Revised Terms of Reference [28/11/2000]

Heavily Modified Waters in Europe Case Study on the River Lagan, the Tidal Lagan Transitional Water & the Port of Belfast Coastal Water, Northern Ireland

Peter Hale, David Corbelli, Claire Vincent (Environment and Heritage Service) Meg Postle, Teresa Fenn, John Ash (Risk & Policy Analysts)

Environment and Heritage Service Risk & Policy Analysts 17 Antrim Road Farthing Green House LISBURN Beccles Road BT28 3AL Loddon 00 44 2890 254754 – phone Norfolk 00 44 2890 254761 - fax NR14 6LT Tel: +44 1508 528465 Table of Contents page PART I 4 1 Preface [to be drafted by project managers] (1 page) 5 2 Summary Table (2 pages) 1 3 Introduction (2 pages) 1 3.1 Choice of Case Study 1 3.2 General Remarks 1 4 Description of Case Study Area (3 pages) 3 4.1 Geology, Topography and Hydrology 3 4.2 Socio-Economic Geography and Human Activities in the Catchment 3 4.3 Identification of Water Bodies 4 4.4 Discussion and Conclusions 10 PART II 11 5 Physical Alterations (5 pages) 12 5.1 Pressures and Uses 12 5.2 Physical Alterations 13 5.3 Changes in the Hydromorphological Characteristics of the Water Bodies and Assessment of Resulting Impacts 15 5.4 Discussion and Conclusions 16 6 Ecological Status (7 pages) 18 6.1 Biological Quality Elements 18 6.2 Physico-Chemical Elements 27 6.3 Definition of Current Ecological Status 28 6.4 Discussion and Conclusions 29 7 Identification and Designation of Water Bodies as Heavily Modified (6 pages) 30 7.1 Necessary Hydromorphological Changes to Achieve Good Ecological StatusFehler! Textmarke nicht definiert. 7.2 Assessment of Other Environmental OptionsFehler! Textmarke nicht definiert. 7.3 Designation of Heavily Modified Water BodiesFehler! Textmarke nicht definiert. 7.4 Discussion and Conclusions 39 8 Definition of Maximum Ecological Potential (6 pages) 1 8.1 Determining Maximum Ecological Potential 1 8.2 Measures for Achieving MEP 3 8.3 Comparison with Comparable Water Body 5 8.4 Discussion and Conclusions 5 9 Definition of Good Ecological Potential (6 pages) 6 9.1 Determination of Good Ecological Potential 6 9.2 Identification of Measures for Protecting and Enhancing the Ecological Quality 6 9.2.1 Basic Measures 6 9.2.2 Supplementary Measures 6 9.3 Discussion and Conclusions 6 PART III 7 10 Conclusions, Options and Recommendations (5 pages) 8 10.1 Conclusions 8 10.2 Options and Recommendations 8

2 11 Bibliography 9 12 List of Annexes 10

______List of Tables, Boxes, Maps etc. page Table 1 [model heading for a table] Fehler! Textmarke nicht definiert. Box 1 [model heading for a box or map] Fehler! Textmarke nicht definiert. Table 2 [Details on separate groups of water bodies] 9

3 PART I

4 1 Preface [to be drafted by project managers] (1 page)

[insert the standard preface - drafted by the project managers - briefly explaining the European project on heavily modified water bodies as the context for the individual case study. This should explain the context to readers of the case study, who may not be familiar with the European project. ]

5 2 Summary Table (2 pages)

[insert the summary table on the case study already provided; "Annex IV" of the minutes of the kick-off meeting of the European project on heavily modified water bodies.]

Item Unit Information

1. Country UK Northern Ireland

2. Name of the case study (name of water body) Lagan

3. Steering Committee member(s) responsible for the case MM David Corbelli study

4. Institution funding the case study EHS Environment and Heritage Service

5. Institution carrying out the case study EHS Environment and Service

6. Start of the work on the case study Sept. 2001

7. Description of pressures & impacts expected by Date Feb 2002

8. Estimated date for final results Date April 2002

9. Type of Water (river, lake, AWB, freshwater) text River, transitionlal water and coastal water (Port)

10. Catchment area 609 km2

11. Length/Size 70 km

12. Mean discharge/volume m3/s or m3 13. Population in catchment number 450 000

14. Population density Inh./km2

15. Modifications: Physical Pressures / Agricultural influences text

16. Impacts? text

17. Problems? text

18. Environmental Pressures? text

19. What actions/alterations are planned? text

20. Additional Information text

21. What information / data is available? text

22. What type of sub-group would you find helpful? text

23. Additional Comments text

2 3 Introduction (2 pages)

3.1 Choice of Case Study

The Lagan catchment is the most densely populated in Northern Ireland and not only encompasses the city of Belfast with its economic and commercial centre, but also drains some of the most productive agricultural land in Northern Ireland. Industrial and urban development over the last 2 centuries have caused a severe deterioration in water quality in the lower reaches of the Lagan. In the last few years, there has been a large investment programme in the sewage treatment systems, and a decline in traditional industrial activity. Realistic water quality targets, robust routine monitoring and classification systems are now in place to ensure that the water quality within the catchment is maintained and, where necessary, enhanced. The Lagan is subject to a variety of physical pressures due to the level of urbanisation in the lower part of the catchment which has resulted in physical modification both historic for industrial purposes and current for flood defence and navigation. In the flood plain of the catchment there are pressures arising from the agricultural land use and the provision of flood defence. Recent proposals have suggested the reinstatement of the Lagan canal system. The whole area is a good example of a system with several pressures and future management and development issues.

3.2 General Remarks

Five water bodies have been identified within the study area, these have been defined on physical criteria that represent changes in energy and physical structure. Water bodies defined are also based on the pressures upon them and have in some cases been subdivided further to facilitate management options. The case study focuses on a number of pressures (flood defence, land drainage, land take and navigation). This study will contribute to the navigation subgroup and the flood defence subgroup (once it has been established). Figure 1 – Case study area and water bodies identified Figure 1 - Case Study Area and Water Bodies identified River Netw orks Identif ied Zones wit hin Lagan Catchm en t Zon e 5 - Harbour Area Zon e 4 - Im pound men t Zon e 3 - F lo odplain Zon e 2 - Middl e Reaches Zon e 1 - Up lan d Lagan Catchm en t 0 5 10 15 Kilome tres

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2 4 Description of Case Study Area (3 pages)

4.1 Geology, Topography and Hydrology

Geology

The Lagan catchment overlies the Triassic Sherwood Sandstone aquifer, which at present is used as a small water supply. In the future, however, this may become an important public water supply as industrial and population demands grow. The source of recharge to the aquifer is not fully understood, but it is believed that infiltration occurs along the valley margin and in the Antrim Hills. Sands and gravels in the lower end of the catchment may contribute to river base flows. Much of the catchment is underlain by greywackes and mudstones, with a sandstone deposit following the river valley below Waringstown. As a result of glacially induced erosion, the catchment is covered in “drift”, generally comprising till or boulder clay. Although peatlands are prevalent over much of Ireland, only a small fraction of the Lagan catchment is covered in peat.

