CONTENTS

1 INTRODUCTION 1

1.1 BACKGROUND 1 1.2 SCOPE 5

2 COUNTRY REPORT - PORTUGAL 7

2.1 PORTUGAL - THE CONTEXT 7 2.2 THE DESIGNATION PROCESS - THE URBAN WASTE WATER TREATMENT DIRECTIVE 9 2.3 THE DESIGNATION PROCESS - THE NITRATES DIRECTIVE 20

3 MARINE/COASTAL WATER AND ESTUARIES 23

3.1 INTRODUCTION 23 3.2 EUTROPHICATION - OVERVIEW 23 3.3 THE NORTH COAST - VULNERABILITY 25 3.4 THE TAGUS ESTUARY 26 3.5 THE SADO ESTUARY 29 3.6 THE MONDEGO ESTUARY 33

4 REVIEW OF FRESHWATERS DESIGNATED AS SENSITIVE AREAS UNDER THE URBAN WASTE WATER TREATMENT DIRECTIVE 36

4.1 SURFACE FRESHWATER 36 4.2 THE PORTUGUESE CLASSIFICATION SYSTEM 36 4.3 SURFACE FRESHWATER QUALITY - AN OVERVIEW 37 4.4 NITRATE CONTAMINATION 41 4.5 WATERS USED FOR THE ABSTRACTION OF DRINKING WATER 48 4.6 GROUNDWATERS 54

5 REVIEW OF THE WATERS DESIGNATED AS VULNERABLE ZONES UNDER THE NITRATES DIRECTIVE 57

5.1 INTRODUCTION 57 5.2 SURFACE FRESHWATER 57 5.3 GROUNDWATERS 60

6 CONCLUSIONS 78

7 REFERENCES 80

ANNEX ANITRATE CONCENTRATIONS IN GROUNDWATER ANNEX BSURFACE FRESHWATER QUALITY MAPS ANNEX CNITRATE CONCENTRATIONS IN SURFACE FRESHWATER ANNEX DMAPS 1 INTRODUCTION

1.1 BACKGROUND

The objectives of the Urban Waste Water Treatment Directive (UWWTD)1 and the Nitrates Directive2 are to reduce and prevent “pollution”, from urban waste water treatment plants 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. The waters that must be studied and identified under both the Urban Waste Water Treatment Directive (91/271/EEC) and the Nitrates Directive (91/676/EEC) are similar. Consequently, the examination of the identification of these waters has taken place concurrently during this study.

1.1.1 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 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 alia, of the following criteria.” Three criteria are set out:

1. Whether surface freshwaters, in particular those used for the abstraction of drinking water, contain or could contain, if action pursuant to Article 5 is not taken, more than the concentration of nitrate laid down in accordance with Directive 75/440/EEC;

2. Whether groundwaters contain more than 50 mg/l nitrate or could contain more than 50 mg/l nitrate if action pursuant to Article 5 is not taken;

3. Whether natural freshwater lakes, other freshwater bodies, estuaries, coastal waters and marine waters are to be eutrophic or in the near future may become eutrophic if action pursuant to Article 5 is not taken.

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 1 1.1.2 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 eutrophication 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”.

• 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.

Article 5: For the purposes of paragraph 2 in the Directive, Member States shall by 31 December 1993 identify sensitive areas according to criteria laid down in Annex II.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 2 Criteria for identification of sensitive and less sensitive areas

(a) Sensitive areas

A water body must be identified as a sensitive area if it falls into one of the following groups:

• natural freshwater lakes, other freshwater bodies, estuaries and coastal waters which are found to be eutrophic or which in the near future may become eutrophic if protective action is not taken.

The following elements might be taken into account when considering which nutrient should be reduced by further treatment:

• lakes and streams reaching lakes/reservoirs/closed bays which are found to have a poor water exchange, whereby accumulation may take place. In these areas, the removal of phosphorus should be included unless it can be demonstrated that the removal will have no effect on the level of eutrophication. Where discharges from large agglomerations are made, the removal of nitrogen may also be considered;

• estuaries, bays and other coastal waters which are found to have a poor water exchange, or which receive large quantities of nutrients. Discharges from small agglomerations are usually of minor importance in those areas, but for large agglomerations, 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;

• surface freshwaters intended for the abstraction of drinking water which could contain more than the concentration of nitrate laid down under the relevant provisions of Council Directive 75/440/EEC of 16 June 1975 concerning the quality required of surface water intended for the abstraction of drinking water in the Member States if action is not taken;

Areas where further treatment than that prescribed in Article 4 of this Directive is necessary to fulfil Council Directives.

(b) Less sensitive areas

A marine water body or area can be identified as a less sensitive area if the discharge of waste water does not adversely affect the environment as a result of morphology, hydrology or specific hydraulic conditions which exist in that area.

When identifying less sensitive areas, Member States shall take into account the risk that the discharged load may be transferred to adjacent areas where it can cause detrimental environmental effects. Member States shall recognize the presence of sensitive areas outside their national jurisdiction.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 3 The following elements shall be taken into consideration when identifying less sensitive areas: open bays, estuaries and other coastal waters with a good water exchange and not subject to eutrophication or oxygen depletion or which are considered unlikely to become eutrophic or develop oxygen depletion due to the discharge of urban waste water.

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 eutrophication. One 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.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 4 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.

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.

1.2 SCOPE

‘Verification of Vulnerable Zones identified under the Nitrate Directive and Sensitive Areas under the Urban Waste Water Treatment Directive in Portugal’.

The analysis of the parameters/criteria enables the identification of the waters, which should have been identified under either or both Directives and have not been identified. As required by the Commission, the following information has been provided for all these areas:

• location of waters concerned; • detailed assessment of relevant parameters and criteria indicating that the area in question should be identified under either or both Directives; • assessment, identification (agricultural area, agglomeration or others), description (qualitative and quantitative) and characterisation (significance) of all nutrient sources for all relevant areas; • assessment of the transboundary coherence of identified waters; and • information regarding any methodological inconsistencies.

Regarding the Nitrates Directive, where it is considered that areas should be designated as vulnerable zones and have not been, the following information is provided:

• nature of catchment; • nature of land-use;

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 5 • assessment of potential nitrate sources other than agriculture – e.g. urban waste water treatment, industrial sources, atmospheric deposition – and their relative significance; and • identification and assessment of the justification for transboundary incoherence between designations.

During this study, the differences between both Directives (e.g. definition of eutrophication), as well as the possible links between the Directives, have been taken account of.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 6 2 COUNTRY REPORT - PORTUGAL

2.1 PORTUGAL - THE CONTEXT

2.1.1 Background

Portugal is located in the extreme South of Europe and has about 800 km of Atlantic coastline. This coastline is characterised by strong currents and upwelling.

Four major rivers cross the boundary with Spain: the Douro, Tagus, Guadiana and Minho. The other main rivers in Portugal are shorter and more irregular. These are the Vouga, Mondego and Sado.

Figure 2.1 Portugal’s main hydrological Basins

Source: INAG

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 7 In 1990, agricultural areas occupied about 45% of the total mainland area. The trend during the 1980’s was a decrease in arable land (about 2%) and an increase in areas devoted to permanent plantings (11%). Forests and other woodland cover about 36% of the total area.

The most important demographic phenomenon in Portugal is the urbanisation and migration from the inteRior of the country to the coast. About half of the population is concentrated in the Lisbon and Porto areas and the Northern districts of Braga, Aveiro and Coimbra. It is reported ii that over 75% of the population lives within 50 km of he coast.

Due to the irregularity of the pluviometric regime, and hence a necessity for regulating rivers, over 80 reservoirs/lagoons have been constructed. However, the trophic status of these reservoirs is not well known, and little studied, with the exception of the largest ones. This is reviewed in Section 3.2.3 of this report.

2.1.2 Overview of water quality

The state of surface waters with regards to nitrogen compounds is relatively well known in Portugal (as opposed to heavy metals and pesticides). There are several water quality monitoring networks in place in Portugal, one of which is managed by INAG (Instituto da Agua - see figure 2.2). About 25% of the total length of rivers in Portugal are moderately to very polluted, according to the EU classification (Suspended matter, dissolved oxygen (DO),

O2 and ammonia). However, on the whole it appears that nitrogen compounds in waters have been decreasing. The critical problems are found around the main agglomerations but also in rural areas where intensive pig farming, for example, is tacking place.

The quality of coastal waters is, on the whole, satisfactory. The bathing water quality standard, as prescribed by the EC Directive, is generally reached. The worst polluted areas are the Tagus and Sado estuaries where nutrients and large quantities of heavy metals from industry are present. Other estuaries of concern are those of Minho and Mondego, as well as the reservoirs of Albufeira and Obidos. The reservoirs of Aveiro and Formosa are severely polluted, especially by agricultural wastes, causing eutrophication. However, it has been reported (1) that the pollution burden from nutrients is generally lower than in other European countries as the use of fertilisers is generally less intensive in Portuguese agriculture.

(1) OECD (1993), Environmental Performance Review - Portugal, OECD

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 8 Figure 2.2 Water Monitoring Network (INAG)

Water Quality Monitoring Network

stations main rivers secondary rivers hydrological basins

Source: INAG

2.2 THE DESIGNATION PROCESS - THE URBAN WASTE WATER TREATMENT DIRECTIVE

2.2.1 Introduction

It seems that the main strategy used by the authorities was, in the first instance, only to designate waters which presented an unequivocal case (ie. where sufficient information could support a designation, where there were significant urban waste water discharges, traditionally sensitive areas such as ria Formosa, etc.).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 9 Such a strategy appears to have been adopted primarily for economical/ financial reasons. The 4-year review required by the Directive would enable the authorities to obtain further information/ studies on other areas and revise the designations if necessary. The authorities consider, however, that more areas that should have been have been classified 1. This is the case in particular for the Nitrates Directive for which it appears that there are detailed discussions between INAG and the Ministry of Agriculture with regards to the designation of Vulnerable Zones.

2.2.2 Sensitive Areas

Sensitive Areas in Portugal were designated according to three criteria:

• natural freshwater lakes, other freshwater bodies, estuaries and coastal waters which are found to be eutrophic or which in the near future may become eutrophic if protective action is not taken (Criteria 1).

• surface freshwaters intended for the abstraction of drinking water which could contain more than the concentration of nitrate laid down under the relevant provisions of Council Directive 75/440/EEC of 16 June 1975 concerning the quality required of surface water intended for the abstraction of drinking water in the Member States if action is not taken (Criteria 2);

• Areas where further treatment than that prescribed in Article 4 of this Directive is necessary to fulfil Council Directives (Criteria 3).

The water bodies identified as Sensitive Areas are listed in Table 2.1 and are shown on Figure 2.3. In 1994, a report iii on the designation of Sensitive Areas and criteria used to designated such areas was prepared by INAG. It provides a list of 93 Sensitive Areas in surface freshwaters, estuaries and coastal waters. The official designation in 1997 listed a total of 41 Sensitive Areas. The 52 areas which where not designated are listed in Table 2.2. As can be seen, most areas which where not designated are reservoirs, part of a national/natural park or are on the border with Spain.

(A) Surface Freshwaters - Reservoirs

Partly due to the irregularity of the pluviometric regime in Portugal and the need for regulating rivers, over 80 reservoirs have been constructed in Portugal. In such reservoirs, the main eutrophication factor has been considered to be the presence of nutrients which enables the growth of macrophyte algae, the limiting factor being phosphorus (as opposed to nitrates). Other factors such as temperatures, depth, turbulence, etc. are considered to play a major role. The eutrophication status of such water bodies was not identified according to numerical chemical factors.

1 Mrs Mira da Silva (INAG), person. Comm.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 10 Table 2.1 Designated Sensitive Areas - Surface Freshwaters and Estuaries

No. Name Basin Type Criteria Treatment

1 Canicada Rio Cávado Reservoirs 1 No discharge with e.p.>10,000 2 Alto Cavado Rio Cávado Reservoir 1 secondary (p.e.<10,000) 3 Alto Rabago Rio Cávado Reservoir 1 No discharge with e.p.>10,000 4 Venda Nova Rio Cávado Reservoir 1 No discharge with e.p.>10,000 5 Paradela Rio Cávado Reservoir 1 No discharge with e.p.>10,000 6 Guilhofrei Rio Ave Reservoir 1 No discharge with e.p.>10,000 7 Andorinhas Rio Ave Reservoir 1 No discharge with e.p.>10,000 8 Alfandega da Rio Douro Reservoir 1 No discharge Fé

9 Burga Rio Douro Reservoir 1 No discharge with e.p.>10,000 10 Salgueiro Rio Douro Reservoir 1 No discharge with e.p.>10,000 11 Torrao/Tame Rio Douro Reservoir 1/2 No discharge with ga e.p.>10,000

12 Vilar Rio Douro Reservoir 1 No discharge with e.p.>10,000 13 Varosa Rio Douro Reservoir 1/2 No discharge with e.p.>10,000 14 Azibo Rio Douro Reservoir 2/3 No discharge with e.p.>10,000 15 Barrinha de Rio Douro Reservoir 3 No discharge with Ezmoriz e.p.>10,000

16 Ria de Aveiro Rio Vouga whole area 1/3 No discharge with e.p.>10,000 17 Frossos Rio Vouga Pateira 1 No discharge with e.p.>10,000 18 Fermentelos Rio Vouga Pateira 1 No discharge with e.p.>10,000 19 Quiaios coastal stream Lake of Braças e Vela 1 N/P removal between Mondego and Vouga 20 Agueira Rio Mondego Parts of the reservoir ½Secondary originating from river Dão and river Mondego 21 Mira Rio Vouga Lagoon of Mira e 1/3 No discharge Barrinha

22 Febres Rio Vouga Reservoirs of Bunho, 1No discharge Hortas, Coudiçais

23 S. Tomé Rio Vouga Reservoir 1 No discharge

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 11 No. Name Basin Type Criteria Treatment

24 Ervideira coastal stream Reservoir 1 No discharge between Mondego e Lis 25 Tagus Rio Tagus Estuaries of Seixal, 1/3 N/P removal Coina and Moita and Montijo of the Tagus astuary 26 Óbidos Oeste stream Reservoir 3 No discharge

27 Divor Rio Tagus Reservoir 2 No discharge

28 Lagoa de Apostiça stream Stretch of Rio 3No discharge albufeira Guadiana from its confluence with Rio Caia up to its confluence with Rio Chança 29 Guadiana Rio Guadiana Reservoir 2/3 More than secondary

