SPA and Ramsar site, and was proposed as an Important Marine Area by English Nature in 1993. Foulness and Maplin Sands make up the largest continuous sand-silt flats in the UK. Throughout the area the foreshore supports algae such as Enteromorpha as well as eel-grasses. Foulness and Maplin support “one of the largest” continuous areas of dwarf eel-grass in Europe. The weed and eel-grass provide an important food source fro the dark-bellied brent geese. There are also extensive areas of salt-marsh.

Over five years between 1985–86 and 1989–90, the average peak number of over-wintering birds was 144,000, comprising 37,400 waterfowl and 107,000 waders, making it a site of international importance.

Benfleet and Southend Marshes, again a candidate SPA and Ramsar site, is another extensive area of saltmarshes, mudflats and associated hinterland supporting internationally important numbers of wintering dark-bellied brent geese, grey plover and knot and nationally important numbers of wintering ringed plovers and dunlin. Peak numbers of wintering birds between 1985–90 averaged 22,850 waders and 7,600 wildfowl. The mudflats include eel-grass and “dense patches of Enteromorpha”.

The Thames Estuary and Marshes lie further upstream, on both banks. It includes saltmarshes and intertidal mudflats. Freshwater dikes are dominated by reeds and bur-reeds, with sea club-rush soft hornwort and fennel pondweed in the brackish dikes, with an invertebrate fauna including water beetles and dragonflies all possibly vulnerable to eutrophication. It is a candidate SPA and Ramsar site. It supports internationally important numbers of wintering oystercatcher, ringed plover, knot, dunlin, bar tailed godwit, curlew, redshank and turnstone, with a late 1980s average winter peak of 58,900 birds.

The Medway Estuary and Marshes in Kent has saltmarsh and extensive mudflats, rich in invertebrates which “also support extensive beds of Enteromorpha and some eel-grass”. There are internationally important over- wintering numbers of dark-bellied brent geese, shelduck, pintail, ringed plover, grey plover, dunlin, redshank and turnstone.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 90 Finally The North Thanet Coast, on the north-east corner of Kent consists of shingle beach, and low cliffs of London Clay and Thanet Sandstone backing a muddy shore. It is a candidate SPA and Ramsar site.

6.2.1 Chemical profile

Other than for the Colne estuary, the only information seen for the various embayments, estuaries and creeks is for the Blackwater estuary, for which the Environment Agency provided nutrients data. These appear very high1. In the vicinity of the inner estuary samples from Beeleigh Long Weir taken in May 1997 ranged between 551–3,408 µM ammonia N, 2,080–12,300 µM TON, 8,980– 13,190 µM Si and 3,310–5,990 µM P; that from Fullbridge ranged between 122– 3,276 µM ammonia N, 935–11,800 µM TON, 849–12,700 µM Si and 291–5,650 µM P. At the mid point of the estuary, off Osea Pier, between 1993–1997 values ranged between 13.6–108 µM ammonia N, 51–1,980 µM TON, 42.8– 1,840 µM Si and 33–163 µM P. With the exception of phosphorus, the lower values were in the summer months, the higher values in the winter. In the outer estuary, south east of West Mersea, values ranged between 4.88–110 µM ammonia N, 39–1,020 µM TON, 21–1,150 µM Si and 6.11–63.8 µM P, with the highest values in winter.

If the units are correct (see footnote), these are the highest concentrations encountered in this study. The only others that would even approach this level are in the Wash.

6.2.2 Biological effects

Largely uninvestigated. This is surprising given the high nutrient levels and the references to extensive growth of Enteromorpha. For example it is reported in the literature that “English Nature consider Enteromorpha to be a problem in the Blackwater”§. Given evidence from elsewhere in the UK and northern Europe one would have expected an evaluation of any interaction between intertidal Enteromorpha and intertidal eel-grasses, and of any diminution in the sub-tidal depth to which the eel-grasses grow. There may also be concerns regarding species composition changes in the saltmarsh resulting from eutrophication.

It is possible that those responsible for bird conservation might see Enteromorpha as an asset providing valuable grazing for herbivorous birds such as brent geese. But herbivorous birds can feed on either Enteromorpha or eel-grass, so are unlikely to be threatened by action on eutrophication. But carnivorous birds, such as waders, can be adversely effected by algal weed mats. Subtidal eel-grass beds also have an associated community including pipefish, wrass, crustaceans and the cephalopod Sepiola. Eel-grasses are under

1 identified as µ/l [sic] ammonia, TON, silica and phosphorus. The units are assumed in the calculations above to be µM per litre, the normal practice. If the original values were µg, the ammonia values given here would have to be divided by 17 (18 if the units were actually ammonium), TON values divided by 14, silicate by 60 and phosphorus by 31. Even with this adjustment the levels would still be high and symptomatic of hypernutrification.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 91 pressure, Enteromorpha is not, and conservation preference should be given to the former.

The only (scant) data seen on chlorophyll levels is also for the Blackwater. That for Beeleigh Long Weir ranged over 9–63 µg l-1; that for Fullbridge between <1–116 µg l-1 (peak value late November); those off Osea Pier were <1–108 µg l-1 while those south-east of West Mersea ranged from <1 to 14.1 µg l-1. Even if one discounts the values recorded in the vicinity of the inner estuary as of uncertain origin, those for the outer estuary are still indicative of eutrophic conditions. Turbidity values were not included in the data provided by the Environment Agency.

6.3 DESIGNATION UNDER THE DIRECTIVES

With regard to the Mid Essex coast Important Bird Areas referred to sewage as a conservation issue, while the WS Atkins report noted that there “is a risk of eutrophication which might indirectly affect the intertidal communities and the bird populations they support”. The WS Atkins report referred to Thanet as a rocky “algal based system” which “may be expected to be particularly sensitive” to nutrients, although this may be intended to apply most to the areas outside the outer Thames as defined here. Other than this no assessments have been seen.

It is likely that both agriculture and sewage contribute significantly to the nutrient burden in the inshore waters of the outer Thames. Five HNDAs were deemed to occur, in the area defined here as the outer Thames estuary, in the first (1994) round of Designationsxcix. From north to south these were Felixstow/Shotley (HNDA code 42), Clacton (41) and Jaywick (40) on the north bank, and Whitstable/Swalecliff (39) and Margate/Broadstairs (38) on the Kent coast. In the second (1998) round, HNDA status was withdrawn from Swalecliff (in part), Jaywick, Clacton and Shotley. Secondary treatment will now be required for the remainder of the Swalecliff HNDA.

Overall, there does not appear to have been the type of evaluation required by the Directives. On the evidence seen it can be anticipated that designation will be required under both Directives.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 92 7 NATIONWIDE REVIEW

Given the amount of time available for the study, and the difficult in extracting information from the UK authorities, it has not been possible to complete a full review of all the estuarine and coastal sites around the UK to the level of detail of the case-studies ranging from the Ythan to the Solent. This section nevertheless aims to provide a review of the coastal and estuarine sites using the available information.

7.1 EASTERN SCOTLAND

The geology of the river catchments of eastern Scotland typically comprises of mountainous terrain in the upper reaches, with rough pasture making up the bulk of agricultural land, and glacial till in the lower catchment, which often allows intensive arable agriculture. Major settlements are Inverness (at the cusp of the Beauly and Inverness Firths, at the head of the Moray Firth), Aberdeen (between the Don and the Dee estuaries) Dundee and Perth (on the Tay estuary), and Stirling and Edinburgh (on the Forth). These are indicated on Map M.

Circulation

The coastal circulation is predominantly one of Atlantic water entering the North Sea between the mainland, Orkney and Shetland, and passing south down the coast.

Biodiversity

There are many sites of importance to marine birds, which serve as indicators to general marine biodiversity. Starting in the north and working down the east coast, the Caithness Cliffs are a candidate SPA site with internationally important numbers of breeding kittiwake, guillemot and razorbill, and nationally (UK) important numbers of fulmar, cormorant, shag, herring gull, great black-backed gull and black guillemot.

The Moray Basin, Firths and Bays includes a number of National Nature Reserves (NNR), designated and candidate SPAs and Ramsar sites, which contain a wide range of marine habitats. It supports internationally important numbers of wintering whooper swan, greylag goose, wigeon, red-breasted merganser, goosander, oystercatcher, ringed plover, purple sandpiper, bar tailed godwit, curlew, redshank and turnstone and many other populations of national importance. It is also important for marine mammals, including bottle-nosed dolphin and porpoise, and as a nursery area for many fish. Ness to Collieston, on the east coast of Buchan, is a candidate SPA which holds nationally important numbers of breeding shag, herring gull, kittiwake and guillemot.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 93 The Ythan estuary is a NNR and a candidate SPA with internationally important numbers of breeding Sandwich tern and wintering pink-foot geese, and nationally important numbers of breeding eider, common tern, little tern, as well as wintering eider and redshank

The coastal cliffs of Fowlsheugh, south of Aberdeen, is also a candidate SPA which supports internationally important numbers of kittiwake and guillemot and nationally important numbers of razorbill.

Montrose Basin is also a candidate SPA and Ramsar site. It is described in more detail in a later section.

The Firth of Tay has extensive intertidal mudflats, saltmarshes and reedbeds. It is important for wintering and passage waterfowl and breeding reedbed specialists. The Tay estuary has been described as “one of the least contaminated in Europe”c, and as such forms an important reference site. The Eden estuary is in part a NNR and a candidate SPA and Ramsar site. It is also described in more detail in a later section.

Finally, the Firth of Forth includes rocky islands which are in part a NNR, and also designated and candidate SPAs. They provide breeding sites for internationally important number of gannets, shag and lesser black-backed gull and nationally important numbers of other species. The Firth also include large areas of intertidal flats and inshore waters of international importance for wintering pink-foot geese, knot, bar-tailed godwit, redshank and turnstone, and nationally important numbers of other species. It has become apparent that the waters off the Firth, such as Wee Bankie and Marr bank, are, by virtue of the sandeel populations, important feeding sites for marine mammals and seabirds.

7.1.2 Chemical Profile

The nutrient status and behaviour of the major east coast estuaries has now been extensively evaluated, both for individual sites and in comparative assessments. The quality of the work is excellent. Entry to all but the most recent literature can be had via Balls (1994), which also provides the basis for the assessment here.

Dornoch Firth, Cromarty Firth and Beauly/Inverness Firth, all at the head of the Moray Firth, have low levels of nutrients (Table 7.1). Although not clearly apparent from the table, the plots of nutrients against salinity for Cromarty Firth show a underlying increasing trend with salinity which may be the result of sewage discharges into the Cromarty Firth HNDA. While not pristine, these sites are probably as close to natural nutrient levels of any major water bodies in the UK.

Of the other estuaries, the Ythan and Tweed, and in particular the Don and the Forth show elevated levels of ammonia comparable with Southampton Water, many of the polluted south-west English estuaries with the exception

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 94 of the Plym and Welsh estuaries such as the Rhymney. They are however significantly lower than the extreme values recorded in the Clyde estuary.

Table 7.1 Nutrients, percent oxygen saturation and suspended solids in the major east coast Scottish estuaries

NH4 TON PO4 Si O2 O2 suspended µM µM µM µM % solids mg l-1 Dornoch Firth 0–10‰ 0–4.0 1–7 0.5–0.22 3–18 95–110 2–48 10–20‰ 0–3.5 0–9 0.1–0.37 3.5–16 95–110 1–25 20–34‰ 0–3.4 1–8 0.5–0.35 1–9.5 95–117 2.5–15

Cromarty Firth 0–10‰ 0.8–3.8 4–8 0.02–0.30 3.5–19 95–105 0–8 10–20‰ 0–3.0 2–11 0.2–0.45 7–18 95–105 2–9 20–34‰ 0–2.5 0.5–10 0.15–0.60 1–10 90–110 2–15

Beauly/Inverness Firth 0–10‰ 0.8–3.8 3–8 0.8–0.57 2–25 95–100 3–13 10–20‰ 0.2–2.5 3–9 0.30–0.55 9–18 100 8–13 20–34‰ 0–2.7 0.5–8 0.25–0.68 3–14 97–110 3–33

Ythan 0–10‰ 1–18 375–650 0.8–5.5 140–260 100–130 0–250 10–20‰ 2–7 175–350 1,2–3.8 85–155 107–128 15–575 20–34‰ 0–6 0–180 0.1–1.5 0–85 95–117 0–50

Don 0–10‰ 7–27 140–360 1.9–7.0 100–230 92–122 0–8 10–20‰ 3–8 90–210 0.75–3.8 40–120 95–120 2.5–65 20–34‰ 0–5 5–60 0.2–1.8 0–70 70–115 8–62

Dee 0–10‰ 1–9 30–95 0.12–0.40 60–135 100–120 0–62 10–20‰* 5–6 20–70 0.45–0.50 30–75 95–115 40–60 20–34‰ 1–6 0–60 0.20–0.60 0–75 85–110 5–67

Tay 0–10‰ 0–5 20–75 0.05–1.20 20–67 97–105 5–75 10–20‰ 0.5–4.2 18–55 0.40–1.05 20–45 95–102 5–50 20–34‰ 1–3.8 0–35 0.40–1.10 0–35 90–105 2.5–25

Forth 0–10‰ 0–29 25–90 0.4–2.0 16–85 17.5–100 5–230 10–20‰ 8–24 30–75 0.6–1.25 15–60 25–100 20–50 20–34‰ 2.5–18 5–40 0.7–1.4 2.5–37 45–105 0–50

Tweed 0–10‰ 0.5–10 50–250 0.5–2.5 12.5–95 95–125 2–20 10–20‰ 1–4 20–125 0.5–2.0 10–55 95–110 3–15 20–34‰ 0–2.5 0–90 0.1–1.0 1–40 95–120 0–28 Notes: Values grouped to show the range in the upper, mid and lower salinity reaches. Data taken from plots of transects down the salinity gradient taken in April, July, September 1991 and February 1992. * Two samples only Source: Balls (1994).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 95 TON values appear to show a correlation with agricultural activity, although this may also be derived from sewage effluent to a varying degree. The high TON value of the Ythan has already been discussed in the dedicated section. Of the wide range of UK sites reviewed in this report, only some of the Suffolk estuaries and the Essex Colne (and some of the Wash estuaries reviewed in the Phase II report) come close to the TON levels found in the Ythan confirms the highly polluted nature of this estuary. The Don and the Tweed also show markedly elevated levels, while estuaries whose catchments have relatively less intense agricultural activity, such as the Dee, the Tay (and the Spey, marginally lower TON than the Deeci) are markedly lower. The levels for the Don are greater than those for the Solent embayments, and of the same order as those of the Wear, Tees and Humber (Table 7.3). Note that the value given for the Tweed in Table corresponds well with the measurements here.

Phosphorus levels in the Ythan and Don in particular, but also the Forth and the Tweed are elevated. In the case of the Ythan and Don these are greater than the Suffolk estuaries, (but less than the Essex Colne, which is a notable sewage affected site), greater than upper Southampton Water, most sites in the Solent embayments, the Humber, most Welsh estuaries and most south- west English sites. However the Ely estuary (Cardiff), the Axe, and the Exe appear to have higher concentrations, and the Clyde estuary appears to be significantly greater. In the Ythan section it was commented that phosphate had increased in the Ythan, and that this could be sewage derived. This data confirms that the Ythan does have high phosphate concentrations compared to other Scottish estuaries. The Ellon STW may be responsible but is should be remembered that the Ythan catchment also holds the largest pig population in Scotland.

Oxygen levels can indicate major blooms resulting from high nutrient concentrations and suitable conditions. The Ythan again shows very high oxygen saturation, suggesting that blooms may be significant, a dimension that has not so far been emphasised in the debate over the Ythan’s condition. The Don, and the Tweed also have peak saturations, of 120% or greater. On the other hand the Forth shows a major oxygen deficit, down to only 17.5% of saturation, indicative of high oxygen demand. This is likely to be due to the bacterial breakdown of particulate organic nitrogencii, of which sewage is presumably a significant component.

7.1.3 The Eden and Montrose Basin

In addition to these major estuaries Scottish Natural Heritage has expressed concerns about two other east coast sites; the Eden estuary and Montrose Basinciii.

The Eden estuary enters St Andrews Bay, between the Firth of Tay and the Firth of Forth. Although small compared to other Scottish east coast estuaries, it contains a wide variety of habitatsciv and includes all three British species of eel-grass. It is a candidate SPA and Ramsar site, a local nature reserve, and in

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 96 part a National Nature Reserve. Its principle ornithological interest is for passage and wintering waterfowl, especially eider (28% of UK population) red-breasted merganser and bar-tailed godwit. The catchment of the Eden is heavily agricultural and is the site of the only NVZ in Scotland, at Balmalcolm in Fife (designated on the basis of nitrate levels approaching the 50 mg l-1 limit in a public potable water borehole). Considerable areas of algal weed-mats were present in the estuary when surveyed in 1993–94. TON levels at the freshwater limit of the estuary, averaged between 1987–1991, at 612 µM, were closely equivalent to that of the Ythancv.

Montrose Basin lies between the Tay and Aberdeen. It is roughly square, some 3 km across, and with a restricted channel to the sea. It forms the estuary of the South Esk. It is an candidate SPA and candidate Ramsar site, an SSSI and a local nature reserve. The extensive mud flats support annelid worms, the snail Hydrobia and Corophium ‘shrimps’ and mussel beds, all of which are important food for birds. The green algae, and the three species of eel-grass, are grazed by wildfowl. The basin holds internationally important numbers of wintering pink-foot geese, knot and redshank, and nationally important numbers of wintering wigeon, eider and oystercatcher. Between 1981 and 1991 there was a large increase in algal weed mats (principally Enteromorpha), both in its distribution across the basin and in the biomass at individual sites, showing a 30% increase in percentage cover. The weed in places forms dense impenetrable mats, and the biomass at the worst affected sites appears comparable to the Ythan. Capitellid worms – indicators of organic enrichment – have increased in the sediments. The South Esk at the freshwater limit has an elevated nitrogen level with a winter mean of 168 µM, and it is also believed that there may be other sources of nutrientsciv,cv. Montrose Basin has not been put forward by SEPA as either a candidate site for Sensitive Area status or as Nitrate Vulnerable Zone.

7.1.4 Designation under the Directives

Fourteen LSAs were defined in the first round of Designations. These are, from north to south, the HNDAs of Wick Bay, Cromarty Firth, Burghead/Lossimouth, Buckie, Banff, Fraserburgh, , Kincardine Coast (including Aberdeen) Angus north and south, the Firth of Tay, (classified on the map as an estuary), the Forth estuary, the Firth of Forth and the Eyemouth Coast. The second revised round had not been publicly announced at the time of writing. But it is believed that HNDA (and thus LSA) status will be withdrawn from all sites with the exception of Wick Bay, the Cromarty Firth and the Eyemouth coast.

On the basis of the information here, leaving aside the Ythan, the designation of the Firth of Forth as a highly dispersing environment was very questionable. It can also be asked whether the continuation of sewage discharges into naturally oligotrophic sites such as Cromarty is appropriate. The logic of retaining HNDA status here, while de-designating more open sites, including those in the Moray Firth, appears questionable. The issue of oligotrophic sites is elaborated in the section on Welsh estuaries.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 97 No estuarine or coastal sites other than the Ythan were put forward by the Scottish Environmental Protection Agency to the Scottish Office as either eutrophic Sensitive Areas or Nutrient Vulnerable Zones.

7.2 WESTERN & NORTH SCOTLAND

Much of the west coast of Scotland is of an upland, mountainous, nature and hill farming, predominately of sheep but also of cattle, predominates. The most significant exception is the western end of the Midland Valley, in the vicinity of Glasgow, and the adjacent coastal areas, where intensive lowland farming is possible on a larger scale.

The principle west coast nutrient source ((see Maps N) is the Firth of Clyde, classified as a small marginal sea, which receives the effluents of approximately half of Scotland’s population and industrycvi. Much of this enters the Firth via the Clyde Estuary.

Circulation

The long term movement of water off the Scottish west coast is south down the Firth of Clyde and then north through the islands (with local variations) before passing east along the north coast and finally entering the North Sea via the gaps between the mainland, Orkney and Shetland. Superimposed on this long term trend, currents can reverse, such that nutrients will on occasion enter the Irish Sea from the Clyde.

Biodiversity

There are a number of principle biodiversity sites, as indicated by concentrations of bird populations dependent on marine habitats. In the south the inner Clyde estuary is a candidate SPA and Ramsar site, with extensive intertidal mudflats that support internationally important numbers of over- wintering redshank and nationally important numbers of wintering cormorant, scaup, eider, goldeneye, red-breasted merganser, oystercatcher and curlew. The cliffs of Colonsay (a candidate SPA and Ramsar site) support nationally important numbers of breeding kittiwakes, guillemot, and razorbills. Amongst several Islay designated SPA and Ramsar sites is the sea loch of Loch Gruinart, an RSPB reserve, with an intertidal habitat which supports internationally important numbers of over-wintering Greenland barnacle geese (ca. 95% of the Greenland population pass through the site).

The Shiant Isles, in the Minch, midway between the mainland and the Western Hebrides, is a candidate SPA and Ramsar site which supports internationally important numbers of shag, razorbill and puffin, and nationally important numbers of fulmar and guillemot. Internationally important numbers of over- wintering and passage Greenland barnacle geese also occur. There are also a wide variety of SPA and Ramsar sites in the Hebrides, although these are very unlikely to be impacted by anthropogenic nutrients. Priest Island is the outermost of the Summer Isles, 6 km off Ullapool. It is a candidate SPA and

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 98 Ramsar site, supporting one of the largest storm petrel colonies in Britain, of ca. 10,000 pairs. Further north the island of Handa is a designated SPA and Ramsar site which supports internationally important populations of breeding guillemot and razorbill and nationally important numbers of kittiwake and great skua.

Cape Wrath, at the north-west extremity of the Scottish mainland is a candidate SPA sea cliff site, with nationally important numbers of kittiwake, guillemot, razorbill and puffin. At the eastern end of the north coast, the Pentland Firth Islands are a candidate SPA site supporting fluctuating numbers of arctic terns, Sandwich terns, great black-backed gulls and guillemot. Hoy, part of the Orkneys, is a candidate SPA which supports internationally important numbers of breeding arctic skua, great skua and great black-backed gulls and nationally important numbers of breeding fulmar.

The intertidal and subtidal also provide a wide range of habitats ranging from sheltered sea-lochs to exposed headlands. They are important for otters, a wide variety of dolphins and whales, and basking shark. Commercial fisheries are important, although important elements, such as local population of herring, have been much depleted through over-fishing.

7.2.2 Chemical Profile

For most parts of the west coast the principle concern relating to nutrients is that of aquaculture in sheltered locations. While important, this falls outside the scope of the two Directives.

The principle source of nutrients from waste water and agriculture is the Clyde estuary. This, if defined by the 32‰ isohaline at its outer limit, extends from Glasgow some 30 km in a westerly direction to Greenock, beyond which it becomes the Firth of Clyde. However the CSTT report is in error in stating that Scottish estuaries are defined by salinity levels, at least for the Clyde. The boundaries here are more qualitatively defined by SEPA1, using local knowledge. The outer limit of the Clyde estuary lies between the headlands of Barons Point and Cloch Point. The upper limit is set at the tidal weir at Glasgow Green, although there are tidal effects well above this to Dalmarnock (Eastern Glasgow). Included in the nominal Clyde Estuary is the sea loch, the Gare Loch, which is not strictly speaking an estuary though it is affected by estuarine influences due to its position close to the estuary mouth. Definitions of inner and outer estuary are not precise but the inner (or upper) Clyde would refer to the canalised part of the estuary above the Erskine Bridge and the outer (or lower) Clyde would refer to the channel and the adjacent intertidal areas west of the Erskine Bridge. Downstream of the estuary the Inner Firth of Clyde extends down to the Cumbrae Islands and the Outer Firth of Clyde beyond here down to a line drawn between the southern tip of Kintyre and Ballantrae.

1 P. Holmes, pers. comm.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 99 Table 7.2 Clyde Estuary nutrient concentrations at upper and lower salinity limits

NH3+NH4 NO3 NO2 PO4 Si µM µM µM µM µM

Upper estuary, 0‰ salinity 37–152 52–74 1.9–9.9 4.8–17.5 49–84

Lower estuary, 30‰ salinity 5 20 0.8 2 18

Notes: Upper row show the range of values obtained by extrapolating measured values to 0‰ by regression analysis on five sampling occasions (August 89, November 89, March 90, July 90 and March 91). There was no obvious seasonal trend. Lower estuary values taken from plots of silicon versus the other nutrients. Source: Muller et al. (1994)

A summary of nutrient levels in the Clyde estuary between 1989–91 is shown in Table 7.2. These represent the minimum and maximum values. Ammonia concentrations are very high, apparently far greater than other sites with enhanced levels on the east coast Scottish estuaries, the upper Southampton Water the Solent embayments, estuaries in south west England, Wales, or north west England. Phosphorus concentrations are also very high, equivalent to heavily sewage polluted estuaries such as the Colne, the Wear and the more heavily polluted south-west English estuaries.

By contrast, nitrate concentrations are less elevated, for example in the lower range of concentrations of the north-east English estuaries. But they are nonetheless similar to those of the Solent embayments, upper Southampton Water and (using the 30‰ value for comparison) the coastal waters of Lincolnshire, East Anglia and the Outer Thames estuary. They are usually higher than those in the Solent, and are greater than south west England coastal waters.

7.2.3 Biological effects

The only information encountered relating to the biological effects dates from work carried out in relation to monitoring of the “sacrificial” sewage dumping ground in the Firth of Clyde, south of the isle of Butecvii. Chlorophyll levels reached a peak of 15 µg l-1 off the town of Irvine. This was attributed to nutrients from the sewage dumping. “The nutrient enrichment produces phytoplankton populations as represented by the chlorophyll concentration, 10 times the normal level for inshore waters, to the south east of the dumping ground.” Whether this really can be (totally) attributed to the dumping site, which is some distance removed, is open to debate. The area of maximum chlorophyll was some distance removed from the dump site and may also be influenced by coastal inputs, including the HNDA at Irvine.

7.2.4 Designation under the Directives

Ten LSAs were established on the west and north coast of Scotland in the first round of Designations. These are the Solway Firth, the Clyde Coast off Girvan, the Clyde coast off Irvine and Ayr, the Inner Firth of Clyde; Campbeltown; Oban

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 100 Bay, the Minch off Stornoway, Thurso Bay, Kirkwall, in Orkney, and Lerwick Harbour, in Shetland. It is understood that just one site, the Clyde coast off Irvine and Ayr, will be declassified.

On the basis of the Clyde data it would seem that the estuary, at least, would be classified as hypernutrific. It is at least arguable that the Clyde estuary should be classified as an eutrophic sensitive area, even if information the biological effects has generally not been gathered. The same may apply to the inner Firth – the sewage dumping ground in the Firth of Clyde was classified as a suitable ‘sacrificial site’ on the basis of its supposedly low natural dispersion, yet the inner Firth was then classified as an area of high natural dispersion. This is implausible.

The HNDA status of the Solway Firth can also be considered inappropriate given the status of the eastern Irish Sea embayment as a ‘backwater’ where water exchange takes longer than a year, and the now evident eutrophication in this part of the Irish Sea.

Finally the justification behind retaining the designation for enclosed sites, such as the Inner Firth of Clyde, Oban and the inner Solway Firth, when it has been judged necessary to declassify most of the coastal sites in the East of Scotland, has not been elaborated.

With regard to the Nitrates Directive it is considered unlikely that any northern sites, other than possibly on a very localised basis, would be candidates for NVZ status. To the south a case can be made for classification of the Clyde catchment as an NVZ, and possibly also the catchment on the east side of the Firth of Clyde. This might be affected by any future changes in sewage treatment. Similarly the Scottish catchment west of the Solway Firth may now require designation, given the status of the Irish Sea embayment.

7.3 NORTH EAST ENGLAND

The land-use of north east England between the Scottish border and the Humber is dominated by upland farming on the largely impervious rocks of the Cheviot Hills, the northern Pennines and the permeable sandstones of the North Yorkshire Moors, with a predominance of pasture, improved and unimproved (see Map O). There is however a wide coastal fringe of lower land used for mixed farming. In the south of the area there is the intensively arable land on the permeable chalk of Yorkshire Wolds and on Holderness beyond. The major urban areas stretches from Newcastle-upon-Tyne to Middlesborough on the Tees. 7.3.1 Lindisfarne

Lindisfarne and 20 km of adjacent coastline stretches south from near Berwick-upon-Tweed to Budle Bay, and includes extensive intertidal flats of Holy Island Sands and Budle Bay. Eel-grass is present and an important source of food for wintering wildfowl, including the majority of the

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 101 Spitsbergen population of Brent Geese – just 2,310 or 58% of the world population. The area also supports internationally important numbers of wintering greylag geese, wigeon, ringed plover, bar-tailed godwit and redshank, as well as nationally important numbers of 12 other speciesxliv. The WS. Atkins Report on the 27 ‘important areas’ listed Lindisfarne as one of three areas (along with Thanet and the Solent) where nitrate levels were over 4.84 µM N, and states that this ‘gives cause for concern’ but unfortunately no quantitative data is given on ammonia or phosphorus. The report comments on the ‘very sparse’ water quality data for the area.

A study of summer nutrient levels of north-east estuaries revealed significant TON levels for the Tweed, immediately up-current of Lindisfarne, of 80–200 µM in the inner estuary. This is comparable to the Wear, Tees and Humber, and higher than the Tyne. Phosphate levels, at 0.2–2 µM P, were however lower than all but the Humber, while silicate levels were typical. English Nature has expressed its concerns to NRA/EA about the proliferation of green algal weed, but apparently the source of nutrients – sewage or agriculture – has been disputed and no action takencviii. Spartina cord grass has invaded the intertidal zone and eel-grasses are decliningxliv. Any links with one or both are apparently unknown.