Figure 2 – Solid geology of the Lagan catchment

Figure 2 - Solid Geology of the Lagan catchment

AR G IL LA C EO U S R O C K S AN D [S U B EQ U A L/S U BO RD IN A TE] LIM ES TO N E , IN TE R BE D D ED AR G IL LA C EO U S R O C K S W ITH SU B O R D IN ATE S AN D S TO N E AN D E VA PO R I TIC R O C KS AR G IL LA C EO U S R O C K S , U N DIF FE RE N TIA TE D BA S AL T 1E C 0 CH A LK A N D SA ND S TO N E DO L E RIT E 1E B 0 FE LSI TE G RA N O D IO R ITE 1AA C LA M P RO P H YR E G R O U P 1G 00 M U DS T O NE 3S 00 RH Y O LIT E 1B A A SA N D STO N E 3D 00 SA N D STO N E A ND S U B O RD IN A TE B R EC C IA 0 5 10 15 Kil om e tre s

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Topography The Lagan catchment covers an area of 609 km2. The River Lagan rises as a spring on Slieve Croob 30km to the south-west of Belfast, the River being some 70km in length. The "U" shape of the Lagan Valley is characteristic of glacial action and the river itself has had little impact on the overall shape of the valley. For the first few kilometres, the Lagan falls steeply through mountain pastures and quickly develops a meandering character with a shingle bed (water body 1). Below Drummiller the river falls steadily until Magheralin (water body 2), where the gradient

3 reduces and the river becomes sluggish, encouraging weed growth (water body 3a). Downstream of Lisburn the gradient increases again, with consequent increase in the speed of flow, and a reduction in rooted weed growth (water body 3b). At Stranmillis Weir the river enters the tidal impoundment, the lower end of which is defined by the new Lagan Weir, some 4.5 km downstream (water body 4). The Lagan Weir marks the lower limit of the River Lagan, at which point the flow enters the fully tidal Inner Belfast Lough (water body 5). The largest tributary is the Ravernet River, which is approximately 13 km in length and flows through farmland to join the River Lagan immediately upstream of Lisburn. There are also a number of smaller tributaries, many of which are in the Belfast area and are known collectively as the Belfast Streams.

Hydrology

Annual rainfall varies across the Lagan catchment from 950 mm at Belfast to 1200 mm at Slieve Croob. In its upper reaches the Lagan responds rapidly to rainfall, but response in the lower catchment is reduced as a consequence of inundation in the flood plain between Moira and Lisburn. Floods tend to water-log the low-lying areas adjacent to the river, frequently inundating tens of hectares in the reach from Magheralin to Lisburn and Stranmillis.

The typical flows of the River Lagan at Newforge (Just upstream of Stranmillis Weir) show that its discharge is typically quite small. The overall mean flow is 7.86 m3s-1 (cubic metres per second [cumecs]), but the mean summer flow drops to 4.53 m3s-1. During dry spells, mean daily flows have been known to fall to below 0.10 m3s-1. For the winter months (October – March), mean flows reach 16.56 m3s-1, but during storm conditions, discharges have been estimated to exceed 100 m3s-1.

Four weirs at Stranmillis, Lambeg, Hilden and Canal Street (which is a crescent weir with water levels additionally controlled through the old number 12 weir lock at Canal Street) in Lisburn are operated manually by Lisburn Borough Council to control water levels in the river.

Belfast's water supply is piped from Stoneyford, Lough Neagh and the Mourne Mountains and there are no major surface water abstractions from the River Lagan. In the lower reaches, treated effluent from sewage treatment works may contribute as much as 50% of dry weather flow.

4.2 Socio-Economic Geography and Human Activities in the Catchment

Population

At the time of the 1991 census, the population of the Lagan catchment was approximately 450,000. The majority of the catchment’s population lives within the Belfast Urban Area, which includes the city of Belfast, and the Borough of Lisburn.

4 Cultural Heritage and Recreation

Between Lisburn and Belfast, the Lagan flows through an area of high scenic value. The centrepiece of this area is the Lagan Valley Regional Park which extends from Stranmillis Weir to its upper limit at Lisburn at the Union locks, and is managed for conservation and recreation purposes. The park is a very popular and well-used recreation resource; for example, the area around Shaws Bridge is used for jogging, walking, and white water canoeing. Paths, which were formerly part of the canal system, have been surfaced and now provide foot and wheelchair access to the entire Lisburn-Belfast reach. In addition to the recreational value of the area, reaches of the river contained within the park are of high conservation value, and parts of the park are used as an educational resource.

The River Lagan has played an important role in the development of Belfast, a city with a rich industrial and maritime heritage. Belfast experienced rapid growth and increasing prosperity during the Victorian age. During this time new wealth and employment were created by industries such as, rope making, shipbuilding, tobacco and linen. Recent archaeological investigations have unearthed details of pottery making around Ravenhill on the banks of the Lagan. The largest and perhaps best known industry associated with the Lagan is ship building which was first started by William Ritchie in 1791 and continues in Belfast Harbour to this day.

Angling Interest Most angling interest is in brown trout, present throughout the river where there is moderate or fast flow. There are presently three active angling clubs, two on the upper reaches above Moira and another on the lower river at Lambeg. A short section of state owned coarse fishery exists in the main river in its lower reaches.

Land Use There are four broad types of land use in the catchment: · Urban areas · Agricultural land · Forestry · Parkland and land managed for conservation purposes

The urban areas are mainly located in the north of the catchment within the Belfast urban area, which includes Lisburn. Other significant urban areas are Moira and Dromore. Just below 21% of the catchment area is urban. The majority of the Lagan catchment area is used for agricultural activities (approximately 75%), of which dairy farming predominates. A small percentage of the catchment is classed as "natural vegetation" and this occurs mainly around Slieve

5 Croob. 3% of the catchment exists within the Lagan Valley Regional Park. According to CORINE Land-use Classification mapping, only 1% is used for forestry of varying types.

Figure 3 – Land Use of the Lagan catchment

Figure 3 - Land U se of

t he Lagan catchment Airpor ts Bro ad -lea ved Forest Co mp lex C ult ivat ion P at terns Co nife ro us Fo rest Co ntin uou s U rban Fa bric Disco ntin uo us Urb an Fab ric Du mp Site s Go od Pasture Gr een Urb an Area s In dust rial or Comm ercial Unit s In lan d ma rsh es Min er al Ext ract ion Sit es Mixed Past ure Mo ors and Heathl and Nat ural Gr ass lan ds No n-irriga ted Arab le L and Poo r Past ure Port A reas Port a nd L eisu re Facilit ies Princip ally ag ricu ltu re ;Sign ificant Nat ural veg . Ro ad and Rail net w orks/ Associat ed land Un exp loit ed Peat Bog Water Bo dies Water Co urses

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0 5 10 15 Kilometres

6 4.3 Identification of Water Bodies

As considered in 4.1 the geology of the catchment, although being mixed, is exclusively non-erosive and hence contributes very little to the acid neutralising capacity of the river in its natural state. Further, given that it is a relatively small catchment the influences of latitude and longitude are irrelevant to the ecological potential of the river in its natural state (Annex II, system B). The major typological influences relate to the altitude range and more specifically the channel gradient along its travel to the sea, which ultimately defines parameters such as substrate typology, energy of flow, depth, valley shape, transport of solids, ANC etc. This profile is illustrated graphically in Figure 1 and the predominant substrate types, 4 are indicated.

Figure 4 Gradient profile for River Lagan from source to sea

250

200

150

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d

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0 1 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

-50 Distance from Source-1 m km

Based on this profile analysis the River Lagan can be split into a number of distinct typologies (figure 1).

Water body 1 The upper reaches above Dromara have an obviously sharp gradient as the river leaves its source on Slieve Croob. Substrates in this area are strongly dominated by boulder and cobble. The river flow regime is torrential during periods of high precipitation, but with only a low base flow during drier periods. The flora as would be expected is restricted to bryophytes and stonefly, mayfly and caddisfly larvae typically dominate the invertebrate biology. The riparian zones are relatively natural.

7 Water body 2 Between Dromara and Magheralin the gradient becomes progressively gentler and the substrates here are dominated by sands and gravels, interspersed with cobble and boulder. In this zone higher plants begin to colonise marking not only changes in flow but evidencing a degree of enrichment due to the agricultural use of the surrounding lands. The invertebrate biology of this zone is distinct in that organisms such as snails and leeches coexist alongside more pollution sensitive organisms, which is the result of the mixed influences of flow regime and a degree of enrichment. The riparian strip is again relatively natural and continuous.

Water body 3 Between Magheralin and the outskirts of Belfast at Stranmillis Weir the river is deeper and slower being heavily impacted by historic drainage and has a role as a shared. This zone has a very low gradient. Finer particulate matter, deposited from erosion upstream dominates the substrate. The physical typology in this area is expressed in the macrophyte and macroinvertebrate assemblages recorded, as they are distinct from any other zone of the river. The former form extensive stands(see photograph), whereas the fauna is dominated by oligochaetes, leeches, snails, etc. The riparian area in this section is virtually absent.