30 Vigia Rio Guadiana Reservoir 2 No discharge

31 Monte Novo Rio Guadiana reservoir 2 No discharge

32 Murtega Rio Guadiana Murtega stream 2 Secondary

33 Caia Rio Guadiana Reservoir 2/3 No discharge

34 Roxo Rio Sado reservoir 2 More than secondary

35 Monte da Rio Sado reservoir 2 No discharge Rocha

36 Costa da Galé Coastal stream reservoir of Melides, 3No discharge of Galé Santo Andre and Sancha

37 Santa Clara Rio Mira reservoir 2 No discharge

38 Sapal de Rio Guadiana Entire area of Sapal 3No discharge Castro Marim do Castro Marim

39 Ria Formosa Algarve Entire area of the Rio 3 More than secondary streams Formosa with the exception of the Ramahete estuary, Faro canal, Marim canal and Tavira canal

40 Salagos Algarve reservoir 1 no discharge streams 41 Ria de Alvor Alvor stream Entire area 3 Secondary

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 12 Table 2.2 Waters Considered But Not Designated under Directive 91/271/EEC

No. Basin Name Identification

1 Minho river Minho Stretch of the river bordering Spain

2 Lima/Cavado rivers Peneda-Gerès All parts of the river included in the Gerès Natural Park

3 Rio Douro Montesinho Allparts included in the Montesinhos National Park, including the Montesinho reservoir, and the border stretch of the Maças river

4 Douro river Douro Border section of the Douro river

5 Douro river Pocinho Reservoir

6 Douro river Valeira Reservoir

7 Douro river Réga Reservoir

8 Douro river Carapatelo Reservoir

9 Douro river Crestuma-lever Reservoir

10 Douro river Alvão All section included in the Alvão National Park

11 Tagus/Mondego Estrela All sections included in the Estrella National Rivers Park

12 Mondego river Raiva Reservoir

13 Mondego river Fronhas Reservoir

14 Mondego river Açude de Coimba Reservoir

15 Tagus river Cabril Reservoir

16 Tagus river Campinha Reservoir

17 Tagus river Malcata All section included in the Serra a Malcata Natural Park, including the Meimoa reservoir

18 Tagus river Corgas Reservoir

19 Tagus river Pisco Reservoir

20 Tagus river Santa Agueda Reservoir (Marateca)

21 Tagus river Idanha Reservoir

22 Tagus river Penha Garcia Reservoir

23 Tagus river Toulica Reservoir

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 13 No. Basin Name Identification

24 Tagus river Castelo do Bode Reservoir

25 Tagus/Guadiana S. Mamede All sections included in the Serra de S. river Mamede including the Apartadura reservoir

26 Tagus river and Aire e All sections included in the Serras de Aire e Ribeira de Oeste CandeeRios Candeeiros Natural Park

27 Tagus River Boquilobos All sections included in the Natural Reserve of Paul de Bolquilobo

28 Tagus river Maranhão Reservoir

29 Sado river Alvito Reservoir

30 Sado river Monte da Rocha Reservoir

31 Ribeira de Morgavel Morgavel Reservoir

32 Guadiana river Tapada Grande Reservoir

33 Ribeira de Odeaxere Bravura Reservoir

34 Arade river Arade Reservoir

35 Arade river Funcho Reservoir

36 Ave river Andorinhas Reservoir

37 Douro river Torrao Reservoir

38 Douro river Azibo Reservoir

39 Douro river Ranhados Reservoir

40 Douro river Penereiro Reservoir

41 Mondego river Fagilde Reservoir

42 Tagus river Pracana Reservoir

43 Ribeiras de Oeste Sintra/Cascais All sections included in the Sintra/Cascais Natural Park, including the Rio de Mula Reservoir

44 Douro river Santa Maria de Reservoir Aguiar

45 Sado river Sado Natural Reserve of the Sado Estuary

46 Vouga river Qunita das Reservoir Cainhas

47 Ribeiras Costa Protected Areas All protected areas Sudoeste and Vicentina

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 14 No. Basin Name Identification

48 Algarve rivers Formosa National The whole park Park

49 Douro river Águeda Border sections of Águeda river and Tourões river

50 Tagus river Erges Border section of Erges river and Torto river

51 Tagus river Tagus Fronteira Border setion

52 Tagus river Sever Border section

53 Guadiana river Ardila Border section

54 Guadiana river Chança Border section

55 Mondego river Paul de Arzila Paul de Arzila Natural Reserve

56 Mondego river Quinta de Taipal Classified sites of Mounts of Santa Olaia and Ferrestelo

57 Mondego river Paul de Madriz all protected areas

58 Vouga river Açude de Maeira Reservoir

A reservoir is considered to be eutrophic if it fulfils the following criteria:

Table 2.3 Eutrophication factors for reservoirs

Parameter Limit value Methodology

Total phosphorus (µg/l) >35 As referenced in “Water analysis for Aquaculturalists “ (1983)

Chlorophyll a (µg/l) >9 Calculated with the Lorenzen equation (1967)

Light (Secchi) (m) <3 20cm diameter disc Note: These limit values correspond to annual median Source: OECD 1982

Reservoirs will only have been identified as Sensitive Areas if they are used for abstraction of drinking water or recreation by the general public or if their trophic status has a negative impact on its use or the quality defined for its use or by other Directives. Protected reservoirs/lagoons presenting symptoms of eutrophication must also be designated as Sensitive Areas.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 15 (B) Surface Freshwater - Rivers and Estuaries

With regards to rivers and estuaries, no limit values were established to estimate the level of eutrophication. However a series of criteria were used to identify eutrophication in rivers and estuaries:

• occurrence of algal blooms; • alterations in the growth of macrophytes; • oxygen levels; • nutrient concentration; • alterations to flora and fauna; • alterations to benthic communities; • water subject to discharges of significant quantities of nutrient, except where it can be shown that the removal of phosphorus or nitrogen does not influence the level of eutrophication.

It must be mentioned that, due to the lack of long term studies and information, estuaries with strong currents and water exchange and open bays have not been designated and are considered as “Normal Areas”. This will be revised once more comprehensive studies are be available (1) .

(C) Surface Freshwaters Used for the Abstraction of Drinking Water

For application of criteria 2, historic data obtained from the national water quality network were used. This data is analysed in Section 3 of this report. water bodies were identified as Sensitive Area according to criteria 2.

(D) Areas of Ecological Importance

Several water bodies located in areas of high ecological importance were identified as Sensitive Areas.

2.2.3 Less Sensitive Areas

The Directive 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.

(1) DGA & IHRH (1996), Estudo de Avaliacao Da Vulnerabilidade Da Capacidade de Recepcao Das Aguas E Zonas Costeiras Em Portugal.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 16 The Directive also requires Member States to take into account the morphology, hydrology, oxygen depletion and/or specific hydraulic conditions of the receiving water. In Portugal, the entire coast, with the exception of the Algarve coast, has been designated as a Less Sensitive Area.

This decision was based on the characteristics of the West coast of Portugal which is characterised by a straight continental platform with strong currents all along its length. In addition, during the summer, the orientation of the coastline in relation to the dominant winds provoke an upwelling of the deep and cold ocean waters of the Atlantic ocean towards the surface of the coast and back towards the interior of the ocean (upwelling occurs along the west coast from spring to early autumn under fairly strong and steady northern winds, while on the South coast of Portugal, upwelling only takes place when there are suitable (temporary) wind conditions. This phenomenon has a strong influence on the coastal climate. Indeed the climate on the West cost of Portugal is significantly different to the South coast. During the winter, there are strong currents from South to North which are stronger at the ocean surface. This phenomenon results in a water mass transport parallel to the coastline.

With regards to eutrophication, the information used by the authorities tends to show that, in general, the waters of the west coast of Portugal benefit from good levels of water exchange, high tides and strong currents. It is therefore considered that eutrophication resulting from urban waste water discharges to coastal waters is highly improbable. Although several studies claim that no clear signs of eutrophication have been found along the west coast of Portugal, it is known that localised signs of eutrophication have been observed near waste water discharges or near urban areas.

In order to control the effects of discharges of urban waste water into coastal waters and hence designation of Less Sensitive Areas, the following limit values have been established:

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 17 Table 2.4 Parameters for Designating Less Sensitive Areas

Parameters Limit Value at the Observations Analytical Method Surface

Dissolved Oxygen >90% saturation At least 90% of the Winkler method or during summer results must comply electrochemical method

Dissolved nitrates 15 µmole/l during as above molecular absorption winter

Chlorofill a <10 mg/m3 during as above Fluorescence summer

Light (Secchi disk) >2 m during winter as above visual observation

As mentioned above, the waters complying with the above-limit values were designated as Less Sensitive. Indeed, such waters are considered not to harm the environment. This resulted in the entire coast, with the exception of the coast of Algarve, being designated as Less Sensitive Areas. When applying secondary treatment to the receiving waters a reduction of no more than 10% is observed. It was thus considered that a more advanced level of treatment than primary treatment did not present any advantages for the environment.

The water bodies having the characteristics described in Table 2.5 are considered as ‘Normal Areas’ (marine waters).

Table 2.5 Parameters for Designating Normal Areas

Parameters Limit Value at the Observations Analytical Method Surface

Dissolved Oxygen >70% saturation At least 90% of the Winkler method or during summer results must comply electrochemical method

Dissolved nitrates <20 µmole/l during as above molecular absorption winter

Chlorophyll -a <15 mg/m3 during as above Fluorescence summer

Light (Secchi disk) >2 m during winter as above visual observation

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 18 Figure 2.3 Designated Sensitive Areas

Source: INAG

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 19 2.3 THE DESIGNATION PROCESS - THE NITRATES DIRECTIVE

2.3.1 Introduction

Member States must identify “Vulnerable Zones”- usually referred to as “Nitrate Vulnerable Zones”- covering areas of land which form the catchments of waters which are polluted or could be polluted by nitrate from agriculture. Polluted waters are identified either because of eutrophication (defined as enrichment, which is leading to undesirable ecological disturbance), or because

of problems with the drinking water parameter of 25-50 mg NO3-/l.

Article 3.1: Waters affected by pollution and waters which could be affected by pollution if action pursuant to Article 5 is not taken shall be identified by the Member States in accordance with the criteria set out in Annex 1 of the Directive.

Annex 1: A. Waters referred to in Article 3 (1) shall be identified making use, inter alia, of the following criteria:

1. Whether surface freshwaters, in particular those used for the abstraction of drinking water, contain or could contain, if action pursuant to Article 5 is not taken, more than the concentration of nitrate laid down in accordance with Directive 75/440/EEC;

2. Whether groundwaters contain more than 50 mg/l nitrate or could contain more than 50 mg/l nitrate if action pursuant to Article 5 is not taken;

3. Whether natural freshwater lakes, other freshwater bodies, estuaries, coastal waters and marine waters are to be eutrophic or in the near future may become eutrophic if action pursuant to Article 5 is not taken.

2.3.2 The Designation Process

It was indicated by the Portuguese authorities that there were several problems in identifying Vulnerable Zones such as :

• “There has been insufficient monitoring, or no monitoring at all of the nitrate content of surface freshwaters to determine the state of eutrophication ”. (mainly due to the fact the P is the limiting factor and therefore nitrates were not considered to be an issue);

• “ Lack of data on Nitrate levels in the waters concerned obtained over a peRiod of several years, which would allow reliable predictions to be made as to how the situation will evolve and enable us to identify water which will be polluted by a certain date “.

Therefore, the data obtained since 1992 were used to:

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 20 • assess the nitrate levels of waters used for the abstraction of drinking water, identifying waters with nitrate levels >50 mg/l; • assess the eutrophication status of all waters with regards to nitrates and identify those which are eutrophic.

Vulnerable Zones were identified according to the following procedure:

1. “ Surface Freshwaters: first the polluted section of the water course must be delimited. The corresponding VZ will be the part of the drainage area which drains into this part of the water course. The natural contours of this part of the drainage area must also be delimited and any man-made drainage structure taken into account. Examination of the Quality Network data available shows compliance with Article 5 of Directive 75/440/EEC with regards to nitrate levels: this being the case, the criterion will not be applied in the designation of Vulnerable Zones at this stage.

2. Groundwater: In places where groundwater is collected for the abstraction of drinking water, where nitrate levels are more than 50 mg/l, the corresponding VZs are the areas of land which drain into the water tables or aquifers from which the water is abstracted and are polluted mainly from agricultural sources. In cases where the areas in question are adjacent to one another, they may be regarded as a single VZ for the purpose of the Directive.

3. With regards to eutrophication, the following is considered: water, lagoons, reservoirs, rivers and other water courses which is not being used for drinking water production or intended for such use. The limiting factor in these waters is usually a low phosphorous level, not nitrogen. … This criteRion will not be applied in the designation of VZ at this stage.

4. Estuary, coastal and marine waters. Due to the lack of data concerning the state of eutrophication (in relation to nitrates) of such waters, there is no point attempting to designate VZs. If some of these waters are eutrophic, as is likely, the origin of the nitrates will have to be identified. In practice this would be extremely complicated, if not impossible. Therefore, at this stage such waters will not be considered “.

This clearly shows that the procedures applied by the Portuguese authorities to designate Vulnerable Zones, although justifiable, do not entirely fulfil the requirements of Directive 91.676/EEC.

The designated Vulnerable Zones are listed in Table 2.6.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 21 Table 2.6 Designated Vulnerable Zones

Name Type 1 Vila do Conde Unconfined aquifer between Esposende and Vila do Conde 2 Aveiro Aveiro quaternary aquifer 3 Vagos Vagos quaternary aquifer 4 Mira Mira quaternary aquifer 5 Campina de Faro Campina de Faro miocene, jurassic aquifer

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 22 3 MARINE/COASTAL WATER AND ESTUARIES

3.1 INTRODUCTION

This chapter presents an assessment of eutrophication and nutrient enrichment along the coast of Portugal. The first section presents an overview of the eutrophication status of the Portuguese coast. The following sections, all sites which may require designation are assessed and reviewed.

3.2 EUTROPHICATION - OVERVIEW

The Portuguese coast is part of the Iberian Upwelling system. This phenomenon occurs along the western Atlantic coast from spring to early autumn under relatively strong and steady winds coming from the north. On the South coast, upwelling only takes place when westerly winds occur and these will usually be temporary.