Offshore the 1993–96 national baseline spring chlorophyll-a survey indicated levels in the area below 5 µg l-1, although these are of “limited value” in establishing the extent of bloomsxcv.

Designation under the Directives

The UK has not designated any LSAs in the area. Lindisfarne was not put forward as a candidate SA or NVZ in the first round of designations. It is unknown whether it was a candidate in the second round; in any event no SA or NVZ status was declared. There is insufficient information to draw conclusions regarding the eutrophic status.

7.3.2 Lindisfarne to the Tees

The north-east coast between Lindisfarne and the Tees includes two candidate SPA/Ramsar sites. Croquet Island, an important bird breeding island lies offshore of the Northumberland Coast site, which stretches from Alnmouth to North Tyneside. This has a variety of habitat types and internationally important numbers of wintering purple sandpiper and turnstone, and nationally important numbers of wintering ringed plover, golden plover and sanderling, and breeding little terns.

Table 7.3 Summer nutrient concentrations and ratios for north-east England estuaries

Site Year period TON PO4 SiO2 N:P N:Si µM µM µM

Tweed upper estuary 90,92-3 summer 80–200 0.2–2 20–40 40-400:1 2-5:1

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 102 mouth 0.15–15 0.2–0.7 1.5–2 0.75-21:1 0.07-7:1

Tyne upper estuary 90,92-3 summer 50–90 2–6 40 15-25:1 1.2-2.2:1 mouth 0.4–30 0.15–3 0.25–6 2.6-15:1 2-5:1

Wear upper estuary 90,92-3 summer 75–300 15–20 10–80 5-20:1 3.7-15:1 mouth 1–50 0.7–8 1–8 0.2-9:1 1-6.2:1

Tees upper estuary 90,92-3 summer 1.5–300* 5–8 7–30 12.5-25:1 1.2-2.2:1 mouth 8–100 0.4–0.9 1–20 2.7-15:1 1.6-5:1

Humber upper estuary 90,92-3 summer 100–300 0.04–3 10–60 100-2500:1 1-6:1 mouth 60–150 0.8–1 1–30 75-150:1 5-60:1

Notes: Values taken from log-scale plots, so should be treated as approximate. Samples taken from 0.5–1 m depth at low water. Ratios are calculated from original data pairs, not from the ranges shown here. * peak value in mid-estuary, 1236 µM TON. Source: Sheahan et al.cxii

According to the data collected by Sheahan et al.cxii (Table 7.3) summer nutrient levels of the inner Tyne estuary between 1990–93 were hypernutrific, ranging between 50–90 µM TON, 2–6 µM P and 40 µM Si. At the estuary mouth (more indicative of coastal water levels) the equivalent values were 0.4–30 µM N, 0.15–3 µM P and 0.25–6 µM Si. This is below the UK hypernutrific guideline, but does not include ammonium and these are (possibly reduced) summer levels. The N:P ratio at the estuary mouth ranged between 0.75–21:1, that for N:Si was 0.07–7:1. One of two chlorophyll-a 1993– 96 spring spot sample in the vicinity of the Tyne was above 5 µg/l, at 5–7.5 µg/lxcv.

The Wear estuary also discharges into this zone. In summer 1990–93 the upper Wear estuary was also hypernutrificcxii, at 73–300 µM TON, phosphorus at 15– 20 µM, and silicon at 10–80 µM. Equivalent values at the mouth ranged around the definitive level of hypernutrification, at 1–50 µM TON, 0.7–8 µM P and 1–8 µM Si. Ammonia would probably take it consistently over the limit. The adjacent coastal spring chlorophyll-a spot samples were below 5 µg/l. The N:P ratio at the mouth ranged between 0.2–9, while that for N:Si was 1– 6.2:1.

It has been suggested that changes in the benthic communities at 100 m dept off the Northumberland coast, and in the eastern Skagerrak may be due to changes in organic inputs (which might result either from eutrophication or from sewage inputs)cix, cx. The link is best regarded as tentative. It is however interesting to make some further comparisons between the Skagerrak and Kattegat, which are regarded as eutrophic, and these UK sites. There are similarities. The nitrogen levels at the mouths of the Tyne and Wear are comparable with those in the Skagerrak and Kattegat – for example in April 1989 taken at 20–30 metres depth, which ranged from 5 to over 15 µM.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 103 The toxic Chrysochromulina polylepis bloom in 1988 along the Kattegat, Skagerrak and further north along the Norwegian coast was probably the most economically disruptive bloom to date in northern Europe, due to its impact on aquaculture. It was believed to have been caused, in part, by the ‘high’ nitrate content (maximum concentration approached 20 µM, similar to the mouth of the Tyne) a relatively low phosphate concentration, (N:P ratios were 20–30:1), and virtually depleted of silicate. Nitrogen and phosphorus concentrations on the north east coast can be similar, but silicate was not depleted, even though these are summer measurements. The most significant difference is that while these nutrient concentrations are typical of wide parts of the Skagerrak and Kattegat, in this part of UK they would be expected to fall rapidly away from the coast, as the offshore water here will be predominantly of Atlantic origin.

Designation under the Directives

Two sites north of the Tyne were deemed to be LSAs in the first round of designations, with three discharges – Cambois/Newbiggin (57) and Amble (58). Neither LSA was withdrawn in the second round, announced in July 1998. The entire coast between the Tyne and the Tees has been defined as an HNDA (56). The discharges at the time of the first round designations were Dawdon, Warren House, Dene Holme, Seaham, Hendon, Seaton Carew, Brus and Langbaurgh. According to the 1998 Second Round Designation Hendon, Seaton Carew and Langbaurgh all failed their comprehensive study, and will now require secondary treatment, except Hendon, which it is stated will have “partial removal of HNDA status only”.

The nutrient and chlorophyll levels suggest there may be a case to answer regarding eutrophication, but the evidence is insufficient to be conclusive. The relative contribution of agriculture, sewage and other anthropogenic sources are unknown.

7.3.3 Tees Estuary

The Tees estuary has been affected by industrial pollution and land-claim. Nevertheless the remnant intertidal mud – Seal Sands – is still important for its invertebrate life, and nationally important numbers of wintering shelduck, teal, shoveler, knot, sanderling, purple sandpiper, redshank and turnstonexliv. It has been proposed as a candidate SPA and Ramsar site, although not included as an IMA by English Nature.

Brown and red seaweeds decreased in the Tees estuary between 1929–33 and 1970–71, accompanied by an increase in green and blue-green algae which flourished in the sewage-polluted water. The Tyne and Wear estuaries showed similar patterns in the 1970s. But in the wake of a partial reduction of toxic pollution in the Tees since the 1970s, although brown and red seaweed have continued to decline, green algal mats have erupted on previously barren areascxi, – a case of the removal of one problem apparently revealing another.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 104 This receives support from a MAFF phytoplankton bioassay of the nutrient status of UK estuaries and the North Seacxii, which indicated that phytoplankton growth was on some occasions suppressed below that expected for the nutrient concentrations in the Tees (and also in the Tyne and Humber). The authors suggested that this “indicated the possible presence of phytotoxic material”. The same report gives nutrient levels for 1990, 1992 and 1993 in the inner, mid and outer estuaries. For the Tees the upper estuary TON ranged between 1.5–300 µM N (and to 1,236 µM at one mid-estuary site, one of the highest level encountered in the research for this report) but phosphate and silicate were more stable, between 5–8 µM and 7–30 µM respectively. These values indicate that the Tees is hypernutrific as defined by the UK, especially as these are summer levels, when nutrients might be expected to be at their lowest levels.

With regard to toxic inhibition it should also be noted that phytoplankton plant growth of a mesocosm community of six North Sea species was found to be significantly inhibited by triazine herbicide concentrations set at levels that occur in the inner German Bight in 1991–92cxiii, and that this may be a widespread phenomena relevant to this and other UK sites. The 1993–96 spring baseline survey indicated that the area off the Tees maintained elevated values of chlorophyll-a throughout the summer of 7.5–10 µg l-1xcv.

Designation under the Directives

Algal mats and offshore phytoplankton abundance are indicative of eutrophication in the Tees and its vicinity. The suppression of eutrophication by other forms of pollution may be an important factor, and there is a prospect that the successful application of hazardous substance controls may lead to a more widespread unmasking of eutrophication, given that the site is already hypernutrific. Even if not now eutrophic, both Directives require action where water bodies may become eutrophic if protective action is not taken.

No nutrient budget has been seen for the Tees, so it is not possible to state definitively which Directives apply: it is likely that both effluent covered by the UWWT Directive and agricultural sources will be important.

7.3.4 Tees to the Humber

There are two IMAs on this stretch of coastline. The Robin HoodÕs Bay IMA on the North Yorkshire Moors coast, stretches from Maw Wyke Hole to Beast Cliff. It is important for its extensive intertidal rocky shores with associated algae and rocky shore communities which are sensitive to . The 1994 WS Atkins report stated that “There are no water quality data available [and thus] no discussion about general concerns … can be made”.

Bempton Cliffs and Head is also a candidate SPA and a IMA. The cliffs support internationally important numbers of breeding kittiwake (85,400 in 1987) and nationally important numbers of guillemot (32,600), razorbills

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 105 (7700), puffins (7000) as well as fulmar, gannet, shag and herring gull. Many of these species exploit the naturally nutrient rich waters (the Flamborough Front) where Atlantic water flowing down from the north mixes with coastal waters. The WS Atkins report had no water quality data for the site. No information on biological effects has been seen from south of the Tees to the Humber, other than coastal chlorophyll-a spot samples for 1993–96. All of these were under 5 µg l-1.

Designation under the Directives

Between the Tees and the northern edge of the Robin Hood’s Bay IMA are two sites deemed to be HNDAs in the First round; Saltburn/Brotton (55) and Whitby (54). There are no HNDAs within the IMA. Between Robin Hood’s Bay and Cliffs are two further HNDAs, Scarborough (53) and Filey (52). No changes were made in the 1998 designation.

The chlorophyll-a spot samples suggest that widespread eutrophication is unlikely. However reliance on this data alone would appear to be insufficient to determine the status of these coastal waters with any confidence. As one passes south along this section of coast it becomes increasingly likely that nutrients will eventually be carried to North Sea offshore areas that suffer from eutrophication.

7.4 HUMBER TO THE THAMES

7.4.1 Lincolnshire Coast

The Lincolnshire coast has no actual or candidate SPAs or Ramsar sites between those of the Humber and the Wash. There are no embayments (see Maps P). The rivers flowing from the dip slope of the predominantly arable Lincolnshire Wolds are short. The most important river is the Great Eau, discharging at Saltfleet, in the northern sector. The coastline, and fringing intertidal flats, are exposed.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 106 Table 7.4 Lincolnshire 1995 nutrients, oxygen salinity, turbidity and chlorophyll.

Date NH4 TON PO4 SiO2 O2 salinity turbid. plant N:P N:Si µM µM µM µM % ‰ % trans pigs.

Jan. 0.36– 50–67.0 0.97– 12.5– 93.75– 30.75– 20–95 4–9 20–25 3.5–4 5.71 1.45 18.31 95 33.25

March ? ? ? ? 93–95 30.5–33 60–98 - - -

May 0–1.07 0–50 0–1.29 0–8.75 96–128 32.7–33.5 93–98 10–160 - -

July 0–3.57 0–28.6 0.32– 0–1.25 93–118 33.3–34 84–100 - 0.5–10 2–100 0.97

August* 1.43– 0–21.4 0.32– 0–2.50 90–122 33.6–34.6 90–97.5 5–55 1–7 - 5.0 1.29

Sept. 1.78– 3.57–25 0.64– 1.67– 90–94 33.5–34.4 90–95 3.5–5 - - 7.14 1.45 6.67

Notes: Continuous sampling from Sea Vigil, taken from 1 metre depth. The data extracted here extends from Donna Nook in the north to Gibraltar Point. Data was read off from small-scale graphs, so should be treated as approximate. Oxygen is percentage saturation, salinity is parts per thousand, turbidity is percentage transmission, ‘plant pigs.’ are uncalibrated fluorescence units of solvent extracted plant pigments, predominantly chlorophyll and phaeophytin, and represent an approximate index of plant abundance. N:P and N:Si are atomic ratios, converted from the mass ratios given in the source. These are for individual samples and cannot be calculated for the nutrient ranges given here because e.g. a minimum N and minimum P value will probably come from two different sites. *The August summary excludes data from an off-shore excursion. Source: Anon. (1997). Sea Vigil Water Quality Monitoring. The Lincolnshire Coast 1995. Environment Agency, Anglian Region. Peterborough.

The total population in the catchment is 88,000, of which over 40,000 people live in Louth, Skegness, Mablethorpe and Sutton-on-Sea. Skegness, which is served by Ingoldmells, the only HNDA discharge in the area. There are no industrial discharges. The population can increase by 150,000 during summer, with an additional 33,000 day visitorsxcvii.

Chemical profile

These are taken from the 1995 Sea Vigil transects along the Lincolnshire coastxcvii, and were continuous with those for the Thames (where additional details regarding the interpretation of the transects are given) and East Anglia. The survey points were typically 2.5 km offshore. The results are set out in Table 7.4.

Winter (January) nitrogen and phosphorus levels were vastly in excess of UK guidelines on coastal hypernutrification. In molar terms nutrient levels were 0.36–5.71 µM ammonium N, 50–68 µM TON N and 0.97–1.4 µM P. There was also some phytoplankton growth.

From May to September all nutrient levels were generally significantly depressed, and peak depressions were associated with peak plant pigment levels, oxygen supersaturation and peak turbidity, indicative of significant

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 107 blooms. The accompanying commentary notes that although the Lincolnshire coast has only “minor freshwater inputs” the data exhibits an “unexpectedly varied concentration profile for each nutrient”. The authors suggest that this may be due to residual water from the Humber estuary. This may be correct, but local inputs cannot be ruled out. For example in two transects extending out from the coast approximately 5 km north and south (down-current) of the Ingoldmells HNDA off-shore discharge, plant fluorescence showed a very marked spike at 60 units 1 km offshore on the southern transect, three times the general background level extending to 11 km offshore. This was matched by oxygen supersaturation (105% or greater), while samples taken north of the HNDA showed no such peaks. (Turbidity was higher inshore at both transects, while data on nutrients, if collected, were not presented). This shows marked local variation at a point distant from the Humber.

Biological Effects

Little is known regarding the status of the Lincolnshire coast prior to 1992xcvii. In 1995, in addition to the plant pigment measurements a more limited series of spot samples of chlorophyll-a were made. Maximum levels were ca 5 µg l-1 in January and March; 15 µg l-1 in May (and with over half the sites at ca 10 µg l-1 or above); ca 5µg l-1 in July; and 7.5 and 15 µg l-1 in August (only two spot samples taken). The two spot sites in the 1993–96 spring average were 5–7.5 µg l-1 and over 10 µg l-1.

Designation under the Directives

The only HNDA established in the first round of designations is Ingoldmells (47). No change to its status was made in the 1998 round. The coastal waters are hypernutrific, phytoplankton growth can be significant, and nutrient levels are significantly reduced from winter levels. The Sea Vigil report notes that “the main pollution risks arise from agriculture and sewage outputs” but also that “the data so far is not sufficient to determine the status of these coastal waters” xcvii. The report draws attention to ammonia peaks that on occasion occur in the vicinity of Sutton-on-Sea (mid-coast) and at Chapel St Leonards (just north of Ingoldmells).

The Sea Vigil report also notes that bathing waters in the vicinity of the Ingoldmells discharge have complied with EC Bathing Water Directives “from 1988 to 1993” The date of publication was 1997.

7.4.2 East Anglian Coast

East Anglia is based on permeable chalk, covered with varying thicknesses of glacial tills, sands and gravels. With the exception of the Brecklands, the associated low chalk ridge and greensand running north to eastern edge of the Wash, and the adjacent Cromar glacial moraine, the land is intensively farmed, being the most productive arable land in the UK. This is due to low rainfall and well drained soils. The relatively infrequent rainfall implies that the nutrient flux to surface waters will be characterised by infrequent bursts, with greater short-term nitrogen concentrations. Nutrient losses have been

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 108 accentuated by intensification, with consequent loss of hedgerows and watercourse borders (both of which act as buffer strips), accelerated drainage, and the canalisation of streams.

The main East Anglian rivers draining directly to the coast are, in the north, the Rivers Bure, Yare, Wensum and Waveney, which drains via the estuary of Breydon Water and also via Oulton Broad. In the south are the estuaries of the Ore/Alde, The Deben, the Orwell and Stour, on the border with Essex, have already been dealt with in a separate section (see Essex & Suffolk Estuaries).

Major settlements include Norwich, King’s-Lynn and Bury St Edmunds inland, and an urban strip from Winterton-on-Sea to Lowestoft, including Great Yarmouth, and in the south. As with the Lincolnshire coast, the resident population is greatly increased in the tourist season.

Regarding coastal conservation value, the north Norfolk coast is part of the Wash IMA, extending east to Cromer, and is also a designated SPA and Ramsar site, these extending 40 km from Hunstanton in the Wash to Salthouse in the east. It includes intertidal sands and muds, saltmarshes, brackish lagoons, reedbeds and grazing marshes. The eutrophication interest is in regard to the impact of elevated nutrient levels in the brackish lagoons (natural at Holme and Cley-Salthouse and artificial at Tichwell and Cley) and in the dikes such as at Holkham, which have high aquatic plant diversity. The area supports internationally important numbers of breeding Sandwich tern and little tern, and wintering pink-footed geese, dark-bellied brent geese, and nationally important numbers of white fronted geese, shelduck, pintail, oystercatchers, avocet, ringed plover, grey plover, redshank, black headed gull and bearded titciv.

Great Yarmouth North Denes candidate SPA is a shingle beach and dune system, nominated for its little tern colonyciv and is unlikely to be directly affected by eutrophication.

MinsmereÐWalberswick is in parts a NNR and an RSPB reserve, a designated Ramsar site and a candidate SPAciv. The marine interest is the Blyth estuary, and shallow brackish lagoons and saltmarsh. The Blyth estuary is enclosed along its lower reaches, opening up into a shallow basin 2.5 km inland. Its eutrophication status is therefore of interest: unfortunately no information has been encountered. The area supports nationally important numbers of wintering European white-fronted geese and avocet, as well as freshwater and terrestrial species.

OrfordnessÐHavergate is in part a NNR, a Designated SPA and a candidate Ramsar site. It is primarily of estuarine interest and is described in the section on Suffolk and Essex estuaries.

Chemical profile

These are taken from the 1995 Sea Vigil transects along the East Anglian coastxcvii, and were continuous with those for the Thames and Lincolnshire.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 109 The section extends from Holme next the Sea at the mouth of the Wash, to Harwich in the south. The results are set out in Table 7.5.

Table 7.5 East Anglian 1995 nutrients, oxygen, salinity, turbidity and chlorophyll

Date NH4 TON PO4 SiO2 O2 salinity turbid. plant N:P N:Si µM µM µM µM % ‰ % trans pigs.

Jan. 0–5 35–107 1.29– 11.7–25 93.5–95 29–34.5 0–100 4–18 33–230* 3–8.2 1.93

March ? ? ? ? 91.5–97 30.7–33.7 75–98 6–33 - -

May 0.25–2.14 0–53.6 0–0.81 0–7.5 98–135 33.2–33.8 95.5–99 40–180 - -

July† 0–14.3 0–3.57 0–0.91 0.33– 85–100 33.7–34.2 87–100 8–17.5 6.6–39 2–6 8.33

Sept. 0.21–8.57 0.5–12.1 0.16– 0–8.33 87–107 33.5–34.75 82–100 3–16.5 - - 0.89 Notes: The data extends from Holme next the Sea at the mouth of the Wash, to Harwich in the south. Elaborations and explanations as for Lincolnshire, Table 9.4. * Exceptional N:P ratio of 230:1 and N:Si of 8.2 at Aldeburgh, sustained maximum of N:P 73:1 and N:Si of 4.6:1 between Holme next the Sea and Wells. † The July data used excludes an offshore excursion. Source: Anon. (1997). Sea Vigil Water Quality Monitoring. The Lincolnshire Coast 1995. Environment Agency, Anglian Region. Peterborough.

As with the Thames and Lincolnshire coast, winter nutrient levels were well in excess of those defined as hypernutrific. Ammonia nitrogen ranged from 0– 5 µM N, TON over 35–107 µM and phosphorus from 1.3–1.9 µM. Similarly, nutrient levels at other times of the year were significantly depleted, supersaturation of dissolved oxygen occurred, and increased turbidity was sometimes associated with algal blooms.

There was considerable variation within the section. Levels of nutrients were often high adjacent to the Wash, and can probably be attributed to it. Nutrient levels were typically lower along the remainder of the north Norfolk coast but generally began to increase from Winterton to Harwich. The southernmost part of this sector receives nutrients from the estuaries discussed in the section on Suffolk and Essex estuaries.

Looking at the entire data set, from Lincolnshire to the Thames, while there were sometimes hints at a north-south trend, there was considerable intra- section variability. It also has to be remembered that this data is for one year and inter-annual variation will be considerable, so drawing firm conclusions on north-south trends would be inadvisable on this basis alone.

Biological effects

Plant pigment levels indicated that there was some phytoplankton activity even in winter, with patchy peaks from Winterton to south of Aldeburgh reaching the highest levels recorded between the Humber and the Thames.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 110 Although markedly lower than those later in the year, they were positively correlated with some remarkably high turbidity levels (light transmission of less than 25% off Winterton, Great Yarmouth and Lowestoft). Data on dissolved oxygen hinted at increases in oxygen levels (but never supersaturated) in the vicinity of pigment peaks near Aldeburgh and Lowestoft, but not at Winterton.

From spring to autumn phytoplankton blooms were clearly apparent, with associated oxygen supersaturation and nutrient depletion. The 1993–96 spring bloom chlorophyll-a spot samples had no East Anglian sites with less than 5µg l-1, 4 sites between 5–7.5 µg-1, 7 between 7.5–10 and one over 10µg l-1, which was adjacent to the Wash. It was quite clear that was phytoplankton growth was significantly greater from the Humber to the Thames than that to either the north or south, and that phytoplankton growth was especially high in the Wash and the outer Thames (above 10 µg l-1). The data from Lincolnshire was insufficient to make a comparison with East Anglia.

Designation under the Directives

In the first round of designations five HNDAs were established. These were (running from north to south) North Norfolk (46), Mundesley/North Walsham (45), Great Yarmouth (44), Lowestoft (43), and Shotley/Felixstowe (42). In the 1998 second round HNDA status was withdrawn for Lowestoft and Shotley/ Felixstowe, while that from Great Yarmouth will now require secondary treatment. The eutrophic status of the major Suffolk estuaries have already been discussed. Of the northern estuaries Breydon Water, Oulton Broad and the associated tidal waters of the Waveney would appear to be vulnerable to eutrophication, requiring designation.

The eutrophic condition of the freshwater Broads are well known, and high nitrate levels in the River Waveney has resulted in its designation an NVZ. This does not extend to the tidal waters. No information was available to allow evaluation of the decision not to designate Breydon Water as a sensitive area or NVZ. Similarly no information has been seen on nutrient trends in the brackish water lagoons on the north Norfolk coast.

7.5 THAMES TO THE SOLENT

The catchment of the south-east coast from the Isle of Thanet in the east to Chichester Harbour in the west is that of the heavy clays and sandstones of the Weald, fringed by the chalk North and South Downs (see Map Q). The farming in the western Weald is mixed, with significantly more woodland than typical for England on what were once unworkable clays and poor sandstone heaths.

The eastern Weald also included specialist agriculture such as fruit and hops. The chalk was once sheep pasture, with woodland on the steepest scarps. Much of the sheep pasture has been converted to arable since the 1960s – which has implications for the underlying chalk aquifer.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 111 The major catchments, all of secondary scale, are (running from east to west) The Stour, The (East Sussex) Rother, The Ouse, The Adur, and the Arun. There are no major estuaries or intertidal areas in the area. The largest expanse of intertidal is at the extreme eastern end, those of Sandwich Flats, off the mouth of the Stour.

Sandwich Flats forms part of three conservation areas reckoned to be of international importance specifically for their marine interest, and is the southern part of the Thanet Coast candidate SPA, Ramsar and IMA, already described in the section on the outer Thames. The second is Pagham Harbour, a small embayment at the western end (essentially a smaller continuation of the adjacent Solent embayments). This is a designated SPA and Ramsar site with intertidal mudflats “rich in invertebrates and algae” which supports internationally important numbers of dark-bellied brent geese and nationally important numbers of ducks and wading birds. The third site, one of the 27 Important Marine Areas proposed by EN, is the Seven Sisters, mid-way along the coast, where the South Downs meet the sea. This area was proposed because of the extensive chalk bedrock in the inter- and sub-tidal, with its associated algal-based community.

7.5.1 Chemical Profile

Data not seen. The WS Atkins reportxc states that TON levels were equivalent to less than 4.8 µM N, that ammonia levels are “low”, that there was no phosphate data and that dissolved oxygen levels were above the relevant standards.

Computer models suggest that the water circulation immediately off-shore moves in small–scale circulatory gyres (see introduction to next section). Further off the coast the residual current is from west to east, eventually taking the nutrient burden towards areas such as the Dogger Bank, the Continental Coastal Zone and the Skagerrak and Kattegat.

7.5.2 Biological Effects

Unknown. The 1993–96 spring chlorophyll-a baseline survey reports average levels under 5 µg l-1 throughout the area.

7.5.3 Designation under the Directives

In the first round of LSA designations a large number of pre-existing sewage discharges were designated as HNDAs. From west to east these were Bognor

Regis (31), Littlehampton (32), Portslade/Worthing East/Worthing West (33), Brighton/Seaford Bay (34), Eastbourne (35), Hastings (36) and (in part) Hythe/ Dover/Folkestone/Margate (38).

In the second round, discharges at sites 32–36 were deemed to have failed their comprehensive studies. These were Littlehampton, Brighton (Portobello), Newhaven, Eastbourne and Hastings. These will now receive

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 112 secondary treatment. In addition HNDA status was withdrawn from HNDA 31 (Bognor) and for the “qualifying discharge to be transferred elsewhere”.

The HNDA status of site 38 (east Kent) remained unchanged. Without inspecting the evaluations for all the HNDAs it is impossible to state whether the policy is being applied consistently.

Almost certainly there will be no nutrient budgets for the catchments allowing agricultural, sewage and other anthropogenic inputs to be evaluated. It is not possible to draw firm conclusions regarding Sensitive Area or NVZ status. However it is certain that nutrients from these catchments will reach eutrophic areas in the North Sea.

7.6 SOLENT TO THE SEVERN

In south-western England the catchment geology is complex (see Map R). Broadly there are porous chalk and sandstones in the east; less permeable metamorphosed and unmetamorphosed sedimentary rock surrounding the granite cores of Bodmin, Exmoor and Dartmoor to the west; and a small but complex geological area around Bristol.

Rainfall is higher that in eastern England. As a result there is a greater emphasis on livestock and less on arable farming. Upland farming is important on the granite moors.

Land-based morphology

The coastline is indented, and is increasingly characterised on the southern coast, as one moves west, by flooded rias with slow water exchange with the sea. The major coastal features on the south coast are, from east to west, the embayment of Poole Harbour (adjacent to the major urban centre of Bournemouth); the tidal ‘lagoon’ of the Fleet behind Chesil Beach; and the south-west ria systems including the Exe estuary, the Dart, Yealm, Tamar, Fowey, Fal and Helford. The significant urban centre of Plymouth lies on the Fal estuary: Exeter is at the head of the Exe and Truro on the edge of the Fal. Other than this the population is dispersed.

On the north coast, rivers are shorter, estuaries restricted, and urban settlements small. The more significant estuaries are (from west to east) those of the Camel, emerging into Padstow Bay; the Taw, entering Bideford Bay; and the Parrett and other rivers draining the Somerset Levels and entering Barnstaple Bay. The exception to this generally smaller scale is the Severn estuary and the major conurbation of Bristol.

Currents

Currents are complex. In the Channel there is a net flow of water from the Atlantic through the Straits of Dover to the North Sea. This means that natural nutrient levels in the south west will be among the lowest in the UK.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 113 However there is a current ‘watershed’ to the south of the Isle of Wight with off-shore water from the west only entering the eastern Channel to a limited degree. Moreover the trajectories resulting from the superimposition of tidal forces upon these underlying currents are complex. Water circulation models suggest that there is a tendency for water to break away to form small-scale circulatory gyres (c.f. Fig 2.13 in the North Sea QSRcx) adjacent to the coast, which may result in localised build up of nutrients. These complex patterns are visible in infra-red satellite imageslxv. The same images suggest a similar pattern to the north in the Celtic Sea and Bristol Channel between the south- west coast of England and Ireland and Wales.

Biodiversity

The south-west of England, particularly the southern coast, is particularly rich in marine life and this is reflected in the large number of biodiversity sites. There are eight relevant actual or candidate Special Protected Area and/or Ramsar sites on the south west peninsular, and no less than fourteen Important Marine Areas. Six SPA and/or Ramsar Sites and nine IMAs lie on the south coast. In the WS Atkins report on IMAs eutrophication is generally raised as an issue of concern for any enclosed site, Eel-grass is often recorded at enclosed sites. Maerl beds (calcareous red algae), relatively scarce in the UK, also occur at several locations. Issues concerning phytoplankton biodiversity are rarely considered.

Poole Harbour, west of the Solent, is a candidate SPA and Ramsar site. It is a very large embayment (83 km shoreline) in which low freshwater inputs, the narrow 350m opening to the sea and a double high tide have all contributed to the creation of extensive salt marsh and mudflats. The intertidal has abundant invertebrates, particularly in sheltered intertidal bays, while tube- worm beds are a prominent in the middle of the Harbour. It supports internationally important numbers of wintering shelduck, black-tailed godwit and redshank, along with many nationally important populations. Poole Harbour is part of the Poole Bay and Isle of Purbeck IMA. The IMA includes hard and soft shores in sheltered and exposed areas, the lagoonal harbour, mudflats, saltmarsh and chalk coastline. According to the WS Atkins report, algae, including maerl, are essential components of the site. The green algae Ulva lactuca is listed, but no eel-grass.