Water body 4 This water body is defined by physical modifications (Stranmillis and Lagan Weir) and represents the transitional zone of the Lagan. The position of Stranmillis Weir marks the freshwater limits of the River and the Lagan Weir marks the boundary between estuarine and coastal waters under the Urban Waste Water Treatment Directive. Downstream of the Lagan Weir, salinities of >30 are the norm. This area is impounded in order to cover the unsightly, anoxic muds. The salinity regime is managed and hence variable. There is no riparian strip and the channel boundaries are completely artificial. This water body has been declared as a sensitive area under the Urban Waste Water Treatment Directive (2001). The main nutrient inputs to the area are from 2 major waste water treatment works and an industrial fertiliser plant in water body 5.

Water body 5 Water body 5 extends from the Lagan Weir to the end of the dredged channel in the approaches to Belfast Harbour. This water body is defined again by its physical alterations. The Port and Harbour area and extends from the Lagan Weir to the end of the dredged shipping channel in the approaches to the Port of Belfast. The area is characterised by engineered walls, docks, wharfs and reclaimed land. There are 3 major dredged channels; Victoria, Herdman and Musgrave Channels. The reclaimed land is the home for most of the heavy industry and in Northern Ireland; a ship building and repair yard, aircraft manufacturer and major fertilizer plant. As the major Port in Northern Ireland, the reclaimed land also houses many storage and distribution centres

8 including oil, coal, timber, grain, and animal feed. In addition to freight traffic, the Port of Belfast also has many passenger ferries including new generation high speed ships.. This water body has also been declared as a sensitive area under the Urban Waste Water Treatment Directive (2001).

Figure 5 – Water Bodies identified on the Lagan catchment

Figure 5 - Water Bodies identified on the Lagan catchment River Networks

Zo ne 1 - Uplan d Zo ne 2 - Mid dl e Reaches Zo ne 3a - F lo odplain Up stream Zo ne 3b - Floodplain Down sream, Zo ne 4 - Impoundment Zo ne 5 - Harbou r Area Lagan Cat ch ment 0 5 10 15 K il om etres

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Table 1 [Details on separate groups of water bodies]

Name of the Main pressures Main physical Water bodies Section page group of the group alterations of the of the group referring to numbers group the group Zone 1 Water body 1 Part II

Zone 2 Agriculture, Land drainage, Water body 2 Part II Flood defence weirs

Zone 3 Agriculture, Land drainage, Water body 3 Part II Flood defence weirs Zone 4 Urbanisation Weirs, walls Water body 4 Part II Zone 5 Navigation, Walls, dredging Water body 5 Part II Industrial land activity, heavy take, shipping activity urbanisation including high speed ferries

Figure 6 - Physical alterations to the River Lagan A map should be provided showing the water bodies relative to the modified characteristics. This section should include discussion of: · the main issues which were considered important in identifying the water bodies; · any problems experienced in identifying the water body;

9 · comments on the level of differentiation (minimum size of water body) which was considered appropriate. ]

4.4 Discussion and Conclusions

Many of the discussions in identifying water bodies were completed at a River Lagan workshop, 2001.

10 PART II

11 5 Physical Alterations (5 pages)

5.1 Pressures and Uses There are relatively few pressures on the River Lagan inflicted by the major users. The upper free flowing sections above Magheralin are an important recreational resource for game angling. Comparatively, the middle sections between Moira and Lisburn have little or no commercial value in terms of fishery, but the reinstatement of salmon into a number of tributaries such as the Ravernet, Glen and Minnow Burn have kindled a new angling impetus in the lower sections of the catchment. There is relatively little water abstraction from R Lagan, other than in the headwaters at Dree (this may now be defunct??) to augment the main supply from Fofanny WTP and to feed put and take fishery lakes downstream of Dromore. There are also abstarctions at Hilden and also above Dromore for hydropower but these have limited impacts. However, there are obvious pressures imposed by the fact that over half the population of Northern Ireland live and work in the Lagan valley. These pressures are primarily as a result of Waste Water Treatment effluent disposal, which although being, by and large, from modern treatment works, are discharged onto what is a modest size of river in a European context. Discharges from point sources from industries, such as creameries contribute to the pollution pressures imposed on the river, as well as diffuse inputs associated with agricultural activities in the catchment. Inevitably, the high concentration of people within the catchment, in a Northern Ireland context, generates its own pressures in terms of the effects of urbanisation, which include flood defence (flood protection is mainly at the towns Dromore, Donaghcloney , & Bulls Brookbank), flow management and run-off impacts which include storm overflows. Inevitably, these have a negative impact on legitimate recreational usage. In terms of physical and anthropogenic pressures in the R Lagan catchment, these can be artificially divided into two categories: historical and contemporary. Historically the river modification has resulted from water abstraction mainly associated with the linen industry, which has declined significantly since the 1950s and the influences of cuts for the canal that connected Lough Neagh with the port of Belfast. The linen industry has resulted in the construction of 10 major weirs in the freshwater section, which still result in discontinuity of flow, artificial flow regimes in specific sections of river, sediment mobility, barriers to migrating fish etc. More recent physical and anthropogenic pressures are associated with changes in the flow characteristics of the main river as a result of intensification of agricultural practice, urbanisation and demographic changes, particularly those that have occurred between Lisburn and Belfast. Inevitably, watercourse management practice and the resultant biological/ecological responses that result, also affect water chemistry. Physical pressures in the upper reaches of the River Lagan above Dromore are mainly confined to the consequences of disruption caused by the weirs at Dromara, Bulls Brook, Dromore, Blackskull, Donaghcloney, Ballymacaine, and Magheralin (Map?). However, there are some minor problems associated with periodic water abstraction at Dree in the torrential section of the river. The channel planform in the middle reaches of the river, between Moira and Lisburn, has been and continues to be defined by the influences of arterial drainage. Inevitably the U-shaped channel profile influences the flow characteristics in a region characterised by shallow contours. In turn, this leads to fine sediment deposition, which encourages infestation with rooted aquatic plants (see Photograph 1). Here agricultural land use is intensive by Northern Ireland standards. The main crops include cereal,

12 potatoes, carrots, cabbages and other vegetables stimulated by the widespread application of artificial fertilisers. The relics of the now disused navigation canal are also particularly evident in the sections of the River Lagan downstream of Lisburn. However, here the main pressures on the river are due to urbanisation resulting in extensive channel management as a means of flood defence, although there is little evidence of existing current channel management. The main channel management between Lisburn and Stranmillis is the protection of the tow path. The section of river between the Stranmillis and the new impoundment in central Belfast is little more than a concrete-sided channel. The salinity regime in this section of river is artificially managed, which in turn restricts the ecological potential. Major pressure on this stretch of the river is urbanisation i.e. combined sewer overflows into the impoundment. In addition, there are organic inputs from the freshwater stretch of the River, particularly in autumn with leaf fall. The decaying leave and combined sewer overflows result in organically enriched sediments in water body 4, which in turn have a high sediment oxygen demand. These sediments scavenge oxygen from the overlying water column and the problem is exacerbated by saline stratification, low flow conditions and in higher temperature conditions typical of summer periods. Despite the water quality pressures in this area of the River, this water body is used extensively for recreational purposes, in particular, rowing, canoeing and occasionally, water sports events. On the seaward side of the Lagan Weir, the area is typified by the heavy modifications of the Port of Belfast, and resultant commercial activities. Indeed, part of the outer harbour is reclaimed land resulting in anthropogenically influenced changes in current patterns in this area as well as periodic dredging. As with any intensively urbanised area, there are major problems associated with run- off, combined sewer overflows, WWTW discharges, consented industrial discharges and accidental pollution problems.