A paper presented by Portugal iv at an OSPAR ad hoc working group on eutrophication looks at the trend of phytoplankton biomass (Chlorophyll -a mg/m3) during the 80’s and 90’s. The results are summarised below.

Results of the study

Surface values from 12 sampling stations located along a transept 1 (coastal- coast), 15 (shelve edge) and 60 (oceanic-offshore) miles from the coast were analysed. The results show that the surface values are low and similar with a minimum of 0.04 mg/m3 and a maximum of 1.74 mg/m3. The spatial distribution shows that Chlorophyll -a concentrations attain a maximum value of 1.74 mg/m3 at the coastal stations and 1.46 mg/m3 at the shelf edge stations and 0.47 mg/m3 at the oceanic stations.

Figure 3.1 Spatial maximum chlorophyll a (mg/m3)

1.8

1.6

1.4

1.2 1 C S

Chl a Chl 0.8 O 0.6

0.4 0.2 0 Transept 00 Transept 01 Transept 02 Transept 03

Source: IPIMAR

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 23 When looking at yearly trends, the maximum reached is 5 mg/m3 at the coastal station, which is still well below the maximum of 50 mg/l. Also, it is very low when compared to the values found in northern Member States such as Germany (10 µg/l) and Holland (90-100 µg/l).

It is reported that all waters studied are well oxygenated with values of saturation greater than 80%. It must, however, be mentioned that episodes of algal blooms have occurred off the Portuguese coast and have had harmful consequences. It is though that the appearance of flagellate blooms is a consequence of oceanographic conditions such as winds and currents which sustain the development of flagellatesv.

The report also indicates that the phytoplanktonic biomass of the coastal stations during the peRiods 1985-1987 and 1994-1996 were similar. “Nevertheless, in winter the chlorophyll decreased strongly at coastal stations and exhibited an opposite trend at the oceanic stations, which is the result of the current systems corresponding to the climatological wind systems. Of the west coast of Portugal and Spain, the wind stress is directed southwards during the summer, and upwelling develops as a result of the associated offshore Ekman transport. During winter, a reversal of the meridional component of the wind northwards induces an onshore Ekman transport north to about 40ºN, which is accompanied by the poleward surface current”.

The results tend to show that there is no increasing trend, no difference between the different regions along the coast, and no clear signs of eutrophication (or its symptoms) in Portuguese coastal waters. However, the author mentions that “we should keep in mind that the relationship between phytoplankton biomass and eutrophication is not clearly understood and can be related to abiotic conditions”.

A report by Oliveira & Cabecadas (1996)vi mentions that certain lagoons and estuaries along the Portuguese coast have very complex topographies (enclosed arms, etc) and show seasonal signs of eutrophication (poor oxygenation, increasing nutrient levels and development of microalgae). The main ones are:

• Ria de Aveiro reservoir (designated as a Sensitive Area in 1997); • Sado Estuary; • Ria Formosa Reservoir (designated as a Sensitive Area in 1997);

Symptoms of Eutrophication

In general it can be said that the exposure of the open west coast to strong wave action and tidal currents rapidly disperses polluted waters discharged from rivers or coastal towns. Therefore, changes in the natural flora on account of pollution have not been noticed, with the exception of occasional events near harbours or sewage discharges. It must, however, be mentioned that due to a lack of long-term studies, there is limited information on changes or modifications. Indeed, very limited reliable information is available on

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 24 coastal algal vegetation. Nevertheless, in spring and summer, occasional green tides of Ulva rigida, Ulactua and Enteromorpha spp (free floating species) have occurred on the south coast. The settlement of dense communities of the invasive Sargassum muticum in large semi-open basins of sand and mud bottoms on the Minho coast (North of Porto) has also been observed.

However, in the most important estuaries/reservoirs (Douro, Ria de Aveiro, Tagus and Sado), there is a strong tidal current which prevents or reduce the risk of eutrophication IV. However, investigations by J.C. Marques (Coimbra University) have shown eutrophication in the Mira and Mondego estuaries and a progressive increase in Enteromorpha spp. populations and biomass together with reduction in Zostera beds in the southern arm of the Mondego estuary.

Signs of red tides have already been observed in Portuguese coastal waters. It is assumed that the development of such red tides is associated with certain specific nutrient and physical conditions.

Generally, the morphology of the main estuaries and reservoirs, together with the tidal regime, favours good water exchange and hence limits eutrophication to localised areas. On the open coast, strong wave action and tidal currents rapidly disperse urban and industrial effluents. No algal proliferation or significant changes in benthic population have been observed, except occasionally near coastal towns. The invasions of sargassum muticum (in the North), green tides of Ulva in the South, as well as the red tide blooms in several coastal areas, are generally thought to be un-related to eutrophication (Olivera & Cabeçadas).

It is therefore reasonable to assume that, due to natural conditions, the marine waters of the west coast of Portugal are not affected by eutrophication and a more advanced treatment than primary treatment would not significantly improve the quality of marine waters. There are, however, several areas along the coast (in harbours and estuaries) which show clear signs of eutrophication (very localised and often temporary) and which do not qualify for designation as Less Sensitive Areas.

3.3 THE NORTH COAST - VULNERABILITY

It was reported (1) that the Portuguese littoral is facing degradation caused by urbanisation, industrial and agricultural activities and tourism and that water pollution caused by the use of agro-chemicals and discharge of waste water (urban and industrial) are the main causes of degradation of the ecosystem. Although the major urban centre along the coast have more or less efficient waste water treatment plants (1), most of them still discharge directly to sea.

(1) DGA & IHRH (1996), Estudo de Avaliacao Da Vulnerabilidade Da Capacidade de Recepcao Das Aguas E Zonas Costeiras Em Portugal.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 25 Although it is clear that this creates an impact on the local environment, there currently are no reports which enable a thorough scientific assessment of the situation (eg. the macroinvertebrate community is almost unknown, the fish populations need to be studied in more detail from the point of view of conservation (as opposed to economic concerns), etc).

It has been widely agreed that it is urgent for systematic scientific studies to be initiated (according to inter-regional plans) and which would allow a scientific data base on these ecosystems to be established.

3.4 THE TAGUS ESTUARY

The estuary can be clearly divided into three zones:

• the upper zone: relatively shallow zone which consists of delta; • the central zone which is the largest one with an average depth of 7 m; • the terminal zone which made up of a straight and deep canal (46 m).

The estuary is roughly pear-shaped, approximately 30 km long and varies in width from about 15 km at the northern upstream section to 2 km at the mouth (south of Lisbon). The circulation in the estuary is mainly driven by tides which have a 2-4 m amplitude. However, the circulation in the mouth of the estuary is also influenced by the wave field.

To the south of its central part, the estuary extends into the Setubal Peninsula in four different parts:

• Seixal estuary; • Moita estuary; • Coina estuary; • Montijo estuary.

Although these are directly linked to the Tagus estuary and are, as such, integral parts of it, they are considered to be estuaries on their own as their characteristics are very different to any other part of the Tagus estuary. As inlets in the Peninsula, these water bodies are characterised by poor circulation and water exchange and hence are subject to higher risks of eutrophication. These four estuaries have been designated as Sensitive Areas by the Portuguese authorities.

The Tagus river is the main input of freshwater into the estuary and the average flow rate is about 200 m3/s. Outside the estuary, in the zone where a sea outfall is located, the wind and currents also play an important role in driving the flow. The upstream section of the estuary is very shallow with extensive inter-tidal flats. Downstream, the depth reaches 40 m in the entrance channel which is 14 km long.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 26 Figure 3.2 The Tagus Basin and Tagus Estuary

Patudos Reservoir

Punto Canas Valada

Stations Principal rivers Secondary rivers

Tejo Estuary

Source: INAG

The presence of elevated concentrations of bacteria of faecal origin, especially in front of urban areas such as Lisbon, have been reported in several studies vii. In the Zone cala do Norte , in the proximity of the mouth of the River Trancão, there are seasonal problems caused by organic pollution (causing oxygen depletion) and toxic metals from industries located in Sacavém and Vila Franca de Xira.

Several studies have assessed the behaviour of nitrates in the estuary, which is considered to be stable. Indeed, the main sources of nitrates in the Tagus estuary are rivers. This means that average concentrations increase with the flow. Nevertheless, values above the dilution limit have been observed and correspond to the “problematic” zones of Cala do Norte and area of discharge of the Lisboa stream.

Figure 3.3 shows the distribution of Chlorophyll -a in the Tagus estuary. Although the data originates from a monitoring campaign carried out in 1983 and is therefore very old, it shows that the highest concentrations occur in the northern part of the estuary, which corresponds to the above-mentioned zone of Cala do Norte.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 27 Figure 3.3 Distribution of Chlorophyll -a in the Tagus estuary

Source: IMAR

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 28 CONCLUSION

Although the estuary, as a whole, does not show clear signs of eutrophication (mainly due to tidal currents), there are localised signs of nutrient enrichment. The main areas where such conditions occur are:

• in the central part of the estuary in and around Lisbon and the Lisboa river; • Cala do Norte at the northern end of the estuary. • in the estuaries of Seixal, Coina, Moita and Montijo which have been designated as Sensitive Areas.

The more detailed studies carried out on the quality of the Tagus estuary were not available at the time of writing and therefore, a more detailed assessment could not be carried out. However, there is little doubt that enrichment is occurring in these areas and it is most likely that they do qualify for designation as Sensitive Areas.

3.5 THE SADO ESTUARY

The drainage basin of the Sado estuary covers 7,640 km2 and is characterised by a central bay and a 35 km long, narrow channel. The Sado estuary is dominated by a wide tidal flat bay and narrow channel and has two main freshwater sources, namely the Sado river which contributes up to 90% of the freshwater inflow (wet/dry regime and significant interannual variation) and the Marateca river (see Figure 3.4). The tidal regime in the estuary is semi- diurnal with amplitudes ranging from 1-4 m. The upper limit for salt intrusion is near the town of Alcacer do Sal and the tidal influence extends 25 km upstream (IV). Some parts of the estuary are characterised by salt marshes, especially around Marateca Bay. Industrial and urban activities are well established along the northern shore and agriculture dominates the entire basin. Agriculture is known to be the main source of diffuse pollution in the estuary (mainly tomatoes and rice covering about 10,000 Ha). However, the strong tidal currents in the estuary appear to reduce or prevent serious eutrophication.

It has been established that the nitrates and phosphorus in the estuary originate mainly from the Sado river and, to a lesser extent, from the Marateca river. Studies on the phytoplankton biomass of the estuary were carried out in 1993 by L. Cabeçadas. A monitoring programme has also been carried out by the Instituto Hidrografico in the upper and lower estuary since 1986.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 29 Figure 3.4 The Sado Basin and Sado Estuary

Alcacer Channel Marateca Bay

The Sado Estuary

Comporta estuary

Source: INAG

The above mentioned studies, as well as studies carried out by Cabeçadas and Brogueira (1991) and Oliveira (1992) seem to show that the estuary’s system is moderately productive and that clear symptoms of eutrophication and/or blooms have not been detected. In addition, Oliveira and Cabeçadas conclude: “Although there is evidence that nitrogen is the limiting nutrient to phytoplankton productivity along the estuary, the Alcace zone presents + higher nutrient levels in winter (NO3 - N up tp 96 µM, NH4 - N up to 70 µM,

SiO2 up to 160 µM) compared to the main body of the Marateca Bay (NO3 - N

up tp 21 µM, NH4+ - N up to 76.5 µM, SiO2 up to 52 µM and Chlorophyll a up to 14.3 mg/m3). “. It has also been shown that toxic algae only appear sporadically and always at very low densities.

It is accepted that the phytoplankton community in the estuary is controlled by several factors which result in different temporal and spatial scales for the response to environmental changes. Cabeçadas viii observed that comparatively high cell numbers of nanoplanktonic flagellates and relatively high spring and summer concentrations of Chlorophyll -a seem to be a general feature in the upper estuarine region (despite inadequate light conditions). However, the study concludes that there are no obvious signs of eutrophication in the upper zone in the Sado estuary (either in terms of the quantitative level of phytoplankton or in terms of species composition changes).

However it has been shown that, from the month of February, there is a relative stabilisation of the water column in the estuary which is associated

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 30 with an increase in solar radiation and higher nutrient concentrations which initiate the “spring blooms”. Similarly, Chlorophyll -a concentrations undergo a clear seasonal variation. However, there is a slight spatial variation as well (from South to North) which indicates the riverine origin of Chlorophyll -a in the Sado estuary.

Some studies have studied the influence of nitrogen and phosphorous from aquaculture units. Indeed some areas of the estuary (Marateca Bay and Alcacer Channel) have, since the beginning of the 90’s, been utilised for aquacultural activities and the establishment of fish farms. In the Marateca

Bay, NO3 and Si patterns show different behaviour than NH4. During winter, concentrations show an increase at flood. Pointing to a transport of nutrients from the estuary into the Bay and during summer, the lower values observed towards the estuary suggest instead an export of these nutrients to the estuary. In the Alcacer channel, peak concentration of NO3 occurred at low tide and minimum concentrations at flood tide, and near the bottom. This indicates an export of nitrates to the estuary through the Sado river. The conclusions were that these have no influence on the quality of the estuary.

Nitrates values vary seasonally with values between 1-8 mmol/L. During winter nitrate concentrations vary between 7-18 mmol/L. During spring, concentrations range between 4-5 mmol/L. The hydrodynamics of the estuary indicate that incoming water is mainly of coastal oceanic origin. Water from the central estuary shows much lower concentrations of nutrients and Chlorophyll -a. throughout the year than around the vaRious inlets.

With regards to phosphorus (P), adsorption/desorption of P and precipitation/flocculation of humic material occurring at the freshwater/sea water interface at different tide stages and states lead to an equilibrium of P forms and almost constant level of phosphate in the lower estuary (Babeçadas, 1993)ix. Considering that the estuary is subjected to considerable freshwater inputs, it is assumed that ‘buffer mechanisms’ must operate systematically and, to a large extent, control phosphate levels in the system.

It can be concluded that nutrients reach relatively high levels in winter and that phytoplankton biomass reaches relatively high levels in spring, bottom waters never became anoxic, even by late summer. This indicates that these nutrients are being efficiently utilised and that the system can handle relatively large amounts of nutrients. The results collected between 1979 and 1993 do not show any sign of increase/decrease.