Continuing westward, The Fleet (a designated SPA and Ramsar site) is a highly unusual habitatxliv; a tidal lagoon behind the storm beach of Chesil Beach, the latter having a length of 26 kilometres. It is shallow, generally less than 2 m depth, and varies from almost freshwater at the western end to full salinity at Portland Harbour. Plant life includes a wide range of algae, brackish water flowering plants including beaked and spiral tasselweeds (Ruppia maritima and R. cirrhosa) and two species of eel-grass. The invertebrate community is “highly distinctive” including very rare UK species, while 23 species of fish have been recorded and it is a nursery for bass. Mudflats and saltmarsh are also present. It supports nationally important numbers of bird species. Aerial photographscxiv show that the land backing the Fleet is arable, often to the water margin, while the towns of Weymouth and Portland lie on

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 114 either side of the mouth. The Fleet is part of an IMA which also includes Portland Harbour. All three eel-grass species are recorded for the IMA, but no green algae were listed.

Lyme Bay is an IMA with shingle and sandy beaches with a subtidal of hard reefs and soft sediments. No green algae or eel-grass were reported. The Exe estuary, a candidate SPA and Ramsar site, and an IMA, is over 10 km long. The mudflats support invertebrate animals, eel-grass1 and Enteromorpha and Ulva algae; there are also mussel beds. By virtue of its south-westerly location in the Britain it is of particular importance to birds in hard winters at sites further east and north. Even in more typical years it supports internationally important numbers of dark-bellied brent geese, along with many nationally important populations. The authors of the review of SPA and Ramsar sites did not consider the poor water quality resulting from faecal bacteriaxliv a disadvantage to birds. Rather they feared that cleaner water could result in an expansion of the shell-fish industry to the bird’s detriment. However they state that in future the estuary requires management to ensure that damaging activities are away from sensitive areas.

The Torbay and Dart estuary IMA has a wide variety of habitats including a drowned river valley, calcareous and non-calcareous rocks substrates, sand and mud. The species list is correspondingly long. No green algae are listed, but one eel-grass is listed, Zostera marina.

The Bolt Tail to Slapton IMA, including the Salcombe Estuary, has similarities (with regard to marine characteristics) to Torbay. No green algae or eel- grasses are listed.

The ‘Tamar Complex’ candidate SPA and Ramsar site is made up of the meeting of the estuaries of the Tamar, Lynher, Yealm and Tavy, whose watersheds cover a significant part of Cornwall and Devon. Plymouth is on the eastern shore. There are extensive tidal mudflats, which support beds of algae “especially Enteromorpha”, eel-grass and “moderately rich polychaete [worm] communities”. The tidal Tamar has rocky shore and subtidal habitats with invertebrate communities “the best examples of their type” in Southern Britain. The Tamar Complex is of national importance for wintering black- tailed godwit and avocet. This area is part of the Plymouth Sound, Tamar and Yealm IMA, which also includes the Eddystone Rocks some kilometres offshore. No green algae are listed, but eel-grasses are present.

The IMA between Dodman Point and the Lizard includes estuarine, rocky and soft sediment habitats. The Helford estuary and Fal estuary lie within the area. Maerl beds (Phymatolithon spp.) are present. No green algae are reported in the WS Atkins account, but Z. marina is listed. Nevertheless green algae do occur. On the reference transects within the Helford voluntary marine conservation area, surveyed since 1986, green algae, particularly Enteromorpha, have become ‘luxuriant’, while the eel-grass has been lostcxv.

1 listed in the account in reference xliv, not mentioned in the WS Atkins report.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 115 The coast around the Isle of Scilly is a candidate SPA and an IMA. The clean waters support a diverse marine fauna and flora. These in turn support internationally important numbers of breeding lesser black-backed and great black-backed gulls and wintering turnstone, along with nationally important numbers of other birds. Neither green algae or eel-grasses are listed.

North coast biodiversity sites

Moving to the north coast, there is an IMA at St Ives Bay, including a shallow estuary and sandy bay. Ulva, Cladophora and Enteromorpha are listed, eel- grasses are not. A second IMA extends from Trevose Head to Boscastle, which includes the Camel Estuary. which has hard and soft substrates in both sheltered and exposed conditions. Again, Ulva and Enteromorpha are recorded as present, eel-grasses are not. Lundy is an offshore IMA less likely to be affected by eutrophication. No green algae or eel-grasses are listed. The Taw and Torridge Estuary, entering Barnstaple Bay, is a candidate SPA, comprising mud and sand-flats, rocky outcrops, and saltmarshes, with bird numbers at or close to national importance. Just to the east is the Ilfracombe to Combe Martin IMA, mainly of rock with some sandy substrates. Enteromorpha is listed.

Finally there is the large and complex estuary of the Severn, which also receives inputs from four major rivers, two (The Parrett and Avon) on the south bank. It is in part a NNR, and a designated SPA and Ramsar site, and an IMA It includes Bridgewater Bay at the mouth of the estuary. All three species of eel-grass are present: no green algae are recorded on the WS Atkins species list. The extreme tidal range means that there are extensive intertidal areas, but also that it is a high energy environment, with the consequence that much of the muds, sands and rocks are species poor and low in biomass. Nevertheless it supports nationally or internationally important numbers of 17 species of winter and passage wildfowl. Bridgewater Bay, is the largest European shelduck moulting area after the Wadden Sea, with approaching 2000 birds.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 116 Table 7.6 Mean annual ammonium, TON, ortho-phosphate and oxygen saturation levels for IMA sites between the Solent and the Exe

Site NH4 TON PO4 O2 year number of year quarters µM µM µM % samples sampled

Poole Bay & Isle of Purbeck Hengistbury Head 1.2 10.7 0.74 - 93 3 1,2 Anvil Point 1.3 7.14 0.48 - 93 2 1,2 St Aldmelms 1.2 7.5 0.55 - 93 2 1,2

Portland & The Fleet Weymouth Bay 1.2 7.5 0.45 - 93 2 1,2 Portland Bill 1 8.21 0.47 - 93 2 1,2 Chesil 0.94 7.14 0.39 - 93 2 1,2

Lyme Bay

sea 1 nm off Lyme Regis 2.5 7.14 0.42 109 93 2 NP, 6 O2 1,3

sea 1 nm off Charton Bay 2.66 7.14 0.43 107 93 2 NP, 4 O2 1,3

sea 1 nm of Seaton 2.5 7.14 0.43 108 93 2 NP, 6 O2 1,3

upper Axe estuary 3.34 275 8.32 106 90-93 53,8,24,16 NP 1-4:1,3:1-3;1-3

7,4,28,40 O2 mid-channel Axe estuary 4.2 201 5 107* 90-93 16,8,36,15 NP as above

8,4,46,34 O2 Bridport 1.05 7.5 0.37 - 93 2 1-2

Exe estuary Lower Wear 19.1 261 8.87 95 90-93 21,12,17,17 NP 2-4:2-3:

(upper estuary) 5,6,25,41 O2 1,3-4:2-3 mid-estuary 10.9 94.3 3.64 93.7 90-93 36,22,29,33 NP as above

7,11,41,67 O2 Cockwood 5.33 32.1 1.48 98.2 90-93 40,22,35,33 NP as above

(lower estuary) 6,11,49,67 O2

Notes: The mean of annual means is given when there is more than one years data. Sampling frequency and distribution across a year can be highly irregular. Where unusual concentrations are indicated the frequency and distribution of sampling should be assessed, by inspecting the final three columns. See text for explanation of final two columns. * dissolved oxygen average of 123% in 1991 (from third quarter only) indicative of bloom. Source: WS Atkins Review

7.6.2 Chemical Profile

Information on nutrients is fragmentary in the WS Atkins review. Annual means are given, but the data appeared to be gathered almost at random over the four quarters of the year. Fortunately the spread of the data is recorded. Values are given for each quarter, but these are only of the maximum and minimum values, again of limited use. Salinity data is not presented in the WS Atkins annex.

Finally many locations were in the vicinity of a sewage discharge, which could lead to unrepresentative results. These values have been stripped out of the analysis that follows, leaving a restricted sub-set. (see Table 7.6 through to

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 117 Table 7.9. In many cases four years of data are available, and the uneven sampling in any one may to some extent be smoothed out. But a more detailed appraisal would have to take account this uneven coverage, using the final three columns in each table1.

TON values of 50 and 100 at some sites appear suspiciously uniform, suggesting low precision and substitution of detection limits rather than actual measurements. Footnotes are used to highlight points from the database not apparent from the mean values given in the table.

The nutrient concentrations of Poole Bay and the Isle of Purbeck (Table 7.6) and of Portland and The Fleet are based on very few, offshore, samples. Neither Poole Harbour or The Fleet appears not to have been sampled. The nutrient levels given are unremarkable compared to east coast coastal waters. There is rather more data for Lyme Bay IMA, especially for the Axe estuary. The nutrient levels in Lyme Bay are consistent at the different locations. Ammonium values are towards the middle of the range of coastal values generally recorded in Table 5.3. TON are towards the lower end of the range of coastal sites.

Ammonium values in the Axe were elevated but not extreme. TON values were high, especially so in the upper estuary (275 µM), which was of the same order (bearing in mind these are annual means) as those of the Suffolk and Essex inner estuaries, and those of NE England (Table 7.3) although only about half that of the Ythan at 0‰ in 1991–92. Phosphorus, at 8.3 µM P in the inner estuary was higher than in the Ythan, or in the Ore/Alde, Deben or Stour, perhaps roughly equivalent to NE England estuaries, but less than in the Essex Colne or the Wear in Tyne and Wear.

TON and phosphorus levels in the Exe estuary were also elevated and similar to those of the Axe. But in the upper estuary ammonium levels were also markedly elevated at 19.1 µM, similar to those recorded in the upper estuary of Southampton Water. Unlike the Axe, where annual average oxygen saturation was over 100%, oxygen levels showed a minor depression throughout the estuary.

1 The first of these gives the years when sampling took place. The second to last column gives the number of samples taken in each year, separated by commas. Note that a different number of samples were often taken for dissolved oxygen than for ammonium, TON and phosphorus. The last column gives the distribution of sampling across the four quarters of each year when sampling took place. Thus 2,4:2-4:1 indicates that at least one sample was taken in each of the second and fourth quarters of the first year, in the second, third and fourth quarters of the second year, and in the first quarter of the third year.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 118 Table 7.7 Mean annual ammonia, total oxidisable nitrogen, ortho-phosphate and oxygen saturation for IMA sites between Tor Bay and Plymouth Sound

Site NH4 TON PO4 O2 year number of year µM µM µM % samples quarters sampled

Tor Bay to Dart estuary

Tor Bay transect 1/4 1.0 3.57 0.42 105 93 3 NP, 6 O2 2-3 (outer bay)

Tor Bay transect 3/2-4 1.31 3.57 0.43 107 93 9 NP, 27 O2 as above (mid bay) Tor Bay transect 4/1-3 1.13 3.57 0.42 107 93 as above as above (inner bay)

Dart upper estuary 9.5 95.7 1.61 87 90-93 82,15,23,30 NP 2-4:2-3:1-3:1-3

12,15,23,45 O2 Dart mid-estuary 4.87 51.9 0.84 94.2 90-93 35,24,29,32 NP as above

(White Rock) 11,24,29,60 O2 Dart lower estuary 2.28 17.9 0.65 100 90–93 36,30,36,39 NP 2-3:2-3:1-3:1-3

(Higher Noss Point) 24,30,30,67 O2

Bolt Tail to Slapton Kingsbridge upper estuary 3.59 55.7 0.85 106 90-93 19,10,18,16 NP 2-3:2-3:2-3:1-4

(Park Farm) 10,11,14,38 O2 Kingsbridge ‘mid-estuary’ 1.78 7.5 0.48 109 90-93 48,24,36,36 NP 2,4:2-3:2-3:1-3

12,24,27,113 O2 Kingsbridge lower estuary 1.51 4.82 0.84 105 (90)-93 36,23,36,30 NP 2,4:2-3:2-3:1-3

(Mill Bay) 0,18,30,103 O2 Kingsbridge outer estuary 1.82 6.66 1.23 95.7 90-92 24,12,24 NP 2-3:2:3

(off Bolt Head) 6,9,18 O2

Plymouth Sound & estuaries Tamar mid-estuary 6.11 112 1.03 85 90-93 7,9,11,36 NP 2-3:1-2:1-3:1-4

7,7,11,76 O2

Lynher mid-estuary 5.42 82.3 1.03 90 90-93 8,14,24,32 NP 1-2:1-2:1-3:1-4

13,14,24,66 O2

Yealm mid-estuary 3.64 73.7 0.83 96.5 90-93 13,8,12,12 NP 1-4:1,3:1-3:2-3

(Cofflete Creek) 13,7,12,12 O2

Plym estuary 34.4 37.5 3.64 84.2 90-93 13,10,23,28 NP 1-3:1-2:1-3:2-4

(Laira Bridge) 14,10,20,87 O2

Tavy estuary 8.5 103 1.74 88.7 90-93 9,8,12,12 NP 3-4:3-4:1-2:1-3

9,8,11,12 O2

Inner Plymouth Sound 3.28 17.3 0.75 88 90-93 4,72,106,132 NP 3:1-2:1-3:1-4

(Bridge) 4,70,104,319 O2 Outer Plymouth Sound 3.75 13.8 0.68 96 91-93 14,36,24 NP 1-2:1-3:3-4

(Breakwater) 14,36,68 O2 Notes: Mean of annual means given when more than one years data. For other details see Table 7.6 and text. Source: WS Atkins review

Nutrient levels throughout Tor Bay were lower than in Lyme Bay. Similarly, while nutrient levels are elevated in the Dart estuary, they are less than in the Axe and Exe, and nitrogen appears lower than the Suffolk and Essex estuaries although phosphorus is similar except for the Colne, which is very much higher. Mean oxygen saturation was 87%, suggesting significant deoxygenation during part of the year.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 119 Table 7.8 Mean annual ammonium, TON, phosphate and oxygen saturation for IMA sites between Dodman Point and the Lizard

Site NH4 TON PO4 O2 year number of year µM µM µM % samples quarters sampled

Dodman Point to Lizard Helford upper estuary 3.21 319 § 1.10 95.2 90-93 8,8,12,8 1,4:1-2:1-3:2,4 (Bonallack Barton) Helford mid-estuary 2.99 93.3 † 0.62 94.5 90-93 4,17,32,22 NP 1:1-2:1-3:2

(Groyne Point) 4,17,32,60 O2 Helford mid-estuary 3.17 132 0.86 106 90-93 9,4,11, 8 NP 1-3:1-2:1-3:1

(Polwheveral Creek) 97,113,110,105 O2 Helford estuary mouth 2.19 24.1 0.63 95.7 90-93 4,24,36,24 NP 1:1-2:1-3:2

4,24,36,67 O2

Truro mid-estuary 25 305∞ 3.42 78.7∞ 90-93 12,8,12,12 NP 1,3-4:1,3:

(Truro town) 16,8,12,12 O2 1-3:1-3 Truro mid-estuary 27.6 139 3.29 81 90-93 12,8,12,53 NP as above

(Malpas) 16,8,12,12 O2

Tresillian mid-estuary 9.83 420 # 3.42 95.2 90-93 16,8,12,12 NP 1-4:1,3:1-31-3

(Treffry) 16,8,11,12 O2 Tresillian mid-estuary 10.4 210 2.04 91.5 90-93 16,8,12,12 NP as above

(St Clements) 16,8,11,12 O2

Fal upper estuary 7.72 21.4 1.44 95.7 90-93 14,8,10,17 NP 2,4:1,3:1-3:1-3

(River Ruan) 14,7,10,32 O2 Fal mid-estuary 5.67 103 1 95.7 90-93 7,13,16,23 NP as above

7,13,16,49 O2

Carrick Roads 4.09 9.07 0.67 93 90-93 8,24,16,24 NP 4:1,3:2-3:2-3

(mid-channel) 3,24,16,82 O2 Sea, 4 km off Mullion 1.94 3.57 0.67 106 92 6 2-3

Notes: Mean of annual means given when more than one years data. For other details see Table 7.6 and text. § TON maximum values of 465.7–663.6 µM in first quarter 90–92. † TON average value of 289.2 µM in 1990. ¶ dissolved oxygen maximum of 128–135% in second quarter 91-93 indicative of blooms. ∞ TON maximum values of 414.3–717.1 µM in first quarter 90–93 and dissolved oxygen minimum of 4% in second quarter 1990 indicative of severe sewage-based pollution # maximum TON of 792.9 µM in third quarter 1990. Source: WS Atkins Review

In the Bolt Tail to Slapton IMA, Kingsbridge estuary nutrient levels are ca. half those of the Dart estuary, (although there were few first and last quarter samples). Levels in the outer estuary (effectively coastal) were lower than east coast sites. Annual mean oxygen here was 106%.

Of the estuaries entering Plymouth Sound, two – the Tamar and Tavy – have mid-estuary TON levels above 100 µM. The Tamar, at least, flows though “intensively cultivated land” cxvi. The Lynher and Yealm mid-estuaries have TONs of 82.3 and 73.7. The Plym estuary TON level was lower, but it had a very high value of 34.4 µM ammonium N (and a maximum first quarter value of 199 µM), and phosphorus was also raised, at 3.64 µM.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 120 Phosphorus is higher than the Suffolk estuaries reviewed earlier, although less than for the Colne and the Wear, and similar to the highest values for the Solent embayments. These elevated nutrient levels remain apparent in the outer parts of Plymouth Sound, where nutrient levels are equivalent to those found in major east coast outer estuaries and coastal waters, and those of the Solent.

The IMA stretching from Dodman Point to the Lizard had the highest TON levels in the South West peninsular. The Helford estuary had a TON of 319 µM in the upper estuary. Ammonia and phosphorus, while elevated, were not exceptional. The Truro estuary had high values of ammonia (second highest in south-west), TON (a maximum of 727 µM in the first quarter of 91–93 – greater than the Ythan, though only based on a single data point) and phosphorus, while oxygen levels were significantly depressed. The Tresillian had the highest south-western annual TON of 420 µM, with a peak in the third quarter of 793 µM, while the Fal also had high ammonium and TON.

These TON levels in the Truro and Tresillian estuaries were consistent with the earlier 1990–91 peak values reported in the First Round Candidate Sensitive Area proposal from the Regional office of the NRA. Nitrogen levels fell rapidly at sampling points further off-shore to levels below those in the UK definition of hypernutrification, but did not include the necessary winter measurements. Phosphorus levels remained above the defined level.

There was no information on nutrient levels around the Scilly Isle in the WS Atkins report. Moving to the mainland north coast (Table 7.9) and St Ives Bay IMA, nutrient levels in the bay were unexceptional, but nutrient levels in Hayle estuary were raised. The same was true of the Camel estuary in the North Cornwall IMA. But, on the available evidence, in both cases the elevation was not as great as the Axe, Exe, and Dodman Point /Lizard sites. No nutrient data has been seen for the Taw estuary, which has been designated as a eutrophic sensitive area in the 1988 designation round. Not being within an IMA site, it was not included in the WS Atkins review.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 121 Table 7.9 Mean annual ammonium, TON, phosphate and oxygen saturation for IMA sites between St Ives and the Severn estuary

Site NH4 TON PO4 O2 year number of year µM µM µM % samples quarters sampled

St Ives Bay

St Ives Bay west 2.11 7.14 0.52 109 93 3 NP , 6 O2 1-2 (site 4)

St Ives Bay central 2 7.14 0.45 99 93 3 NP, 9 O2 as above (site 1)

St Ives Bay east 2.22 7.14 0.51 110 93 3 NP, 6 O2 as above (site 5)

Hayle estuary 6.11 109 3.35 105 ¤ 90-93 9,8,12,8 NP 3-4:1,3:1-2:3:2

(by St Erth estuary) ¤ 12,8,12,8 O2 Hayle estuary mouth 5.05 46.4 1.83 99.7 90-93 9,8,12,8 NP as above

13,8,12,8 O2

North Cornwall Camel mid-estuary 6.11 177 1.77 93.5 90-93 13,713,12 1-2,4:1,3: 1-3:1-3 Camel estuary 3.79 37.5 0.61 95.7 90-93 11,16.19,24 NP 1,4:1,3:1-3:1-3

(by Padstow town) 11,16,19,66 O2 Camel lower estuary 1.87 28.6 0.64 97.5 90-93 3,21,30,34 NP 1:1,3:1-3:1-3

(Doom Bar) 3,22,30,100 O2

Ilfracombe to Combe Martin sea off Ilfracombe n.d. n.d. n.d. n.d. - - -

The Severn (south bank) Newcombe (Portishead, 1.38 133 4.54 101 91-93 2,4,2 NP 2,4;2-4;1 NP

Avonmouth) 1,2,2 O2 2;3-4;1 O2 upper estuary, mid-channel 1.62 127 4.39 101‡ 91-93 1,4,2 NP 2:2-4:1

1,2,2 O2 mid-estuary, mid-channel 1.25 95 3.77 99.2 91-93 2,4,2 NP 2,4:2-4:1

(English & Welsh Grounds) 1,2,2 O2

Notes: Mean of annual means given when more than one years data. For other details see Table 7.6 and text.

¤ First quarter 91 TON maximum of 557.1 µM and second quarter 93 dissolved O2 maximum of 133% indicative of bloom status. ‡ First quarter 93 maximum dissolved oxygen value of 123.1% Source: WS Atkins Review

The majority of the sampling sites in the Severn estuary were on the northern, Welsh, side. One site, Newcombe, was on the southern bank, with a TON of 133 µM. Mid way between the banks, the site identified as ‘upper estuary’ had a TON of 127 µM, ammonium of 1.62 and phosphorus of 4.39. The other ‘mid- estuary’ sites were below the bridges where the estuary was 7.5 km across, and nutrient levels were lower The obvious comparison would be with the Humber, but this is difficult without salinity data. They appear to be of the same order of magnitude. (see the Humber section).

7.6.3 Biological Effects

Data on the biological effects of the elevated levels of nutrients recorded here is very scarce. There are two partial exceptions to this, for Helford estuary and for the Tamar.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 122 Part of the Helford estuary is a voluntary marine conservation area. Surveys in 1986 had eel-grass on three of eight transects used for long-term annual monitoring, with densities up to 62 plants m2. However all eel-grass had disappeared by 1988, and had not reappeared by 1993. Enteromorpha was noted as being abundant in 1990; this may indicate that the increase of green algae was not contemporaneous with the disappearance of the Zostera. The extremely rapid disappearance also suggests that factors other than eutrophication may (also) have been involved. Nevertheless it should be noted that nutrient levels in Helford estuary were amongst the highest in the south western IMA’s, and were much higher than at Grevelingen Lagoon, in the Netherlands, where conditions are clearly ideal – eel-grass expanded to become the dominant non-microscopic plant after the estuary was barricaded, and water clarity increased. In the lagoon mean winter ammonium plus nitrate nitrogen (phosphorus was not reported) was only 50 µM, amongst the lowest of the major Dutch estuaries and coastal embaymentscxvii, and where nitrogen rather than light was believed to limit total plant production.

Table 7.10 Properties of Dutch estuaries, coastal lagoons and coastal waters

North Ems- Wadden Wester- Ooster Grevelin- Veerse Sea Dollard Sea scheldt - genmeer Meer coastal scheldt

Winter N, µM 36 250 86 329 71 50 214 chlorophyll-a, µg l -1 15 40 30 30 5 5 100 plant production . 160 210 275 240 320 450 salinity, ‰ . 0–17 10–17 0–17 15–17 14–16 8–12 turbid. extinct. m-1 . 1–7 0.5–3 0.5–7 0.4–1.5 0.2–0.5 0.3–1.4 area (km2) . 460 1200 300 350 108 22 residence time, d . 14–70 8–15 30–90 5–40 180–360 ±180 freshwater load m3s-1 . 150 400 100 20 5 3 tidal + + + + + - - stratification . ± - - - ± +

Notes: ‘Turb. extinct.’ is the extinction coefficient of the water, a measure of turbidity. Winter N is the mean winter concentration of ammonium and nitrate nitrogen. Chlorophyll-a is phytoplankton chlorophyll only. Plant production is total plant production, measured in grams carbon per m2 per year. Some data is provisional. Source: Nienhuis (1992).

The only other south-west site for which relevant information has been seen is the Tamar. In 1982–83 intense blooms of self-sustaining brackish water species were studied in the upper estuary of the Tamar. Chlorophyll-a levels reached 400–450 µg l-1, and oxygen saturation 140%cxvi. Unfortunately nutrient levels, if recorded, were not included in the research paper. The 1993-96 spring baseline chlorophyll-a survey reported levels below 5 µg l-1 from the Solent to the Severn.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 123 7.6.4 Designation under the Directives

Less Sensitive Areas

Fourteen LSAs were designated in south west England in the First Rounds. The HNDA status of two, Portishead and Avonmouth (14) and Kingstone Seymore (15) had to be withdrawn when the government lost the Judicial Review regarding the attempted redefinition of the Severn estuary as a coastal water. The remaining twelve HNDAs remain in existence. Many lie within or close to IMAs and other areas important for biodiversity. These are, starting from the Solent and working round to the Severn, those of Swanage (HNDA 28), within the Poole Bay/Isle of Purbeck IMA; Weymouth (27), within the Fleet – Portland Harbour IMA; Lyme Regis/Charmouth (26) and Bridport (25), both within the Lyme Bay IMA; Dawlish/Exmouth/Sidmouth (24), offshore of the Exe estuary IMA; Teignmouth (23) between Exmouth and Torbay IMA; Torbay- Sharkham (22), within the Torbay IMA; Penzance/St Ives/Camborne/Redruth (21), in the St Ives IMA; Parranporth (20); Newquay (19); Bude (18); Bideford (17); and Minehead/Watchet (16).

Sensitive Areas and NVZs

The available data on coastal nutrient levels in the area make it difficult to sustain a case of extreme hypertrophic eutrophication on the model of continental waters, or even those of e.g. the Humber, Wash or outer Thames estuary. However the relevant comparison is with the original nutrient levels, and the consequences for biodiversity. Within the rias the situation is different. Nutrient levels are elevated, in the most extreme cases to levels that are high judged by other UK or continental sites.

Three estuaries, The Truro, the Tresillian and the Taw have been designated as Sensitive Areas in the Second Designation round on the basis of eutrophication. For the first two this reverses their rejection in the first round. Other estuaries with nutrient levels almost as high have not been designated. For one, Helford, there is evidence of changes in species composition – the loss of eel-grass and an increase in algal weeds that would be consistent with eutrophication. As elsewhere in the UK, the necessary research to demonstrate that hypernutrification is not having an effect on biodiversity has not been systematically initiated.

No nutrient budgets have been seen, which makes it difficult to judge the relative contributions of sewage and agriculture. Nevertheless it can be expected that both are likely to make a significant contribution. There would appear to be a valid case for designation six catchments as Sensitive Areas and Nitrate Vulnerable Zones. These are the Axe, the Exe, the complex of estuaries around Dartmouth, the complex in the vicinity of Plymouth, the Falmouth complex and Helford, and the Taw. Some of these have now been designated Sensitive Areas, but there are no NVZs.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 124 7.7 WALES

The bedrock of Wales is dominated by older igneous and metamorphic rock of limited fertility, by mountainous terrain, and by upland pastoral farming. Thus, while permeable rock systems such as limestone exist, they are of little relevance with regard to aquifers and run-off. Fertile areas with intensive agriculture is limited to a few favoured locations such as the Vale of Glamorgan – a coastal plane in south-east Wales – and the land surrounding Milford Haven, in Dyfyd. The Vale of Glamorgan is based on sandstones and limestones. The Isle of Anglesey, in the north-west is also low-lying and includes good farming land based on soil overlying hard impermeable rock. The population is concentrated along the coastal margin, principally in the south-east, in Cardiff, Newport and Swansea, the only urban centres with populations greater than 50,000 (see Map S).

Circulation Patterns

The flow through the Irish Sea is weak, with an long-term northerly direction. Water from the Bristol Channel passes along the Welsh south and west coast. Information is sketchy, but Cardigan Bay, as part of the eastern Irish Sea probably has slow a circulation pattern with the residence times of the water measured in many monthscxviii.

Biodiversity

There are a wide range of coastal sites of importance to biodiversity. The Severn estuary has already been described. Continuing in a clockwise direction, Swansea Bay is a candidate SPA and Ramsar site supporting nationally important numbers of ringed plovers and sanderling.

The Burry Inlet, off Carmarthen Bay, is the largest intertidal area on the south coast of Wales, with sand and mudflats. The north shore is backed by urban development (Llanelli), but the southern side supports saltmarsh. It is in part a National Nature Reserve, and a candidate SPA and Ramsar site. It holds internationally important numbers of wintering shelduck, wigeon, teal, pintail, oystercatcher and knot, and nationally important numbers of wintering shoveler, golden plover, grey plover, sanderling, curlew and turnstone, as well as passage waders and terns. Carmarthen Bay itself is also a candidate SPA and Ramsar site, with the estuaries of the Taf, Tywi and Gwendraeth, and a wide range of other coastal habitats. It supports nationally important numbers of breeding cormorant and wintering common scoter, oystercatcher and sanderling.