5.2 Physical Alterations

Although, there is some water abstraction in the upper reaches of the river, large sections would be regarded as being semi-natural to a point as far downriver as Magheralin. Within this section of river there are several weirs, which predictably influence the flow regime, encourage sediment deposition as well as encouraging significant levels of scouring during periods of precipitation as well as acting as physical barriers to migrating fish. Although some now have fish passes this programme is incomplete due to ownership issues. In the middle reaches between Moira and Lisburn the immediate catchment is intensively farmed. This is water body 3(a) which has been subdivided into 2 sections based on the nature of physical modification and management options. The channel in this section of river has a classical U-shaped profile and due to the low gradient of the river, flows are particularly slow through this flood plain. This is an area of periodic flooding which has little physical alteration carried out by the Rivers Agency for flood defence purposes. Sediment deposition is hence enhanced with the dominant substrate being sand and silt encouraging excessive growths of rooted macrophytes each summer (Photograph 1). This high level of biological activity is also expressed in sediment anaerobiosis. While sections of this part of the river have undoubtedly been

13 straightened, there is still evidence of the relic natural meanders, although some were removed by private land owners approximately 10 years ago. The impact of regular channel management is also evident in the riparian buffer strip, which is for the most part narrow and discontinuous, a situation that persists through much of the river’s remaining journey to the sea. Significant sections of the lower river between Lisburn and Belfast have been straightened and canalised as a relic of navigation and in order to prevent flooding in this predominantly urban area (this is water body 3b). The situation is also reflected in the heavy management of many of the feeder streams in order to enhance the flow characteristics as a means of flood prevention, rather than showing any concern for the natural status of these watercourses. There are still channel cuts throughout the lower river, which are relics of the navigation canal. While these have the potential for use as flood relief and may be the subject of restoration, during the summer periods they represent areas of stagnant water with the associated biological problems of infestation by duckweeds, sediment anaerobiosis, oxygen level fluctuation, pH swings etc. The current physical modifications in water body 4 are more recent with the Lagan Weir being brought into commission in November 1993. This stretch has long been associated with water quality problems and has had a number of weir structures over the years to attempt to compensate for the low dissolved oxygen, stratification and anoxic mud flats. The Lagan Weir was specifically designed to impound the tidal waters on the incoming tide to cover the unsightly and pungent anoxic mud flats, allowing the regeneration of the water front area of Belfast. From this perspective, it has certainly been a successful development. This stretch is heavily modified with largely armoured banks, and little or no intertidal or habitat diversity. A further physical alteration has been the installation of bubble diffusers at the time of the installation of the Weir. This was an attempt to break down saline stratification and also to directly input compressed air into the water column. The initial bubbler systems which transversed the river were riddled with problems. However, the experience has been used to install a much improved longitudinal line of bubblers up the River which are effective.

The physical changes in water body 5 have taken place over the last 150 years, since the development of Belfast as a trading centre. The Port infrastructure is essential for the economics of Northern Ireland. Downstream of the Lagan weir the waters of the harbour area are fully saline but the riparian area is strongly modified due to commercial development.

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5.3 Changes in the Hydromorphological Characteristics of the Water Bodies and Assessment of Resulting Impacts

The changes in hydromorphological characteristics are numerous and fully dependent on their location within the River Lagan catchment. For example, water abstraction up river of Dromara (water body 1) results in periodic pressure on the volume of water available to maintain flows in the more torrential sections. Inevitably this can result in some of the upper reaches being reduced to minor trickles during the Summer periods. The widespread presence of weirs can exacerbate this problem and additionally enhance deposition in areas of the river upstream during low flow periods. Conversely, they will contribute to erosion downstream during periods of high precipitation as well releasing higher than normal sediment loads under spate conditions. Further, they represent a physical barrier to fish migration into the upper reaches. The middle reaches act as a sink for these sediments as their deep sedate nature encourages deposition, which is expressed in terms of heavy macrophyte infestations throughout the Summer and early Autumn of each year as well a substrate anaerobiosis. In turn, these macrophyte growths act a physical barrier to water movement resulting in periodic flash flooding when heavy precipitation precedes die- back. The relic sections of the canal act as holding areas in which high levels of biological activity occur during the Summer periods as evidenced by the heavy surface growths of duckweeds and sediment gasing. During the colder wetter months, this biomass is transferred downstream to be deposited behind the major weirs in Belfast and within the Belfast Harbour area, contributing to enrichment of the sediments in these areas and the associated problems of dexygenation of the overlying waters during the warmer months when bacterial activity is high. The two impoundments at Stranmillis and the new Lagan weir strongly influence salinity levels behind the latter, inevitably resulting in a failure to optimise the biological potential of this section of river (water body 4). In the harbour area physical disturbance, due to boat traffic and maintenance dredging, influences the biological elements to a high degree (water body 5). Contemporary accounts described the flood plain reach of the Lagan between Lisburn and Moira as having been shallow, with a gravel or stony bottom, and meandering (water body 3a). This stretch was dramatically over-deepened and widened in a (1950s?) drainage scheme and is now too wide and deep to maintain any significant water flow under summer low flow conditions. Consequently its summer appearance is typically of a long narrow shallow pond, its surface several metres below field level, and choked with emergent vegetation. Under spate conditions, this stretch may be constrained by constrictions at road bridges and winter flooding still occurs on surrounding land. Very significant water quality problems occur, including low summer DO and high BOD levels. There are nevertheless fish present where there is open water, including eels trout, pike and roach. Salmon must somehow manage to pass upstream and downstream through this reach.

15 Flow control in the lower reaches is maintained at the freshwater limit by the Stranmillis weir beyond which the Lagan Weir artificially maintains the salinity regime. Under normal management regime tidal activity is restricted to rise and fall only above natural half tide level.

A secondary function of the Weir as a flood defence system during exceptionally high tides. Historically, many of the basements of City Centre buildings flooded in high tide conditions.

Water body 5 is essentially a coastal marine zone, with freshwater influence only under high river flows. It is very different from its ancestral state with encroachment of vertical dock walls . Very little remains of the original mudflat and saltmarsh habitats.

5.4 Discussion and Conclusions

Figure 6 – RHS sites on the Lagan catchment

Incomplete picture of historic river maintenance and current picture

[Discuss lessons learned, any problems encountered and how they were overcome.]

The physical and hydromorphological changes in water body 5 have taken place over the last 150 years and since the development of Belfast as a trading centre. The Port infrastructure is essential for the economics of Northern Ireland.

The current physical modifications in water body 4 are more recent with the Lagan Weir being brought into commission in November 1993. This stretch has long been associated with water quality problems and has had a number of weir structures over the years to attempt to compensate for the low dissolved oxygen, stratification and anoxic mud flats. The Lagan Weir was specifically designed impound the tidal waters on the incoming tide to cover the unsightly and pungent anoxic mud flats, allowing the regeneration of the water front area of Belfast. From this perspective, it has certainly been a successful development.

A secondary function of the Weir as a flood defence system during exceptionally high tides. Historically, many of the basements of City Centre buildings flooded in high tide conditions.

However, the Weir has not reduced the cause of the water quality problems in the impoundment. A £6billion project is currently being planned by the Water Service to upgrade the sewerage system of Belfast. This will dramatically reduce the volume

16 discharged from combined sewer overflows into impounded stretch of the Lagan and is expected to improve water quality in the longer term.

Bubble diffusers were installed at the time of installation of the Weir in an attempt to brreak down saline stratification and also to directly input compressed air into the water column. The initial bubbler systems which transversed the river were riddled with problems. However, the experience has been used to install a much improved longitudinal line of bubblers up the River which are effective.

17 6 Ecological Status (7 pages)

Monitoring in the River Lagan and its tributaries has been largely restricted to sanitary chemical determinants, including BOD, dissolved oxygen and ammonia, and benthic macroinvertebrates, on which national classifications have been based.

While information relating to fisheries and the macrophyte biology is available the study of these elements has been much less comprehensive and systematic. There has been little structured investigation of either the phytoplankton or phytobenthos of the river and its tributaries. What records exist for phytobenthos, are restricted to observations of nuisance growths of specific filamentous algae or heavy accumulations of diatoms.