Figure 3.5 illustrates land use around the Sado estuary. From this map it is clear that both the Sado and Marateca rivers are bordered by arable land (annual culture) which are probably a major source of nutrients in the river and which adds to the inputs from aquaculture.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 31 Figure 3.5 Soil Use Around the Sado Estuary

Artificial space Land cover Arable land: Annual crops (CORINE) Permanent Cultures Heterogeneous agricultural areas Forests Area of dense vegetation Open spaces Maritime zones Continental waters

Source: INAG

The dark green areas indicate the presence of forests and the light green areas indicate the presence of permanent vegetation. The red area shows the town of Setúbal which is surrounded by heterogeneous agricultural areas (northern shore of the estuary). It also indicates that the land alongside the Marateca and Sado rivers is essentially agricultural (arable) land. Agricultural land also dominates around the Comporta estuary. This must undoubtedly contribute to the nutrient loading in both rivers and the estuary.

Conclusion

Although there no clear signs of eutrophication in the estuary and the average value for the chemical parameters (nutrients, Chlorophyll -a, dissolved oxygen, etc) are currently not causing extreme oxygen depletion and excessive growth of phytoplankton, the Marateca Bay is an enclosed embayment which is poorly flushed and presents seasonal signs of high nutrient enrichment (although no signs of eutrophication). It may, however, be considered as vulnerable to an increase in anthropogenic nutrient loads. Any future developments (eg. aquaculture, etc) in its drainage basin must be carefully controlled. This also applies to the Alcacer channel where “spring blooms” occur and where there is a general nutrient increase during the summer period.

It is therefore considered that both the Marateca Bay and the Alcacer channel should be designated as Nitrate Vulnerable Zones, together with their respective drainage basins.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 32 3.6 THE MONDEGO ESTUARY

The Mondego estuary is located on the Atlantic coast of Portugal near the town of Figueira de Foz, a commercial harbour of vital regional importance. The estuary is composed of two arms (north and south) with very different hydrographic characteristics. The north arm, where the harbour is located, is deeper and it is through this arm that most of the freshwater flows. The south arm, on the other hand, is almost silted up in its upstream section. In other words, the water circulation in the south arm is mainly tidal. Very little water comes from the Pranto river.

Human activities around the Mondego estuaries have been developing/ diversifying considerably in the last few years. The main pressures which increase the estuary’s vulnerability are:

• the lack of a waste water treatment plant in the region of Figueira da Foz. There is a 100% seasonal increase in population during the summer in that region.;

• the direct discharge of urban waste water into the estuary in four `different locations: Ponte de Gala, Camara Municipal, Trapiche and Marina.

• Rio Pranto discharges directly into the estuary. The waters of the Pranto river contain high levels of nutrients and other chemicals which are responsible for the occasional eutrophication of the south arm of the estuary (which is a known source of tensions with the owners of aquaculture units);

• High discharges of organic pollutants and nutrients from the estuary of Armazéns

Figure 3.6 The Mondego Estuary

Source: IMAR

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 33 As mentioned above, besides the harbour facilities and dredging activities, the Mondego river supports industrial activities, salt works and aquaculture units. The discharges from agricultural areas in the river valley may also be significant during certain periods.

Therefore the organic enrichment of the estuary from agricultural activities and other sources leads to the estuary’s eutrophication and the presence of thick layers of macroalgae (mainly enteromorpha spp. and Ulva spp.). These blooms are periodic and occur from March to September/October (1) . According to IMAR, “depending on the species affected, the abundance can increase or decrease. Vertical migrations upward of many species can occur. This affects the predation of macroinvertebrates by wading birds “.

Figure 3.7 Land use in the Mondego Basin

Land cover (CORINE)

Mondego estuary Artificial space Arable land: Annual crops Permanent Cultures Heterogeneous agricultural areas Forests Area of dense vegetation Open spaces Maritime zones Continental waters

(1) IMAR (1999), the Mondego Estuary

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 34 CONCLUSIONS

Although the results of more detailed analysis were not available at the time of writing, it has be shown that periodic blooms occur on the Mondego estuary and result in a thick layer of macroalgae. The estuary is therefore highly eutrophic from March to September.

The organic enrichment has been show to originate from agricultural activities around the estuary. This is confirmed in Figure 3.7 which clearly shows that both the estuary and Mondego river are surrounded by arable land and permanent heterogeneous agricultural land.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 35 4 REVIEW OF FRESHWATERS DESIGNATED AS SENSITIVE AREAS UNDER THE URBAN WASTE WATER TREATMENT DIRECTIVE

4.1 SURFACE FRESHWATER

The quality of surface freshwaters is reviewed in this section of the report. The first section provides an overview of water quality in 1998 for each region. This will be followed by an assessment of nitrate pollution, eutrophication in reservoirs, waters used for the abstraction of drinking water and groundwaters.

4.2 THE PORTUGUESE CLASSIFICATION SYSTEM

Water quality monitoring is carried out by the five regional environmental authorities (DRA Norte, DRA Alentejo, DRA Centro, DRA Lisboa e Tejo Vale and DRA Algarve). The monitoring network consists of a total of 276 stations. This corresponds to a density of approximately 3.1 station/1000 km2.

Surface freshwaters intended for the abstraction of drinking water are classified according to the criteria defined in the Decreto-Lei nº 236/98 (Chapter II - Section 1), transposing Directive 75/440/EEC which defines three classes of water: A1, A2 and A3. Different treatment levels are prescribed for each category.

Surface water courses (for multiple uses) are classified according to 27 criteria, the main ones being summarised in Table 4.1.

Table 4.1 Surface freshwater classification criteria

Parameter A B C D E

pH 7-7.9 <7 - >8 <6 - ≥9 Temperature (ºC) <= 20 21-25 26-28 29-30 >30 Conductivity (uS/cm) <= 750 751 - 1000 1000 - 1500 1500 - 1300 >3000 SST (mg/l) <= 25 25.1 - 30 30.1 - 40 40.1 - 80 > 80 DO (% Sat) >= 90 89 - 70 69 - 50 49-30 < 30

BOD5 (mg/l O2) <= 3 3.1 - 5 5.1 - 8 8.1 - 20 > 20

COD (mg/l O2) <= 10 10.1 - 20 20.1 - 40 40.1 - 80 >= 80.1

Ox. (mg/l O2) <= 3 3.1 - 5 5.1 - 10 10.1 - 25

N-NH4 (mg/l) <= 0.1 0.11 - 1 1.1 - 2 2.01 - 5 > 25

N-NH3 (mg/l) 0-0.5 5.1 - 25 25 - 50 50.1 - 80 > 80

P2O5 (mg/l) <0.54 <= 0.94 > 0.94 >= 80.1 Total Coliforms (N/100ml) <= 50 50-5000 5000 - 50000 > 50000 Faecal coliforms (N/100 ml) <= 20 21-2000 2001 - 20000 >20000 Key: A=not polluted, B=temporarily polluted, C=polluted, D=very polluted, E= extremely polluted

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 36 Other surface freshwater bodies (for multiple use) are classified according to the following criteria:

Table 4.2 Classification of surface freshwater for multiple use

PARAMETERS Q1 Q2 Q3 Q4

Dissolved Oxygen (mg O2/l) 8 7 5 4

NH4 (mg/l) 0.04 0.2 1 2

BOD5 (mg O2/l) 3 5 7 9

Orthophosphate (mg P2O5/l) 0.1 0.2 0.7 1

Nitrates (mg NO3/l)25305070 Faecal coliform (/100 ml) 20 2000 20 000 30 000

Compatible use aquaculture aquaculture human supply Human supply bathing water bathing water (A3) (>A3) human supply human supply (A1) (A2) irrigation

The three classification systems will be referred to in several sections of this chapter.

4.3 SURFACE FRESHWATER QUALITY - AN OVERVIEW

4.3.1 Introduction

As mentioned at the beginning of the report, there has been a shift of population from inland areas to the coast. This has been accompanied by a similar trend in industrial settlements and therefore pollution burden of surface freshwater. The mainland rivers are said to present less problems has they drain areas of low(er) population densityx. Eutrophication is also known to be a common problem in reservoirs in Portugal. Another important factor is the seasonality. Indeed, pollution shows a distinct seasonality which is related to river run-off. Reservoir management doesn’t provide either for a guaranteed minimum flow for the preservation of ecological processes.

As reported by WWF, ”industrial effluents are disposed untreated in rivers. Very few industries have effluent treatment installations, and even those which dispose of such systems do not operate them. […]. The worst pollution incidences occur in the river AVE, north of the city of Porto, which drains an area with several textile industries, in the river Alviela which receives the effluents of the numerous pig-farms and tanneries located in its catchment […]. Furthermore, due to the inappropriate use of pesticides and fertilisers, diffuse pollution is becoming a serious environmental problem especially in the Ave basin and in Alentejo.”

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 37 4.3.2 Regional Environmental Directorates (DRA) - Surface Freshwater Monitoring

A number of monitoring station from the national monitoring network have been selected in all Regional Environmental Directorates (DRA) in order to carry out a monthly assessment of the evolution of surface freshwater quality throughout the country. This started in July 1998 and, at the time of writing, data are available up to March 1999. The accompanying colour-coded maps are presented in Annex B of this report.

The results, as made available by INAG, are summarised in Table 4. 3

Table 4.3 National Overview of Surface Freshwater Quality

Date DRA Basin Section Quality / Criteria

July 1998 North Ave Overall Overall bad quality due to low dissolved oxygen and Alentejo Guadiana, high faecal coliforms Sado

August 1998 North Minho, Lima, Overall Decrease in quality due to a Cávado, Douro clear increase in organic matter related to urban/ industrial waste water discharges and a decrease in river flows.

September 1998 North Minho, Lima Overall Improvement in quality and Douro

Douro Pocinho Low oxygen levels reservoir

LVT Tagus Overall High levels of organic matter

Divor High levels of total reservoir coliforms resulting in Class D-E designation

Alentejo Guadiana, overall High levels of organic matter

Azenhas dos High levels of total Cerieiros coliforms resulting in Class D-E designation

Sado Overall High levels of organic matter

Alvito High levels of total coliform reservoir resulting in Class D-E designation

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 38 Date DRA Basin Section Quality / Criteria

Mira Overall High levels of organic matter

October 1998 North Cavado, Ave Overall Worsening of the overall situation due to high phosphate levels

Alentejo Guadiana Monte da High levels of coliform Vinha, resulting in designation in Azenha dos Class E Cerieiros, Ardila and Tapa Grande

November 1998 North Cavado, Ave Overall Improvement of the overall quality

Centro Rib. De Oeste Overall “severe” problems due to urban waste water without treatment or with inadequate treatment

LVT Tagus As for November 98

Alentejo Sado, Mira As for September 98

Guadiana Monte da Bad quality due to total Vinha, coliform Azenha dos Cerieiros, Ardila, Pulo de Lobo

Algarve Ponte Pereiro, Designated in Class E due Vidigal to total coliforms

December 1998 North Minho, Douro Overall limited degradation

Centro Rib, Oeste Overall As for November 98

LVT Tagus Overall As for November 98

Alentejo Guadiana Monta de High level of total coliforms Vinha

February 1998 North Minho, Douro, Overall improvement Vouga

Source: INAG

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 39 Overall it can be observed that, during summer months, the basins of northern Portugal (Cávado, Ave, Douro, Minho and Lima) are characterised by high concentrations of faecal coliforms and low dissolved oxygen which indicates contamination from urban waste waters. Similar situations occur in the Guadiana basin (and more particularly in Monte de Vinha, Azenha dos Cerieiros, Ardila and Tapa Grande), Ribiera de Oeste (Centre region), Tejo basin (especially the Divor reservoir), Sado basin (Alvito reservoir)

4.3.3 Direction Regional do Ambiente - Lisboa and Tagus Valley

(A) Rio Alviela

The basin of the Alviela river covers an area of about 327 km2 and is located in the same area as the Tagus river (and is part of the Tagus basin itself). It includes the districts of Santarém, Alcanena, Golegã and Torres Novas. Due to the geological characteristics of the region, surface waters and groundwaters are linked and have high productivity.

Pollution sources in the region include agriculture with the most frequent crops being tomatoes, maize, wheat, beans and fruits. However, industrial activities in the region are also very important. Indeed, 85% of the country’s leather production units are in the Alcanena district, which represents 65% of national production. This is the main activity in the region and is the main source of pollution. However, the majority of industrial facilities in the region are equipped with pre-treatment units and discharges are treated by the ETAR de Alcanena plant.

In 1993, all samples taken in the Alviela, Monsanto and Carvalho rivers where classified as Q4 (see section 4.2 for the classification system). In 1997, 4 out of 7 for Alviela river, all on Carvalho river still classified as Q4. Although it is not specified which criteria was responsible for classification in Q4, the characteristics of the Q4 waters are those of waters contaminated by urban waste waters. However, an exact interpretation is impossible at this stage.

It is, however, known that the Pisão river makes a significant contribution to the contamination of Alviela river. The worst results where observed in the Carvalho river. After the confluence with the Carvalho river the quality of the Alviela river largely improves. Indeed the levels of orthophosphates and organic matter decrease but the nitrate concentration appears to increase, especially during the dry season. It seems that only when the Minde and Mira d’Aire treatment station will come into operation, will the quality of Carvalho improve.

(B) Rio Trancão

The Trancão river starts near Alto do Casal (Malveira) and after flowing for about 30 km, discharges into the Tagus river, in its estuary near Sacavém. Its basin covers an area of about 288 km2 which is heavily populated with about 400,000 inhabitants distributed between 271 agglomerations.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 40 Currently there are 11 monitoring stations where samples are taken on a monthly basis. These are located on three rivers: Loures, Póvoa and the Trancão itself. The stations of Ponte Canas, Ponte Pinhal and Ponte Resinga are part of the OSPAR network which aims at preventing marine contamination. The waters were also classified according to the criteria defined in Table 4.2. of this report.

An analysis of the data shows that:

• the Póvoa has the highest concentrations of BOD5 which clearly suggest organic pollution originating in that area. There are no indications as to the exact sources of organic pollution. • In Ponte Sacavém, the sea and strong tidal currents provide good dilution and hence low values are observed for most parameters. • The basic treatment provided hasn’t had any practical effects on water quality in this basin.