The western coast of Dyfed forms the Pembrokeshire Coast National Park and a backdrop to coastal waters with high biodiversity, ranging from coastal cliffs, to bird islands such as Skomer and Skokholm to rias, notably that of Milford Haven and the Cleddau estuary, grey seal breeding sites, and subtidal marine reserves. The Pembrokeshire Cliffs are a proposed SPA, Skokholm and Skomer are in part a National Nature Reserve, and a designated SPA, and Grassholm Island is also a designated SPA.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 125 Cors Fochno and Dyfi is an estuary on the mid-west coast, partly a NNR and designated Ramsar site, and a candidate SPA. It includes the RSPB reserve of Ynys–Hir. The estuary includes sandbanks and mudflats, saltmarsh and creeks backed by an unusually extensive tract of unmodified actively growing raised mire. It is important for plants, insects and wintering wildfowl, including nationally important numbers of wintering Greenland white- fronted geese and wigeon.

Glannau, Aberdaron and Ynys Enlli, in Gwynedd, incorporates the tip of the Lien peninsula and the Isle of Bardsey. It is a NNR of importance, the marine interest being the nationally important breeding colony of Manx shearwaters and other seabirds. The Glannau Ynys Gybi (Holy Island Coast) further to the north, off Anglesey, is a similar habitat and a candidate SPA.

Various sites on the west and north coast of Anglesey (Ynys Feurig, Cemlyn Bay and The Skerries) are candidate SPAs due to internationally important numbers of breeding Sandwich and roseate terns and nationally important numbers of breeding common and arctic terns, all of which will be sensitive to changes in fish populations.

On the north-west coast Traeth Lafan and Conway Bay is a large intertidal of sand and mudflats attracting nationally important numbers of moulting great crested grebe and wintering curlew and oystercatchers. To the east, marking the border with England, the Afon Dyfrdwy/Dee estuary is a designated SPA and Ramsar site, and an IMA, with extensive intertidal flats and saltmarsh, supporting internationally important numbers of wintering shelduck, teal, pintail, oystercatcher, knot, dunlin, black-tailed godwit, curlew, redshank and turnstone, and nationally important numbers of breeding little tern. It is surrounded by considerable urban development. The WS Atkins report notes that Enteromorpha is present and that the site is potentially at risk of eutrophication due to its enclosed nature.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 126 Table 7.11 Mean annual ammonium, TON, phosphate and oxygen saturation for Severn estuary (north side) and Dee estuary

Site NH4 TON PO4 O2 year number of year µM µM µM % samples quarters sampled Severn estuary (Wales) Wye estuary 3.57 1.94 5.19 81.8 90–93 25,8,10,11 NP 1-4;1-4;1-4;1-4

(Chepstow) 9,10,11,10 O2 Usk upper estuary, 12.5 143 6.61 71.7* 90–93 16,10,12,8 TON 1-4;1-4;1-4;1-4

Newport 16,95,12,8 NH4 (Caerlon Bridge) 16,10,12,9 P

16,10,12,8 O2 Usk mid estuary 6.75 121 4.88 73.8 90–93 16,17,12,8 TON P 1-4;1-4;1-4;1-4

(Newport Bridge) 16,100,12,8 NH4

16,9,12,7 O2

Usk estuary mouth 3.67 94.5 4.16 - 91 85 TON P 89 NH4 2–3 (No. 1 buoy) Rhymney lower estuary 24.6† 118 2.74 - 90,92 3,1 2-3;4 (Cardiff) Taff lower estuary 5.22 97.2 4.10 103 90,92 3,3 NP 1-2;4 NP

(Cardiff) 90-3 O2 11,12,11,3 O2 1-4;1-4;1-4;1 O2 Ely estuary 14.5 140 8.5 87.2 90,92 5, 2 NP 1-2;4 NP

(Cardiff) 90-3 O2 12,12,12,3 O2 1-4;1-4;1-4;1 O2 Dee Estuary & Wirral

offshore, west 1.10 8.77 0.67 102 93 2 TON, 3 NH4 P O2 1-2 TON

(WLA5) 1-3 NH4 P O2 offshore, east 0.84 8.46 0.67 111 93 as above as above (WLA10)

Mostyn tip 3.83 9.36 0.84 97.7 92 4 NP, 5O2 3-4 NP, 1-3 O2 (Welsh bank) Llanarch-y-Mor 3.72 11.9 1.06 - 92 4 3-4 Notes: Mean of annual means given when more than one years data. For other details text. * lowest dissolved oxygen value of 43.6%, first quarter 1991

† 68.3 µM peak NH4 third quarter 1990 Source: WS Atkins

7.7.2 Chemical Profile

The main areas of interest regarding ‘traditional’ eutrophication resulting from high population and intensive agriculture are in the areas of high population – in the south extending from Carmarthen and Swansea Bays, along the coast off the Vale of Glamorgan to the Severn estuary. In the north the principle area of interest is the Dee estuary.

Nutrient inputs from Wales in the late 1980s were estimated in the Irish Sea Reportcxviii. Inputs to the Welsh south and west coasts were ca 6000 tonnes nitrogen from rivers, 1000 tonnes from direct discharges and less than 500 from industry. Phosphorus inputs were put at 500 tonnes from rivers with smaller amounts from direct discharges and industry. Welsh direct discharges to Liverpool Bay (in the broad sense) were estimated to be 3000 tonnes nitrogen and 500 tonnes phosphorus, while other sources were unquantified but probably small.

TON nitrogen concentrations in the Welsh estuaries entering the Severn estuary were elevated, but might be considered to be in the lower part of the range for heavily polluted estuaries. However ammonium concentrations

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 127 were significant, including an annual mean of 24.6 µM for the Rhymney and a peak value of 68 µM in 1990. Phosphorus levels were also high. Both are indicative of sewage pollution.

Table 7.12 Mean TON river inputs, river flow-weighted TON and estuary area-weighted TON.

Estuary River TON Flow weighted Area weighted µM mM.sec-1 mM.sec-1 .ha-1

Mawddach Mawddach 21.4 123 Wnion 37.1 205 328 0.286

Glaslyn/Dwyryd Glaslyn 29.3 179 Dwyryd 49.2 207 386 0.186

Dyfi Dyfi 55.7 2150 1.07

Milford Haven W. Cleddau 299 1540 E. Cleddau 217 1360 2900 0.529

Teifi Teifi 141 4440 14.7

Clwyd Clwyd 236 1590 3.79

Rheidol/Ystwyth Rheidol 109 700 Ystwyth 62.9 471 1171 65.0

Notes: For major Welsh estuaries, but excluding those discharging to the Severn estuary. Source: Jones (1995).

No direct measurements of nutrient levels on other south, west and north coast Welsh estuaries have been seen. However Jones (1995) has assembled data on TON concentrations in the lower reaches of major Welsh rivers, and derived TON estuary loadings from these (Table 7.12)cxix. From these it can be seen that the estuarine TON concentrations are unlikely to be hypernutrific in the conventional sense, although levels in the estuaries of the west and east Cleddau, and the Clwyd may be significant. It also shows that even where river inputs are relatively low, the effect on an estuary where this is confined may be significant, c.f. the Teifi.

A limited set of data has been seen for the Dee, on the north Wales/English border. If typical they would suggest that nutrient levels here are lower than sites such as upper Southampton Water and the Solent embayments, and of the same order as the Solent and the North Sea coast.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 128 7.7.3 Biological Effects

No information on eutrophication related effects in individual Welsh estuaries has been seen with the exception of the pro-forma for the Tywi estuary, which stated that Phaeocystis algal blooms occurred as a result of eutrophication. Turning to the coast, the 1993–96 baseline chlorophyll-a survey records two sites mid-way along the south Welsh coast as having levels between 5–7.5 µg l-1. Other than this chlorophyll levels are below 5 µg l-1 along the southern and much of the western coasts.

However the situation changes radically as one moves towards the north Welsh coast. The west coast of Anglesey, and adjacent mainland has chlorophyll levels consistently between 5–10 µg l-1. The entire north coast from Anglesey to the Dee – 80 km east to west – had levels above 10 µg l-1 with the exception of the coast off the Dee estuary, which had levels of 5–7.5 µg l-1. This is indicative of significant eutrophication. This area forms the southern margin of Liverpool Bay, and further discussion is reserved until the next section.

Beyond ‘traditional’ eutrophication, Jones (1995), for the Countryside Council for Wales (the statutory body for wildlife protection in Wales) highlights concerns that there has been little attention addressed towards the potential changes which increased nutrients will have on the low nutrient (oligotrophic) estuaries which are common in Wales. The background TON concentrations in such rivers (not estuaries) “might be speculated to be ≤0.5 mg l- 1 [70 µM l-1]. In turn, the present concentrations in some of these rivers suggest that the TON concentrations may have increased 2-3 fold above historical background levels i.e. a proportionately high perturbation factor”.

Jones goes on to raise concerns over plant assemblages (such as salt marsh, phytoplankton and benthic diatoms) which are adapted to nutrient poor conditions. Specifically, there are Red Book species such as dwarf spike rush, Eleocharis parvula, and Welsh mudwort, Limosella australis in the Glaslyn estuary, and their presence may be related to low nutrient status. Their tolerance to increased nutrient levels, and the possibility that they may be crowded out by more vigorous species that thrive in higher nutrient conditions, are matters of concern. His conclusions have wider relevance than just the Welsh situation. These were that, in the UK:

• Low nutrient status, oligotrophic estuaries exist, and are systems which are worth preserving in their own right; • Water Quality Objectives in the past have had little bearing for long term maintenance of nutrient-poor estuaries; • There is a general lack of any rigorous monitoring programmes recording long term biological or chemical changes in estuaries and adjacent coastal waters, and this is particularly so in low nutrient systems; • From a conservation standpoint, invariably there is insufficient information given by developers to quantify the impact of new discharges;

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 129 • There is a lack of information on the nutrient concentrations and thresholds necessary to sustain plants and plant assemblages; and • Catchment management plans, and the goals set out in them, are of crucial importance in setting the terms for future conservation of low nutrient systems. It may be appropriate in some estuaries to set a long-term goal of return to background nutrient levels even if this is not a practical proposition in the short term.

7.7.4 Designation under the Directives

In the first round nine Welsh LSAs were designated. These were, starting in the Severn estuary and working clockwise, Cardiff (HNDA 13), Llentwit Major/Aberthaw (12), Afan/Neath (11), Tenby/Saundersfoot (10), Aberaeron (9), Holyhead (8), West Colwyn Bay (7), Towyn (6), and Prestatyn (5). In the 1998 round the HNDA status of Prestatyn, Afan/Neath and Cardiff were withdrawn. One estuarine site was defined as a eutrophic Sensitive Area, the Tawe estuary, due to the construction of the Swansea Barrage. No estuarine or coastal sites have been defined as Nitrate Vulnerable Zones under the Nitrates Directive.

As for elsewhere in the UK no nutrient budgets have been seen that allow the relative contributions of sewage and agriculture to be judged. In the absense of any evidence to the contrary, both should be regarded as significant. On the basis of the available evidence there would seem to be a prima face case for the designation of eutrophic Sensitive Areas and Nitrate Vulnerable Zones along the entire northern coast of Wales. There also appear to be grounds for designation regarding some of the south-central estuaries – stretching from Carmarthen Bay in the west to the Usk in the east. There may also be reason for concern regarding the impact of the significant nutrient burden derived from the Severn estuary, including their ultimate impact in the Irish Sea (see the section on Offshore Effects). The concerns of Jones regarding the impact of nutrients on oligotrophic estuaries and coastal waters do not appear to have been addressed.

The Irish Sea Report contains some (now dated) information on the compliance of Designated bathing beaches with Directive 76/160/EEC. In 1988, 20 designated beaches on the west and north coast of Wales complied with the Directive and four did not. The latter were in the vicinity of Pwllheli on the west coast and Conwy, Rhyl and Prestatyn on the north coast.

7.8 NORTH WEST ENGLAND

The geology of north-west England is dominated by the volcanics and slates of the Lake District to the north, and the permeable lowland sandstone to the south, largely overlain with glacial deposits, with alluvium and peat mosses towards the coast. Rainfall in the Lake District is high, and agriculture is dominated by pasture land, with extensive upland sheep farming. Population is low, with only one urban centre with a population greater than 50,000 –

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 130 Barrow in Furness. The lowlands have lower rainfall and intensive agriculture, but the area is also an important centre of population, with the major conurbations of Liverpool and Manchester. Other major urban areas with populations over 50,000 are Blackpool, Preston, Southport and Blackburn (see Map T).

Circulation

The western Irish Sea between the Welsh and Scottish coast is shallow, the vast majority of it being under 50 metres in depth. It also has the lowest salinity found in the Irish Sea. In the words of the Irish Sea report “The eastern Irish Sea, and Liverpool Bay in particular, forms a backwater within which the residence time is increased, possibly by more than a year”cxviii. Further discussion is reserved for the section on Offshore Effects.

Biodiversity

Working from south to north, important sites for biodiversity include the Mersey estuary, a candidate SPA and Ramsar site, with extensive intertidal mudflats and saltmarshes, of international importance for over-wintering shelduck, wigeon, teal, pintail, dunlin and redshank, and nationally important numbers of wintering great crested grebe, grey plover and curlew. The Ribble and Alt estuaries comprise a large area of mud and sandflats, backed by saltmarsh. It includes internationally important numbers of wintering Berwick’s and whooper swan, pink-footed geese, shelduck, wigeon, teal, pintail, oystercatcher, grey plover, knot, sanderling, dunlin, black-tailed godwit, bar-tailed godwit and redshank, and nationally important numbers of wintering golden plover, lapwing and curlew, and breeding common tern. It is in part a NNR, and a designated SPA and Ramsar site.

Morecambe Bay is an IMA, and a candidate SPA and Ramsar site. Again, mud and sandflats predominate. It supports internationally important numbers of 12 species of over-wintering birds and nationally important numbers of a further nine. There are internationally important numbers of two species of passage migrants, and internationally important numbers of one breeding species, Sandwich tern, and nationally important numbers of a further six. Just to the north of Morecambe Bay is the Duddon Estuary, with intertidal flats, saltmarsh and lagoons. It is in part a NNR, and a candidate SPA and Ramsar site, which supports internationally important numbers of wintering pintail, knot and redshank, and nationally important numbers of over-wintering shelduck, red-breasted merganser, oystercatcher, ringed plover, curlew, sanderling and dunlin, and breeding little tern. Offshore the Lune Deep has a substrate of boulder and cobbles, with characteristic fauna.

The Cumbrian coast from the Ravenglass estuary to St Bees Head is an IMA which includes hard and soft substrates and an estuarine habitat. Finally the Solway Firth is the third IMA in the region. It is in part a NNR, and a designated SPA and Ramsar site. There is a large area of tidal flats, exceeded in area in the UK only by Morecambe Bay and the Wash. It is an internationally important site for wintering whooper swan, pink-footed geese,

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 131 barnacle geese, scaup, oystercatcher, knot, bar-tailed godwit, curlew and redshank, and nationally important numbers of wintering shelduck, pintail, goldeneye, golden plover, grey plover and dunlin. The WS Atkins report suggests that it is possibly at risk from eutrophication.

7.8.2 Chemical Profile

As there has been awareness of the potential eutrophication of this area for many years it was anticipated that the UK authorities would have extensive data on the area. Unfortunately none was received. Information from other sources was limited and dated.

Nitrogen inputs from the Mersey to the eastern Irish Sea in the 1980s were believed to be of the order of 21,000 tonnes from the rivers, 4000 tonnes from direct discharges and 500 tonnes from industrial sources. By way of comparison his is approximately half that of the 57,000 tonnes from these three sources from the Humber during the same periodcxx. Phosphorus inputs were ca 3000 tonnes from rivers, 300 from direct discharges, with no significant inputs from industry. This is about one quarter of the ca 13,000 tonnes phosphorus input from the Humber.

Nitrogen inputs from the vicinity of the Ribble amounted to 7000 tonnes via rivers, ca 1000 tonnes from industry and a further 1000 tonnes from direct discharges. Phosphorus discharges via the rivers was put at 1000 tonnes, while that from direct discharges and industry were unknown. Inputs from the Lake District were estimated to be 8000 tonnes from the riverine sources, and 2000 tonnes from direct inputs, with no estimate for industry. Phosphorus amounted to 500 tonnes via the rivers and 12,000 tonnes from a single industrial discharge – then the major source of phosphorus in the Irish Sea. It is believed that this discharge has now ceased.

Some (scant) data exists for offshore sites of the three north-western IMAs (Table 7.13). These suggest that nitrogen levels are just above the hypernutrific guideline. But these values are annual means. Winter TON values were 14.4– 21.46 µM for Morecambe Bay, 20.9–23.6 for the Cumbrian coast and 19.5–20.0 for Solway, well in excess of the guidelines, albeit on the basis of two measurements per site. The annual means for phosphorus are well above the guideline. Thus every indication is that the eastern Irish Sea is indeed hypernutrific, a situation confirmed by offshore data.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 132 Table 7.13 Mean annual ammonium, TON, ortho-phosphate and oxygen saturation levels for IMA sites in north-west England

Site NH4 TON PO4 O2 year number of year quarters µM µM µM % samples sampled

Morecambe Bay

SLC30 0.95 8.64 0.70 107 93 3 N O2 2 P 1-4 N O2 1-3 P

SLC35 1.65 11.7 0.74 105 93 3 NH4 P O2 2 N 1-4 O2 NH4 P 1-3 N

Cumbrian coast

East of Isle of Man 0.77 11.8 0.89 125 93 2 N O2 3 NH4 P 2-3 O2 1-3 P

(SLC10) NH4 1-2 N

East of Isle of Man 0.48 11.7 1.08 108 93 3 NH4 P O2 2 N as above (SLC15)

Solway Firth SLB5 0.65 11.4 0.79 103 93 as above 1-3 SLB10 0.99 10.2 0.73 107 93 as above 1-4

Note: See text for further description. Source: WS Atkins Review

7.8.3 Biological effects

Information on biological effects is similarly scant. Nevertheless the 1993–96 baseline spring chlorophyll-a surveyxcv shows that more than 50% of the sites stretching from Anglesey to the Scottish Border were in excess of 10 µg l-1. The same source states that chlorophyll levels are sustained in this area through the summer. Thus by the UK’s own guidelines the eastern Irish Sea is not only hypernutrific but eutrophic. This has recently been confirmed by long-term data from off the Isle of Man.

According to the Irish Sea Study Group report, Phaeocystis blooms were a regular feature between 1978–88, with up to 49 days of ‘significant’ blooms. The run of data is too short to determine trends and unfortunately there is no long term data. However a paper in press at the time of writing reports evidence of increasing nutrient concentrations and phytoplankton growth off the Isle of Man coast over the past four decadescxxi. Given the direction of currents, the major source of nutrients will be from this area of the English coast.

7.8.4 Designation under the Directives

The first round of designations established four LSAs in the area. These are, from south to north, North Wirral, (HNDA 4), Breystones (3) Workington South (2) and Workington North (1). In the 1998 round, the HNDA status of one, North Wirral, was withdrawn. However the application of secondary treatment this will have little effect on nutrient levels.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 133 There are no coastal or estuarine eutrophic Sensitive Areas or Nutrient Vulnerable Zones in the region. Nutrient budgets have not been seen but, given the size of the area, it is likely that agricultural nutrients will be a significant source.

The Irish Sea Report, while noting that there was “no conclusive proof” that blooms were increasing in frequency or that nutrient concentrations were increasing with time (since overtaken by events) stated in 1990 that “Continuing high nutrient loads to open sea areas with weak circulation, such as the eastern Irish Sea, may enhance the general productivity of the area and influence the magnitude of phytoplankton blooms. This is a potentially harmful trend and one which justifies concerted efforts to reduce nutrient inputs to susceptible areas”. Eutrophication is, of course, a well established and accepted phenomena. Given all these points, and additional offshore data, it would now seem inescapable that the entire catchment to this embayment of the eastern Irish Sea should have been established as a eutrophic Sensitive Area and Nutrient Vulnerable Zone.

In 1988, 30 of 40 designated bathing beaches failed to comply with the standard. It is known that efforts have been made to improve water quality since then, but information was not supplied by the UK authorities, and it has not been possible to establish this independently in the time available.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 134 8 OFFSHORE EFFECTS

Offshore sites have lower concentrations of nutrients than coastal waters and estuaries. Nutrients from agriculture and sewage may be directly detectable in the form of plumes from inshore sites, but also occur as ‘recycled’ nutrients that have passed through one or more biological cycles, and which may incorrectly be included as part of the ‘natural’ component. Another important consideration are the time delays: nutrients that pass through an estuary in mid-winter, when growth is low and whose impact may be classified as minimal. will necessarily reach certain offshore sites during periods of peak demand. Atmospheric anthropogenic inputs of nitrogen will represent the major component where there are few riverine sources, such as the northern North Sea, but the atmospheric transport of phosphorus is regarded as insignificant.

A considerable amount is known regarding offshore processes in the North Sea. Less is known about the Irish Sea and the Channel.

8.1 NORTH SEA

Notable early reviews of North Sea eutrophication are Gerlach (1988)cxxii and Brockmann et al. (1988)cxxiii along with the text – negotiated by government- nominated scientists – of the 1993 North Sea Quality Status Reportxxvi, and the Sub-Regional reports that formed the basis for the QSR. Since then there have been numerous additional publications in the scientific literature.

8.1.1 Northern North Sea

Given the prevailing wind direction, is likely that the UK makes a significant contribution to North Sea atmospheric inputs. Overall there have been long term increases in atmospheric inputs of nitrogenous compounds, especially in the second half of this century, with a levelling off over approximately the last decade. In the early 1990s atmospheric inputs from the UK, from all sources, was estimated to be 846,000 tonnes per annum, of the same order of magnitude as UK fertiliser usagecxxiv.

Part of this will enter the northern North Sea, via the surface interface where phytoplankton are concentrated. This may be significant as nitrogen is expected to be the limiting nutrient of this intruding Atlantic water. Stratification routinely occurs in the summer months, cutting off phytoplankton from the bulk of natural water-column nutrients. As a result the water is generally depleted of natural nutrients as it moves south from the continental shelfcxxv. Eutrophication, if it occurs here, will display symptoms relevant to an oligotrophic system and major blooms of the scale, and species composition, observed further south are not to be expected, nor have they been observed.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 135 Interestingly, extensive blooms of the oceanic coccolithophore Emiliania huxleyi do occur over large tracts the northern North Sea, giving a chalky coloration to the sea. Writing in a global review, Kilham and Hecky (1988) noted that E huxleyi “is a remarkable coccolithophore because it responds to [nutrient] enrichment. Only one other member of this group, Gephyrocapsa oceanica, behaves in a similar manner. All of the remaining coccolithophores (about 20 species in the western North Atlantic) are K-selected and do not respond to enrichment under any circumstances.”cxxvi

The 1993 Sub Regional Reports for the North Sea (prepared for the Ministerial North Sea Conferences) west and east of Shetland and the northern-central sea are adamant that anthropogenic inputs (mainly via the atmosphere) are “insignificant compared to the natural flow of nutrients in the area and there is no evidence of eutrophication effects”. A more cautious interpretation would be that insufficient evidence has been gathered from which to draw any conclusions, and that eutrophication (as understood scientifically) in these northern and central waters might be regarded as conceivable but undemonstrated. Least this appear far-fetched, the impact of remotely sourced atmospheric inputs of

NOx on Norwegian lakes at similar latitudes should be recalled.

Whether this would amount to an ‘undesirable’ effect, in the terms of the Directives, will partly depend on commitments regarding biodiversity as, so far as is known, a species such as E huxleyi has no toxic or other adverse effects on human interests such as fishing1. Principle atmospheric sources include power plants, vehicles (both outside the scope of the Directives), agriculture (principally via ammonia from manure, which may also be considered to fall outside the scope of the Nitrates Directive) and ammonia losses from sewage plants.

8.1.2 Central & Southern North Sea

Even though it is conceivable that there may have been significant percentage increases in northern North Sea nutrient inputs, it is unlikely that the low absolute change would be picked out from the sampling noise of conventional monitoring. The consensus emerging from e.g. the EU-funded and widely respected ERSEM ecosystem model of the North Sea is that “the line from the river Humber to southern Norway separates the region of noticeable anthropogenic influence of riverine and atmospheric input from the northern areas, which is mainly influenced by the Atlantic nutrient inflow.”cxxvii

In broad terms UK east coast water, with its riverine nutrient burden, will be trapped close to the UK coastline as it moves southwards until it reaches approximately the Humber, where it first begins to spread outwards before crossing the southern North Sea, along with water from the Thames and input from the English Channel. This then moves north-east, passing over the

1 Herring fishermen in the pre-sonar days of the 1930s regarded what they called ‘white water’ as a good sign for the presence of herring, unlike the blooms of Phaeocystis and the diatoms Rhizosolenia and Thalassiosira (‘weedy water’ or ‘Dutchman’s baccy juice’) where catches were poor. There was some scientific research to support the latter, it being suggested the the cause was the absense of grazing zooplankton rather than the phytoplankton per se. (Hardy, A (1970), The Open Sea: Its Natural History. Part I: The World of Planton (Second Edition). Collins, London.)

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 136 Dogger Bank or Oyster Grounds, along the outer fringe of English Channel water and the predominantly continentally influenced water off the Dutch and German coast, progressively mixing all of the time. Thus UK east coast river water will, at one extreme, make relatively little contribution to inshore areas of the Dutch coastline, whereas by the time it reaches the Skagerrak the UK and continental water can be regarded as well mixed and contributing approximately in proportion to the original riverine inputs.

Water from the UK has a relatively long track before it reaches the eutrophic areas on the continental side of the North Sea. Before one can make the step from comparing UK and continental river-water contributions, to that of nutrients, the significance of denitrification in the southern North Sea has to be taken into account. In the late 1980s it was thought that offshore denitrification in the North Sea could remove small to moderate amounts of nitrogen from the system – between 8–20%cxxviii,cxxix,cxxx. However later work carried out in the south-east North Sea most affected by anthropogenic inputs suggests a much lower removal rate here, and for the North Sea as a whole, accounting for between 1.5 and 3% of the entire North Sea anthropogenic loadcxxxi. It therefore appears that a substantial amount of UK nutrient inputs will indeed be available for transportation to remote areas.

Overall nutrient and phytoplankton profile

The nitrate levels in the North Sea are fairly well characterised, especially from the 1980s onwardsxxvi,cxxvii Between 1984–1993 mean offshore winter nitrate levels along a line between the Humber and southern Norway was ca 5 µM l-1, increasing rapidly toward the Continental Coastal Zone to maximum levels greater than 25 µM in the inner German Bight. The areas of elevated nitrate levels off the UK coast are more confined, with levels above 10 µM restricted to areas immediately offshore of the Humber and Wash down to the Thames. The fall in nitrate offshore will partly be due to dilution by offshore water, and partly from its incorporation into biomass, detritus and subsequent recycling. The latter is significant – the nitrogen necessary to support the mean annual primary production levels in English coastal waters is three times the actual inputs, and six times the inputs to the Dogger Bank and Oyster Bedscxxxii.

Phosphorus levels along the Humber – southern Norway boundary in 1984– 1993 were of the order of 0.6 µM, rising to 0.8 or greater off the Humber/Wash area and the Thames, while it was well in excess of 1 µM off the continental coast from Belgium to the southern Danish coast. Overall, chlorophyll levels in the southern and central North Sea broadly reflect nutrient concentrations and water circulation patterns. A comprehensive survey was conducted in 1988-89cxxxiii. Starting from a low winter base, by March 1989 chlorophyll concentrations were increasing with some sites over 8 µg l-1 with the highest concentrations in the Southern Bight, off the Rhine. By the end of April very high concentrations were present in the coastal waters of Belgium, the Netherlands and the German Bight, and were greater than 8 µg l-1 over much of the south-eastern North Sea. One site had a value of 56 µg l-1. These very high concentrations were due to blooms of

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 137 Phaeocystis. By the end of May these extreme values had subsided, although chlorophyll remained above 4 µg l-1 along the continental coast. There was something of a resurgence in August, with levels reaching 8–16 µg l-1 in the inner German Bight.

By comparison, chlorophyll levels in offshore UK waters were lower. Nevertheless restricted areas off the Humber and Wash, and off the Kent coast, rose to between 4–8 µg l-1 at various intervals between late April and early September. These can be considered in conjunction with the values tabulated earlier in this report for coastal waters, which were too shallow to be sampled by this survey vessel (as were those in the immediate coastal waters off the continental coast).

Dogger Bank

The track taken by UK nutrients across the sea, and the speed of the current, are affected by mean wind direction, which varies from year to year. If it is displaced towards the north-west it passes over the Dogger Bank. This is a very shallow area of water and phytoplankton therefore remain in relatively well illuminated conditions. Growth is maintained throughout much of the year, and it is a naturally productive site – the derivation of the word ‘Dogger’ is believed to come from an obscure Middle Dutch phrase, referring to a (long-since degraded) cod-fisherycxxxiv. Because of the phytoplankton growth, nutrient levels tend to be lower here than in adjacent waters.

The general survey of 1988-89 revealed elevated levels of chlorophyll in the vicinity of Dogger Bank – typically between 4–8 µg l-1 between February and to June, peaking at between 8–16 µg l-1 in May–June. Krönke (1990)cxxxv documented changes in the benthic invertebrate community between the 1950s and 1980s when she re-examined sites at the eastern, Tail End, of the Bank. Species of fast growing polychaete worms known to be tolerant of poor environmental conditions had increased, as had the brittlestar Amphiura filiformis, also known to thrive at sites enriched by organic matter. Other species, particularly long-lived bivalves, had decreased, and were represented in the 1980s only by young individuals. Overall, biomass had decreased. Both organic enrichment and heavy metal contamination of the Dogger Bank had increased, and Krönke speculated that a combination of these factors might be responsible for the change. She also cited other research indicating that water passing over the Dogger Bank was predominantly from UK coastal waters. The impact from beam trawling is one obvious factor that might cause similar changes, but she reported that fishers and fisheries biologists maintained that the site had been unimportant for commercial fisheries during the 1980s, and that the unchanged abundance of the delicate sea urchin Echinocardium cordatum, supposed to suffer severely from beam trawling, argued against such an explanation1.