6.1 Biological Quality Elements

In terms of water chemistry and invertebrate fauna the entire R Lagan shows evidence of degradation. At its best, it would be described as being “fair” quality with some reaches exhibiting somewhat more degraded conditions. Occasionally “good” quality status has been achieved but this tends to be both marginal and transient. Macroinvertebrates Figure 7

18 Figure 1 is a representation of the biological quality of the River Lagan and the Ravernet tributary in 2000 based on 3 season macroinvertebrate data and classification generated from RIVPACS III+ (Northern Ireland version). This classification is relatively typical for the river.

Figure 8

Reference to Figure 2 shows that, in terms of macroinvertebrate classifications for 2000, many of the feeder tributaries are showing evidence of pollution pressure that is not primarily a function of the hydromorphological characteristics of the river system. Rather, they are a reflection of the pollution pressures that affect the catchment.

However, when the underlying data are considered, there are clear impacts affecting specific sections of the main river that are undoubtedly a function of the physical rather than pollution pressures affecting the invertebrate biology.

Molluscs, leeches, midge larvae and oligochaetes dominate the invertebrate fauna of the middle sections of the River Lagan (water bodies 3a&b). These are acknowledged as being pollution tolerant. Less well represented are organisms that indicate that water quality conditions are satisfactory. It might be implied that this section of river is subject to some form of pollution stress. However, there are no obvious point inputs in this stretch of river that could account for the biological quality experienced. The more likely explanation relates to the depositing nature of this section of river that is strongly influenced by the mobilisation effects upstream that are exacerbated by presence of weirs. The high organic content of these sediments results in partial or total anaerobiosis, thereby restricting invertebrate colonisation or the river-bed throughout this section. In this instance biological potential appears to be restricted as a result of natural processes.

19 A second classic expression of hydromorphological limitations occurs between the Stranmillis and Lagan weirs (water body 4). Here the management of the salinity regime over a range between fully saline and freshwater domination inherently restricts biological colonisation

The tidal Lagan sediments are dominated by organic enrichment indicators such as oligochates, spionids and capitellids. The brackish nature of the water body is demonstrated by the presence of chironomids. Notably absent from the fauna are molluscs such as hydrobid mud snails, which may be indicative of the absence of a regular tidal regime and the extremely variable salinity regime. The absence of any bivalve mollusc may be indicative of the poor quality of the bed sediments.

Even within the Belfast Harbour area the restricted colonisation of the bed sediments by invertebrates is thought to be associated with the physical disruption of the habitat by boat traffic including high-speed ferries and frequent dredging. A typically estuarine fauna is to be found in some of the less disturbed sediments in quiescent areas within the harbour limits. The presence of epifauna such as soft corals, mussels and hydroids on hard structures such as pilings may be indicative of acceptable water quality. However more research would be needed to assess the extent and quality of such fauna before a robust quality statement could be made. Macrophytes

There are no European classifications for rivers based on macrophytes. Northern Ireland has trialed several including that proposed by Haslam (1987). This classification is illustrated in Figure 3. Figure 9 – Haslam Classifications for the River Lagan and Ravernet (1998)

Phytobenthos

20 It is obvious from the classification that the river is showing classic evidence of enrichment. However, it gives no real indication as to the scale of the rooted aquatic plant growths in the middle reaches of the Lagan between Moira and Lisburn. This is readily apparent from Photograph 1 below.

As with invertebrates the presence of these excessive plant growths are a direct consequence of this stretch of river acting as a sediment “sink”. It might be argued that this level of growth reflects the availability from point source upstream but the only known input is close to Magheralin and here the flora is very different (Photograph 2) and certainly much less extensive. Figure 10 - Excessive Rooted Plant Growths in Middle Sections of River Lagan

Figure 11 – River Lagan below Creamery at Magheralin

21 The obvious implication is that the macrophyte infestation observed in the middle sections of the river (Photograph 1) is due to problems higher in the catchment, that are linked to hydromorphological processes. Regular management drainage in these middle reaches to remove both the plants and the sediments in which they are rooted has done nothing to arrest these excessive growths of plant material. Excessive free floating plant material dominates the stagnant waters in the canal cuts. RA say that they do not maintain in this way, very little in the use of machinery in this section, forgot weed cutting, can we clarify?

A contrasting situation occurs in the section of river between Stranmillis and the new Lagan weir. Here plants have failed to colonise due to the vagaries of the salinity regime imposed by the management of this section of the river. Some small clumps of fucoids have been observed attached to pontoons just upstream of the Lagan weir demonstrating the potential for colonisation.

Even in the harbour area marine macroalgae have failed to colonise due to the influence of disturbance of commercial shipping and dredging despite abundant supplies of N and P. During the Littoral Survey of Northern Ireland (Wilkonson et al 1988) one site on the edge of the waterbody (of the Culloden Hotel) demonstrated a low algal species diversity. A total of 24 species, of which 50% were opportunistic green algae (OGA’s) were observed. For comparison purposes sites in outer Belfast Lough exhibit species diversity values in excess of 71. Freshwater inputs into the harbour are indicated by the tell tale presence of OGA’s.

Fish Fauna There are 17 Fish species known to be present in the freshwater and estuarine reaches of the river Lagan system including the river, its tributaries, lakes and ponds: Table 3 River Lamprey Lampetra fluviatilis Bream Abramis brama Brook Lamprey Lampetra planeri Gudgeon gobio gobio Eel anguilla anguilla Roach Rutilis rutilis Atlantic salmon Salmo salar Rudd Scardinius erythrophthalmus Brown and Sea Trout Salmo trutta Stone loach Neomacheilus barbatulus Pike Esox lucius Nine spined stickleback Pungitius pungitius Carp Cyprinus carpio Three spined stickleback Gasterosteus aculeatus Perch Perca fluviatilis Thick lipped mullet Chelon labrosus Flounder Platicthys flesus

It is worth noting that this list does not include Chub, Dace, Barbel or Grayling, species

22 not native to and historically absent from Ireland but which would occur in a similar river in England, Wales or Southern Scotland. (Does not mean, perhaps suggests)This means that the faster flowing deeper riffles and glides of the River Lagan can contain mainly brown trout with some stone loach and gudgeon.

Water Quality and Fish Fish kills occur regularly in the upper reaches of the river and in tributaries, killing mainly brown trout, salmon fry and stone loach. Silage effluent is probably the single largest cause of fish kills but there have also been industrial accidental spills and failures in overloaded sewage works in recent years. The extent of weed and algal growth in the river points to a very significant diffuse load of organic matter and nutrients. It is not unusual for summer electrofishing to find no salmon or trout fry in physically suitable habitats, implying that some pollution incidents may go undetected. Some smaller tributary streams have been consistently almost fishless in recent years.

Fish Habitats for Salmonids There are significant areas of potential salmonid juvenile habitat in the upper Lagan and the Kinallen/Waringsford, Ravernet, Collin and Minnowburn tributaries (water bodies 1&2). However, good clean gravel spawning areas are limited, due to highly silted gravels and a history of extraction of gravel from the river by official and unofficial and drainage works. Drainage maintenance activities and small scale unofficial drainage works continue to occur on a damaging scale, particularly in streams through farmland. There is considerable potential for physical restoration works. The Lower river from Lisburn to Belfast (water body 3b) also contains significant areas of fast flowing shallow water with pool-riffle sequences, but only where the 1700s canal construction left loops of the main river intact and bypassed by the canal. Even where the navigation used the river itself, weirs merely flooded out some areas of faster flow and, now that the navigation has become derelict, some of these are re-forming pool-riffle sequences. A good example exists downstream of the Red Bridge, Newforge. Throughout the river there is considerable scope for fishery habitat restoration by removal of redundant weirs formerly associated with linen or other mills, without affecting future Navigation restoration plans.

Because of the absence of cyprinid fishes typical of moderately fast flowing lowland rivers elsewhere (See above – no chub, dace, barbel or grayling in Ireland), the best fishery use available of much of the Lower Lagan is likely to be as salmon and trout habitat.