4.4 NITRATE CONTAMINATION

The data used by the Portuguese authorities(1) in relation to nitrate concentrations in surface freshwater are presented in Annex C of this report. It shows that only in a few areas, for the year 1996, have seasonal peaks of nitrate concentrations occured. These are:

Table 4.4 NO3 - Seasonal Peaks (1996)

DRA Region Name of monitoring station NO3 (mg/l) Month

North Marachao 43.800/48.00 July/August Monte Azenhas 44.6 September Ponte do Porto 46.6 August Castelo 49.2 September

Centre Amor Milagres 74 November

Lisbon/Vale Tagus reservoir dos Patudos 114.5 April Punto Canas 55.58 May

Amongst the above monitoring stations, the main problems appear to be the Patudos reservoir and Punto Canas which are located on the Tagus (as shown in Figure 3.2) and which have nitrate concentrations well above 50 mg/l.. Marachao is located on the Cavado river in the North.

INAG has also made available the results of the surface freshwater monitoring network which provides monitoring data for at least the last ten

(1) as provided by INAG (March 1999)

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 41 years or so (1) . This database covers the entire country but the available information varies significantly (quantitatively and qualitatively) both from one region to another and from year to year. The main parameters

consistently measured which are of interest to us are Chlorophyll -a and NO3.

An assessment of the data available for the years 1994-1998 revealed that no

surface freshwater bodies had nitrate concentrations above 50 mg NO3/l or concentrations approaching this limit-value. On the other hand, many showed high levels of Chlorophyll -a. Table 4.5 lists all monitoring points with high Chlorophyll -a values.

Table 4.5 Chlorophyll -a concentrations in surface freshwater

Basin Name Chlorophyll -a (µg/l) Date

Minho/Ancora Monção 13.6 08/1996 15.8 05/1997

Canado Alto Cavado reservoir > 10 07-11/1996/7

Douro Lameirão 10.2 - 128.3 06-10/1996 Aç. Veiga de Chaves >20 summers Rib. De Pena >20 summers Anelhe 30-138 08-11/1996/7 Miranda do Douro reservoir 20-54 summers Semealho 10-53 summers Pinhão >10 summers Penereiro reservoir 15.4-73.0 year round Bemposta reservoir >20 summers

Vouga Carvoeiro 10-367 summers Ponte Requeixo 12-52 year round Pte S. João Loure 10-36 April-October

Mondego Nelas 10-56 summers Ponte Faia 155 06/1998 245 07/1998 Aguieira reservoir >10 year round Ferreirós >10 April-October Ponte Mucelas 198 06/1998 Ponte Cabouco 572 06/1998 Ponte Penacova 781 07/1998 Ac. Raiva 698 06/1998

Lisboa and ribeira Monte Real 133-782 June-September costera Amor >20 summers Ponte Mestras 11-65 summers Ponte Pedrinha >10 summers Almeirão >100 June-july

Guadiana Monte Novo reservoir (abstr) 13-150.8 1994

(1) available on INAG's web site: http://set.inag.pt:80/snirh

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 42 All of the surface water bodies mentioned above have summer chlorophyll-a concentrations above 10 µg/l. It is not unreasonable to assume that such concentrations indicate a degree of eutrophication. According to the Portuguese classification, a reservoir or lake will considered eutrophic if Chlorophyll -a concentrations are above 30 mg/m3.

4.4.1 Eutrophication - reservoirs and lagoons

Introduction

Due to hydrological pressures (spatial and temporal irregularity of water availability), numerous reservoirs were built throughout Portugal. There are a total of 163 reservoirs located throughout the country. The location of the main reservoirs is shown on Figure 4.1.

Figure 4.1 Reservoirs

Source: DGA

These reservoirs were built for several different purposes, including:

• Energy production • Irrigation • Supply of water for domestic use • Supply of water for industrial use

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 43 The proportion of use is illustrated in Figure 4.2 and 4.3.

Figure 4.2 Use of reservoirs

Key: Energ=Energy, Raga=irrigation, Ab.con= domestic use, Ab.ind= industrial use Source: INAG

In the main basins (Douro, Tagus, Guadiana), the reservoirs are mainly used for supply of water for domestic use. On the other hand, to the North of the Tagus river, this water is mainly used for energy production and to the South, for irrigation. Figure 4.3 illustrates the use of these waters in the main hydrological basins.

The quality of these waters is therefore crucial and it appears that it has often been the reason for inadequacy for their planned or future use (INAG, 1998). A detailed list of all lakes and reservoirs with their individual use could not be obtained.

INAG published a report in 1996 on the quality of surface freshwaters in Portugal (peRiod 1994/95). It focused on the biological quality of a series of water bodies, most of which were reservoir and dams. In relation to eutrophication, a trophic state index (TSI)1 was derived for all water bodies investigated :

Table 4.6 Indicator of Eutrophic State

TSI STATUS TSI <45 Oligotrophic 45 52 Eutrophic

Other eutrophication factors used were light penetration (minimum 3m) and concentration of Chlorophyll -a (< 10 µg/l).

All water bodies investigated had TSI values > 53 that indicates signs of eutrophication in all of them. In addition all water bodies had Chlorophyll -a concentrations and Secchi disc readings that would qualify the water body as eutrophic. The data is summarised in Table 4.7.

1 TSIcla=9.81 Ln{cla} / 30.6 and TSI ds = 60 - 14.41 ln ds

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 44 Figure 4.3 Reservoir water use by basin

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 45 The majority of the reservoirs listed show clear signs of eutrophication . However, no detailed assessment of the quality of each individual reservoir, their uses and the sources of nutrients was carried out. It therefore seems that each of these reservoirs should be considered for designation under both Directives. An overview of the quality of each reservoir is provided below.

Table 4.7 Indication of Eutrophication xi

TSI Chlo -a Secchi Comments

Albufeira de Miranda 60 20.7 2.6 showing signs of advanced eutrophication

Albufeira do Pocinho 58 15.7 2.2 considered to be eutrophic

Pinhão (albufeira da Régua) 54 10.6 1.8 considered to be eutrophic

Rio Mosteirô (albufeira do 55 11.8 2.7 considered to be eutrophic Carrapatelo)

Albufeira do Carrapatelo 53 9.4 3.1 considered to be meso-eutrophic with a trend towards improvement

Entre-os-Rios 53 9.7 2.4 considered to be mesotrophic but trends seem to show a trend towards eutrophication

Albufeira de Crestuma - Lever 53 9.9 2.1 considered to be mesotrophic but trends seem to show a trend towards eutrophication

Ponte de Canaveses 60 19.7 1.9 showing signs of advanced eutrophication

Albufeira de Caniçada 53 10.3 4.4 Oligotrophic but with high potential for eutrophication to take place

In another study (Gil, 1996) xii, the quality of a series of reservoirs and small rivers were assessed in order to determine their trophic status. The water bodies are managed by EPD and therefore the monitoring is also carried out by EPD. With the monitoring results obtained the reservoirs were classified according to the criteria defined in the National Plan of Environmental Policy (Plano Nacional da Politica de ambiente (PNPA) - MARN, 1994) and the results compared (see Table 4.8).

On the whole, the EDP data shows that five reservoirs are identified as eutrophic and not classified or classified as mesotrophic under the PNAP scheme. The main reason for this is that, under the PNAP scheme, the retention time, which can differ significantly from one lake to another, was not taken into account (ie Fratel reservoir);

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 46 Table 4.8 Eutrophication in EDP lakes

Name Status - PNPA Status - EDP

Alto Lindoso Eutrophic Mesotrophic

Alto Rabagão - Mesotrophic

Caldeirão Eutrophic Mesotrophic

Castelo Bode Mesotrophic Mesotrophic

Fronhas Eutrophic Eutrophic

Paradela Mesotrophic Oligotrphic

Pracana Eutrophic Eutrophic

Raiva Mesotrophic Mesotrophic

Salamonde Mesotrophic Mesotrophic

Torrão Eutrophic Eutrophic

Touvedo - Mesotrophic

Vilarinho Furnas Oligotrophic Oligotrophic

Bemposta Eutrophic Eutrophic

Bouça - Mesotrophic

Carrapatelo Eutrophic Eutrophic

Crestuma Eutrophic Eutrophic

Fratel Mesotrophioc Eutrophic

Miranda - Eutrophic

Picote - Eutrophic

Pocinho Eutrophic Eutrophic

Régua - Eutrophic

Valeira - Eutrophic

On the other hand, a series of reservoirs classified as eutrophic under the PNAP scheme were classified as mesotrophic under the EDP scheme. The reason for this is that EDP considers that the time period during which waters are anoxic or have values inferior to 20% saturation must be taken into account as opposed to PNAP which considers only the water depth.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 47 Therefore, according to the results of this study, the following water bodies should be considered for designation under either or both Directives:

• Fronhas reservoir; • Pracana reservoir; • Bemposta reservoir; • Torrao reservoir; • Carrapatelo reservoir; • Crestuma reservoir; • Miranda reservoir; • Picote reservoir; • Pocinho reservoir; • Régua reservoir; • Valeira reservoir.

However, and as stated above, more information on the use of the these water bodies as well as nutrient sources is required for their designation as Vulnerable Zones. Such studies were not available at the time of writing.

One reservoir which is not mentioned above and which shows clear signs of eutrophication is the Magos reservoir. This reservoir was constructed near the town of Salvaterra de Magos, in the hydrographic basin of the Tagus river. Two of the main factors contributing to the lake’s eutrophication are agricultural activities and local climatic conditions (long exposure to sun). Indeed the main source of nutrient is agricultural effluents coming from upstream of the reservoir which are rich in nitrogen and phosphorous. It is however considered that urban waste water should also be taken into account. This reservoir has limited use (as defined in the Decreto Regulamentar 2/88), does not classify as a protected area and is mainly used for irrigation of rice fields in the region (about 534 ha). Its secondary uses are sailing, swimming and fishing. In 1987, the Magos reservoir was included in Class C, according to a classification made for all reservoir according to their use. Class C means the reservoir is “moderately polluted, sustaining a fish community (the more resistant species), recreation without direct contact and irrigation in general “. It was commented by Almeida et al. xiii that this eutrophication process is not irreversible and that this reservoir should be included in a programme. Obviously the main step is to reduce nutrient inputs into the reservoir.

4.5 WATERS USED FOR THE ABSTRACTION OF DRINKING WATER

As detailed in annex II of the Directive, surface freshwaters intended for the abstraction of drinking water which could contain more than the concentration of nitrate laid down under the relevant provisions of Council Directive 75/440/EEC of 16 June 1975 concerning the quality required of surface water intended for the abstraction of drinking water in the Member States if action is not taken, should be designated as Sensitive Areas.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 48 Figures 4.4 shows the quality and proportion of surface freshwater abstracted from 1993-1998. It shows that the quality of the water abstracted has largely improved since 1993. However, a non-negligible proportion (>10%) of the abstracted water is still of A3 quality.

Figure 4.5 shows the surface water abstraction points throughout the country. As can be observed, abstraction of surface freshwater is mainly carried out in the northern part of Portugal and, to a lesser extent in the upper part of the Tagus basin and western part of the Mondego basin.

Figure 4.4 Quality of surface water abstracted

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 49 Figure 4.5 Surface Water Abstraction Points

Surface Freshwater Abstraction Points

abstraction Point main rivers secondary rivers hydrological basins

Source: INAG

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 50 4.5.1 Tagus Basin

According to the results obtained during a monitoring programme carried out by DRARN/LTVxiv, several waters are classified in category A3 and are not suitable for abstraction of drinking water. The parameters responsible for such classification suggest contamination from urban waste water that renders these waters unsuitable for drinking water:

• Rio da Mula reservoir (Penha Longa river): COD • Valada (Tagus river): Cadmium, faecal streptococci; • Olhos Agua (Alviela river): faecal streptococci; • Mouriscas (Rio FRio river): COD

Although nitrate concentrations in these waters do not appear to be an issue, the COD is high and clearly shows contamination. High concentrations of faecal streptococci in Olhos Agua also seem to show contamination of ‘domestic’ origin. It must be noted that during the year 1995/96, Olhos de Agua and Mouriscas were falling in category A1. This clearly shows a degradation of water quality in this region. The situation in the Alviela basin is discussed in the next section.

As mentioned before, the water quality at Valada (where 280,000 m3 are abstracted from the Tagus sub-system every day and released directly into the Tagus) is of A3 (according to the criteria of Directive 75/440) and is due to parameters which indicate pollution of urban origin (faecal coliforms, BOD5 and phosphates).

4.5.2 Alviela Basin

As stated above, Olhos de Agua is located in the Alviela basin which is part of one of the most important hydrogeological units in the country. In this system of aquifers of high productivity, groundwaters and surface waters are highly inter-linked. The lower part of the basin is a zone of predominantly agricultural activity (arable). The most frequent crops are tomatoes, wheat, maize, melons and fruit trees. The upper part of the basin lies on less fertile soils and is therefore characterised by a higher number of industries. A treatment plant was built in 1988 in Alcanena and treats most industrial effluents (pre-treated at the industrial plant). This plant has a capacity of about 10,000 m3/day with an organic load of 400,000 population equivalent.

In 1997, monitoring at 10 stations (7 on the Alviela , 1 on the Monsanto and 2 on the Carvalho) was carried out in order to classify the rivers. All monitoring points were in categories 3 and 4 which are characterised by nitrate concentrations > 50 mg/l, orthophosphate concentrations above 0.7

mg/l and dissolved oxygen of 5 mg O2/l. It is assumed that the Pisão river contributes significantly to the pollution of the Alviela. In general, the quality of the Monsanto river is not as bad as it may appear. The worst results have been obtained for the Carvalho which also contributes to the pollution of the Alviela. After their confluence, a decrease in organic matter and an increase

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 51 in nitrates can be observed. However treatment stations have been planned for Minde and Mira d’Aire. These will treat industrial effluent from the region and it is thought that it will considerably improve the quality of the Carvalho river.

CONCLUSION

Rio de Mula reservoir, Olhos de Agua and Mouriscas should be considered for designation under the Urban Waste Water Treatment Directive. Although there are figures indicating existing problems, more detailed information is required in order to confirm whether this water body (or part of it) should be designated or not.

4.5.3 The Ave basin

The basin of the Ave is located in the North of Portugal and surrounded by the Cavado and Douro basins. The source of the Ave is located in the Serra da Cabreira (1,200 m) at about 93.5 km from the mouth of the river at Vila do Conde. The main tributaries are the Pele, the Pelhe and the Este on the North bank and the Selho and Vizela on the South bank. The basin is characterised by high precipitation, amongst the highest in the country.