1 note that Heip (1995)cxlvi is mistaken in asserting that Krönke attributed these changes in species composition to fisheries effects.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 138 Krönke’s interpretation was contentious, not least with the UK authorities. The negotiated 1993 Sub-Regional report merely notes Krönke’s ‘speculation’, although the overall North Sea report stated that the abundance and biomass of infauna (animals living within the sediments) had increased on the Dogger Bank. Nevertheless her work has not been refuted, although additional complications have since become apparent. Ultimately any attempt to attribute change to any one factor is likely to be unrealistic. Beam trawling is probably greater than Krönke was lead to believe (cf. Fig 5.6 of the 1993 North Sea Quality Status Report). It has also become clear that the organic carbon content of the sediments of the Tail End, at 0.16%, or of the Dogger Bank proper, at 0.12%, are not particularly high in the North Sea contextcxxxvi.

However this should not automatically be taken to be evidence against enrichment, both because it is the relative change that is important, and that enrichment results from a balance between addition and removal, and both the rates and mechanisms underlying either remains unquantified. UK-sourced water may typically track further south than the Dogger Bank and Tail End. Yet, on the basis of the prevailing currents, the UK remains the most likely source for the significant heavy metal and other contamination of the site, and as these reach the area, then so must nutrients.

Oyster Grounds

When UK-sourced water tracks further to the south-east, then it will pass over the Oyster Grounds. In a Dutch study of eutrophication of the Oyster Grounds (Peeters et al. 1995) it appears to be assumed that this is the normal track, as the anthropogenic nitrogen and phosphorus component passing over the Dogger is modelled as being near-zero (their Fig. 17)cxxxvii. In 1988–90 April surface layer dissolved inorganic nitrogen over the Oyster Grounds varied from ca 9.7 µM in 1989 to ca 0.2 µM in 1990. (the latter apparently indicating an even further south-east displacement of UK water, as displacement to the north-west by continental coastal water would result in increased nitrogen levels).

No values were given in that study for phosphorus, but Tett and Walnecxxxii give 1988-89 winter values of 7.2 µM TON, 0.86 µM phosphorus and 5.3 µM silicon, giving an N:P ratio of 12:1 and an N:Si value of 1.7:1, suggesting the potential for nitrogen limitation, reinforced by the summer N:P ratio of 2:1 from the surface stratified layer. These values were part of a transect that, moving towards the continental coast, rose in winter to 9.9 µM TON, 0.86 µM P and 5.3 µM Si at the Frisian frontal zone, and 28.1 µM N, 1.19 µM P and 9.4 µM Si within the Frisian coastal water.

Actual data for chlorophyll-a in the surface layer of the Oyster Grounds, reported by Peteers et al., ranged from virtually zero to 7 µg l-1 between 1988 and 1990. Interestingly they also documented considerable phytoplankton growth in the bottom water, peaking at 14 µg in summer 1989 and 18 µg in summer 1990. These peaks were at the site furthest from the continental coast, 175 km distant. The work also confirmed earlier observations regarding

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 139 oxygen deficiencies in the bottom layer, down to ca 50% in the summers of 1989, at sites 100 and 175 km distant from the coast.

These chlorophyll levels, and the oxygen depletion, led the authors to conclude that the area was eutrophic. Yet, as for the Tail End and Dogger Bank, the organic carbon content of Oyster Ground sediments is not high in the North Sea context, at 0.12%cxxxvi, again indicating the caution that is required in interpreting such values. According to Peteers et al.’s model, the worst eutrophication events will occur when nutrient rich water from the continental coastal zone impinges on the Oyster Banks, but this regime is predicted to occur only 15% of the time. Overall, UK sourced waters can be expected to be the more influential.

Tett and Walne document a mean summer peak in water column chlorophyll at the Frisian frontal region, of ca. 175 µg l-1. In the water closer to the continental coast, nutrients were higher but the turbid water limited phytoplankton growth, while further offshore, over the Oyster Grounds “the water was clearer but nutrients were depleted”. Nevertheless their measurements of summer chlorophyll still reached 80 µg l-1. Other field data has also shown nitrate to be severely depleted in the summer months in the Oyster Groundscxxxviii. The implication is that, were nutrients less, phytoplankton levels would have been lower. UK-sourced nutrients will be a significant (but unquantified) component here compared to sites closer to the continental coast.

Overall the conclusion seems clear. Recycled nutrients from the UK can be expected to contribute to the eutrophication of sites such as the Dogger Bank and/or the Oyster Grounds. While the effect may be less marked than in the continental coastal zone, they start from a lower natural baseline1.

The UK counter-argument

Of course, if it could be demonstrated that nutrient levels at these sites had not changed since the early part of this century, then this might be taken as evidence against any impact from anthropogenic inputs – although the link is not absolute. In the relevant 1993 Sub-regional Quality Status Reports for offshore areas in the central and southern North Sea the UK submitted just such an analysis. Its officials, at North Sea Conference negotiations, used these to back up the UK’s claim that there was no evidence for any trend in nutrient levels, and thus for eutrophication, in either English coastalcxxxix or offshore waters adjacent to the UKcxl such as the Dogger Bank and Oyster Grounds. This formed an important part of the UK administration’s case rejecting any requirement laid upon them to reduce nutrient inputs to the North Sea by 50%.

1 Rergarding other sites, Lohse et al.cxxxvi recorded an organic carbon content of 0.54% in the Silver Pit, an area of deeper water between the Dogger Bank and the Wash. This is exceeded in their North Sea survey only by the German Bight and deep water Skagerrak sites. The Silver Pit is therefore a prime candidate for assessment for eutrophic effects closer to the UK coast although, so far as is known, this has not been studied.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 140 However, inspection of that analysis makes it clear that it by no means supported such a firm conclusion. First, it was only for phosphorus. Unlike nitrate, there is a reversible buffering mechanism which means that a significant part of any additional phosphorus inputs would be expected to be adsorbed onto suspended particulate matter, reducing the change in dissolved concentrations observedcxli, and making phosphorus a relatively insensitive indicator. Second, nutrient ratios at these offshore sites suggest that nitrogen is more likely to be limiting than phosphorus. Third, the overall analysis actually indicated that the winter means “show an increasing trend of around 20% over the period 1935–89”. Only when this data was subdivided into monthly intervals did the trend fell below the level of statistical significance. Yet this was the aspect that the UK administration chose to emphasise. One explanation could indeed be that the overall result was simply the result of a temporal bias in the date at which samples were taken from 1935 to 1989, resulting in a spurious increasing trend. But it may simply be that, by sub- dividing the information, any trend was overwhelmed by statistical noise resulting from too little data in each interval. The account in the sub-regional reports appears to note concerns about this procedure, but the necessary information was not provided to pursue this aspect further here.

Fourth, and most crucially, inspection of the map of the data used show that the analysis includes virtually no data for English coastal waters (ICES sector 3b), and indeed is not even confined to the UK off-shore sector, but extends throughout the southern North Sea, including the outer Continental Coastal Zone. Any conclusion of no change thus contradicts the vast bulk of evidence (cf. Fig 3.19 of the overall Quality Status Report) which provides strong support for a change in phosphorus concentrations in this area, particularly in the southern portion of the southern North Sea in both UK and continental waters, although with a greater change, as to be expected, in continental waters. This conclusion is reinforced by the recent ERSEM simulation, described earlier, of the development of eutrophication since 1955cxxvii. For these four reasons the UK counter-argument should be discarded.

Similarly, while Howarth et al. (1993) argued that “the total winter loading of nutrients in the southern North Sea is dominated by regeneration rather than the supply of ‘new’ nutrients from the rivers, atmosphere or oceans”cxlii, it is clear, as Tett and Walne (1995) point out, that the “regenerated nutrients must themselves have come from somewhere. In the long term, mean concentrations in the region must be the result of a balance between inputs of new nutrients from rivers and the atmosphere, and losses by burial or denitrification in the sediment, and dilution by oceanic inflows.”

German Bight and Skagerrak

On leaving the Oyster Grounds, some water from the UK coast will reach the German Bight. One estimate is that 6.6 million tonnes of inorganic material from English coastal waters is deposited each year in the German Bight which is, along with the Skagerrak, the main depositional area for North Sea material (Dyer & Moffet (1993), in Lohse et al. (1995)cxxxvi). Yet in relative terms this is a minor contribution, and the 1993 Sub Regional report for the German

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 141 Bightcxliii, (co-authored by Denmark & Germany) concluded that UK coastal waters are (typically) of secondary importance at the southern boundary of the area. More normally, UK water briefly enters the northern margin, on a track toward the Skagerrak.

When this nutrient rich water from the southern North Sea reaches the southern coast of the Skagerrakcxliv it is typically mixed and diluted with Atlantic water, and the nitrate level falls to 5–20 µM l-1. Heilmann et al. (1991) were unable to identify a trend in nitrate concentration off the north-west coast of Denmark between 1980–1990 (although this may be too short a period to expect this to emerge from inter-annual variation) and noted that nitrate concentrations are only occasionally higher than that recorded in the northern North Seacxlv.

Compared to the German Bight to the south, and the Kattegat to the east, little work had been carried out on average phytoplankton levels in the open Skagerrak – that most relevant area to the consideration of the impact of UK- sourced nutrients. Instead it is clear that the major concerns related to eutrophication in the Skagerrak are two-fold: the occasional pulses of nutrient rich surface water that cause disproportionate effects to both the natural environment and human concerns and, second, the deposition of large amount of organic material sourced from throughout the southern North Sea which settle in the deeper parts of the Skagerrak which thus acts as the North Sea’s “dustbin”cxliv.

An example of the former was the Chrysochromulina polylepis bloom of April 1988 (the most costly to date, due to the associated death of numerous Norwegian farmed salmon). According to the Sub-Regional Report this was due to “A large body of water with high nitrate content (maximum concentration in the northern Kattegat close to 20 µM l-1), relatively low phosphate content and virtually depleted silicate content ... [which] was identified as originating from the southern North Sea”.cxliv It concludes that such events “have been a regular feature of recent years”.

The deposition in the deeper parts of the Skagerrak of large amounts of organic material means that the organic carbon content of the silt is of the order of 3%, compared to a range in values for the southern North Sea of 0.06– 1.3%. The Skagerrak would always have had elevated levels, but it is clear that major changes have occurred at some time between 1914 (when a classic and detailed study of the Skagerrak was made) and 1985cxlvi. Mean total benthic biomass had increased from 74 to 131 g wet weight m2, and while in 1914 biomass decreased linearly with depth, this relationship had disappeared by 1985. Different groups of organisms had responded in different ways, with echinoderms (e.g. brittlestars, starfish, urchins) and annelids (worms) increasing respectively from 30 to 60, and from 15 to 38 g wet weight m2. These represent a major change in community structure, and the increase in biomass links it unequivocally to eutrophication. Unlike other sites showing related effects, such as the Kattegat and the German Bight, persistent local eutrophication has not occurred. Instead the cause of the

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 142 benthic change is unequivocally the deposition of material originating from both sides of the southern North Sea.

Designation under the Directives

In summary, the eutrophic status of the continental margin of the North Sea is not disputed by any North Sea government, including that of the UK. There are also good grounds for regard the Oyster Grounds as being eutrophic. The status of the Dogger Bank is more controversial. The balance of probabilities is that the phytoplankton biomass has increased throughout the entire southern North Sea during this century and, as discussed earlier, eutrophic effects in the northern Sea cannot be ruled out, although the characteristics will be different from those further south.

This was accepted by all North Sea governments in para. 31 of the Esbjerg 1995 Ministerial Declaration, which states that the measures for Sensitive Areas and NVZs will be required throughout the North Sea and its catchment, unless ‘comprehensive scientific studies’ demonstrate that nutrient inputs do not cause or contribute to eutrophication within the North Sea. The UK negotiated an ambiguous footnote, to which France acceded, which the UK clearly believes maintains the status quo, of no UK commitment to reduce nutrient inputs. While this may have been the intent of the UK, it is not what the footnote states.1 Ultimately however the Declaration is not a legally binding document even if it provides an insight into the stance of the UK administration in 1995.

Even if the North Sea is accepted to be eutrophic, as scientifically defined, these leaves three outstanding issues with regard to the Directives. Is the eutrophication ‘undesirable’ in the terms of the Directives definition? Does the UK contribute nutrients to any eutrophic areas in the North Sea? And what is the magnitude of that contribution?

‘Desirable’ eutrophication This question arises because, although eutrophication clearly affects biodiversity and habitats, some (Dutch) fisheries

1 the full text of Paragraph 31 of the Esbjerg Ministerial Declaration and the accompanying footnote is: “31. Therefore the Ministers AGREE to remain committed to reach the reduction targets set by the previous Conferences and to strengthen the implementation of measures as soon as possible. Fundamental elements in fulfilling these goals in the EU and European Economic Area are, inter alia,: i) to apply in the North Sea and its catchment the measures for sensitive areas under the Urban Waste Water Directive and to apply the measures for vulnerable zones under the conditions of the Nitrates Directive, including the criterion of contribution to pollution as mentioned in Article 3 of the Nitrates Directive†. These measures will be implemented for the whole North Sea and its catchment, except for those parts of the North Sea where comprehensive scientific studies, to be delivered by 1997, demonstrate to the satisfaction of the Committees set up under the respective Directives or the relevant European Economic Area body that nutrients inputs do not cause eutrophication effects or contribute to such effects in other parts of the North Sea. It is expected that these measures will, in newly identified areas, be applied as soon as technically possible after 1998; ii) full implementation of Council Directive 91/271/EEC on Urban Waste Water Treatment in accordance with the timetable stipulated therein or as amended in the future; and iii) action to achieve the reduction for nitrate losses from agriculture under the national action plans required by Council Directive 91/676/EEC. These states will take complementary action necessary to meet the commitment in coordination with these action plans. In parallel, Member States to EU will endeavour to optimise the application of existing EU wide provisions, i.e. Regulation 2079/92 on agri-environmental measures and Regulation 1756/92 on set-asidde schemes, to this end.

The accompanying footnote reads:† France and the United Kingdom consider that Urban Waste Water Treatment and Nitrates Directive, together wit the OSPAR Convention 1992 provides the protection for the North Sea that is needed in respect of this proposal and will enable significant further improvements to be made; and consider that this proposal adds nothing to what will be achieved by them fulfilling their obligations under these Directives.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 143 scientists have argued that eutrophication has enhanced the productivity of the North Sea fisheries. They regarded eutrophication as desirable, and that the nutrient reduction measures will reduce this productivity.

There are three counter-arguments to this. First it appears that much of the increase in phytoplankton biomass is via an increase in Phaeocystis. Species in this genera form colonies encapsulated in a jelly and appear to be unpaleable to many species of zooplankton, the next link in the food web, although they are eaten by some species when the colonies break up. A low-level debate regarding the food-value of Phaeocystis has continued in scientific circles for some years. However the ERSEM collaboration – involving many of the relevant experts – in their ecosystem model of the North Sea, created a catagory of ‘inedible phytoplankton’ to represent Phaeocystis, and this can be regarded as representing the current balance of opinion.

The second counter-argument is that toxic blooms, and those of species such as Chrysochromulina, which also appear to be enhanced by nutrient enrichment, impose a significant cost on parts of the fishing industry. The third is that the fundamental problem underlying declining fisheries yields is the failure of fisheries management. If this is resolved then yields will increase, and that this is the more appropriate and certain mechanism.

Does the UK contribute to North Sea eutrophication?

If the relevant question, requiring action under the Directives, is set in qualitative terms – does the UK make any contribution to North Sea eutrophication? – then the answer is an unambiguous ‘yes’. UK sourced nutrients enter areas of the North Sea that are accepted, even by the UK, as suffering from the effects of eutrophication, such as the continental coastal zone and the Skagerrak.

However, on those grounds it might be argued that even some Mediterranean EU States are contributing to North Sea eutrophication – Portugal and Spain via ocean currents, and perhaps even Greece via atmospheric deposition under certain meteorological conditions. Does this mean that their territories, too, are required to be declared Sensitive Areas and Nitrate Vulnerable Zones on the basis of North Sea eutrophication?

If some element of proportion is to be incorporated into the assessment, then the UK’s contribution to specific eutrophic areas needs to be quantified at least to some degree. In technical terms this should be relatively simple. Computer models, of which ERSEM is the most sophisticated, in principle make it easy to determine the source of the nutrients (in normal and exceptional conditions) for any area of the North Sea. In the course of preparing this report the principle researchers of the eutrophication elements of the ERSEM model were contacted. It came as some surprise to find that they were unable to provide this information because the UK authorities had refused to release data on UK nutrient inputs to the ERSEM group, on the supposed basis that the data were unreliablecxlvii.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 144 However in the publications associated with the ERSEM model, some estimate of the contribution of the Thames and Humber has been made for the North Sea as a wholecxxvii. Detailed statistics were used for the continental rivers: for the UK recourse had to be made to the limited information contained in the 1993 Quality Status Report, and associated documentation. From inspection of the graphs of river nutrient trends, it appears that an assumption underlying these calculations is that the UK, not being committed to implementing 50% reductions, will not have been reduced nutrient levels to the extent expected for the major continental rivers.

Dissolved inorganic nitrogen riverine inputs are calculated to have reached a peak in 1987 of 950,000 tonnes (68 giga1 moles, GM N), with the Thames making up approximately 3%, and the Humber 6%, of the total. By the end of the sequence, in 1993, this had fallen to 41 GM, principally via reductions in inputs from the Elbe, Meuse and Rhine. This will include reductions due to control measures and due to reduced rainfall during this period, which (temporarily) reduces nitrogen inputs. In the absence of detailed information for the UK rivers inputs from the Thames and Humber were presumed to have remained relatively constant. As a result the percentage contribution of the Thames and Humber in 1993 was 6 and 12% of the total respectively. For dissolved phosphate phosphorus, the peak in inputs was earlier, in 1981, when it reached 58,000 tonnes phosphorus, or 2 GM P. The Thames and Humber made up 6 and 10% of this total. By 1993 the total load was estimated to have fallen to 0.8 GM P, but the relative contribution of the Thames and the Humber had grown, to 15 and 22% respectively.

One way of assessing the UK contribution is on a per capita basis. For example the Humber catchment human population, 11 millionxix, is some 6.7% of the total population of 164 million living within the entire North Sea catchmentxxvi. On this basis, even without placing much weight on the apparent relative increase in UK loadings, the UK appears to be contributing more than average to the overall North Sea nutrient burden from rivers. Given prevailing wind directions it is also likely that the UK contributes more than average to the atmospheric deposition of nitrogen. If the North Sea as a whole is regarded as undergoing eutrophication, on this basis the UK is required to implement the measures required for Sensitive Area and Nitrate Vulnerable Zones throughout its North Sea catchment.

With regard to specific areas, nutrients from the major continental sites and those of the UK have a similar track length to reach the Skagerrak. It may be reasonable to suppose that the UK contributes to the seabed enrichment of the Skagerrak approximately in proportion to the riverine inputs. It may be relatively simple to refine this estimate using the ERSEM model. The UK contribution to the continental coastal zone is likely to be considerably less, and that to the Oyster Grounds and Dogger Bank, considerably more, than the per capita average. In addition there are other off-shore sites, such as the

1 giga: billion, 109

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 145 Silver Pit, which may have been significantly affected by UK inputs but which so far appear to have escaped attention.

Subject to some of these minor clarifications the case for the UK to implement Sensitive Area and NVZ status for its North Sea catchment appears overwhelming.

8.2 OTHER OFFSHORE AREAS

Without the stimulus of the North Sea Ministerial Conference, there has been far less research on offshore nutrient trends and effects in areas other than the North Sea. Nevertheless recently published research has now demonstrated significant and unambiguous eutrophication in at least some areas.

8.2.1 Irish Sea

A paper in press at the time of writing, Allen et al.cxlviii, based on long term monitoring in the northern Irish Sea, demonstrates major and unambiguous changes in nutrient concentrations between 1955 and the early 1990s, and a more varied but still statistically significant increasing trend of phytoplankton.

Chemical profile

The sampling site is at the tip of the Isle of Man, on the outer edge of the embayment between the headlands of the Lleyn Peninsula in Wales and the Mull of Galloway, Scotland. Between 1960 and 1984 the median January- February TON virtually doubled, from ca. 5 to 8 µM l-1, in a very tight increasing trend. While the absolute levels are far lower than the classic inshore example of the German Bight (annual means from ca. 140 µM in 1962 to 250 µM in 1992cxliii) the relative change is virtually identical. The winter phosphorus concentrations also showed a marked and statistically significant increasing trend, from ca. 0.5 µM in 1955 to ca. 0.85 µM in the late 1970s, then remaining at or around this level until the end of the time series in 1992. Again this is similar to the pattern in the German Bight, where phosphorus concentrations increased in the 1960s and early seventies, levelling off at approximately double the initial annual concentration of ca. 0.5 µM (when the winter peak was ca. 1.0 µM)cxxii.

Biological Effects

Irish Sea chlorophyll-a levels over the period monitored, between 1965 and 1992, showed a significant (but more noisy) increases in May-June (to maximum levels of ca. 5 µg l-1; again less than the peak values observed in the North Sea continental coastal zone), but not during any other part of the year. Nutrient levels reached their minimum during June and July, and the chlorophyll increase therefore occurred before nutrients reached their minimum levels. Allen et al. speculated that phytoplankton growth continued into the summer months, but was masked by grazing pressure as the

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 146 zooplankton responded to the increase. The nutrient pattern, with nitrate showing no increasing trend from March to June, but an increase in phosphorus during this period, suggests that nitrate is the limiting nutrient (as would the approximate N:P ratio of 10:1), and this is to be expected for an off-shore site.

The circulation pattern in this part of the Irish Sea is usually from south to north, but can be variable (see also the relevant sections of the Nationwide Review). However it is impossible to ignore the proximity of the site to north- west England, the largest centre of population in the Irish Sea catchment. The apparent problems in Liverpool Bay have already been noted. A gyre is known to develop just west of the Isle of Man sampling sitecxlix, which can entrain water from the UK coast for many months, finally to be released the following winter. It therefore has to be assumed that the source of the nutrients is anthropogenic, and that while some input from Ireland is likely to occur, the bulk will come from the UK.

Designation under the Directives

Inputs from both sewage treatment plants, from industry, and from agriculture can be assumed to be present in significant amounts. These results make it highly likely that, had long-term monitoring been carried out in the inner waters of this embayment, similar trends, but at higher concentrations, would have been detected; indeed it appears inconceivable that circumstances could be otherwise. If this eutrophication is regarded as ‘undesirable’ (and to do otherwise would mean the Directives were being interpreted inconsistently compared to the North Sea) it now appears inescapable that Sensitive Area and NVZ status should now be applied at least to the catchment area of the UK embayment stretching from the Lleyn Peninsula in the south to Mull of Galloway in the north.

Given the marked nature of the change in this relatively remote part of the Irish Sea – the only site where such information is available, or at least has been published – it is very likely that analogous changes will have occurred elsewhere in the Irish Sea, although the absolute levels may be less in other offshore areas. At the very least the burden of proof now rests on any authority wishing to assert the absence of eutrophication, and of whom it would now be reasonable to expect a substantial case to justify the continued absence of control measures.

8.2.2 English Channel

Nutrient concentrations were routinely sampled in the western English Channel approximately 40 km SSW of Plymouth between 1930 and 1987cl when monitoring was discontinued. This area could be expected to be predominantly influenced by relatively pristine Atlantic water, although it is within a mixing area for coastal and Channel waters.

There were no obvious trends in phosphorus over this period, which typically varied seasonally between virtually zero and sampled peaks of 0.4–0.6 µM l-1

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 147 P (sampling was not continuous, so these should not be taken as the actual peaks). The same was true of nitrate, although this was measured over a shorter period, from 1974–87. During that time concentrations varied seasonally between near-zero and sampled peaks usually less than 10 µM. Thus there was no evidence here of the increasing trends detected in the North and Irish Seas. This was to be expected. However there were transient peaks of phosphate, which appeared more frequently, and showed greater amplitude, at 70 m depth than at 5 m. Nitrate did not display similar peaks, and there was no data on ammonium levels. One immediate suspect was sewage sludge from Plymouth, dumped in the English Channel during this period. But the site was over 25 km distant, and the peaks were only observed in summer, which is difficult to explain. Similarly, the authors were unconvinced that the anomalies could be explained by coastal water impinging on the site. They speculated that it might be the result of decay of the sedimented spring phytoplankton bloom, or of Phaeocystis, but the matter was left unresolved.

On this basis there is no evidence that the eutrophication problems encountered in south-west English estuaries extend offshore to affect the Western Channel. So far as is known, there are no equivalent data sets for offshore sites in the eastern English Channel, where anthropogenic influences are more likely to occur.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 148 9 REFERENCES