Coarse Fish Habitats Good coarse fish habitats are very limited, even in low gradient areas, due to the river

23 being a relatively restricted channel with high winter flows and without any significant marginal refuges for coarse fish in high flows. Some refuges exist in the former canal stretches between Belfast and Lisburn (water body 3b) but these are often not contiguous with the main river channel. There are no lakes on the main channel of the river. The remaining flooded reaches of the former Lagan canal support some coarse fish, particularly the stretch from the river to Lough Neagh and the Broadwater reservoir. It is probably unrealistic to expect a significant high value coarse fishery on the river.

Fisheries

The main angling interest in the Lagan catchment are centred on the upper reaches above Magheralin(water body 2) and in the lower river sections 9water body 3b) and the associated tributaries. The upper reaches are used for trout angling. In contrast the interest in the lower reaches is limited to salmon fishing following the reinstatement in a number of tributaries. Salmon fishing in the upper river is non-existent due to the barriers posed by weirs without fish passes.

The middle sections appear to attract little fisheries interest. While this may be due to the macrophyte problems the absence of winter anglers indicates low fishery potential. If this is the case, it is due to the same problems that influence the macroinvertebrate fauna and the macrophytes.

Despite the poor oxygen conditions in water body 4, migratory fish have been able to make passage through the impounded stretch. Fish present are what might be expected in this condition – a limited population of estuarine flounder, eels, sea trout and salmon on passage, and grey mullet in summer. Some freshwater fish (brown trout, bream) are resident in a short reach immediately downstream of Stranmillis weir. Marine Fish Population

The local fish population in Water Body 5 has been the subject of a long term investigation using the fish impinged on the intake screens of Belfast West power station which is located in the Herdman Channel, a side channel within the docks complex. This investigation commenced in 1989 and the analysis of data from 1990 to 2000 shows that of the 54 species of fish recorded by this programme in Belfast Lough as a whole 37 have been recorded from Water Body 5 at Belfast West.

Of the fish species caught at Belfast West in Water Body 5, 9 species have been identified as Estuarine Resident under the system of classifying fish assemblages based on their estuarine usage. This system takes into account the nature of reproduction, feeding, and spatial and temporal usage of an area.

Table 4

Estuarine Resident species

Worm pipefish, Nerophis lumbriciformis Rock goby, Gobius paganellus

Greater pipefish, Syngnathus acus Common goby, Pomatoschistus microps

24 Short spined sea scorpion, Myxocephalus Sand goby, Pomatoschistus minutus scorpius

Pogge, Agonus cataphractus Flounder, Platichthys flesus

Butterfish, Pholis gunnellus

Diadromous Species (Catadromous or Anadromous)

Sea lamprey, Petromyzon marinus Salmon, Samo salar

Common eel, Anguilla anguilla Three spined stickleback, Gasterosteus aculeatus The list of estuarine resident and diadromous species found in Water Body 5 at Belfast West Power Station.

In addition to the estuarine resident species there are also four species which are classsified as diadromous. These are predominantly migrant species which use the estuary to pass between salt and fresh waters for spawning and feeding. Small numbers of salmon have been caught in the Outer Lough at Kilroot and at Belfast West and there is evidence of occasional adult fish returning to Belfast Lough which have been caught at the power stations. The three spined stickleback is a species which generally occurs in estuaries and a variety of freshwater habitats. Changes in salinity are of lesser importance than levels of dissolved oxygen and is therefore absent from badly polluted rivers and estuaries.

Of the estuarine resident species listed above, flounder have been recorded in Water Body 4 whilst of the diadromous species common eel and salmon have also been recorded (see Table Ref ).

Of the species discussed above it is believed that all could inhabit Water Body 4 especially the lower reaches in the vicinity of the weir.

Phytoplankton

. During the 1990’s extensive phytoplankton surveys were conducted by IRTU/EHS. The salinity regime between Stranmillis and the new Lagan weir is variable and this part of the system is prone to stratification. Adventitious algal species have been frequently recorded in considerable numbers along the halocline. However exact study of algal bloom development was impossible due to the erratic flushing of the impounded waters. Between 1999 and 2001 47 species have been recorded. The species diversity and variabilty observed reflects the highly dynamic nature of the hydraulic regime. Some nuisance species have been identified within the Lagan between 1999 and 2001. These species include Chaetoceros sp., Pseudonitzschia sp., certain Dinophysis sp. and, Skeletonema sp which are known to be related to such effects as fish gill clogging, amnesic and Diarrhetic shellfish poisoning and anoxic conditions respectively. At present the abundance of these species are negligible so are of little concern, but have potential to be problematic given a change in environmental conditions.

25 Toxicity is exacerbated by eutrophic conditions with high N:P ratios, evident particularly in species known to cause paralytic shellfish poisoning. This becomes of increasing concern where phosphate levels in detergents are decreased with increasing nitrogen levels discharged from modern waste water treatment works, effectively causing a positive impact on toxicity. Phytobenthos

There has been no systematic study of phytobenthos in the Lagan system. However, growths of the blanket weed, Cladophora agg. are not an uncommon feature of the shallower sections of the river particularly close to discharge points from WWTWs.

Shortfalls in existing information

From the foregoing there are a number of obvious gaps in the scientific information available not least of which is the whole issue of sediment transfer in the context of the hydromorphology of the system as a unit.

There needs to be more detailed study of the phytoplankton and phytobenthos elements in the context of the Water Framework Directive.

Fisheries data are incomplete.

Proposals for additional measurements

Monitoring of rivers in Northern Ireland has essentially followed the UK model and in this respect the Lagan catchment has been better studied than most. Indeed, the use of macrophytes as an ecological assessment tool is arguably much more developed in Northern Ireland than elsewhere.

There are shortfalls in the use of all the biological elements included in Annex V of the Directive and these presumably will be addressed through Common Strategy. None of these shortfalls are specifically unique to the River Lagan.

26

6.2 Physico-Chemical Elements

There are a number of examples where the physical alterations affect the supporting physico-chemical elements. These include: (i) Fluctuations in the oxygen regime in the middle reaches as a result of plant photosynthesis and respiration processes as well as bed sediment oxygen demand that have been linked to sediment deposition (see above) and the morphological characteristics of this section of river; (ii) The presence of stagnant water in the canalised sections is problematical for very obvious reasons; (iii) Salinity fluctuation in the Stranmillis/new Lagan weir section with associated variable depth halocline These examples are primarily driven by changes to the hydromorphological regime in the river rather than pollution per se.? ; Although the changes in hydormorphic regime in the impoundment and harbour area have created sediment oxygen demand problems, this situation is exaccerbated by serious anthropogenic pressures such as CSOs, WWTWs and industrial discharges.

Parallel investigations of biota and physicochemical studies have been conducted into the water quality of the Tidal River Lagan since 1990 and as part of this programme there is an extensive set of water quality data for the impounded reach. Of particular interest to fisheries management is the data on dissolved oxygen levels especially in recent years since 1998 when continuous recording dissolved oxygen senors were deployed for week long periods throughout the year. This data indicates that there are considerable problems with Figure 12

King's Bridge. Depth averaged dissolved oxygen 4/8/98-10/8/98

10

9

8

7

6 D.A. values 2 mg/l limit 5 4 mg/l limit

D.O. (mg/l) 4 6 mg/l limit

3

2

1

0 11:21:57 23:21:57 11:21:57 23:21:57 11:21:57 23:21:57 11:21:57 23:21:57 11:21:57 23:21:57 11:21:57 23:21:57 11:21:57 04/08/98 04/08/98 05/08/98 05/08/98 06/08/98 06/08/98 07/08/98 07/08/98 08/08/98 08/08/98 09/08/98 09/08/98 10/08/98

27

dissolved oxygen levels in the impounded reach (Water Body 4) especially during the summer months. At this stage it is difficult to state with any degree of certainty what the expected duration of these events are or to what extent they exist throughout the entire length of water body 4 at any one time. There is, however, sufficient evidence to suggest that such low levels could cause problems for migratory fish such as salmonids.