This basin lies on fertile soils and is characterised by a high population density and industrial plants (textiles mainly). There are nine abstraction points in the Ave basin, six of which are located on the Ave, one on the Este and two on the Vizela.

On the basis of data gathered during successive monitoring campaigns, it is widely recognised that, generally, the quality of the water in the entire basin is very low and that the water is not suitable for any use (especially abstraction of drinking water). Only the monitoring stations located upstream of the river show better results. In 1992, all monitoring data showed that the entire basin requires designation in Class 3 (according to Directive

75/440/EEC). The main pollutants appear to be oil, faecal coliform, P2O5 and

N-NH4. The main cause for such low quality was the lack of waste water treatment facilities.

The most polluted areas are those of Guimarães, Santo Tirso and Vila Nova de Famalicão where the majority of industries are located, together with about 50% of the bassin’spopulation. The main source of pollution is urban waste water as well as industrial effluents.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 52 Figure 4.6 The Ave Basin

Source: INAG

CONCLUSION

The results from the above-mentioned report clearly indicate that the entire Ave basin would have qualified for designation under the Urban Waste Water Treatment Directive. One of the reasons for which it may not have been designated is the plans made under the PEDIP programme, involving treatment capacity of about 1,220,000 p.e. and providing tertiary treatment. Indeed, it was a greed in 1991 that three waste water treatment plant would be built on the Ave basin and should significantly improve the water quality on the entire basin:

• Gondar: 0.35 m3/s or 270,000 p.e. • Rabada: 0.70 m3/s or 480,000 p.e. • Trofa: 0.70 m3/s or 390,000 p.e.

4.5.4 Alentejo

In 1997, a monitoring campaign took place in the region of Alentejo. The aim was to assess the quality of (a) surface freshwater used for the abstraction of drinking water and (b) surface freshwater with multiple uses (including recreation - direct contact), as required by Directive 77/197/EEC.

With regards to waters used for the abstraction of drinking water, all were classified as A1 in relation to nitrate concentrations (See Section 4.2).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 53 Nevertheless, several water bodies were classified as A2 or A3 in relation to

dissolved oxygen and BOD5. These are:

• Apartadura Class A2: Faecal coliforms

• Ardila Class > A3: BOD5 • Monte ClerigoClass >A3: Dissolved oxygen

• Monte Novo 1 Class >A3: BOD5

• Rocha de Nora Class >A3: BOD5

• Santa Clara 1 Class A3: BOD5

When compared to the 1996 results, no quality improvement can be observed and the classification remains identical.

It must be noted that the samples in Monte Clerigo reservoir were taken in deep waters and, consequently, the DO and BOD results are not considered to be serious. Indeed this reservoir is almost redundant and is not monitored anymore, with the exception of peRiodic measurements in relation to groundwater quality in the area.

In Monte de Rocha, it appears that effluents released by a nearby cattle- rearing unit is the cause for high BOD and signs of eutrophication.

With regards to waters intended for multiple uses, the majority of waters are classified in class C (see Section 2) which means that these are suitable for most uses under the condition that they undergo rigorous treatment.

Two water bodies show a decline in quality between 1996 and 1997. These are the reservoirs of Monte de Rocha and Monte Novo. Both have been designated as Sensitive Areas in 1997. Other water bodies classified in the C- D categories are Ardila (>= C), Bufo (>= C), Caia (C), Moinho da Gamita (D), Monte Clerigo (>=C), Monte da Vinha, (>=C), Povoa e Meadas (>=C), Pulo de Lobo, Roxo (>= C), Santa Clara (C), Vigia (C) and Tapa Grande (C).

On the other hand, an improvement of the general situation is seen in the Divor, Ardila, Gafete and Azenha de Cereeiro reservoirs.

4.6 GROUNDWATERS

The regions where occurrence of groundwater contamination (from anthropogenic sources) is most likely are the regions of Centre, North and Algarve.

In the North, the main problems arose from:

• Barcelos district: 11.5% of the samples taken between 1987 and 1990 were considered to be chemically unsuitable for use (especially in relation to

1 Designated as Sensitive Area by the Portuguese Authorities

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 54 nitrate concentrations). Only 28.8% were considered to be chemically and bacteRiologically suitable;

• Esposende district: over 25% of the samples taken between 1987 and 1990 show high nitrate concentrations (> 50 mg/l). Due to the presence of coliforms, about 82% of the samples were considered to the bacteRiologically unsuitable;

• Porto district: Nitrate concentrations in the region have been high in the past (>50 mg/l). A decreasing trend has however been observed in the last few years.

In the Centre, the contamination of groundwater is due to both point sources (eg. domestic waste water discharge) and diffuse sources (eg excessive use of pesticides).

• It is reported that in the region of Estarreja (aquifer system of Baixo Vouga), the pollution level in the superficial aquifer has reached significant levels due to discharges from both urban settlements and the Chemical Complex of Estarreja.

In the hydrographic region of the Tagus, the following groundwater problems have been detected:

• Sandro river valley: strong contamination of organic origin has been

detected and nitrate concentrations ranging between 74 and 471 mg/l NO3 have been measured. The main sources of pollution are thought to be agricultural, industrial and domestic.

• Almada/Seixal: this area is contaminated by heavy metals of industrial origin.

In the region of Alentejo, agricultural activities are believed to be the cause for high nitrate concentrations in the aquifer of Odemira.

In Algarve, nitrate concentrations in groundwater are high and mainly caused by intensifying agricultural activities and excessive use of pesticides and fertilisers. In 1991, the average nitrate concentration in the surface aquifer of

Campina de Faro was 195,94 mg/l NO3.

A study (1) assessed the vulnerability of groundwaters in Portugal, the results of which showed that the most vulnerable aquifers are those located along the coast, especially in the region between Espinho and Nazaré (Plio-quartenary formation of sandy origin). Also of high vulnerability are the calcareous formations of the Jurassic and Cretaceous, which essentially occur in the Algarve between Cabo de S. Vicente, Almádena and Estômbar, Escarpão

(1) DGA & IHRH (1996), Estudo de Avaliacao Da Vulnerabilidade Da Capacidade de Recepcao Das Aguas E Zonas Costeiras Em Portugal

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 55 ( between S. Bartolomeu and the Southwest of Castro Marim), the west of Lisbon near Serra da Arrábida, to the east of Sesimbra and to the west of Santiago do Cacém.

In a more general way, studies carried out in the region of the Centre, Lisboa e Vale do Tagus and Algarve have shown both positive trends (eg. Porto and Algarve) and stabilisation (eg. Vale de Tagus and lower Mondego) of the levels of nitrate in groundwaters.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 56 5 REVIEW OF THE WATERS DESIGNATED AS VULNERABLE ZONES UNDER THE NITRATES DIRECTIVE

5.1 INTRODUCTION

The methodology used by the Portuguese authorities to designate Vulnerable Zones is described in Section 2 of this report. In terms of available data, the main source for surface freshwater was the national monitoring network which included drinking water abstraction points. With regards to groundwaters, the national groundwater monitoring network was being ‘upgraded’ at the time of designation in order to ensure that all required data are available.

5.2 SURFACE FRESHWATER

5.2.1 Introduction

One of the region most affected by nutrients from agricultural sources is the Centre-West region where animals density is very high. In that region, many water courses are contaminated by nutrient from agriculture. These water courses are also subject to extreme flow variations (drought during summer months). Other regions which are know for the vulnerability of their groundwaters are the Tagus basin, Algarve, the Setùbal peninsula, as well as the calcareous plains of Sierra de Aire e Candeeiros. Nitrate measurement in

these regions have shown concentrations up to 300 mg NO3/l.

As reported by WWF x, the worst pollution incidences occur in the river Alviela which receives the effluents of numerous pig-farms located in its catchment and the Ave basin and Alentejo where inappropriate use of pesticides and fertilisers are making diffuse pollution a serious environmental threat.

5.2.2 Monitoring

As mentioned above, the national monitoring network, which covers the entire territory, provides nitrate concentrations in surface freshwater. The surface freshwater monitoring data used by INAG to designate Sensitive Areas was provided to ERM. The data provides nitrate concentrations in freshwaters for the year 1996. It appears that no surface freshwater bodies

have nitrate concentration strictly above 50 mg NO3/L. Nevertheless, some areas show nitrate concentrations approaching this limit-value, some of which are areas with well-known problems (eutrophication, agricultural run-off, etc).

The monitoring points showing the highest nitrate concentrations are listed in Table 5.1.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 57 Table 5.1 Nitrate Concentrations in Selected Surface Freshwater Monitoring Points

Name Region Basin NO3 (mg/l) Date

Açude Veiga Chaves (abst.) North 41.1 01/1996 Arcozelo (abst.) North 40.700 01/1996 Castelo (abst.) North 49.2 09/1996 D.A. Caniçada (abst.) North 43.40 10/1996 Foz do Tamega (abst.) North 41.00 01/1996 Marachão (abst.) North 48.00 07/1996 Marachão (abst.) North 43.80 08/1996 Monte Azenhas (abst.) North 44.60 10/1996 Segude (abst.) North 42.70 07/1996 Castanheiro North 47.40 06/1996 Ponte do Porto North 46.40 07/1996 Ribeira de Pontes North 43.50 10/1996 Milagres Centro 40.67 01/1996 Reservoir dos Patudos LTV 114.95 04/1996 Pt Canas LTV 55.58 05/1996

Source: INAG, 1996

Lisboa and Tagus Basin

It is acknowledged that agricultural activities are the main source of nitrates in the surface freshwaters of the Tagus valley. More specifically the districts most affected by nutrients are those of xv:

• Alcobaça • Caldas da Rainha • Rio Maior • Lourinhá • Torres Vedras • Moita • Montijo • Palmela

All of these districts are shown on Figure 5.1.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 58 Figure 5.1 Districts affected by nutrients from agriculture

1. Alcobaça 1 2. Caldas da Rainha 3. Rio Maior 2 4. Lourinhá 3 5. Torres Vedras 4 6. Moita 7. Montijo 5 8. Palmela

7 6 8

The river basins which are most affected are :

• Rio Tornada • Rio Arnoia (Lagoa de Obidos) • Rio Sizandro • Rio Grande

Lagoa de Obidos

This lagoon is a fragile coastal system which possesses both large intrinsic and use value. This lagoon presently suffers from erosion and pollution of its inner waters.

Magos Reservoir

As mentioned in Section 3.2, the Magos reservoir was constructed near the town of Salvaterra de Magos, in the hydrographic basin of the Tagus river. A series of studies have shown, without reasonable doubt, that this lagoon is eutrophic. Two of the main factors contributing to the lake’s eutrophication are agricultural activities (by far the main pressure) and local climatic conditions (long exposure to sun). Indeed the main source of nutrients is agricultural effluents coming from upstream of the reservoir and which are rich in nitrogen and phosphorous.

The latest pollution case in the lagoon is related to ‘blue’ algae which poses severe health hazards for both the animal and human communities. According to studies done by Salvaterra’s Health Centre, the level of Blue algae is about fourteen times above the permissible level. Consequently, any contact with water must be avoided.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 59 The contamination has reached such levels that one proposed solution was to empty the lagoon ,clean it and fill it up again. This clearly is not a long term solution and only reflects the pressure created by agricultural practices in the area.

5.3 GROUNDWATERS

5.3.1 Introduction

Williams & Mousco (1992) mentioned that aquifers are affected by agricultural pollution in the Ave basin, north of Lisbon (pig-farming) and Algarve. The plains of the Tagus basin, Algarve and Serra de Aire e Candeeiros are know to be very vulnerable to groundwater contamination.

Some measurements have shown concentrations above 200 mg NO3/l (see Figure 5.1b).

Figure 5.1b Nitrate Concentrations in the regions of Estremadura, Baixo Tejo and Sado

Sources: Lobo Ferreira et al., 1994

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 60 5.3.2 Monitoring

Groundwater monitoring has been carried out in Portugal since about 1978 (at NUTS I and II scales) but concentrated on the aquifers of Algarve, lower Tagus, Sado and Aveiro.

The groundwater monitoring data provided by the Portuguese authorities consists of the results in five aquifers, all which have already been designated as Vulnerable Zones:

• Villa do Conde • Aveiro • Vagos • Mira • Campina de Faro

Comprehensive data is available for the region of Algarve, which is considered to be the most problematic area with regards to groundwater contamination by nitrates from agriculture. A study by J.P. Lobo Ferreira (1995) xvi aimed to characterise the vulnerability of Portugal’s groundwaters in relation to nitrate pollution resulting from urban, agricultural and industrial activities. The most vulnerable acquifers are those of :

• Silves - Querença • Falfosa; • Vale da Rosa; • Chaveca; • Laranjeiro; • Faiana.

However, aquifers which are less vulnerable than those listed above are not protected from nitrate contamination. For example, the Campina de Faro (designated as Vulnerable Zone) and Campina de Luz de Tavira aquifers are significantly contaminated by nitrates.

The situation in the areas of the above-mentioned regions considered to be most affected by nitrate pollution is summarised below.

5.3.3 Aquifers of Algarve

The Algarve’s main aquifers are shown in Figure 5.2.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 61 Figure 5.2 Algarve's main aquifers

Source: INAG

Analytical Results

The results provided by DRA Algarve indicate that several aquifers have high nitrate concentrations. These are listed in Table 5.2.

Table 5.2 Groundwater Quality in Algarve

MONITORING STATION MAP REFERENCE NITRATES (MG/L) DATE

Quinta Grande 595/171 92.290 05/96

Cerca do Ouro 596/604 143.880 05/96 Cerca do Ouro 596/604 60.700 11/96

Aroal 596/605 64.330 05/96

Alto Hortas JK6 600/62 68.420 05/96 Alto Hortas JK3 600/63 84.180 11/96

Nora TD2 600/190 60.940 05/96 Nora 600/190 57.260 11/96

Alporchino 604/69 50.060 05/96 Alporchino 604/69 48.130 11/96

Maritenda 605/282 90.100 05/96 Maritenda 605/282 78.620 11/96

Fabrica do Sumol 606/434 109.300 05/96 Fabrica do Sumol 606/434 101.530 11/96

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 62 Paço Branco 607/134 105.300 05/96 Paço Branco 607/134 80.620 11/96

Pé Outeiro 607/329 80.620 05/96

S.Pedro 608/67 108.640 05/96 S. Pedro 608/67 65.070 11/96

Campina 608/477 55.520 05/96 Campina 608/477 69.120 11/96

Covões 609/9 78.430 05/96

Montenegro 610/20 104.300 05/96 Montenegro 610/20 103.290 11/96

Brejo 611/71 54.500 05/96 Brejo 611/71 55.800 11/96

Fábrica de Cimento/Subetão 611/92 65.830 05/96 Fábrica de Cimento/Subetão 611/92 69.660 11/96

Campina de faro 611/156 209.700 05/96 Campina de Faro 611/156 176.620 11/96

Areal Gordo 611/225 93.140 05/96 Areal Gordo 611/225 85.210 11/96

In the region of Algarve, only the Campina de Faro miocene jurasic aquifer was designated as Vulnerable Zone by the Portuguese authorities. There are however numerous other points showing very high nitrate concentrations which would qualify for designation under the Nitrate Directive.