i Anon (1997). Nitrates Directive (91/676/EEC) – The Ythan Catchment and Estuary. November 1997. SEPA, November 1997. ii http://www.sepa.org.uk/pressrel/sepapr4797.htm iii Pugh, K. (1998) Water quality and aquatic biology of the River Ythan. pp. 150–163 in The Ythan: A Festschrift for George Dunnet. (ed. M. L. Gorman). Aberdeen University Department of Biology. iv Raffaelli, D. (1998). Community ecology of the Ythan Estuary. pp. 138–149 in The Ythan: A Festschrift for George Dunnet (ed. M. Gorman). University of Aberdeen Biology Department, Aberdeen. v Raffaelli, D. (in press b). Impact of catchment land-use on an estuarine benthic food web. In: NATO Workshop on Ecology 1997; A disturbance of Benthic Systems. (eds. J. Grey & W Ambrose) vi Balls, P. W., A. Macdonald, K. Pugh & A. C. Edwards (1995). Long-term nutrient enrichment of an estuarine system: Ythan, Scotland (1958–1993). Environmental Pollution 90, 311–321. vii Balls, P. W. (1994). Nutrient Inputs to Estuaries from Nine Scottish East Coast Rivers; Influence of Estuarine Processes on Inputs to the North Sea. Estuarine, Coastal and Shelf Science 39, 329–352. viii pers. obs. ix Raffaelli, D., S. Hull, & H. Milne (1989). Long term changes in nutrients, weed mats and shorebirds in an estuarine system. Cal. Biol. Mar. 30, 259– 270. x Raffaelli, D., J. Limia, S. Hull, & S. Pont (1991) Interactions between the amphipod Corophium volutator (Pallas) and macroalgal mats on estuarine mudflats. Journal of the Marine Biological Association of the UK 71, 899–908. xi Raffaelli, D. (in press a). Nutrient enrichment and trophic organisation in an estuarine food web. In: Symposium on Marine Benthos (ed. J Marques). xii Raffaelli, D., J. Raven & L Poole (in press). Ecological impact of green macroalgal blooms. Oceanography and Marine Biology: An Annual Review, 36; 000–000. xiii Raffaelli, D., P. Balls, S. Way, I. Paterson, S. Hohmann & N. Corp (submitted). Eutrophication-related trends in the ecology of the Ythan estuary, Aberdeenshire, Scotland. Submitted to Aquatic Conservation, July 1998. xiv Valiela, I, K. Foreman, M. LaMontagne, D. Hersh, J. Costa, P. Peckol, B. DeMeo-Anderson, C. D’Avanzo, M. Babione, C. Sham, J. Brawley & K. Lajtha (1992). Couplings of watersheads and coastal waters: Souces and consequences of nutrient enrichment in Waquoit Bay, Massachusetts. Estuaries 15, 443–457. xv Ménesguen, A. & J-Y Piriou (1995). Nitrogen loadings and macroalgal (Ulva sp.) mass accumulation in Brittany (France). Ophelia 43, 227–237. xvi North East River Purification Board (1993). Nitrates Directive (91/676/EEC) - The Ythan Catchment and Estuary. NERPB TR 93/1. April 1993. Now available from SEPA, the successor to NERPB. xvii Scottish Office. Earl of Lindsay, answer to a Parliamentary Question from Lord Lyell, 24 January 1996.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 149 xviii Scottish Office press release, dated 29 September 1998. “No further nitrate designations at present”. xix Anon (1993). The Quality of the Humber Estuary (1980–1990). National Rivers Authority, Bristol. 108 pages. xx Anon. (1995). Sea Vigil Water Quality Monitoring: The Humber Estuary 1992–1993. National Rivers Authority, Peterborough, June 1995. xxi Anon. (1996). Sea Vigil Water Quality Monitoring: The Humber Estuary 1994. National Rivers Authority, Peterborough, February, 1996. xxii Anon. (1998). Sea Vigil Water Quality Monitoring: The Humber Estuary 1995. Environment Agency, Peterborough, January 1998. xxiii Anon. (undated) Humber Estuary: Quality Report 1993, Second edition. Humber Estuary Committee of the National Rivers Authority. xxiv Anon. (undated) Humber Estuary: Quality Report 1994. Humber Estuary Committee of the National Rivers Authority. xxv Anon. (undated) Humber Estuary: Quality Report 1995. Humber Estuary Committee of the National Rivers Authority. xxvi North Sea Task Force (1993) North Sea Quality Status Report 1993. Oslo and Paris Commissions, London. p. 11. xxvii M. Justice, EA Willerby Office, pers. comm. xxviii Saunders, R.J., T. Jickells, S. Malcolm, J. Brown, D. Kirkwood, A. Reeve, J. Taylor, T. Horrobin, & C. Ashcroft. (1997). Nutrient fluxes through the Humber estuary. Journal of Sea Research 37, 3–23. xxix Salomons, W., B. L. Bayne, E. K. Duursma & U. Förstner (eds.) (1998). Pollution of the North Sea: An Assessment. Springer-Verlag, Berlin. xxx Anon. (1995) Progress Report: 4th International Conference on the Protection of the North Sea. Esbjerg, Denmark, 8–9 June 1995. Ministry of the Environment and Energy, Danish EPA, Copenhagen. xxxi Howarth, R. W. et al. (1996). Nitrogen cycling in the North Atlantic Ocean and its watersheds. Report of the International SCOPE Nitrogen Project. Biogeochemistry 35, 75–139. xxxii Wollast, R. (1988). The Scheldt Estuary. pp. 183–193 in Salomons, W., B. L. Bayne, E. K. Duursma & U. Förstner (eds.). Pollution of the North Sea: An Assessment. Springer-Verlag, Berlin. xxxiii Aston, S. R. (1983). Natural water and atmospheric chemistry of silicon. In Silicon Geochemistry and Biogeochemistry (ed. S. R. Aston). Academic Press, London, pp. 77–100. xxxiv Billen, G., M. Somville, E. de Becker and P. Servais (1985). A nitrogen budget of the Scheldt hydrographic basin. Netherlands Journal of Sea Research, 19, 223–230. xxxv Fichez, R., T. D. Jickells and H. M. Edmunds (1992). Algal blooms in high turbidity, a result of the conflicting consequences of turbulence on nutrient cycling in a shallow water estuary. Estuarine, Coastal and Shelf Science, 35, 577–592. xxxvi C. Ashcroft, Environment Agency Anglian Region, pers. comm. xxxvii Uncles, R. J., A. E. Easton, M. L. Griffiths, C. Harris, R. J. M. Howland, I. Joint, R. S. King, A. W. Morris & D. H. Plummer. (1998). Concentrations of suspended chlorophyll in the tidal Yorkshire Ouse and Humber Estuary. Science of the Total Environment. 0. 00–00.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 150 xxxviii Anon. (1995). LOIS Land-ocean interaction study. Newsletter 7. LOIS Office, Plymouth Marine Laboratory. xxxix Anon (1998) CASI image “Lower Humber estuary: 19th August 1996: Unsupervised classification of inter tidal areas.” Environment Agency National centre for Instrumentation and Marine Surveillance, Bath. xl N. Cutts, Institute of Estuarine and Coastal Studies, University of Hull, pers. comm. xli Anon (1994). Establishing the Nutrient Status of UK coastal waters: The JoNuS Programme. MAFF, Lowestoft. xlii Macrory, M. (1996). Court quashes Gummer’s decisions on Urban Wastewater Directive. ENDS Report 253, 46–47. xliii Anon. (1994) Wash Zone Report: A Monitoring Review. National Rivers Authority, Central Area, Brampton. July 1994. xliv Pritchard, D.E., S. D. Housden, G. P. Mudge, C. A. Galbraith & M. W. Pienkowsik (eds) 1992. Important bird areas in the UK including the Channel Islands and the Isle of Man. RSPB, Sandy. xlv Anon. (1995) Sea Vigil Water Quality Monitoring: The Wash 1992–1993. National Rivers Authority, Anglian Region, Peterborough. xlvi Anon. (1996) Sea Vigil Water Quality Monitoring: The Wash 1994. National Rivers Authority, Anglian Region, Peterborough. xlvii Rendell, A. R., T. M. Horrobin, T. D. Jickells, H. M. Edmunds, J. Brown & S. J. Malcolm (1997). Nutrient cycling in the Great Ouse estuary and its impact on nutrient fluxes to The Wash, England. Estuarine, Coastal and Shelf Science, 45, 653–668. xlviii Saunders, R., C. Klein & T. Jickells (1997). Biogeochemical nutrient cycling in the upper Great Ouse Estuary, Norfolk, UK. Estuarine and Coastal Shelf Science 44, 543–555. xlix Nedwell, D. B. & M Trimmer (1996). Nitrogen fluxes through the upper estuary of the Great Ouse, England: the role of the bottom sediments. Marine Ecology Progress Series, 142, 273–286. l Fichez, R., T. D. Jickells & M. M. Edmunds (1992). Algal blooms in high turbidity, a result of the conflicting consequences of turbulence on nutrient cycling in a shallow water estuary. Estuarine, Coastal and Shelf Science 35, 577–592 li Cooper, S. R. & G. S. Brush (1993). A 2,500-year history of anoxia and eutrophication in Chesapeake Bay. Estuaries 16, 617–626 lii S. Malcolm, MAFF Marine Labs, Lowestoft pers. comm. liii Trimmer, M. D. B. Nedwell, D. B. Sivyer & S. J. Malcolm (1998). Nitrogen fluxes through the lower estuary of the river Great Ouse, England: the role of bottom sediments. Marine Ecology Progress Series 163, 109–124. liv Joint, I & A. Pomroy (1993). Phytoplankton biomass and production in the southern North Sea. Marine Ecology Progress Series 99, 169–182. lv M. Yates, ITE Monk’s Wood, pers. comm. lvi North Sea Task Force (1994). North Sea Quality Status Report 1993. North Sea Subregion 5 Assessment Report (ed. H. Karup). Ministry of the Environment / Danish Environmental Protection, Copenhagen. lvii North Sea Task Force (1993). North Sea Quality Status Report 1993. North Sea Subregion 8 Assessment Report 1993. Norwegian State Pollution Control Authority (SFT). Scandinavian University Press, Oslo.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 151 lviii I. Patterson, Marine Conservation Officer, East Midlands Team, English Nature. pers. comm. lix Anon. (1998). Environmental Activities Report 1997. Anglian Water, Peterborough. lx Elliot, M., V. N. de Jonge, G.K.L. Burrell, M.W. Johnson, G. L. Phillips & T. M. Turner (undated). Trophic Status of the Ore/Alde, Deben, Stour and Colne Estuaries. Volume 1. Reports in Appied Marine Biology. The University of Hull. 109 pages. lxi P.J. Johnes, (1994). Modelling nutrient loading on the Ore/Alde and Deben estuaries, 1930–1990. Department of Geography, Univesity of Reading. NRA Research Contract. 33 pages plus appendices. lxii Sage, S., D. B. Nedwell & G.J.C. Underwood (1996–7). Sediment, water quality and phytobenthic interactions in the River Deben. Environment Agency Research Contract No 1206. Department of Biological Science, Univeristy of Essex. 85 pages. lxiii Anon. (1994). Wash Zone Report: A Monitoring Review. National Rivers Authority, Central Area, Brampton. July 1994. lxiv Anon. (undated) Humber Estuary: Quality Report 1994. Humber Estuary Committee of the National Rivers Authority. lxv Harris, G.P. (1986). Phytoplankton Ecology: Structure, function and fluctuation. Chsapman and hall, London. Fig 3.6, p. 60. lxvi Møhlenberg, F. (1995) Regulating mechanisms of phytoplankton growth and biomass in a sallow estuary. Ophelia 42, 239–256. lxvii Hywel-Davies, J. & Thom, V., supplimented by L. Bennett (1986) The Macmillan Guide to Britain’s Nature Reserves. Macmillan, London. 780 pages. lxviii Casey, H, S.M. Smith & R.T. Clarke. (1990). Trends and seasonaltiy in the nitrate concentrations and loads of the Bere Stream (Dorset) for the period 1966–1986. Chemical Ecology 4, 85–94. lxix V. Hackel, pers. comm. lxx Ladle, M. & D.F. Westlake (1995). River and stream ecosystems of Great Britain. pp. 343–388 in Ecosystems of the World 22; River and Stream Ecosystems. (eds C.E. Cushing, K.W. Cummins & G.W. Minshall) Elsevier, Amsterdam. lxxi Casey, H. (1975). Variation in chemical composition of the River Froam, England, from 1965 to 1972. Freshwater Biology 5, 507–514. lxxii Williams, P.J. LeB. (1980). Phytoplankton in Southampton Water. In The Solent Estuarine System. NERC Publications, Series C, No. 22, pp. 73–75. lxxiii Crawford, D. W., D. A. Purdie, A. P. M. Lockwood and P. Weissman (1997) Recurrent Red-tides in the Southampton Water Estuary Caused by the Phototrophic Ciliate Mesodinium rubrum. Estuarine, Coastal and Shelf Science 45, 799–812 lxxiv Soulsby, P.G., D. Lowthion, M. Houston & H.A.C Montgomery (1985). The role of sewage effluent in the accumulation of macroalgal mats on intertidal mudflats in two basins in southern England. Netherlands Journal of Sea Research 19, 257–263. lxxv Montgomery, H.A.C. & P.G. Soulsby (1980). Effects of eutrophication on the intertidal ecolgy of Langstone Harbour, U.K., and proposed control measures. Progress in Water Technology, 13, 287–94.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 152 lxxvi Memorandum, dated 19th August 1993 from Colin Reid, Pollution Control Officer NRA Southern Region, to Simon Leaf, EC Directives Scientist. lxxvii Anon (1993). The extent of eutrophication in Langstone Harbour. National Rivers Authority Southern Region, Technical Services Science Group. June 1993. Report Number DL/LH1/93. lxxviii Montgomery, H.A.C., P.G. Soulsby, I.C. Hart and S.L. Wright (1985). Investigation of a Eutrophic Tidal Basin: Part 2 – Nutrients and environmental aspects. Marine Environmental Research 15, 285–302. lxxix Balls, P. W., A. Macdonald, K. Pugh & A.C. Edwards (1995). Long-term nutrient enrichment of an estuarine system: Ythan, Scotland (1958–1993). Environmetnal Pollution 90, 311–321. lxxx Beddig, S., U. Brockmann, W. Dannecker, D. Körner, T. Pohlmann, W. Puls, G. Radach, A. Rebers, H-J. Rick, M. Schatzmann, H. Schlünzen & M. Schulz (1997). Nitrogen Fluxes in the German Bight. Marine Pollution Bulletin 34, 382–394. lxxxi Haynes, F. N. & Coulson, M. G. (1982). The decline of Spartina in Langstone Harbour, Hampshire. Proc. Hants Field Club & Arch. Soc. 38, 5– 18. lxxxii Lendertse, P.C. (1992). Veeeegetatieontwikkeling op de Boschplatt ban Terschelling tussen 1953 en 1990 in relatie tot stiksgofgehalten in de bodem. Vrije Universiteit, Amsterdam. 35 pages. Conclusions summarised in the Quality Status Report of the North Sea Subregion 10; The Wadden Sea – see next reference. lxxxiii Anon (1993). Quality Status Report of the North Sea. Subregion 10. The Wadden Sea. (eds. F. de Jong et al.) Common Wadden Sea Secretariat (CWSS), Wilhelmshaven, FRG. lxxxiv Schories, D. A. Albrecht & H. Lotze (1997). Historical changes and inventroy of macroalgae from Königshafen Bay in the northern Wadden Sea. Helgoländer Meeresuntersuchungen. 51, 321–341. lxxxv Valiela, I. et al. (1992). Couplings of Watersheds and Coastal Waters: Sources and Consequences of Nutrient Enrichment in Waquoit Bay, Massachusetts. Estuaries 15, 443–457. lxxxvi Court Stevenson, J. (1988). Comparative ecology of submersed grass beds in freshwater, estuarine and marine environments. Limnology & Oceanography 33, 867–893. lxxxvii Memorandum, dated 24th March 1993 from Mike Beard, Environmental Protection Officer NRA Southern Region, to Peter Bird, EC Directives Officer. lxxxviii Den Hartog, C. (1994). Suffocation of a littoral Zostera bed by Enteromorpha radiata. Aquatic Botany 47, 21–28. lxxxix Raffaelli, D. (1997). Community ecology of the Ythan estuary. In The Ythan: A festschrift for George Dunnet. (ed. M.L. Gorman). Aberdeen University Department of Zoology, pp.138–149. xc Wright, J. (1994). Water Quality Objectives in Important Marine Areas. WS Atkins Water for English Nature. Final Report February 1994. xci Alastair Burn, English Nature, pers. comm. (1995). EN internal document. Water Quality of estuaries and coastal waters – A summary and analysis of the BEC report for English Nature. xcii Jordan. M. B. & I. Joint (1998). Seasonal variation in Nitrate:phosphate ratios in the English Channel 1923–1987. Estuarine, Coastal and Shelf Science 46, 157–164.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 153 xciii Anon. (1995). Sea Vigil Water Quality Monitoring: The Wash, 1992–1993. National Rivers Authority, Anglian Region, Peterborough. xciv Anon. (1996). Sea Vigil Water Quality Monitoiring: The Wash 1994. National Rivers Authority, Anglian Region, Peterborough. xcv http://www.environment-agency.gov.uk/state_of_enviro/index.html Viewed 32 October 1998. xcvi North Sea Task Force (1993) North Sea subregion 3b Assessment Report 1993. Ministry of Agriculture, Fisheries and Food Fisheries Laboratory, Lowestoft. xcvii Anon. (1997). Sea Vigil Water Quality Monitoring: The Lincolnshire Coast, 1995. Environment Agency Anglian Region – Marine Section, Peterborough. xcviii Parsons, T. R, M. Takahashi & B. Hargrave (1984). Biological Oceanographic Processes. Third Edition. Pergamon Press, Oxford. Table 10, p. 48. xcix Anon. (1994). Urban Waste Water Treatment Directive 91/271/EEC. High Natural Dispersion Areas England and Wales - Index Map as at May 1994. Department of Environment, London. c Sholkovitz, E.R. (1979). Chemical and physical processess controlling the chemical composition of suspended material in the River Tay estuary. Estuarine and Coastal Marine Science 8, 523–545. ci Pugh, K.B. (1998) Water quality and aquatic biology of the River Ythan. pp 150–163 in The Ythan: A festschrift for George Dunnet (ed. M.L Gorman). Aberdeen University. cii Balls, P.W. (1992) Nutrient behaviour in two contrasting Scottish estuaries, the Forth and Tay. Oceanologica Acta 15, 261–277. ciii Letter of 7th October 1994, “Nitrate Vulnerable Zones” from Roger Crofts, Chief Executive, Scottish Natural Heritage to M. M. Cassie, Scottish Office Agricultural & Fisheries Department. civ Prichard, D.E., S. D. Housden, G. P. Mudge, C. A. Galbraith & M. W. Pienkowsik (eds) 1992. Important bird areas in the UK including the Channel Islands and the Isle of Man. RSPB, Sandy. cv Mathieson, S. & S. M. Atkins (1995). A review of nutrient enrichment in the estuaries of Scotland: impliations for the natural heritage. Netherlands Journal of Agricultural Science. cvi Muller, F.L.L., M. Tranter & P.W. Balls (1994). Distribution and transport of chemical constituents in the Clyde estuary. Estuarine, Coastal and Shelf Science 39, 105–126. cvii Clark, R. B. (1989). Marine Pollution. Second Edition. Clarendon Press, Oxford. cviii Lesley Smith, English Nature, Northumberland Office, pers. comm. cix Austin, M.C., J.B. Buchanan, H.G. Hunt, A.B. Josefson & M.A. Kendall (1991). Comparison of long-term trends in benthic and pelagic communities of the North Sea. Journal of the Marine Biological Association, 71, 179–190. cx North Sea Task Force (1993). North Sea Subregion 8 Assessment Report 1993. Norwegian State Pollution Control Authority, Oslo. cxi Hardy, F. G. S. M. Evans & M. A. Tremayne (1993). Long-term changes in the marine macroalgae of three polluted estuaries in north-east England. Journal of Experimental Marine Biology and Ecology 172, 81–92.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 154 cxii Sheahan, D., J. Thain & S. Bifield. (1996). Deployment of an algal bioassay for measuring the nutrient status of the UK North Sea from 1990 to 1993. Scientific Symposium on the North Sea Quality Status Report 1993, 18–21 April 1994, Ebeltoft. Proceedings. (eds. J. Andersen, H Karup, U.B. Nielsen), pp. 183–188. Ministry of Environment and Energy, Danish Environmental Protection Agency, Copenhagen. cxiii Bester, K., H. Hühnerfuss & B Neudorf (1996). On the distribution and impact of triazine herbicides in the North Sea. Scientific Symposium on the North Sea Quality Status Report 1993, 18–21 April 1994, Ebeltoft. Proceedings, (eds. J. Andersen, H Karup, U.B. Nielsen). pp. 102–104. Ministry of Environment and Energy, Danish Environmental Protection Agency, Copenhagen. cxiv Brunsden, D., R. Gardner, A. Goudie & D. Jones (1988) Landshapes. David & Charles, Newton Abbot. Plate 6.6, p. 138. cxv Tompsett, P.E. (1994) Helford river survey: Monitoring Report No. 4 for 1993. World-Wide Fund for Nature UK. Godalming. cxvi Jackson, R.H., P.J. le B. Williams, & I.R. Joint. (1987). Freshwater phytoplankton in the low salinity region of the River Tamar estuary. Estuarine, Coastal and Shelf Science 25, 299–311. cxvii Nienhuis, PH. (1992). Eutrophication, water management, and the functioning of Dutch estuaries and coastal lagoons. Estuaries, 15, 538–548. cxviii Irish Sea Study Group (1990). The Irish Sea: An Environmental Review. Part Two. Waste Inputs and pollution. Liverpool University Press. p. 40. cxix Jones, R. (1995) The effects of elevated nutrients on more oligotrophic estuarine ecosystems. pp. 17–21 in The impact of nutrients in estuaries: Proceedings of a workshop on 23 May 1995 (ed. D.B. Nedwell). University of Essex, R&D Interim Repoort 639/1/A. cxx Morris, A.W. (1988). The estuaries of the Humber and Thames. pp. 213– 224 in Pollution of the North Sea: An Assessment. (eds. W. Salomons, B.L. Bayne, E. K. Duursma & U. Förster). Springer-Verlag, Berlin. cxxi Allen, J.R., D.j. Slinn, T.M. Shammon, R.G. Hartnoll & S.J. Hawkins. (in press). Evidence for eutrophication of the Irish Sea over four decades. Limnology and Oceanography, 00, 000-000. cxxii Gerlach, S. A. (1988) Nutrients – an overview. pp. 147–175 in Environmental Protection of the North Sea (eds. P. J. Newman & A. R. Agg). Heinemann, Oxford. cxxiii Brockmann, U., G. Billen & W. W. C. Gileskes (1988). North Sea nutrients and eutrophication. pp. 348–389 in W. Salomons, B. L. Bayne, E. K. Duursma & U Förstner (eds) Pollution of the North Sea: An Assessment. Springer- Verlag, Berlin. cxxiv Pitcairn, C (ed.) (1994). Impacts of nitrogen deposition on terrestrial ecosytems. Report of the United Kingdom Review Group of Impacts of Atmospheric Nitrogen. Prepared at the request of the UK Department of Environment. ISBN 1 870393 22 8. cxxv Postma, H. (1978). The nutrient content of North Sea water: changes in recent years, particularly in the Southern Bight. Rapports et proces-verbaux des reunions, Conseil permanent international pour l’exploration de la mer 172, 350–357. cxxvi Kilham, P., & R. E. Hecky (1988). Comparative ecology of marine and freshwater phytoplankton. Limnology and Oceanography 33, 776–795. cxxvii Pätsch, J. & G. Radach (1997). Long-term simulation of the eutrophication of the North Sea: temporal development of nutrients,

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 155 chlorophyll and primary production in comparison to observations. Journal of Sea Research 38, 275–310. cxxviii Brockmann, U. H., R. W. P. H. Laane, & H. Postma (1990). Cycling of nutrient elements in the North Sea. Netherlands Journal of Sea Research 26, 239–264. cxxix Law, C. S. & N. J. P Owens (1990). Denitrification and nitrous oxide in the North Sea. Netherlands Journal of Sea Research 25, 65–74. cxxx van Raaphorst, W., H. T. Kloosterhuis, A. Cramner, & K. J. M. Bakker (1990). Nutrient early diagenesis in the sediments of the Dogger Bank Area, North Sea: pore water results. Netherlands Journal of Sea Research 26, 25–52. cxxxi Lohse, L., J. F. P. Malshaert, C. P. Slomp, W. Helder & W. van Raaphorst (1993). Nitrogen cycling in North Sea sediments: interaction of denitrification and nitrification in offshore and coastal areas. Marine Ecology Progress Series 101, 283–296. cxxxii Tett, P. & A. Walne (1995). Observations and simulations of hydrography, nutrients and plankton in the southern North Sea. Ophelia 42, 371–416. cxxxiii Joint, I & A Pomroy (1993). Phytoplankton biomass and production in the southern North Sea. Marine Ecology Progress Series 99, 169–182. cxxxiv Simpson, J. A. & E. S. C. Weiner (1989) Oxford English Dictionary, Second Edition. Clarendon Press, Oxford cxxxv Krönke, I. (1990). Macrofauna standing stock of the Dogger Bank. A Comparison: II. 1951-1953 versus 1985-1987. Are changes in the community of the northeastern part of the Dogger Bank due to environmental changes? Netherlands Journal of Sea Research 25, 1898–198. cxxxvi Lohse, L., J. F. P. Malschaert, C. P. Slomp, W. Helder & W. van Raaphorst (1995). Sediment-water fluxes of inorganic nitrogen compounds along the transport route of organic matter in the North Sea. Ophelia 41, 173–197. cxxxvii Peeters, J. C. H., F. J. Los, R. Jansen, H. A. Haas, L. Peperzac & I de Vries (1995). The oxygen dynamics of the Oyster Ground, North Sea. Impact of eutrophication and environmental conditions. Ophelia 42, 257–288. cxxxviii Ruardij, P., H. Van Harne & H. Ridderinkhof (1997). The impact of thermal stratification on phytoplankton and nutrient dynamics in shelf seas: a model study. Journal of Sea Research 38, 311–331. cxxxix North Sea Task Force (1993). North Sea subregion 3b Assessment Report 1993. Ministry of Agriculture, Fisheries and Food Fisheries Laboratory. Lowestoft. cxl North Sea Task Force (1993). North Sea subregion 7b Assessment Report 1993. Ministry of Agriculture, Fisheries and Food Fisheries Laboratory. Lowestoft. cxli Billen, G., C. Lancelot & M. Meybeck, (1991). N, P and Si retention along the aquatic continuum from land to ocean. In R. F. C. Mantoura, J.-M. Martin & R. Wollast (eds.) Ocean Margin Processes in Global Change, pp 19–44. Wiley, London. cxlii Howarth, M. J., K. R. Dyer, I. R. Joint, D. J. Hydes, D. A. Purdie, H. Edmunds, J. E. Jones, R. K. Lowry, T. J. Moffat, A. J. Pomroy & R. Procter (1993). Seasonal cycles and their spatial variability. Philosophical Transactions of the Royal Society of London A343. 383–403. cxliii North Sea Task Force (1993). North Sea Subregional Assessment Report 5. Danish Environmental Protection Agency / North Sea Task Force / Bundesamt für Seeschiffahrt und Hydrographie. Copenhagen.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 156 cxliv North Sea Task Force (1993). North Sea Subregional Assessment Report 8. Norwegian State Pollution Control Authority / Scandinavian University Press, Oslo. cxlv Heilmann, J. P., D. S. Danielssen & O. V. Olsen (1991). The potential of the Jutland Coastal Current as a transporter of nutrients to the Kattegat. ICES CM 1191/C:34. cxlvi Heip, C. (1995). Eutrophication and Zoobenthos dynamics. Ophelia 41, 113–136. cxlvii Radach, G. (1998). personal communication by email, 7th September 1998. cxlviii Allen, J. R., D. J. Slinn, T. M. Shammon, R. G. Hartnoll & S. J. Hawkins (in press). Evidence for eutrophication of the Irish Sea over four decades. Limnology and Oceanography 00, 000-000. cxlix Hill, A. E., J. Brown & L. Fernand (1997). The summer gyre in the western Irish Sea: shelf sea paradigms and management implications. Estuarine, Coastal and Shelf Science 44, 83–95. cl Jordan, M. B., and I. Joint (1998). Seasonal variation in nitrate:phosphate ratios in the English Channel 1923–1987. Estuarine, Coastal and Shelf Science 46, 157–164.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI III - 157 Annex A

Maps Map A The Ythan Catchment Map B The Ythan Estuary Map C The Humber Catchment Map D The Humber Estuary Map E The Wash Catchment Map F The Wash Estuary Map G The Suffolk Catchment Map H The Suffolk Estuaries Map I The Solent Catchment Map J The Solent Embayments Map K Porthsmouth, Langstone and Chichester Harbour Map L The Thames Estuary Map M Scotland - Eastern Coast Map N Scotland - Western Coast Map O England - North East Map P England - Humber to the Thames Map Q South-Eastern England (Thames to the Solent) Map R South-Western England (Solent to the Severn) Map S The Welsh Coast Map T The Solent Embayments Map U Offshore Effects

FINAL REPORT

European Commission, DG Environment

Verification of Vulnerable Zones Identified under the Nitrates Directive and Sensitive Areas Identified under the Urban Wastewater Treatment Directive

NORTHERN-IRELAND

March 2000

Environmental Resources Management 6 Merrion Square, Dublin 2, Ireland Telephone 00 353 1 662 0499 Fax 00 353 1 676 9502 Email [email protected] http://www.ermuk.com FINAL REPORT

European Commission, DG Environment

Verification of Vulnerable Zones Identified under the Nitrates Directive and Sensitive Areas Identified under the Urban Wastewater Treatment Directive

March 2000

Reference 5765

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INTRODUCTION

This Final Report details the preliminary findings of a project carried out on behalf of the European Commission - DG Environment entitled:

Verification of the Vulnerable Zones Identified Under the Nitrates Directive and Sensitive Areas Identified Under the Urban Waste Water Treatment Directive

Contract B4-3040/98/000705/MAR/D1

This report presents the results of the investigations carried out in Northern- Ireland. The results of the investigations are summarised below.

IMPLEMENTATION OF DIRECTIVE 91/271/EEC AND DIRECTIVE 91/676/EEC

1. Directive 91/271/EEC

The interpretation and implementation of the UWWTD in Northern Ireland follows that of other parts of the UK, and the reader is referred to the UK report for the general background to implementation.

(a) Sensitive Areas

Two freshwater bodies have been identified as Sensitive Areas under the Urban Waste water Treatment Directive:

• Lough Neagh • Lough Erne

No estuarine or coastal Sensitive Areas have been established in Northern Ireland. No candidate assessments have been seen; it is not known if any have been carried out. Prime candidates for examination regarding eutrophication would be the enclosed loughs – Lough Foyle, Larne Lough, Belfast, Strangford and Carlingford Loughs.

(b) Less Sensitive Areas

Three less sensitive areas (HNDAs, Areas of High Natural Dispersion) have been established in Northern Ireland. These are Lough Foyle, Belfast Lough and Carlingford Lough respectively. These serve Londonderry/Derry, Belfast and Newry respectively. As with other parts of the UK the designation of HNDAs appears highly questionable.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT I 2. Directive 91/676/EEC

The interpretation and implementation of the UWWTD in Northern Ireland follows that of other parts of the UK, and the reader is referred to the UK report for the general background to implementation.

Vulnerable Zones

No Vulnerable Zones were identified in the round of site designations.Based on groundwater quality data dated collected in recent years, three Vulnerable Zones were identified in January 1999. These are:

• Cloughmils; • Comber (1); • Comber (2).

AREAS REQUIRING DESIGNATION UNDER DIRECTIVE 91/271/EEC AND DIRECTIVE 91/676/EEC

In relation to the Urban Waste Water Treatment Directive, the analysis shows that a number of marine/coastal waters do qualify for designation as Sensitive areas. These areas are:

• Lough Foyle; • Bann Estuary; • Belfast Lough; • Carlingford Lough.

In relation to the Nitrates Directive, the analysis shows that the number of samples analysed for some groundwater sites was very low and often is too low for any meaningful comparisons to be carried out. However, two sites have been identified as having elevated nitrate concentrations and requiring designation under the Nitrates Directive. These are:

• Belaghy; • Buckna

Table 1 Areas warranting Sensitive Area and/or Vulnerable Zone Designation

Water Body Required Designation Criteria SA NVZ

Lough Foyle ü ? Eutrophication Bann Estuary ü - Eutrophication Belfast Lough ü - Eutrophication Carlingford Lough (inner estuary) ü - Eutrophication Strangford Lough ? ? Eutrophication Belaghy - ü Nitrate concentrations Buckna - ü Nitrate concentrations

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT II 1 DESIGNATION PROCESS IN NORTHERN-IRELAND

1.1 INTRODUCTION

Unlike the Republic no attempt appears to have been made in Northern Ireland to systematically organise monitoring and compile data with regard to implementation of these Directives at estuarine and coastal sites. Nevertheless some information was made available. Together with that from the Republic, and that already available for Scotland, Wales and England, this allowed a good picture to be build up of the relative condition of individual sites within the island of Ireland to be set within an international context.

1.2 IMPLEMENTATION OF DIRECTIVE 91/271/EEC

The interpretation and implementation of the UWWTD in Northern Ireland follows that of other parts of the UK, and the reader is referred to the UK report for the general background to implementation.

Sensitive Areas

Two freshwater bodies have been identified as Sensitive Areas under the Urban Waste water Treatment Directive:

• Lough Neagh • Lough Erne

No estuarine or coastal Sensitive Areas have been established in Northern Ireland. No candidate assessments have been seen; it is not known if any have been carried out. Prime candidates for examination regarding eutrophication would be the enclosed loughs – Lough Foyle, Larne Lough, Belfast, Strangford and Carlingford Loughs. Strangford Lough (at least) is of significant wildlife interest and may qualify on the basis of the need to conform with the requirements of other Directives.

Less Sensitive Areas

Three less sensitive areas (HNDAs, Areas of High Natural Dispersion) have been established in Northern Ireland. These are Lough Foyle, Belfast Lough and Carlingford Lough respectively. These serve Londonderry/Derry, Belfast and Newry respectively. As with other parts of the UK the designation of HNDAs appears highly questionable.