6.3 Definition of Current Ecological Status

To date ecological status has been defined using national classifications based on chemistry and invertebrates. No attempt has yet been made to define ecological status using all elements. The influence of anthropogenic changes to hydromorphology has been the result of several research and monitoring programmes mostly interpreted using expert judgement, but also utilising the classifications that are currently accepted nationally and others that would be considered as being potentially developmental. The approach is not ideal and will require modification based on the tools that are developed through the Common Strategy approach. This must inevitably take into account the most appropriate elements specific to the Lagan and must be within the context of reference condition typology and the unique nature of the Irish flora and fauna.

All water bodies (1-5) would appear to fail the objective of good ecological status based on current information and classification systems. However it is more difficult to determine if this is due to pollution inputs or physical pressures. It is likely that the status of water bodies 1&2 is dependant on pollution pressures rather than those caused by physical modification. Water bodies 3(a&b), moderate/poor status as a result of significant physical modification and will be subject to the HMWB designation tests. Water body 4 is generally classified as unsatisfactory or seriously polluted under the Northern Ireland Estuary classification scheme. The stretch immediately upstream of the Weir is of good quality. The failure to meet good status is primarily due to low dissolved oxygen concentrations and contaminated sediments. Water body 5 is seriously polluted under the Northern Ireland Coastal Waters classification scheme. This is primarily due to the presence of contaminated sediments. Both of these areas will be subject to the HMWB designation status.

28 6.4 Discussion and Conclusions

Shortfalls in existing information

From the foregoing there are a number of obvious gaps in the scientific information available not least of which is the whole issue of sediment transfer in the context of the hydromorphology of the system as a unit.

There needs to be more detailed study of the phytoplankton and phytobenthos elements in the context of the Water Framework Directive.

Fisheries data are incomplete.

Proposals for additional measurements

Monitoring of rivers in Northern Ireland has essentially followed the UK model and in this respect the Lagan catchment has been better studied than most. Indeed, the use of macrophytes as an ecological assessment tool is arguably much more developed in Northern Ireland than elsewhere.

There are shortfalls in the use of all the biological elements included in Annex V of the Directive and these presumably will be addressed through Common Strategy. None of these shortfalls are specifically unique to the River Lagan.

Sampling of fish in Water Body 4 and 5

As already indicated sampling in Water Body 5 at Belfast West Power Station has been part of a long term monitoring programme since 1989. In March 2002, Belfast West is due for closure and this will effectively cease routine sampling in this part of Inner Belfast Lough.

No routine fish sampling by EHS or its agencies has taken place in Water Body 4 and this has broadly reflected operational interests as well as technical difficulties. Being placed in a mainly urban setting access to the impounded stretch has until recent years proved difficult for a vessel of sufficent size to undertake the trawling necessary. In addition, the nature of the soft muds found throughout the impounded reach, together with the amount of debris generated as a by-product of its urban setting has discouraged the use of conventional beam trawling equipment, which has been used successfully in the remaining transitional waters.

Fyke netting which is a sedentary trap net is planned for water body 4 later in 2002 which will demonstrate its potential for use in this area and provide some additional evidence of existing fish species.

29 7.Identification and Designation of Water Bodies as Heavily Modified

7.1 Necessary Hydromorphological Changes to Achieve Good Ecological Status

A series of measures have been proposed in the tables below. These are split into measures in response to problems associated with;

· Weirs and blockages to continuity/ fish passage

· Changes to natural hydrological Regime

· Physical alteration to habitat

Changes to land use /planning

(see table 5)

The measures identified to deal with problems within the reaches have been assessed using an appraisal framework developed specifically for the assessment of Heavily Modified Water Bodies. This framework is in the form of a series of proformas, developed as part of the Heavily Modified Water Bodies project for the Environment Agency and Department for Environment, Food and Rural Affairs (DEFRA). This methodology has then been applied to the Northern Ireland case study, the River Lagan.

The proformas are split into two levels of assessment:

1) a screening stage where those measures that would have significant adverse effect on the intended uses, are not technically feasible or are clearly disproportionately costly are screened out. Such measures are assumed to fail either of the two tests, as given in Article 4.3(a) (for significant adverse effects) and Article 4.3(b) (for technical feasibility and disproportionately costly) of the Water Framework Directive; and

2) a detailed assessment methodology where those measures which have not been screened out are then considered in greater depth. This includes costing of the measures and comparison of these costs with a range of potential benefits. Thus, the more detailed part of the assessment takes the form of a cost-benefit analysis. There is also provision, however, for those impacts which cannot be expressed in monetary terms to be given a qualitative ‘rating’ of the relative size of impacts. This approach helps to ensure that the methodology is applied consistently and reduces the potential for a decision to be made on the quantified impacts only.

30 Full sets of completed proformas for the Lagan are given in Annex #. This section summarises the findings of the assessment and highlights points of particular interest that arose during the assessment.

Table 7.1 summarises the hydromorphological changes that are considered necessary to achieve good ecological status for the four water bodies that are affected by modifications. Water Bodies 1 and 2 are excluded from the HMWBs assessment as ecological status in these two reaches is most likely dependant on pollution pressures rather than physical modification (see Section 6.3). The changes shown in Table 7.1 are those that have been assessed in Proforma 1.

Proforma 1 is used to undertake Test 4.3(a) (would restoration have a significant averse effect on uses?). Therefore, it is necessary to describe (i) the modification and intended uses and (ii) to describe the impacts of restoration on the intended uses. These impacts are then rated as being ‘small’, ‘moderate’ or ‘large’. The decision as to the significance of any impacts is based on judgement, although guidance is available to help with this decision. Wider impacts also need to be described, covering all other impacts of the restoration measure. These include the positive (ecological) impacts of moving to good ecological status as well as any other impacts (positive or negative). The assessment for Water Body 4 (new Lagan Weir to Stranmillis), for example, discusses wider impacts from contamination moving upstream from the docks or combined sewer overflows (CSOs).

31 Table 5 Summary of Hydromorphological Changes Required to Achieve GES

Water Body

4 3b 5 3a Stranmillis to Lisburn to Seward side of Magheralin to Lisburn new Lagan Stranmillis new Lagan Weir Weir

Remove weirs, replace Remove weirs, take Remove weirs, Remove developed current road bridges with out straightened soften banks, area including single span bridges, restore sections and leave raise river bed harbour sewage straightened sections and river to reform pools and make river works, airport, make the channel narrower, and riffles (as is channel narrower motorway and create a buffer strip happening in river bridge/road; stop alongside the realigned already) dredging stretches of the river, in which trees are planted to shade the river during summer

The next step is to determine the significance of these wider impacts (‘small’, ‘moderate’ or ‘large’). This then allows a judgement to be made as to whether the restoration measure is considered to have significant adverse effect. In order to conclude ‘yes’ (i.e. the measure would have significant adverse effect), it needs to be obvious that this is the case. Where it is not obvious, the response is ‘unsure’ and the measure is taken forward for more detailed assessment.

The Lagan assessment shows that the restoration measures for Water Bodies 4 and 5 are both considered to have significant adverse effects. For both reaches, this is a clear cut decision as there would be large impacts on the intended use plus large impacts on other (indirect) uses. For Water Bodies 3a and 3b, it is ‘unsure’ whether the restoration measures would have significant adverse effect and more detailed assessment is required.

7.2 Assessment of Other Environmental Options

The restoration measures are not the only way to achieve good ecological status. Where the restoration measures are considered to have significant adverse effect on the intended uses (or where the assessment in Proforma 1 is ‘unsure’), it is necessary to consider significantly better environmental options that would minimise impact on the intended use. Such measures are described in Proforma 2, where they are also tested for technical feasibility. All feasible measures are then taken forward to Proforma 3 for

32 assessment against Test 4.3(b) – are there alternatives that would not be disproportionately costly?

Table 7.2 presents the significantly better environmental options considered in Proforma 2. All of the measures are considered to be technically feasible and are, therefore, taken forward to Proforma 3.