In general, high nitrate concentrations in the Algarve’s groundwaters are due to the intensification of agricultural activities, and hence use of fertilisers and pesticides.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 63 Figure 5.3 Groundwater Monitoring Network in Algarve

Monitoring point principal river secondary river Basin

Source: INAG

In general it can be said that the calcareous aquifers, such as the Silves- Querença aquifer, are the most vulnerable to nutrient pollution. The upper Jurassic formations and Cretaceous formations (eg Falfosa, Vale da Rosa, Chaveca, Laranjeiro, Faina, etc) also are relatively sensitive to pollution. The Miocene aquifer in Campina de Faro has been significantly polluted by nitrates for a time and it is estimated that there will be great difficulty in improving the quality of the aquifer. The aquifer adjacent to Campina de Faro is also a carbonaceous Miocene aquifer separated by impermeable formations. The pollution in this aquifer is said to progress from top to bottom only.

Other aquifers showing high nitrates concentrations are those of Campina da Luz de Tavira which are located in Miocene and Cretaceous formations. All of the above-mentioned aquifers are areas of intense agriculture. In the region of Ribeira da Quarteira-Montenegro, the highest nitrate concentrations vary between 61 and 221 mg/l. The source of nitrates in this region is estimated to be solely agriculture. High nitrate concentrations can also be found in the south-west of Algarve and North of the agglomerations of Lagos and Portimao (Unida de Alvor-Albufeira), where most measurements are between

50 and 100 mg NO3 /l.

A study carried out in 1994 by DRNA Algarve, provided additional data. The monitoring points with high nitrate concentrations which were not included

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 64 in Table 5.2 are listed in Table 5.3. in some instances it shows extremely high nitrate concentrations (eg Patacão - 248.80 mg nitrate/l).

Table 5.3 Nitrate concentrations in groundwaters (Algarve)

NAME MAP REFERENCE NO3 DATE

Monte Ruivos 026/587 57.60 12/92 Monte Ruivos 026/587 79.60 03/93 Monte Ruivos 026/587 62.96 01/94

Fonte de Louseiros 206/595 254.50 12/92 Fonte de Louseiros 206/595 238.10 03/93 Fonte de Louseiros 206/595 236.80 06/93 Fonte de Louseiros 206/595 175.58 09/93 Fonte de Louseiros 206/595 282.84 01/94

Paço Branco 134/607 131.20 03/93 Paço Branco 134/607 183.90 06/93 Paço Branco 134/607 81.56 09/93 Paço Branco 134/607 162.28 01/94 Paço Branco 134/607 52,00 03/94 Paço Branco 134/607 56.48 09/94

Vale da Rosa 453/607 61.70 12/92 Vale da Rosa 453/607 56.70 03/93 Vale da Rosa 453/607 58.30 06/93

Campina da Luz 366/608 55.28 09/93 Campina da Luz 366/608 93.50 03/93 Campina da Luz 366/608 95.61 06/93 Campina da Luz 366/608 89.55 09/93 Campina da Luz 366/608 95.29 01/94

Patacão 093/610 248.80 03/93 Patacão 093/610 230.60 06/93 Patacão 093/610 213.20 09/93 Patacão 093/610 216.60 01/94

Marchil 189/610 123.80 06/93 Marchil 189/610 123.30 09/93 Marchil 189/610 119.19 01.94

Brejo JK3 071/611 53.80 01/93 Brejo JK3 071/611 52.20 06/93 Brejo JK3 071/611 53.50 09/93 Brejo JK3 071/611 57.62 01/94

João D’Ourem 085/611 56.60 12/92 João D’Ourem 085/611 61.60 03/93 João D’Ourem 085/611 63.20 06/93 João D’Ourem 085/611 59.94 09/93

It is recognised that these high nitrate concentrations are correlated with agricultural practices in the region of Algarve. This can also be confirmed by the soil-use map below which shows that a majority of the land in Algarve is used as mixed agricultural land and arable land.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 65 Figure 5.4 Soil Use in the Algarve

Land Use (CORINE)

Artificial space Arable land: Annual crops Permanent Cultures Heterogeneous agricultural areas Forests Area of dense vegetation Open spaces Maritime zones Continental waters

Aquifers with high nitrate concentrations

The aquifers with high nitrate concentrations are briefly reviewed in this section. The graphs illustrate the nitrate trends in these aquifers (including several of the points listed in Table 5.2 and Table 5.3).

(a) Covões aquifer

Due to very high nitrate concentrations which reflect severe contamination of agricultural origin, the water quality of this aquifer is classified as A3. There appears to be a cycle in these concentrations. The highest concentrations are measured in November. It must be mentioned that measurements have only to be taken at one sample point for the whole aquifer. The graph below shows nitrate concentration trends.

Source: INAG

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 66 (b) Querença-Silves

As a whole, the water quality of this aquifer is very good (A1). However, over the years, occasional degradation of this quality is observed, mainly due to nitrate contamination.

(c) Albufeira-Ribeira de Quarteira aquifer

The quality of this aquifer is, as a whole, A1. However, in the northern part of the aquifer (monitoring point 596/604), very high concentrations of nitrates have been observed. These are said to be point source events and not representative of this zone. A cycle is also observed in nitrate concentrations. The highest concentrations are observed in April-May.

Source: INAG

(d) Quateira aquifer

Although the global quality of this aquifer is A1, there are clear signs of significant nitrate contamination of agricultural origin in the middle of the aquifer (monitoring point 605/282). This is illustrated in the graph below:

Source: INAG

(e) João de Venda-Quelfes aquifer

In this aquifer there are several points which show high nitrate concentrations (mainly points 607/134 and 607/278). This contamination result from agricultural activities. This is illustrated in the graphs below.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 67 Source: INAG

(f) Luz de Tavira

The overall degradation in the quality of this aquifer is due to an increase in nitrate concentrations. The trend shows that even when the nitrate limit- value is not reach, the nitrate concentration remains very near the limit. The worst situation is encountered at monitoring point 608/67 (as shown below).

(g) São Bartolomeu aquifer

Overall the quality of this aquifer is classified as A3, mainly due to nitrate concentrations. The highest concentrations are observed in points 600/63 and 600/190). The graph below shows that concentrations are on the increase.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 68 Source: INAG

Conclusion

The most severely affected parts of the Algarve are those of Campina de Faro and Ria de Alvor, both of which have been designated as Sensitive area. Only Campina de Faro was designated as a Vulnerable Zone. Generally, the source of nitrates in this region is agriculture and the most recent studies carried out show an increasing trend of nitrate concentrations in groundwaters. The zones in SW Algarve may present high nitrate concentration due to high vulnerability caused by sedimentary rocks.

• The high nitrate concentrations in the Alvor reservoir region are mainly due to an increase in agricultural activities and increased use of fertilisers. This shallow groundwater resources do, therefore, appear to qualify for designation under Directive 91/676/EEC. • The zone of Quarteira Montenegro also presents nitrate concentrations well above the limit, the source of which can be assumed to be solely agriculture. This zone, therefore, appears to qualify for designation under Directive 91/676/EEC. • SW Algarve: here again, the high nitrate concentrations are related to agricultural activities, which suggests that the groundwaters qualify for designation under Directive 91/676/EEC.

As illustrated above, it seems that the following aquifers do qualify for designation as Vulnerable Zones:

• Covões; • Querença-Silves; • São Bartolomeu • Albufeira - Ribeira de Quarteira; • São João da Venda - Quelfes; • Luz de Tavira; • Quarteira.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 69 5.3.4 Central Region

Estarreja

In conjunction with the industrial development in this region, agricultural activities in the region of Estarreja have also increased over the last few years. This has also influenced population density which has now reached 200 inhabitants/km2. A Sensitive Area was also designated in the region of Estarreja (Ria de Aveiro). In this region the average annual concentration lies

around 80 mg NO3/l, with values up to 260 mg/l. The high nitrate concentrations around the chemical complex of Estarreja seem to be a specific case. In an assessment carried out in 1989 (Mestrado de Silva, 1989), 40 wells out of 60 showed concentrations above 50 mg/l nitrate.

Cantanhede - Aveiro - Ovar

A study assessing figures collected in 1983-1984 in the quaternary waters of the lower Vouga groundwater system available. The distribution of the data

collected shows concentrations above 46 mg NO3/l in several locations (11 in total) around Ria de Aveiro. According to Cristoxvii, the high values show a clear lack of adequate infrastructure for urban waste water and an increasing use of fertilisers and pesticides. The Cretaceous and Jurassic systems adjacent to the quaternary system showed lower nitrate concentrations - reaching 30

mg NO3/l on only two occasions.

In this region, the Aveiro quaternary aquifer was designated as a Vulnerable Zone.

5.3.5 Alentejo

Evora

A study by Chambel (1992) showed that nitrate concentrations have reached a high levels in the region of Evora where more than 50% of measurements

made showed concentrations above 50 mg NO3/l.

The statistical distribution of these values, according to soil formations, is as follows:

Table 5.3 Nitrate concentrations in the Evora region

NO3 (mg/l) Arithmetic mean Average Maximum Minimum

Total 70.6 52.1 285.2 10.5 Quartzodiorito 75.7 55.8 285.2 19.8 Gnaisse 57.4 42.2 210.8 10.5 Corneana 60.0 71.3 124.0 19.2 Xisto 114.1 63.2 248 31.0

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 70 It is believed that the waters intended for the abstraction of drinking water around Evora are very much prone to contamination by nitrates. Deeper aquifers, however, do not show nitrate contamination. The nitrates are clearly of agricultural origins.

Elvas - Vila Boim

In a report by Silva (1991) the distribution of NO3 concentrations collected during two monitoring campaigns in the region are compared (max: 322 mg

NO3/l, min: 22 mg NO3/l and average 81 mg NO3/l). The majority of wells have concentrations between 50 and 100 mg NO3/l.

Although it shows globally similar values, concentrations are very different (at some places and at some periods) and seem to demonstrate a certain instability in nitrate concentrations in groundwater. It has been established that the nitrates are of agricultural origin.

Beja District

Another study looked at nitrate concentration in groundwaters used for the abstraction of drinking water in the region of Beja. It appeared that several measurements showed concentrations well above 50 mg/l.

Gouveia (1994) reported that a large number of measurements made in the Beja region are well above 50 mg/l. Their distribution is shown in Annex A of this report. It has been established that the nitrates are of agricultural origin.

Verride (lower Mondego valley)

A study carried out in 1989 showed that a large number of wells located East of Figueira da Foz have nitrate concentrations well above 50 mg/l (8 wells with concentration between 50 and 100 mg/l and 3 wells with concentrations between 100 and 200 mg/l).

Figures indicate a declining trend in nitrate concentrations and have nitrate concentrations below 30 mg/l by the end of the 1980’s. However, a few wells still showed concentrations well above 60 mg/l (up to 160 mg/l) by the end of 1980’s.

Odemira District

It was reported by Gouveia (1994) that all several areas in the district have high nitrate concentrations due to agricultural activities.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 71 CONCLUSION

Several areas of the Central region also show high nitrate concentration in groundwaters.

• Aveiro - Ovar region. The Portuguese authorities designated the Aveiro quaternary aquifers as Vulnerable Zone. This zone extends to the south- east of the agglomeration of Aveiro. Although adjacent groundwater systems have much lower nitrate concentrations, the system around Ovar (north of Aveiro) also shows very high nitrate concentrations in groundwater. It was shown by Lobo Ferreira (1995) that groundwaters in this zone are particularly vulnerable due to floods and are affected by sandy formations of generally high permeability. It therefore seems that the Vulnerable Zone should be extended northwards along the coast which is mainly formed of arable land (annual crops).

• High NO3 concentrations were also detected around Estarreja. It seems however that such nitrate levels are due to industrial activities in the region and that it therefore does not qualify for designation.

• Aquifers have also been found to have high nitrate concentrations of agricultural origins in the districts of Beja, Evora and Elvas.

5.3.6 Lisbon and the Tagus Valley

For this region, nitrate measurements in groundwaters have been made since 1956 and include a total of 861 water bodies. The spatial distribution of nitrate concentrations in both water bodies and wells is shown in Figures 4.5 and 4.6 respectively. As can be seen in Annex A, the majority of groundwaters with concentrations above 50 mg/l are shallow groundwaters. The most severe conditions are in the alluvial formations of the Tagus and the sandy zones on the peninsula of Setubal. This is related to the high vulnerability of the whole area. The situation in deep aquifers is a lot better, although concentrations between 50 and 100 mg/l were recorded in several wells to the SW of Alcobaca. Figure 5.5 show the land use in the region.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 72 Figure 5.5 Land Use in the Tagus Basin

Land Use (CORINE)

Source: INAG

Other data from Novo (1991) show repeatedly high nitrate concentrations (>

50 mg NO3/l) in the Torres Vedras zone near the Sizandro river. Nitrate values there ranged between 74 and 471 mg/l. In this case, the contamination is of industrial origin.

More generally, high nitrate concentrations have been recorded in several

locations in the region, including several above 200 mg NO3/l: Rio Maior (325,3 mg/l), Seixal (274,5 mg/l), Almeirim (226,1 mg/l) and Torres Vedras (203,5 mg/l).

CONCLUSION

As mentioned above, the are several wells showing high nitrate concentrations in shallow groundwaters in the region. The most alarming cases appear to be associated with alluvial formations of the Tagus and Setubal peninsula, which according to Lobo Ferreira (1995) also are highly vulnerable to nitrate pollution. Figure 5.5 shows that the areas along the Tagus river and upstream of the Sado estuary are mainly arable land (annual crops).