Normal Areas

Information on STP discharges to other areas in Northern Ireland is still awaited. However it can be expected that most discharges will be under 15,000 p.e. and thus facing a 2005 deadline for secondary treatment.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 1 1.3 IMPLEMENTATION OF DIRECTIVE 91/676/EEC

The interpretation and implementation of the UWWTD in Northern Ireland follows that of other parts of the UK, and the reader is referred to the UK report for the general background to implementation.

Vulnerable Zones

No Vulnerable Zones were identified in Northern Ireland until January 1999. Based on groundwater quality data collected during the last few years, three Vulnerable Zones were identified in January 1999. These are:

• Cloughmils; • Comber (1); • Comber (2).

Although more detailed information about the designated areas was requested, nor further information could be obtained.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 2 2 THE SURFACE WATER AND GROUND WATER DATA ACQUIRED FROM NORTHERN IRELAND

2.1 METHODS

The surface water data for Northern Ireland was acquired from the UK Environment Agency in August 1998. This data set was reasonably complete, but the measurements and site names were located in different files. The groundwater data distributed by the EA was, however, impossible to analyse. Many site grid references were missing and some of the existing references located the sites in the Irish Sea. The groundwater data acquired in February is more comprehensive but many grid references are still missing and only a very small number of sites have been sampled with the frequency demanded by the Nitrates Directive.

In this section, we summarise the results of the analysis of all the data acquired for surface waters and groundwaters during the 1992 round of site designations. The methods used are the same as those described in the final report for England and Wales and all the ‘concentration’ maps have been annotated using the same colour coding. The chapter includes a list of sites containing very high concentrations of phosphate and some statistical information on the concentrations of nitrate recorded in waters that were either not georeferenced or were sampled at relatively infrequent intervals.

2.2 THE SURFACE WATER NITRATE CONCENTRATIONS RECORDED IN NORTHERN IRELAND

Table 1.1 shows the results of a re-analysis of all the nitrate data supplied by the EA from its ‘surface water’ database for 1992. The main problem with the data was the restricted seasonal coverage. In Northern Ireland, 37 % of the sites included in the original survey had been sampled on fewer than 12 occasions whereas the equivalent figure for England and Wales was 27%.

Table 1.1 The surface water nitrate results acquired during the 1992 round of site designations in Northern Ireland.

Total number of sites sampled 211 Number of sites with incorrect or incomplete Grid References 0 Number of sites sampled on fewer than 12 occasions 79 Number of sites included in the final analysis 132

The top panel in Fig. 1.1 shows the frequency distribution of the average concentration of nitrate and the lower panel the frequency distribution of the maximum concentration of nitrate recorded at all the sites included in the final analysis. At most sites, both the average and maximum concentration of nitrate was in the lowest (0 to 25 mg l-1) concentration range. A few sites had

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 3 maximum concentrations in the 25 to 40 mg l-1 range but no sites reached the 50 mg l-1 threshold specified in the Nitrates Directive.

Fig. 1.1 The average (top panel) and maximum (bottom panel) concentrations of nitrate measured at all surface water sites sampled at least twelve times in 1992

Mean N conc. (n>=12)

150

100

50

0 0-25 mg/l >25 - 40 >40 - 50 > 50 mg/l mg/l mg/l

Max. N conc. (n>=12)

150

100

50

0 0-25 mg/l >25 - 40 >40 - 50 > 50 mg/l mg/l mg/l

The colour-coded maps in Figures 1.2 and 1.3 show the average and maximum nitrate concentrations recorded at the same sites. The site with the highest recorded nitrate concentration (42 mg l-1) was situated on the Clogh River at Garryford Bridge. Several sites on the River Lagan had relatively high concentrations of nitrate but these were well below the 50 mg l-1 level specified in the Nitrates Directive.

2.3 THE GROUND WATER NITRATE CONCENTRATIONS RECORDED IN NORTHERN IRELAND

As mentioned in the previous section, recent data on groundwater quality have been used in Northern Ireland to identified three Vulnerable Zones (January 1999). However, these data were not available at the time of writing and the analysis has been based on the data which was provided by the authorities in 1998 and which was used in the first round of designations. Table 1.2 shows the results of the analysis of all the groundwater nitrate data acquired in 1998.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 4 Figure 1.2 Mean Nitrate Concentration

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 5 Figure 1.3 Maximum Concentrations

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 6 A very high proportion of the groundwater sites listed had incorrect grid references and could not be located on the regional map. Most of the remaining sites had only been sampled at infrequent intervals so only six sites could be included in our standard analysis.

Table 1.2 The ground water nitrate data acquired during the 1992 round of site designations in Northern Ireland.

Total number of sites sampled 56 Number of sites with incorrect or incomplete Grid 26 References Number of sites sampled on fewer than 12 occasions 24 Number of sites included in the final analysis 6

The top panel in Fig. 1.4 shows the frequency distribution of the average concentration of nitrate and the lower panel the frequency distribution of the maximum concentration of nitrate found at the selected sites. The number of frequently sampled sites is too small for any meaningful comparisons but it would appear that at least two sites should have been considered for designation in 1992.

Fig. 1.4 The average (top panel) and maximum (bottom panel) concentrations of nitrate measured at all the groundwater water sites sampled at least twelve times in 1992.

Mean N conc. (n>=12)

80

60

40

20

0 0-25 mg/l >25 - 40 >40 - 50 > 50 mg/l mg/l mg/l

Max. N conc. (n>=12)

60 50 40 30 20 10 0 0-25 mg/l >25 - 40 >40 - 50 > 50 mg/l mg/l mg/l

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 7 The two groundwater sites identified as having elevated nitrate concentrations were: Belaghy BH (DO47156) and Buckna BH (D204084). The colour coded maps in Figures 1.5 and 1.6 show the average and maximum concentrations of nitrate recorded at all the frequently sampled sites. The maximum nitrate concentrations recorded at the sites excluded from this analysis fell into the following mapping categories: 0-25 mg l-1 (42 sites), 25-40 mg l-1 (5 sites) and >40 mg l-1 (3 sites).

Land use maps clearly indicate that the source of nitrates in the two grounwaters mentioned above is agriculture. Therefore, the two sites do require designation as Vulnerable Zones under the Nitrates Directive. However, due to the limited data available, it is not possible at this stage to evaluate the extent of the Vulnerable Zones which must be identified. Consequently, the Map in Annex a only indicated the location of the two sites.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 8 Figure 1.5 Mean Concentration

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 9 Figure 2.6 Maxiumum concnetr

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 10 2.4 THE SURFACE WATER ORTHOPHOSPHATE CONCENTRATIONS RECORDED IN NORTHERN IRELAND

Table 1.3 shows the results of an analysis of all the orthophosphate data acquired from the EA from its ‘surface water’ data-base for 1992. Since the same samples were used for the surface water orthophosphate and nitrate analyses the total number of frequently sampled sites was again 132.

Table 1.3 The surface water orthophosphate data acquired during the 1992 round of site designations in Northern Ireland.

Total number of sites sampled 211 Number of sites with incorrect or incomplete Grid References 0 Number of sites sampled on fewer than 12 occasions 79 Number of sites included in the final analysis 132

Fig. 1.7 The average (top panel) and maximum (bottom panel) concentrations of orthophophate measured at all the surface water sites sampled at least twelve times in 1992.

Mean OP conc. (n>=12)

80

60

40

20

0 0-25 µg/l >25 - 50 >50 - 100 > 100 µg/l µg/l µg/l

Max. OP conc. (n>=12)

150

100

50

0 0-25 µg/l >25 - 50 >50 - 100 > 100 µg/l µg/l µg/l

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 11 The top panel in Fig. 1.7 shows the frequency distribution of the average concentration of nitrate and the lower panel the frequency distribution of the maximum concentration of orthophosphate found at the selected sites. The most striking feature of these distributions is the high frequency of sites with very high concentrations of orthophosphate. In England and Wales (Chapter 4), only 35 % of the sites had average orthophosphate concentrations that were greater than 100 ug l-1 but here the proportion in this ‘high nutrient’ category was 50%.

The colour coded maps in Figures 1.8 and 1.9 show the mean and maximum orthophosphate concentrations recorded at the selected sites in 1992. The mean concentration map suggests that the most productive waters were located to the south and east but very high maximum concentrations were recorded throughout the region. Some of the sites identified in these maps may, of course, be located in the Lough Neagh and Lough Erne catchments (two sites already designated under the UWWT Directive). No Sensitive Area maps were, however, dispatched with the raw data and there is no simple way of establishing the topographic let alone the 'functional' limits of these complex catchments.

Table 1.4 lists all the sites where the maximum concentration of orthophosphate recorded in 1992 was more than 1.0 mg l-1.

Table 1.4 A list of sites in Northern Ireland where the maximum concentration of orthophosphate exceeded 1.0 mg l-1 in 1992.

Site Name Site Code Maximum concentration

Roe River at Roe Br. 02/02/Q050 4.91 Lagan River at Drum Br. 05/01/Q250 3.76 Ravernet River at Spruce Field 05/01/Q910 3.38 Irvinestown Tributary at Necarne 36/06/Q700 2.81 Torrent River at Newmills 03/06/Q410 2.58 Clogh River at Glarryford 03/01/Q910 2.26 Ballynahinche River at Caseys Br. 05/02/Q600 2.21 Lagan River at Spencers Br. 36/10/Q050 1.88 Woodford River at Aghalane 06/01/Q650 1.70 Newry River at Barnmeen 05/01/Q200 1.65 Lagan River at Shaws Br. 03/06/Q503 1.62 Tall River at Drumard Br. 03/02/Q500 1.62 Six Mile Water Below Ballyclare 05/01/Q100 1.45 Lagan River at Stranmillis 05/02/Q200 1.44 Anncloy River at Annacloy Br. 05/03/Q040 1.44 Blackwater River Ballymartin Br. 36/06/Q620 1.35 Irvinestown Tributary Tyllyclea Br. 05/01/Q550 1.34 Lagan River at Youngs Br. 05/02/Q500 1.30 Lagan River at Lisburn 05/01/Q400 1.29 Enler River at Kennel Br. 05/04/Q200 1.28 Quoile River at Quoile Br. 05/02/Q025 1.21 Lagan River at Moores Br. 05/01/Q500 1.10 Ballynahinche River at LC Br. 05/02/Q300 1.03

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 12 In the England and Wales section, a table listing all the sites where the maximum concentration of orthophosphate was greater than 0.5 mg l-1 was produced. If the same procedure was adopted for Northern Ireland, the list would include all the sites covered by the 1992 survey. Many of the high orthophosphate sites listed in Table 1.4 are situated on the River Lagan, a medium sized river entering the Irish Sea through the port of Belfast. Whilst its catchment is primarily agricultural land, the lower portion of the river drains an urban landscape that includes several sewage treatment works.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 13 Figure 2.8 ujtyurtyu

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 14 Figure 2.9 hjfghjghj

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 15 2.5 CONCLUSIONS

In the 1992 round of site designations, no sites were designated under the Nitrates Directive and only two water bodies were designated under the UWWT Directive (Lough Neagh and Lough Erne).

In relation to surface freshwater, our analysis of the data confirms that these decisions were technically correct. The surface water nitrate results summarised in Figure 1.2 and 1.3 are surprisingly low for an area that supports very intensive agriculture. In the Lough Neagh catchment, Smith et al (1981) reported that there was an upward trend that could be correlated with the increased use of nitrogenous fertiliser. Some recent studies have, however, suggested that the quantity of nitrate leached from soils in Northern Ireland is lower than that in the South of England, even though the amount of fertiliser used was very similar (e.g. Jordan and Smith, 1985).

The only 'eutrophication' index used in this analysis is the measured concentration of orthophosphate. It is, however, important to emphasise that this only provides a measure of potential production. Very little biological information was available for the river sites in 1992 and the two lakes designated under the UWWT Directive may have been the only sites that could be adequately assessed. The leaching of phosphate from agricultural land is , however, recognised as a serious problem and is a subject of intensive study by the Aquatic Sciences Division of the Department of Agriculture (Foy and Kirk, 1995; Foy et al, 1995 and Lennox et al., 1997). However, as for the Republic of Ireland, there are clear indications that phosphorus is the limiting factor for the eutrophication of freshwater lakes in Northern Ireland and that nitrates do not contribute significantly to the excessive/accelerated growth of algae and higher forms of plant life.

In relation to marine/coastal waters, our analysis shows that a number of sites do qualify for designation as Sensitive areas. These areas are:

• Lough Foyle; • Bann Estuary; • Belfast Lough; • Carlingford Lough.

In relation to grounwaters, the number of samples analysed for some groundwater sites was very low and is too low for any meaningful comparisons to be carried out. However, two sites have been identified as having elevated nitrate concentrations and requiring designation under the Nitrates Directive. These are:

• Belaghy; • Buckna

As the available information on groundwater was very limited, it has not been possible to assess the extent of the required designation. Therefore only the location of these sites is indicated on the Map in Annex A.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 16 3 COASTAL AND MARINE WATER

3.1 INTRODUCTION

Unlike the Republic, no systematic review and status report of the territory has been encountered. However some raw data on marine, coastal and estuarine sites has been supplied by the Department of the Environment Northern Ireland to ERM. This includes TON, phosphorus, chlorophyll and oxygen, but not water transparency or salinity.

Surprisingly, data on ammonia was absent from the data set provided. For a very small proportion (65 of 680 records) a value for ‘total soluble nitrogen’ is given, and some indication of ammonia levels can be estimated by subtraction of TON from this value. However these have to be treated with caution; ammonia concentrations will usually be small in comparison to TON, and the use of the residual value after subtraction of TON from the TSN value, as an indicator for ammonia, may thus be considerably distorted by any error in TON measurement.

A comparison of the these derived values with those from the Republic and Britain suggest that they may indeed overestimate ammonia concentrations. They should thus be interpreted with great caution.

3.2 LOUGH FOYLE

Lough Foyle is on the north coast and lies on the border of the Irish Republic and Northern Ireland. It is some 32 km in length and has a surface area of 190 km2. According to the Irish QSR it is monitored by the Department of the Environment Northern Ireland, and is managed according to a joint plan compiled by the two administrations. The major rivers entering Lough Foyle are the Mourne to the south (with water from both the Republic and Northern Ireland) and the Faughan and Roe to the east (catchments entirely within Northern Ireland). Londonderry/Derry is the major municipality in the catchment.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 17 Table 3.1 Lough Foyle. Oxygen, nutrients and related parameters. Sampled between 1994–98. No ammonia data given; however ‘total soluble nitrogen’ values are given for a very limited number of sites and dates. For these ammonia values have been estimated by subtraction of the TON value. These individual values are entered in the mean value row of the table. No information was provided on salinity or turbidity. Nutrient ratios were not calculated from the raw data due to the general absence of ammonia data.

Site season value salinity turbidity O2 TON NH3+NH4 P N:P chl-a ‰ m % µM µM µM µg l-1

Lough Foyle Site 1 T s n/a n/a 101 179 n/a 1.98 n/a 8.87 Site 1 T u n/a n/a 92 103 31.6, 1.21 n/a 2.50 34.9 Site 1 T t n/a n/a 79 41.3 n/a 0.52 n/a 0.19 Site 1 R s n/a n/a 98 128 n/a 1.80 n/a 26.0 Site 1 R u n/a n/a 88 59.4 n/a 0.99 n/a 8.56 Site 1 R t n/a n/a 79 20.0 n/a 0.44 n/a 1.66

Site 2 T s n/a n/a 105 103 n/a 1.38 n/a 4.83 Site 2 T u n/a n/a 89 65.3 33.8, 1.07 n/a 2.41 36.5 Site 2 T t n/a n/a 75 20.4 n/a 0.80 n/a 0 Site 2 R s n/a n/a 114 84.4 n/a 170 n/a 33.1 Site 2 R u n/a n/a 86 30.5 n/a 1.04 n/a 10.3 Site 2 R t n/a n/a 70 6.96 n/a 0.73 n/a 2.64

Site 3 T s n/a n/a 95 82.9 n/a 1.35 n/a 3.44 Site 3 T u n/a n/a 87 55.7 23.5, 1.09 n/a 2.32 39.0 Site 3 T t n/a n/a 70 23.8 n/a 0.75 n/a 0 Site 3 R s n/a n/a 112 45.9 n/a 1.35 n/a 31.1 Site 3 R u n/a n/a 89 23.9 n/a 0.89 n/a 10.7 Site 3 R t n/a n/a 72 5.00 n/a 0.61 n/a 2.07

Site 4 T s n/a n/a 105 34.3 n/a 1.09 n/a 4.47 Site 4 T u n/a n/a 95. 21.7 13.9, 0.75 n/a 2.17 3 24.1 Site 4 T t n/a n/a 82 6.75 n/a 0.45 n/a 0.69 Site 4 R s n/a n/a 107 17.1 n/a 0.51 n/a 11.3 Site 4 R u n/a n/a 99. 3.61 n/a 0.21 n/a 4.73 4 Site 4 R t n/a n/a 91 0.02 n/a 0.02 n/a 1.89

Site 5 T s n/a n/a 109 20.4 n/a 0.78 n/a 2.39 Site 5 T u n/a n/a 94 9.55 8.5, 13.7 0.52 n/a 1.43 Site 5 T t n/a n/a 63 1.57 n/a 0.24 n/a 0.71 Site 5 R s n/a n/a 106 11.2 n/a 0.46 n/a 3.64 Site 5 R u n/a n/a 97 2.50 n/a 0.21 n/a 2.19 Site 5 R t n/a n/a 90 0.02 n/a 0.08 n/a 1.25

Source: Environment and Heritage Service of DoE Northern Ireland direct response to ERM.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 18 3.2.1 Chemical Profile

Ammonia As noted in the introduction to the section, the data provided on ammonia for Northern Ireland is very poor. For Lough Foyle there are two individual winter data points for each of the five sites (Table 3.1). These suggest winter ammonia concentrations in the range of 30–40 µM in the innermost three sites, declining at the two outer sites. If accurate and representative this would suggest a very high rank order for the mean, in the

top 10% of values recorded for the UK and Ireland (i.e. a Rmean 0.9–1.0).

Total Oxidised Nitrogen In winter the TON Rmax varied from 0.72 at the innermost site 1 (absolute value 179 µM N), down to 0.29 at site 5. The closest values to these maxima from other Irish and British sites are mostly summer values of limited relevance. In summer the corresponding range in rank was from 0.63 down to 0.17. The maximum value was similar to summer values from the Rogerstown and Maigue estuaries in the Republic, to the inner Belfast Lough, and to the lower Humber and lower Tees in England. The

winter mean rank values ranged over Rmean 0.33–0.79, while those for

summer were Rmean 0.07–0.69

Thus there is some evidence of hypernutrification although these are not amongst the most extreme values observed.

Phosphorus The peak winter value was 1.98 µM P at site 1, which also had the peak summer value of 1.80 µM. Concentrations decline seawards. The

maximum winter rank values ranged over Rmax 0.17–0.52, while the mean

ranks were Rmean 0.21–0.62. The summer range was Rmax 0.05–0.49 and Rmean 0.02–0.52.

Nutrient Ratio As noted earlier it is not possible to calculate nutrient ratios due the general absence of ammonia data.

Oxygen concentrations vary most in summer. Supersaturation possibly increases from site 1 (range 79–101%) to site 2 (range 70–114%) from where it declines to site 5 (90–106%). The lowest winter saturation value is 63% at the most seaward site 5.

Nutrient Budget Exceptionally for Northern Ireland, the Irish QSR provides a nutrient budget for Lough Foyle (Figure 3.1). This indicates that riverine sources are the most important source of BOD, nitrogen and phosphorus. In common with the sites in the Republic, the data on riverine inputs is not broken down into its various anthropogenic and natural components. The total annual budget for nitrogen, of ca. 3,700 compares to a value of ca. 3,450 cited by Service et al. (1998) relevant for the early 1990si.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 19 Figure 3.1 Lough Foyle Riverine inputs black, industrial discharges dark grey, municipal inputs light grey, atmospheric inputs value only. Calculation for 1991–95.

14,000 13,400

12,000

10,000

8,000 tonnes 6,000

4,000 3,234

2,000 750 394 316 82 223 28 2 0 BOD nitrogen phosphorus

Source: Irish QSR.

3.2.2 Biological effects

The data indicates eutrophic conditions in the innermost part of Lough Foyle, with a peak summer phytoplankton chlorophyll concentration of 26 µg l-1 at site 1, 33.1 µg at site 2, 31.1 µg at site 3 and 11.3 µg at site 4. According to the Irish QSR an apparently separate evaluation concluded that “Significant summer oxygen depletion was not encountered and chlorophyll-a concentrations were mostly <10 [µg l-1]. The exception to this was in the southern end where a maximum concentration of 25.7 [µg l-1] was recorded.” The same work apparently evaluated the presence, duration and extent of algal blooms, changes in macrophyte growth, alterations to benthic community structure and the occurrence of paralytic shellfish poisoning. It concluded that “none of these parameters were found to be indicative of an altered trophic status of the lough”. The quality of data underlying such conclusions is unknown. At least for chlorophyll, it appears that it depends on the local interpretation of what comprises an ‘undesirable’ change resulting from hypernutrification, as these appear elevated.

3.2.3 Designation under the Directives

There is evidence of eutrophication in Lough Foyle. There appears to be insufficient evidence to determine whether the contribution of either agriculture or urban wastewater represent an insignificant component of the hypernutrification.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 20 However, it has been shown that riverine inputs are the main N input into the estuary. As can be seen on the cover Map (Annex A of this report), there is a major agglomeration (Londonderry) on the river Foyle just before it enters the estuary. It therefore seem that the lough does qualify for designation as a Sensitive Area under Directive 91/271/EEC.

With regards to Nitrate Vulnerable Zones, as the rest of the land bordering the lough is agricultural land, there seem to be a case for a possible designation as Vulnerable Zone. However the available information (including the land cover map) can not ascertain this and, therefore, the onus rests on the Northern Ireland administration to justify the absence of designation.

3.3 BANN ESTUARY

The Bann estuary lies on the north coast, to the west of Lough Foyle. The River Bann drains Lough Neagh and a significant area of lowland agriculture. The catchment of 5,732 km2 (the largest in Northern Ireland) is predominantly rural. The catchment of Lough Neagh has been designated a Sensitive Area, which should reduce phosphorus inputs (only) to the Bann estuary.

3.3.1 Chemical Profile

Ammonia data consists of a solitary value for winter and summer for each of the four sites (Table 3.2). In winter it suggests a concentration ranging over 38.0–50.8 µM N. In summer the range was 43.1–49.5 µM. Given the very limited information it is difficult to draw any conclusions about trends down the estuary. If it is assumed that the mean would be ca 45 µM, this would give

it a rank value in the top 10% (i.e. Rmean of ca 0.95). There is insufficient information to determine whether this is credible. One might suspect that it is not, at least to this extreme degree. On the other hand the raised phosphorus values (see below) provide circumstantial evidence to anticipate a significant enhancement of ammonia.

Total Oxidised Nitrogen winter values had the range 32.5–132 µM N, these value coming from site 4 but with little if any trend evident along the estuary.

Consequently the Rmax values for all four sites were very similar (0.64–0.65). They were similar to winter values for mid-Belfast Lough and the southern quarter of the Wash. The summer concentrations ranged between 2.25 and 170 µM, with these extremes again coming from site 4 but with little variation

between the sites. The summer Rmax values for the four sites lay between 0.68 and 0.72, similar to summer values for the Deel, Colligan, and Barrow/Nore/Suir estuaries in the Republic and the mid-Stour and lower

Humber in Britain. The winter Rmean range, (0.72–0.73) and summer Rmean range (0.58–0.62) are also very constrained.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 21 Table 3.2 Bann estuary. Oxygen, nutrients and related parameters. Sampled between 1994–98. Although the data was provided in response to a request for marine and estuarine data, the absence of salinity data requires that this table should be interpreted with caution. Other details as in Table 3.1.

Site season value salinity turbidity O2 TON NH3+N P N:P chl-a

‰ m % µM H4 µM µg l-1 µM

Bann estuary Site 1 T s n/a n/a 116 131 n/a 4.5 n/a 17.2 Site 1 T u n/a n/a 97 77.7 38.0 2.75 n/a 8.75 Site 1 T t n/a n/a 73 31.5 n/a 1.20 n/a 0.18 Site 1 R s n/a n/a 115 151 n/a 3.73 n/a 59.0 Site 1 R u n/a n/a 97 37.8 45.2 1.11 n/a 25.5 Site 1 R t n/a n/a 54 11.6 n/a 0.02 n/a 0.00

Site 2 T s n/a n/a 105 129 n/a 4.40 n/a 18.6 Site 2 T u n/a n/a 95. 78.2 42.8 2.64 n/a 8.95 9 Site 2 T t n/a n/a 75 37.1 n/a 1.36 n/a 0.26 Site 2 R s n/a n/a 111 156 n/a 3.77 n/a 62.2 Site 2 R u n/a n/a 98 38.1 49.5 1.33 n/a 23.3 Site 2 R t n/a n/a 78 6.61 n/a 0.02 n/a 0.15

Site 3 T s n/a n/a 105 130 n/a 4.70 n/a 16.7 Site 3 T u n/a n/a 95. 78.5 50.8 2.63 n/a 8.91 4 Site 3 T t n/a n/a 76 37.1 n/a 1.34 n/a 0.42 Site 3 R s n/a n/a 108 160 n/a 5.12 n/a 64.1 Site 3 R u n/a n/a 93. 36.7 44.8 1.57 n/a 23.0 9 Site 3 R t n/a n/a 71 5.69 n/a 0.02 n/a 0.08

Site 4 T s n/a n/a 108 132 n/a 4.30 n/a 15.7 Site 4 T u n/a n/a 96. 75.6 48.9 2.63 n/a 7.95 7 Site 4 T t n/a n/a 81 32.5 n/a 0.88 n/a 0.52 Site 4 R s n/a n/a 113 170 n/a 3.82 n/a 62.7 Site 4 R u n/a n/a 101 33.8 43.1 1.12 n/a 17.4 Site 4 R t n/a n/a 84 2.25 n/a 0.03 n/a 0.29

Source: Environment and Heritage Service of DoE Northern Ireland direct response to ERM.

Phosphorus winter values also showed relatively little change across the sites, with concentrations ranging between 0.88–4.70 µM, maximum winter ranks

between Rmax 0.71–0.74 (similar to lower Belfast Lough and the mid-Deben

estuary in England) and mean winter ranks between Rmean 0.79–0.81 (similar to the lower Belfast Lough, the Deel estuary in the Republic, and the upper Deben in England). Summer rankings had a slightly greater range, with

maximum values between Rmax 0.67–0.76 and mean values between Rmean 0.59–0.68.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 22 These are enhanced levels, significantly so for the mean winter ranks.

Oxygen concentrations in winter varied between 71–116% the peak reflecting an unusually high winter phytoplankton chlorophyll concentration at site 1 (see below). Other than this there was no obvious trend along the estuary. In summer the range was 54–115%, the greatest extremes also originating from site 1.

Input Budget Service et al. provide what appears to be a first attempt at a crude nutrient budget for northern Ireland marine sites, for dissolved inorganic nitrogen (DIN) onlyi. This suggested that only 15.1 tonnes per year DIN was derived from urban wastewater, the remaining 2,111 tonnes per annum being ascribed to catchment inputs. The total input according to this source was the third greatest in overall magnitude in Northern Ireland after Belfast Lough and Lough Foyle. The source of the catchment inputs were not attributed by Service et al.. But the elevated phosphorus concentrations, (and possibly those for ammonia) suggest either an animal husbandry origin or significant STP catchment inputs.

3.3.2 Biological effects

Summer phytoplankton chlorophyll concentrations were massively elevated in the estuary with maximum values of 59.0, 62.2, 64.1 and 62.7 µg l-1 at sites 1 through 4. Remarkably winter concentrations were also high, with values at the four sites ranging from 15.7 to 18.6 µg.

No other aspects of the biology of the estuary have been seen.

3.3.3 Designation under the Directives

On the basis of the evidence available the estuary appears to be both hypernutrific and eutrophic. The bulk of nitrogen, at least, has been calculated by Service et al. to be derived from the catchment. If the headings of their Table 1 are literally correct, then less than 1% of the nitrogen load is derived from (estuarine?) sewage treatment plants. The designation of Lough Neagh’s catchment as an UWWTD Sensitive Area presumably implies some significant STP discharges. In can however be noticed on the land cover map that there is a major agglomeration on river Bann just before in enters the estuary. It therefore seems that the Bann estuary does qualify for designation as Sensitive Area.

With regards to Vulnerable Zones, given the eutrophic state of the estuary, the onus rests with the Northern Ireland authorities to justify the absence of designation for the remainder of the Bann catchment.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 23 3.4 LARNE LOUGH

This lies immediately to the north of Belfast Lough. It is a small lough (approximately 10 km in length) and the catchment is also very restricted. The largest urban site is the town of Larne, at its mouth. The Lough has a restricted tidal range. At the turn of the century biological diversity was high, but by 1982 this was much reduced, this being attributed to the extraction of a clay lubricant and the dumping of waste from cement manufactureii.

3.4.1 Chemical Profile

Ammonia data was restricted to one data point each for winter and summer for each of the 5 sites. In winter the range was 9.85–12.0, in summer between

6.99–10.1. This suggests a high mean value, scoring in the range Rmean of 0.8– 0.9 if these values truly reflect typical ammonia concentrations. However neither TON or phosphorus concentrations are notably high, therefore these ammonia values must be regarded with circumspection.

Total Oxidised Nitrogen winter concentrations showed a declining trend from 4.52–29.9 µM N at site 1 to 5.70–9.77 at site 5. In summer the values

ranged from 0.18–10.4. The winter rank values were Rmax 0.11–0.35 and Rmean

0.27–0.35. The summer rank values were Rmax 0.12–0.14 and Rmean 0.06–0.18. These do not appear excessive for a site of this type.

Phosphorus concentrations in winter varied between 0.42 and 0.89 µM P, with no strong gradient along the Lough. Those for summer ranged between 0.03

and 1.32 µM, these extremes coming from site 2. The winter Rmax range was

0.16–0.23, while that for the Rmean values was 0.29–0.37. These levels do not appear to be particularly elevated.

Oxygen saturation levels ranged between 79–107% in winter, and from 81– 118% in summer.

The Input Budget for dissolved inorganic nitrogen (only) was the smallest of the 7 major sites assessed by Service et al.. 1.9 tonnes per year were attributed to sewage treatment discharges, and 232 tonnes per annum from catchment inputs. However, in terms of the load per unit volume, this was by far the highest, virtually double that of the value of the next highest, Lough Foyle.

3.4.2 Biological Effects

Maximum summer chlorophyll concentrations ranged from 3.65 to 10.3 µg l-1. These are probably elevated above natural levels but are not exceptional compared to other sites. Winter values are unexceptional. No other biological data has been seen.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 24 3.4.3 Designation under the Directive

Limited data make assessment difficult, but Larne Lough does not appear to be a priority for designation as either a Sensitive Area or a NVZ. No information has been provided on the size of the STP discharges to the Lough, so it is not possible to comment on whether the level of treatment will meet the relevant aspects of the UWWTD.

Table 3.3 Larne Lough. Oxygen, nutrients and related parameters. Sampled between 1994–98. Other details as in Table 3.1.

Site season value salinity turbidity O2 TON NH3+N P N:P chl-a

‰ m % µM H4 µM µg l-1 µM

Larne Lough Site 1 T s n/a n/a 107 29.9 n/a 0.89 n/a 4.39 Site 1 T u n/a n/a 91 10.6 9.85 0.73 n/a 1.46 Site 1 T t n/a n/a 79 4.52 n/a 0.46 n/a 0.16 Site 1 R s n/a n/a 114 10.2 n/a 0.84 n/a 10.8 Site 1 R u n/a n/a 95 2.16 9.78 0.38 n/a 5.28 Site 1 R t n/a n/a 81 0.18 n/a 0.07 n/a 0.37

Site 2 T s n/a n/a 101 18.4 n/a 0.79 n/a 1.33 Site 2 T u n/a n/a 95 9.10 10.1 0.67 n/a 0.79 Site 2 T t n/a n/a 83 5.63 n/a 0.42 n/a 0.27 Site 2 R s n/a n/a 116 10.4 n/a 1.32 n/a 7.95 Site 2 R u n/a n/a 100 3.68 9.31 0.46 n/a 4.03 Site 2 R t n/a n/a 86 0.20 n/a 0.03 n/a 0.14

Site 3 T s n/a n/a 102 10.6 n/a 0.77 n/a 1.18 Site 3 T u n/a n/a 94 8.20 12.0 0.65 n/a 0.58 Site 3 T t n/a n/a 81 5.63 n/a 0.42 n/a 0.21 Site 3 R s n/a n/a 118 10.4 n/a 0.70 n/a 9.03 Site 3 R u n/a n/a 100 4.06 8.68 0.43 n/a 3.72 Site 3 R t n/a n/a 86 0.25 n/a 0.22 n/a 0.11

Site 4 T s n/a n/a 106 11.1 n/a 0.81 n/a 0.84 Site 4 T u n/a n/a 96 8.40 11.5 0.63 n/a 0.44 Site 4 T t n/a n/a 80 5.91 n/a 0.42 n/a 0.11 Site 4 R s n/a n/a 109 10.3 n/a 0.81 n/a 4.43 Site 4 R u n/a n/a 99 5.76 6.99 0.53 n/a 1.39 Site 4 R t n/a n/a 90 0.25 n/a 0.23 n/a 0.11

Site 5 T s n/a n/a 105 9.77 n/a 0.81 n/a 0.54 Site 5 T u n/a n/a 96 7.91 8.76 0.64 n/a 0.27 Site 5 T t n/a n/a 88 5.70 n/a 0.49 n/a 0.03 Site 5 R s n/a n/a 115 10.4 n/a 0.75 n/a 3.65 Site 5 R u n/a n/a 100 5.08 10.1 0.49 n/a 1.58 Site 5 R t n/a n/a 93 0.49 n/a 0.13 n/a 0.12

Source: Environment and Heritage Service of DoE Northern Ireland direct response to ERM.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 25 3.5 BELFAST LOUGH

Belfast Lough is approximately 25 km long and on average some 7 km wide. It has a moderate catchment of 900 km2, with a variety of urban and industrial wastewater discharges and also some agriculture. Belfast is the major urban centre in the catchment.

According to Parker et al. (1988)iii concerns about the effects of pollution from sewage date back at least to 1908, when the Royal Commission on Sewage Treatment heard evidence that nutrient inputs from sewers resulted in excessive growth of green weed mats which created a nuisance as it decayed on the shore. According to Parker et al. there have been “no recent reports of this phenomena”, although the thoroughness of this assessment is unknown. Extreme concern was certainly being expressed about pollution from sewage and other sources of pollution in the late 1970s and early 1980s when Boadenii (then Director of Queen’s University Marine Biology Station) wrote that, while various studies had been carried out “Much of this information has not been published yet but any statement that the lough is not polluted (there have been several in recent years) is blatantly untrue” and continues in the next paragraph that “The Lough is fortunately rather shallow so that a relatively small amount of turbulence stirs the water which is kept well oxygenated in spite of (or at times because of?) extreme eutrophication of the inner reaches. The latter have extensive diatom blooms. Diversity of bottom and shore life is reduced considerably and this can be ascribed to the general environmental degradation”. In the mid 1970s, according to Boaden, crude sewage of some 49,000 p.e. and primary treated sewage of approximately 632,000 p.e. were discharged directly to the Lough, as were “large amounts” of phosphates and nitrates. “It is not known to what extent the ensuing eutrophication is depressed by other factors such as heavy metal discharges”.

3.5.1 Chemical Profile

Ammonia Only two winter values are available for each of the six sites (Table 3.2). These vary widely from 6.03 to what would be an extremely high value of 200 µM N. If correct this would place Belfast Lough amongst the most

contaminated sites in the UK, with an Rmax in the region of 0.97 – less than the Tralee Lee and Broadmeadow estuary in the Republic, and the upper Nene estuary by the Wash, but of the same order as the Liffey and Boyne in the Republic and the Clyde in Scotland and other Wash estuaries in England. This is not impossible given the TON and phosphorus concentrations, but should be regarded with circumspection.

Total Oxidised Nitrogen winter concentrations varied between 5.34 and 276

µM N. The associate rank values were a Rmax of 0.42–0.79 and a Rmean of 0.46–0.80. The higher values occurred in the innermost parts of the Lough, and the highest value, while somewhat less than the winter value for the Cork Lee estuary, was greater than of the Feale and Bandon in the Republic, and

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 26 the mid-Stour in England. It was the highest winter value for Northern Ireland.

The values in the table can also be compared with a sampling programme in the mid 1980siii which reported winter nitrate concentrations typically of 20-30 µM in the inner Lough, 15–20 µM in mid-Lough and ca. 10 µM in the outer Lough. It would appear that concentrations have increased, although various other explanations, such as sampling method, inter-annual variation etc. may be possible.

In summer the concentration range was 0.02–260 µM N, with Rmax values between 0.21–0.79 and Rmean values between 0.16 and 0.74. In the 1980s survey nitrate levels typically declined to 0–5 µM throughout the Lough. The maximum summer R value, for site 2, was of the same order as the summer values for the (Cork) Lee, Feale, Bandon, Nore and Broadmeadow estuaries in the Republic, and the upper Humber, Tees and Wear estuaries in England. It was the highest summer value in Northern Ireland.

Phosphorus winter concentrations varied between 0.63–17.3 µM P, with a

Rmax range of 0.60–0.91 and a Rmean range of 0.64–0.94. In summer the concentration range was 0.02–15.7, the Rmax range 0.60–0.91, and the Rmean range 0.12–0.97. Clearly the concentrations in the inner Lough were amongst the highest recorded in either the UK or Eire. The winter Rmax of 0.91 was the highest winter value in the data set. The identical summer Rmax, was of the same order as the Garavogue and Barrow estuaries in the Republic, and annual values for the lower Great Ouse, upper Clyde and upper Welland in Britain.

In the mid 1980s the (orthophosphate, PO4) winter phosphorus concentration ranged up to 3.5 µM P in the inner Lough, to 2.5 µM mid-Lough and to 1.75 µM in the outer Lough. So, as for nitrogen, phosphorus concentrations appear to have increased over this period.

Oxygen saturation levels in winter varied between 59–108%, while those in summer had the range 42–167%, indicative of severe oxygen depletion and significant eutrophication.

Input Budget According to Service et al. the sewage treatment plan dissolved inorganic nitrogen contribution to the Lough was 1,521 tonnes per annum, the industry DIN was 5,559 tonnes and the catchment contribution 193.9 tonnes, making a total annual DIN loading in the early 1990s of 7,274 tonnes. It is unknown whether the industrial discharges have since been reduced. No information is apparently available on BOD load or phosphorus.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 27 Table 3.4 Belfast Lough. Oxygen, nutrients and related parameters. Sampled between 1994–98. Other details as in Table 3.1

Site season value salinity turbidity O2 TON NH3+NH4 P N:P chl-a ‰ m % µM µM µM µg l-1

Belfast Lough Site 1 T s n/a n/a 100 276 n/a 17.3 n/a 7.24 Site 1 T u n/a n/a 77.9 105 78.1,95.0 6.79 n/a 2.84 Site 1 T t n/a n/a 60 40 n/a 3.0 n/a 0.64 Site 1 R s n/a n/a 105 113 n/a 15.7 n/a 90.2 Site 1 R u n/a n/a 71.6 56.3 n/a 8.54 n/a 13.3 Site 1 R t n/a n/a 42 22.2 n/a 1.56 n/a 0.75

Site 2 T s n/a n/a 95 201 n/a 13.9 n/a 11.1 Site 2 T u n/a n/a 83.7 96.8 121,200 7.03 n/a 3.59 Site 2 T t n/a n/a 59 50.7 n/a 3.09 n/a 0.89 Site 2 R s n/a n/a 112 260 n/a 14.1 n/a 33.9 Site 2 R u n/a n/a 83.6 82.2 n/a 7.67 n/a 16.7 Site 2 R t n/a n/a 47 32.3 n/a 1.69 n/a 0.88

Site 3 T s n/a n/a 94 141 n/a 5.60 n/a 14.6 Site 3 T u n/a n/a 88 54.6 57.2,95.0 3.89 n/a 3.88 Site 3 T t n/a n/a 67 28.4 n/a 2.11 n/a 0.11 Site 3 R s n/a n/a 167 68.2 n/a 8.33 n/a 72.6 Site 3 R u n/a n/a 110 28.1 n/a 2.86 n/a 31.2 Site 3 R t n/a n/a 68 3.25 n/a 0.50 n/a 1.10

Site 4 T s n/a n/a 108 106 n/a 5.00 n/a 4.74 Site 4 T u n/a n/a 94 28.2 6.03,32.6 2.01 n/a 1.52 Site 4 T t n/a n/a 83 16.6 n/a 1.05 n/a 0.49 Site 4 R s n/a n/a 153 15.2 n/a 1.62 n/a 26.1 Site 4 R u n/a n/a 106 4.91 n/a 0.58 n/a 10.4 Site 4 R t n/a n/a 55 0.02 n/a 0.04 n/a 0.88

Site 5 T s n/a n/a 101 92.4 n/a 4.64 n/a 12.1 Site 5 T u n/a n/a 90 37.3 40.3,60.6 3.10 n/a 2.87 Site 5 T t n/a n/a 67 22.9 n/a 1.87 n/a 0.55 Site 5 R s n/a n/a 165 54.1 n/a 3.96 n/a 55.5 Site 5 R u n/a n/a 121 13.0 n/a 1.07 n/a 30.4 Site 5 R t n/a n/a 70 1.07 n/a 0.03 n/a 5.20

Site 6 T s n/a n/a 100 39.4 n/a 2.90 n/a 1.21 Site 6 T u n/a n/a 94 15.2 6.9,27.3 1.27 n/a 0.68 Site 6 T t n/a n/a 82 5.34 n/a 0.63 n/a 0.22 Site 6 R s n/a n/a 167 18.0 n/a 0.94 n/a 29.0 Site 6 R u n/a n/a 107 4.67 n/a 0.43 n/a 8.75 Site 6 R t n/a n/a 79 0.26 n/a 0.02 n/a 0.95

Source: Environment and Heritage Service of DoE Northern Ireland direct response to ERM.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 28 3.5.2 Biological Effects

The phytoplankton chlorophyll concentrations, ranging up to 90.2 µg l-1 in summer, and even as high as 14.6 µg in winter, is demonstrative of severe eutrophication. This is supported by the levels of oxygen supersaturation. Service et al. note that “The Lough is known to harbour the causative organism of paralytic shellfish poisoning … and Phaeocystis blooms also regularly occur in summer … The data … clearly demonstrate that Belfast Lough has elevated levels of DIN relative to the Irish Sea background, with higher levels of algal activity throughout most of the growing season. A maximum chlorophyll-a concentration of 60 µg l-1 has been recorded …” The data presented in this report demonstrate that phosphorus and probably ammonia are also highly elevated, and that the peak chlorophyll concentrations are even greater than the 60 µg l-1 cited by Service et al..

No information on other biological effects more recent that the early 1980s (see site introduction) has been seen.

3.5.3 Designation under the Directives

With regard to the UWWTD, Belfast Lough clearly should not be designated a Less Sensitive Area. Given the scale of the discharge Belfast clearly requires at least secondary treatment to be implemented by the end of 2000. With regard to Sensitive Area status, which the Northern Ireland Administration state that they are currently considering, Belfast Lough has been known to be vulnerable to eutrophication since at least the turn of the century, a situation confirmed in the 1970s/early 1980s and again in the early 1990s.

The only issue is the source of this eutrophication, and the relevance of the two Directives. Earlier researchers were apparently in no doubt as to the importance of sewage discharges. However the work of Service et al. draws attention to the scale of the industrial discharges of DIN. If these industrial discharges have and will continue, it would nevertheless seem that STP discharges should still be considered as a significant, although smaller, component (1,521 tonnes per annum compared to 5,559). It may be that the industrial discharges have ceased, or are due to cease, and that the Northern Ireland authority will argue that Sensitive Area status is therefore unnecessary. However, the available data, at the time of writing, do not demonstrate this, and due to the eutriphic characteristic of Belfast Lough and the urban nature of it’s catchment, it appears to qualify for designation as a Sensitive Area.

No information has been seen by which to judge whether NVZ status is warranted. Given the urban nature of much of the catchment, and the relatively small contribution from riverine inputs, it may be suspected that it is not, but again the onus rests with the Northern Ireland authorities to demonstrate the case.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 29 3.6 STRANGFORD LOUGH

Strangford Lough, to the south-east of Belfast, is a large (106 km2) and virtually fully enclosed sea lough communicating with the sea via Strangford Narrows. The catchment is 771 km2 and predominantly rural. The Lough itself is an important biodiversity site, with several National Nature Reserves within it. The National Trust [for Places of Historic Interest or Natural Beauty – the major land-owning private conservation body in the UK] controls much of the intertidal, part of the sub-tidal area and strongly controls or influences many aspects of usage of the Lough.

Diverse plant growth – phytoplankton, macroalgae, seagrass and saltmarsh – feeds a food chain that includes 1,500 identified invertebrate species, and a diverse fish and bird community. There are important tern breeding colonies, while the sand and mud flats provide winter habitat for 30–40,000 waders and over 20,000 wildfowl (ducks and geese). Strangford Lough is a Ramsar site. In the 1970s eutrophication problems at the northern end of the Lough were said to be caused by nutrients from the Comber/Newtownards STP, and pollution from raw sewage also occurred in the Quoile/Killyleagh area, and the general level of treatment of all discharges to the Lough and its catchment were regarded as unsatisfactoryii.

3.6.1 Chemical Profile

Ammonia Two individual winter values for each of the four sites returned a fairly uniform set of values varying from 7.06–10.3 µM N. By way of

comparison a mean of 8.5 µM would score a Rmean of 0.75–0.85 within the general data set. This is elevated, however the reliability is uncertain.

Total Oxidised Nitrogen The winter concentration range varied between 3.15

and 34.5 µM N, these values both coming from site 1. The corresponding Rmax

range was 0.19–0.39; Rmean 0.10–0.47. The summer concentration range was

0.20–17.0 µM, Rmax 0.18–0.25, Rmean 0.08–0.10. These values are moderate considering the enclosed nature of the Lough.

Phosphorus Winter concentrations recorded were in the range 0.61–1.33 µM

P, Rmax 0.29–0.40 and Rmean 0.44–0.54. Summer concentrations were 0.05–0.92

µM, Rmax 0.15–0.26, Rmean 0.19–0.27. These values are perhaps relatively higher than those for TON, possibly indicating a predominance of sewage- sourced nutrient over agricultural inputs, although the level of animal husbandry is unknown.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 30 Table 3.5 Strangford Lough. Oxygen, nutrients and related parameters. Sampled between 1994–98. Other details as in Table 3.1

Site season value salinity turbidity O2 TON NH3+NH4 P N:P chl-a ‰ m % µM µM µM µg l-1 Strangford Lough Site 1 T s n/a n/a 112 34.5 n/a 1.33 n/a 8.78 Site 1 T u n/a n/a 92 16.4 7.06,8.45 1.03 n/a 1.30 Site 1 T t n/a n/a 56 3.15 n/a 0.81 n/a 0.13 Site 1 R s n/a n/a 127 17.0 n/a 0.92 n/a 8.01 Site 1 R u n/a n/a 97 3.04 n/a 0.61 n/a 3.00 Site 1 R t n/a n/a 33 0.20 n/a 0.05 n/a 1.33

Site 2 T s n/a n/a 129 24.7 n/a 1.05 n/a 1.62 Site 2 T u n/a n/a 95.9 14.4 7.42,10.2 0.92 n/a 0.65 Site 2 T t n/a n/a 64 3.61 n/a 0.77 n/a 0.22 Site 2 R s n/a n/a 111 15.4 n/a 0.81 n/a 5.96 Site 2 R u n/a n/a 94 3.27 n/a 0.50 n/a 3.17 Site 2 R t n/a n/a 33.5 0.20 n/a 0.05 n/a 1.38

Site 3 T s n/a n/a 103 14.6 n/a 0.95 n/a 1.06 Site 3 T u n/a n/a 93 9.96 7.41,7.59 0.79 n/a 0.54 Site 3 T t n/a n/a 69 4.63 n/a 0.69 n/a 0.17 Site 3 R s n/a n/a 118 10.4 n/a 0.77 n/a 15.2 Site 3 R u n/a n/a 94 4.58 n/a 0.53 n/a 2.91 Site 3 R t n/a n/a 34 0.52 n/a 0.14 n/a 0.38

Site 4 T s n/a n/a 111 19.1 n/a 0.94 n/a 1.35 Site 4 T u n/a n/a 96 12.0 7.49,10.3 0.81 n/a 0.62 Site 4 T t n/a n/a 69 4.08 n/a 0.61 n/a 0.22 Site 4 R s n/a n/a 119 12.3 n/a 0.77 n/a 14.8 Site 4 R u n/a n/a 92 4.81 n/a 0.49 n/a 3.61 Site 4 R t n/a n/a 33 0.43 n/a 0.08 n/a 0.50

Source: Environment and Heritage Service of DoE Northern Ireland direct response to ERM.

Oxygen saturation levels varied from 56–129% in winter, and from 33–127% in summer. The deoxygenation in the inner estuary appears to indicate a significant BOD loading.

Input Budget for dissolved inorganic nitrogen calculated by Service et al. was 179 tonnes per annum from sewage discharges, and 1,597 tonnes from the catchment.

3.6.2 Biological Effects

Earlier concerns regarding (localised) eutrophication have already been noted. Maximum summer phytoplankton chlorophyll levels recorded in this data set were lower at sites 1 and 2 (with the higher summer and winter nutrient

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 31 concentrations) at 8.01 µg and 5.96 µg respectively, than at sites 3 (15.2 µg) and 4 (14.8 µg).

No recent information on other biological effects has been seen.

3.6.3 Designation under the Directives

With regard to the UWWTD insufficient information was provided to determine whether earlier problems associated with sewage discharges have been resolved. In so far as these relate to eutrophication, and as any new levels of treatment is unlikely to involve nutrient removal, it should be assumed that the problems have persisted unless evidence is provided to the contrary. The low oxygen saturation levels at some sites were also of concern; these need to be accounted for, and any necessary action required by the UWWTD taken.

It is probable that NVZ status is not warranted, but for this to be acceptable to the Commission the Northern Ireland authority should demonstrate that the agricultural component is inconsequential.

3.7 CARLINGFORD LOUGH & DUNDRUM BAY

Carlingford Lough lies on the border between the Republic and Northern Ireland. According to the Irish QSR it is approximately 16 km in length and has an area of 52 km2. According to Service et al. the area of the lough is just 22.3 km2, while the catchment area is 543 km2. Settlements include Omeath, Carlingford and Greenore on the southern shore, Rosstrevor and Warrenpoint on the north, and Newry at the head of Clanrye river. According to the Irish QSR, Newry sewage is subject to primary treatment, but untreated sewage is discharged from some towns into the Lough. The total effluent discharge to the Lough has been estimated to be 60,000 p.e..

The Lough is shallow, mostly under 10 m in depth, with extensive tidal flats. Tidal currents are strong, with the result that the Lough is well mixed. Freshwater inputs are relatively small, with the largest river, the Clanrye, having a summer flow of less than 1 m3 s-1.

The site has been the subject of a study published in 1997iv.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 32 Table 3.6 Carlingford Lough and Dundrum Bay. Oxygen, nutrients and related parameters. Sampled between 1994–98. Other details as in Table 3.1

Site season value salinity turbidity O2 TON NH3+ P N:P chl-a

‰ m % µM NH4 µM µg l-1 µM

Carlingford Lough Site 1 T s n/a n/a 107 38.0 n/a 1.94 n/a 4.99 Site 1 T u n/a n/a 94 23.1 14.2,1 1.15 n/a 1.48 8.4 Site 1 T t n/a n/a 84 6.02 n/a 0.47 n/a 0.27 Site 1 R s n/a n/a 128 22.5 n/a 1.53 n/a 19.4 Site 1 R u n/a n/a 101 3.74 n/a 0.83 n/a 9.47 Site 1 R t n/a n/a 63 0.20 n/a 0.09 n/a 1.96

Site 2 T s n/a n/a 104 34.0 n/a 1.25 n/a 2.10 Site 2 T u n/a n/a 96 17.0 14.4,1 1.01 n/a 0.92 4.6 Site 2 T t n/a n/a 87 2.41 n/a 0.77 n/a 0.17 Site 2 R s n/a n/a 120 16.9 n/a 0.84 n/a 13.8 Site 2 R u n/a n/a 103 2.36 n/a 0.55 n/a 5.46 Site 2 R t n/a n/a 92 0.20 n/a 0.17 n/a 1.64

Site 3 T s n/a n/a 102 21.4 n/a 1.57 n/a 1.79 Site 3 T u n/a n/a 94. 12.7 9.47,1 0.95 n/a 0.80 2 0.3 Site 3 T t n/a n/a 82 1.85 n/a 0.71 n/a 0.20 Site 3 R s n/a n/a 112 11.6 n/a 0.77 n/a 12.1 Site 3 R u n/a n/a 101 2.03 n/a 0.46 n/a 4.09 Site 3 R t n/a n/a 86 0.28 n/a 0.23 n/a 1.21

Site 4 T s n/a n/a 108 18.2 n/a 1.20 n/a 2.02 Site 4 T u n/a n/a 99 10.6 9.69,1 0.81 n/a 0.80 0.2 Site 4 T t n/a n/a 91 1.67 n/a 0.61 n/a 0.24 Site 4 R s n/a n/a 121 9.56 n/a 0.79 n/a 8.78 Site 4 R u n/a n/a 102 2.30 n/a 0.49 n/a 3.76 Site 4 R t n/a n/a 71 0.20 n/a 0.26 n/a 0.96

Dundrum Bay T s n/a n/a 107 19.4 n/a 1.01 n/a 4.88 T u n/a n/a 99 9.65 8.11,9 0.75 n/a 1.33 .41 T t n/a n/a 91 0.40 n/a 0.33 n/a 0.06 R s n/a n/a 117 10.9 n/a 0.86 n/a 11.9 R u n/a n/a 99 3.21 n/a 0.49 n/a 3.60 R t n/a n/a 83 0.17 n/a 0.21 n/a 0.37

Source: Environment and Heritage Service of DoE Northern Ireland direct response to ERM.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 33 3.7.1 Chemical Profile

Ammonia two individual winter measurements for each of four sites indicated a range of 9.47–18.4 µM N. If correct, a mean of 13.5 µM would score

a Rmean of ca. 0.9, which would be significantly elevated. Dundrum Bay has two winter ammonia measurements for one site of ca. 8–9 µM. This is at the higher end of the observed range for a coastal water.

Total Oxidised Nitrogen winter concentrations had the range 1.67–38.0 µM

N, a Rmax range of 0.27–0.41 and a Rmean of 0.36–0.52. The summer

concentration range was 0.20–22.5 µM, with Rmax between 0.10–0.32 and

Rmean between 0.06–0.14. Dundrum Bay had a winter range of 0.40–19.4 µM,

and a summer range of 0.17–10.9. The winter Rmax was 0.29, that for summer 0.16 – unexceptional values.

Phosphorus winter concentrations had the range 0.47–1.94 µM N, a Rmax

range of 0.27–0.41 and a Rmean of 0.36–0.52. The summer concentration range

was 0.20–22.5 µM, with Rmax between 0.10–0.32 and Rmean between 0.06–0.14.

The winter phosphorus range for Dundrum Bay was 0.33–1.01, with a Rmax of

0.32, while the summer range was 0.21–0.86, with a Rmax of 0.22. These are unexceptional values.

Oxygen saturation values were unexceptional in winter, 82–107%, but in summer showed a wider range of 63–128%. The winter oxygen range in Dundrum Bay was 91–107%, that for summer was 83–117%, indicative of a phytoplankton bloom.

Input Budget Service et al. attribute 4.9 tonnes per annum DIN to sewage treatment discharges to the Lough, and 521 tonnes to catchment DIN. As with other sites, the relative importance of natural and anthropogenic inputs to the catchment, and the quantification of individual anthropogenic components, has apparently not been attempted.

3.7.2 Biological Effects

Phytoplankton chlorophyll concentrations ranged over 1.96–19.4, the highest levels, indicative of some eutrophication, present in the inner parts of the Lough. No other measures of biological parameters have been encountered. The highest summer level, of 11.9 µg l-1, was elevated for a coastal site.

3.7.3 Designation under the Directives

As just described there is some evidence of eutrophication in the inner estuary. As there are two agglomeration upstream of the inner estuary, it can be assumed that it qualifies for designation as a Sensitive Area under the Urban Waste Water Treatment Directive.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 34 3.8 REFERENCES

Foy R.H., Smith R.V., Jordan C.and Lennox S.D.(1995). Upward trend in soluble phosphorus loadings to Lough Neagh despite phosphorus reduction at sewage treatment works. Water Research, 29, 1051-1063.

Foy R.H., Kirk M. (1995). Agriculture and water quality: a regional study. Journal of the Institution of Water and Environmental Management, 9, 247- 256.

Jordan, C, and Smith, R.V. (1995). Factors affecting the leaching of nutrients from an intensively managed grassland in County Antrim, Northern Ireland. Journal of Environmental Management, 20, 1-15.

Lennox S.D., Foy R.H., Smith R.V., Jordan C. (1997). Estimating the contribution from agriculture to the phosphorus load in surface water. In: Phosphorus loss from soil to water (ed. Tunney H., Carton O.T., Brookes P.C., Johnston A.E.) p55-75. Wallingford, CAB International.

Smith, R.V., Stevens, R.J., Foy, R.H. and Gibson, C.E. (1981). Upward trend in nitrate concentrations in rivers discharging into Lough Neagh for the period 1969-1979. Water Research, 15, 183-188.

Further references

i Service, M., A.E. Durrant, D. Faughey, J.A. Mills & J.E. Taylor (1998). Sources of nutrient inputs to the coastal waters of Northern Ireland. pp.64–70 in Eutrophication in Irish waters (J.G. Wilson, ed.) Royal Irish Academy, Dublin.

ii Boaden, P.J.S. (1982) Estuarine and Inshore Waters. pp. 101–118 in Northern Ireland: environment and natural resources (eds J.G. Cruickshank and D. N. Wilcock). Queen’s University of Belfast and New University of Ulster. Belfast.

iii Parker, J.G., R.S. Rosell, and K.C. MacOscar (1988) The phytoplankton production cycle in Belfast Lough. Journal of the Marine Biological Association of the UK 68, 555–564.

iv Ball, B., R. Raine, & D. Douglas (1997). Phytoplankton and particulate matter in Carlingford Lough, Ireland: An assesment of food availablility and the impact of bivalve culture. Estuaries 20, 430–440.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DG ENVIRONMENT 35 LEGEND

Rivers

Designated Sensitive Areas

Œ Lough Neagh 4  Lough Erne

3 Areas requiring designation under 91/271/EEC

5 Ž Lough Foyle  Bann Estuary 1  Belfast Lough ‘ 2 Carlingford Lough 7 Areas requiring further investigations 6 ’ Strangford Lough

MAP I AREAS REQUIRING DESIGNATION UNDER 91/271/EEC LEGEND

Rivers Lough

Areas requiring designation under 91/676/EEC

Œ Belaghy 4  1 Buckna

2 Areas requiring further investigations

Ž Strangford Lough  Lough Foyle 3

MAP II AREAS REQUIRING DESIGNATION UNDER 91/676/EEC