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 73 Golegã District

The aquifer formations of the region are part of the larger hydrogeological divisions of the Tagus and Sado sedimentary basin. According to S. Rodrigues et al. (1989), this basin is formed of Miocene and quaternary formations linked together. It can therefore be assumed that it forms a single aquifer. According to DRA, there are about 100 abstraction points varying from a few meters to 270 m depth.

A monitoring campaign carried out in 1996 revealed that, out of 14 stations surveyed, seven had nitrate concentrations higher than the limit value recommended for drinking water. All of these are said to be caused by agricultural activities, urban waste water and industry.

It can be concluded that shallow groundwaters ( < 40m) in this region are contaminated by nitrates and have, in some areas, concentrations above 70 mg

NO3/l. Deeper groundwaters (> 200m) do not appear to be affected. However, there is no detailed information that allows the source of nitrates to be identified in more detail.

5.3.7 Northern Region

Synthetic data

The majority of data in this part of the country are only available in synthetic form and are presented by district.

• Amares

mg NO3/l %

NO3 < 1 34.69

1 ≤ NO3 ≤ 10 36.73

10 ≤ NO3 < 25 18.37

25 ≤ NO3 ≤ 50 9.69

NO3 ≥ 50 0.51

• Terras de Bouro

mg NO3/l %

NO3 < 1 62.35

1 ≤ NO3 ≤ 10 35.49

10 ≤ NO3 < 25 1.85

25 ≤ NO3 ≤ 50 0.00

NO3 ≥ 50 0.31

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 74 • Barcelos

mg NO3/l %

NO3 < 1 20.43

1 ≤ NO3 ≤ 10 36.07

10 ≤ NO3 < 25 25.08

25 ≤ NO3 ≤ 50 11.61

NO3 ≥ 50 6.81

11.5 % of the samples collected in the region of Barcelos between 1987 and 1990 were considered to be of very bad chemical quality, especially with regards to nitrates.

• Esposende

mg NO3/l %

NO3 < 1 16.03

1 ≤ NO3 ≤ 10 29.01

10 ≤ NO3 < 25 28.24

25 ≤ NO3 ≤ 50 19.08

NO3 ≥ 50 6.87

Just under 30% of the samples collected between 1987 and 1990 showed high nitrate concentrations (>50 mg/l). The bacteriological and biological quality of the water was also considered to be bad.

• Montalegre

mg NO3/l %

NO3 < 1 16.03

1 ≤ NO3 ≤ 10 29.01

10 ≤ NO3 < 25 28.24

• Povoa de Lanhoso

mg NO3/l %

NO3 < 1 23.02

1 ≤ NO3 ≤ 10 51.19

10 ≤ NO3 < 25 18.25

25 ≤ NO3 ≤ 50 5.95

NO3 ≥ 50 1.59

• Braga

mg NO3/l %

NO3 < 1 20.05

1 ≤ NO3 ≤ 10 33.52

10 ≤ NO3 < 25 25.00

25 ≤ NO3 ≤ 50 15.11

NO3 ≥ 50 6.32

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 75 • Veira do Minho

mg NO3/l %

NO3 < 0.5 20.80

0.5 ≤ NO3 ≤ 5 56.90

5 ≤ NO3 < 10 15.9

10 ≤ NO3 ≤ 25 5.3

25 ≤ NO3 ≤ 45 1.1

• Vila Real

mg NO3/l %

NO3 < 1 20.54

1 ≤ NO3 ≤ 10 59.92

10 ≤ NO3 < 25 17.43

25 ≤ NO3 ≤ 50 2.11

NO3 ≥ 50 0.00

• Resende

mg NO3/l %

NO3 < 1 0.00

1 ≤ NO3 ≤ 10 0.00

NO3 < 25 51.85

25 ≤ NO3 ≤ 50 46.76

NO3 ≥ 50 1.39

Porto District

The results of monitoring where summarised by Alpendurada et al. (1991) by range of concentration:

Table 5.3 Groundwater concentrations in the Porto District

District % NO3 < 25 (mg/l) 25 ≤ %NO3 ≤ 50 (mg/l) % NO3 > 50 (mg/l)

Amarante 57 14 29 Baiao 78 0 22 Felgueiras 40 0 60 Gondomar 24 13 63 Lousada 100 0 0 Maia 33 24 43 Marco de Canaveses 71 29 0 Matosinhos 29 17 54 Paços de Ferreira 44 34 22 Parades 42 16 42 Penafiel 71 0 29 Porto 39 23 38 Povoa do Varzim 29 42 29 Santo Tirso 58 15 27 Valongo 35 14 51 Vila do Conde 44 26 30 V.N. de Gaia 36 21 43

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 76 The above table shows that several areas have more than 50% of samples which have a nitrate concentrations above 50 mg NO3/l and hence may present severe nitrate contamination. These areas are:

• Feilgueiras • Gondomar • Matosinhos • Valongo

But more generally, the percentage of samples with concentrations above 50 mg/l is relatively high and shows a more general problem in the Porto district rather than localised contamination.

Conclusion

Although no detailed data were made available, the synthetic data clearly shows that a very high percentage of samples taken in the Porto district have nitrate concentrations above 50 mg/l. Particular problem areas include Feilgueiras, Gondomar, Matosinhos and Valongo.

It therefore appears that there is extensive nitrate contamination in the region’s groundwaters and that it should be taken into consideration for designation under Directive 91/676/EEC.

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 77 6 CONCLUSIONS

The following table summarises the water bodies which were identified as qualifying for identification under either or both Directives. For many areas, however, it was not possible to identify the source of nutrients. It is therefore very difficult to identify under which Directive they should be designated.

Table 6.1 Water Bodies Qualifying for Designation

Nº BASIN NAME CRITERIA VULNER SENSITIV ABLE E AREA ZONE

1 Sado Marateca Bay and Alcacer nutrient enrichment and ü Channel (Sado estuary) algal blooms

2 Mondego Mondego estuary eutrophication ü

3 Tagus Mago Reservoir eutrophication ü

ü 4 Algarve Covões aquifer NO3 ü

ü 5 Algarve Querença-Silves aquifer NO3 ü

ü 6 Algarve Albufeira-Ribeira de NO3 ü Quarteira aquifer

ü 7 Algarve Quarteira aquifer NO3 ü

ü 8 Algarve João de Venda-Quelfes NO3 ü aquifer

ü 9 Algarve Luz de Tavira aquifer NO3 ü

ü 10 Algarve São Bartolomeu aquifer NO3 ü

ü 11 Algarve Alvor NO3 ü

ü 12 Sado Evora aquifer NO3 ü

ü 13 Guadiana Elvas-Vila Boim aquifer NO3 ü

ü 14 Guadiana Beja aquifer NO3 ü

15 Tagus Cala do Norte (Tagus Bacteria of faecal origin ü Estuary) and organic pollution

16 Tagus Rio da Mula reservoir Bacteria of faecal origin ü and organic pollution

17 Tagus Tagus (near Valada) Bacteria of faecal origin ü and organic pollution

18 Tagus Olhos de Agua (Alviela Bacteria of faecal origin ü river) and organic pollution

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 78 Nº BASIN NAME CRITERIA VULNER SENSITIV ABLE E AREA ZONE 19 Tagus Mouriscas (Rio Frio) Bacteria of faecal origin ü and organic pollution

20 Ave The whole basin Bacteria of faecal origin ü and organic pollution

21 Tagus Alviela river Q4 quality ??

22 Tagus Carvalho river Q4 qulaity ??

23 Tagus Pisão river Q4 quality ??

24 Tagus Trancão river organic pollution ??

25 Tagus Póvoa organic pollution ??

26 Tagus Punto Canas NO3 ??

27 Tagus Reservoir dos Patudos NO3 ??

28 Cavado Cavado (around Marachao) NO3 ??

29 Douro Miranda reservoir eutrophication ??

30 Douro Pocinhos reservoir eutrophication ??

31 Douro Pinhão (Régua reservoir) eutrophication ??

32 Douro Mosteirõ (Carrapatelo eutrophication ?? reservoir) 33 Douro Entre Rio trend towards ?? eutrophication

34 Douro Crestuma Lever reservoir trend towards ?? eutrophication

35 Tagus Ponte de Canaveses eutrophication ??

36 Mondego Fronhas reservoir eutrophication ??

37 Tagus Pracana reservoir eutrophication ??

38 Douro Torrão reservoir eutrophication ??

39 Douro Bemposta reservoir eutrophication ??

40 Douro Picote reservoir eutrophication ??

41 Douro Valeira reservoir eutrophication ??

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 79 7 REFERENCES

ENVIRONMENTAL RESOURCES MANAGEMENT EUROPEAN COMMISSION - DGXI 80 i Anon. (1993). Eutrophication Symptoms and Problem Areas. Oslo & Paris Commissions. London. 26 pages plus maps. ii OECD (1993), OECD Environmental Performance Reviews - Portugal, OECD Paris. iii INAG (1994), Identificação de zonas sensíveis e menos sensíveis - Directiva 91/271/CEE Águas Residuas Urbanas, INAG Direcção de serviços de recursos hídricos. iv IPIMAR, Seasonal and Spatial Aspects in Chlorophyll a in Portuguese Waters v M.H. Cavaco (1998), Seasonal and Spatial Aspects of Chlorophyll a distribution in Portuguese waters during the peRiod 1985-1996, Bulletin of the Sea Fisheries Institute 2(144), 1998. vi Oliveira and Cabeçadas (1996), Marine Benthic Vegetation, Recent vii IHRH (1996), Estudo de Avaliacao da Vulnerabilidade daCapacidade de Recepcao das Aguas e Zonas Costeiras em Portugal - RelatoRio de Sintese, Instituto de Hidraulica e Recoursos Hidricos. viii Cabeçadas (1993), Ecologia do fitoplâncton do estuáRio do Sado: para uma estratégia de conservacão. Estudos de Biologia e Conservacão da Natureza 10. SNPRCN, Lisboa. ix Cabeçadas and Brogueira (1993), The behaviour of Phosphorus in the Sado Estuary, Portugal, National Institute of Fisheries Research, Lisbon. x D. Hatzilacou, C. Haynes (1996), Protecting the Freshwater Ecosystems of Southern Europe - Strategy for an Integrated Approach, WWF 1996 xi INAG (1996), InventaRio do estado de qualidade das aguas doces superficias, Ano hidrologico de 1994/95, MinisteRio do Ambiente July 1996 xii Lourenco Gil (1996), Classificação trófica das albufeiras exploradas pela EDP, Labelec- Grupo EDP xiii Almeida et al., Programma de monitorisacao de cianobacterias- Albufeiras de Coruche e de Salvaterra do magos xiv DSA-DHR Sector Qualidad de Agua (1999) Qualidad de Aguas Superficiais Destinadas a Producao de Agua Para Consumo Humano xv J.T. Capucho (DRA Lisboa e Vale do Tagus), Pers. Communication (11/02/99) xvi J.P. Lobo Ferreira (1995), Caracterizacão do Estado das Ãguas Subterrâneas em relação à poluição causada por Nitratos, LaboratoRio Nacional de Engenharia Civil. xvii Cristo (1985), Annex B

Surface Freshwater Quality Classification System

A B C D E

PARAMETERS pH 6.5 - 8.5* - 6.0 - 9.0 5.5 - 9.5 - Temperature (ºC) <=20 21 - 25 26 - 28 29 - 30 >30 Condutivity (uS/cm,20ºC) <=750 751 - 1000 1001 - 1500 1501 - 3000 >3 000 SST (mg/l) <=25.0 25.1 - 30.0 30.1 - 40.0 40.1 - 80.0 >80.0 Sat OD (%) >=90 89 - 70 69 - 50 49 - 30 <30 BOD5 (mg O2/l) <=3.0 3.1 - 5.0 5.1 - 8.0 8.1 - 20.0 >20.0 COD (mg O2/l) <=10.0 10.1 - 20.0 20.1 - 40.0 40.1 - 80.0 >80.0 Oxygen (mg O2/l) <=3.0 3.1 - 5.0 5.1 - 10.0 10.1 - 25.0 >25.0 Ammonia (mg NH4/l) <=0.10 0.11 - 1.00 1.10 - 2.00 2.01 - 5.00 >5.00 Nitrates (mg NO3/l) <=5.0 5.0 - 25.0 25.1 - 50.0 50.1 - 80.0 >80.0 Phosphates (mg P2O5/l) <0.54 - <0.94 >0.94 - Total coliforms (/100 ml) <=50 51 - 5000 5001 - 50000 >50000 - Faecal coliforms (/100 ml) <=20 21 - 2000 2001 - 20000 >20000 - Iron (mg/l) <=0.50 0.51 - 1.00 1.10 - 1.50 1.50 - 2.00 >2.00 Manganese (mg/l) <=0.10 0.11 - 0.25 0.26 - 0.50 0.51 - 1.00 >1.00 Zinc (mg/l) <=0.30 0.31 - 1.00 1.10 - 5.00 - >5.00 Copper (mg/l) <=0.020 0.021 - 0.05 0.051 - 1.00 - >1.00 Chromium (mg/l) <=0.05 - - - >0.05 Selénium (mg/l) <=0.01 - - - >0.01 Cádmium (mg/l) <=0.0010 - 0.0011 - 0.0050 - >0.0050 Mercúry (mg/l) <=0.00050 - 0.00051 - 0.001 - >0.001 Arsenic (mg/l) <=0.010 0.011 - 0.050 - 0.051 - 0.100 >0.100 Figure B1 Surface Freshwater Quality in Portugal - July 1998 Figure B2 Surface Freshwater Quality in Portugal - August 1998 Figure B3 Surface Freshwater Quality in Portugal September 1998 Figure B4 Surface Freshwater Quality in Portugal October 1998 Figure B5 Surface Freshwater Quality in Portugal November 1998 Figure B6 Surface Freshwater Quality in Portugal December 1998 Figure B7 Surface Freshwater Quality in Portugal - January 1999 Figure B8 Surface Freshwater Quality in Portugal - February 1999 Figure B9 Surface Freshwater Quality in Portugal - March 1999 Figure B10 Surface Freshwater Quality in Portugal - April 1999 Figure B11 Surface Freshwater Quality in Portugal May 1999 SOIL USE SOIL USE JULY 1998 AUGUST 1998 SEPTEMBER 1998 OCTOBER 1998 NOVEMBER 1998 DECEMBER 1998 JANUARY 1999 FEBRUARY 1999 MARCH 99 APRIL 1999 MAY 1999