The assessment carried out in Proforma 3 is designed to screen out those measures that are clearly disproportionately costly. This decision is based on three criteria:

· the operating and maintenance costs of the existing modification (effectively the baseline costs);

· the capital, and operating and maintenance costs of the alternative measures; and

· a description of potential environmental benefits.

33 Table 6 Summary of Significantly Better Environmental Options

Water Body

4 5 3a 3b Stranmillis to Seward side of Magheralin to Lisburn Lisburn to Stranmillis new Lagan new Lagan Weir Weir

Remove weirs but leave Remove weirs but leave Build new canal Floating harbour straightened sections and in straightened sections; and sea lock (to replace bridges allow river to reform pools docks); airport and riffles naturally and other Provide new infrastructure to (Re)-introduction of river rowing course relocate features to increase the Remove weirs but leave diversity of habitats, including in straightened sections; bed, bank and floodplain allow river to reform pools habitats and riffles naturally

Raise bed levels locally Add fish passes to weirs – various types possible:

- cascade/ladder to Add fish passes to weirs, similar dimensions to various types possible: existing weir

- cascade/ladder to similar - elongated cascade dimensions to existing weir system

- elongated cascade system - constructing by-passes - constructing by-passes

Re-profile banks to Creation of buffer strip to help improve diversity of bank reduce levels of nutrients habitats reaching river

The Proforma 3 assessment for Water Bodies 4 shows that the current modification (impoundment) is considered to have operating and maintenance costs of less than £1 million (less than €1.6 million). These costs have been discounted over 30 years at 6%. The costs of the two significantly better environmental options (‘build a new canal and sea lock’ and ‘provide a new rowing course’) are both expected to have costs in excess €16 million). There are also significant constraints on achieving good ecological status due to the potential for contaminated sediments and water from the docks area to move upstream into the currently impounded area should

34 Lagan Weir be removed.

A summary of all measures assessed to date is then made, with Proforma 4 identifying which measures are considered as having ‘unsure’ impacts on intended uses (Test 4.3(a) – from proforma 1) or where it was ‘unsure’ if the measures were disproportionately costly’ (Test 4.3(b) – from Proforma 3). These measures are taken forward to more detailed assessment. Measures where it was clear that significant adverse impacts would occur or which are obviously disproportionately costly are dropped from the assessment. These measures are recorded in Proforma 5 for completeness.

7.3 Designation of Heavily Modified Water Bodies

The assessments for Water Bodies 3a and 3b show that all measures are carried forward for more detailed assessment. This is in contrast to Water Bodies 4 and 5, where there are no measures to be carried forward. This means that Water Bodies 4 and 5 should be designated as ‘heavily modified’, as all potential measures for improving ecological status fail either Test 4.3(a) or Test 4.3(b). A reason for dropping the measures is also recorded in Proforma 5, as justification is needed in order to designate a reach. For Water Bodies 3a and 3b, it is not possible to make a decision at this point in the assessment on whether to designate or not. This is because it is very difficult to determine whether the measures are disproportionately costly or not based on the assessments undertaken to this point. This happens because the measures being considered have potential environmental (and other) benefits which may outweigh some, or all, of the costs.

The assessment methodology, therefore, moves onto a more detailed estimation of the costs and benefits. An overview of the capital and operating works that would be required to implement the measure is given in Proforma 6. This information forms the basis for costing of the capital works in Proforma 7 and the operating works in Proforma 8. All costs are estimated in present value (PV) terms (i.e. discounted over 30 years at a discount rate of 6%). Proforma 9 brings all of the discounted costs together and compares them with the costs of maintaining the current modification (to give net costs in Present Value terms). For example, Table 7.3 provides the total net PV costs of implementing the five measures carried forward into the more detailed assessment in Water Body 3a.

Table 7Present Value Costs of Measures for Water Body 3a (see also Annex #)

Measure Net Costs (in PV)

35 Current modification: Drainage and land take for agriculture Capital £0 (straightening and widening of channel); weirs for linen industry Operating £110,000 (now not required); road bridges (elevated river beds levels); dredging to remove sediments that have accumulated behind Total1 £110,000 weirs

Remove weirs, replace current road bridges with single span Capital £880,000 bridges, restore straightened sections and make the channel Operating -£63,000 narrower, and create a buffer strip alongside the realigned stretches of the river, in which trees are planted to shade the Total1 £820,000 river during summer

Capital £16,000

Remove weirs but leave straightened sections and bridges Operating -£110,000

Total1 -£90,000

Capital £1,000,000 (Re)-introduction of river features to increase the diversity of Operating -£54,000 habitats, including bed, bank and floodplain habitats Total1 £950,000

Capital £72,000

Raise bed levels locally Operating -£51,000

Total1 £20,000

Add fish passes to weirs – various types possible: Capital £119,000

- cascade/ladder to similar dimensions to existing weir Operating £450

- elongated cascade system Total1 £120,000 - constructing by-passes

The next stage of the detailed assessment is to compare the cost-effectiveness of each measure in terms of the cost per kilometre of good ecological status that is delivered. The aim of this step (given as Proforma 10) is to screen out those measures that provide the same (or a lower) level of benefits as other measures, but at a higher cost. Where the cost-effectiveness of measures is similar, these are carried forward into Proforma 11.

Proforma 11 is the main part of the detailed assessment. It involves considering the impacts (positive and negative) on a wide range of categories, including the environment, recreational use of the river, priced uses of water from the river, the wider environment (including archaeology, heritage and landscape), economic considerations, social considerations and the extent to which the measure fits in with other policies (national, regional and local). The aim of Proforma 11 is to allow the benefits of the measure, plus any additional costs not included in the net PV (capital and

36 operating) costs associated with implementing the measure to be estimated. This then means that the decision as to whether a measure is considered disproportionately costly (or not) is based on as much information as possible.

For this case study, four measures have been assessed using Proforma 11 (two for Water Body 3a and two for Water Body 3b). Information on the baseline and potential impacts has been obtained through consultation with the Environment and Heritage Service (EHS), Rivers Agency and Department of Agriculture – Northern Ireland (DANI). A number of reports have also been used including WS Atkins (1997): Lagan Catchment Draft Water Quality Management Strategy.

For Water Body 3b, both measures are expected to have greater quantified PV benefits than net PV costs, suggesting that the measure(s) are worthwhile from an economic viewpoint. The key question with these measures is which measure to implement. It is possible to use economic decision-making criteria to help. This includes net present value and incremental benefit-cost ratio. The results of using these decision-making criteria are shown in Table 7.4.

Table 8 Use of Economic Decision-Making Criteria to Select the ‘Best’ Measure for Water Body 3b

Measure

Remove weirs, take out straightened sections and Remove weirs but leave in Criteria leave river to reform pools straightened sections; allow and riffles river to reform pools and (as is happening in river riffles naturally already)

Net PV cost of measure -£30,000 -£100,000

PV benefits of measure £900,000 £540,000

Net present value £930,000 £640,000

Incremental benefit-cost 4.1 N/a ratio

Notes: PV benefits of measure takes the lower end of the range given in Proforma 11, in Annex #

- net present value is calculated by subtracting net PV costs from PV benefits

- incremental benefit-cost ratio is calculated by taking the difference in benefits of the two measures and dividing by the difference in costs of the two measures – therefore, it can only be estimated for the most expensive measure

37 As a guide, flood defence appraisals in England require positive net Present Value (i.e. benefits greater than costs), and incremental benefit-cost ratio of 3 to move to the more beneficial measure. This indicates, therefore, that (based on quantified benefits and costs only) the more expensive measure may be preferred. However, there are also significant qualitative benefits that must be taken into account when making a decision. These are summarised in Table 7.5.

Table 7.5 shows that the more expensive measure is expected to generate large benefits for the environment, compared with moderate benefits from the least expensive measure. However, the more expensive measure could also result in significant costs to heritage (although these impacts can be mitigated by careful design of the measure and avoiding impacting on important heritage features such as the canal towpath, or World War II quay at Belvoir). Only the more expensive measure is expected to generate any landscape/townscape benefits.

Table 9 Qualitative Benefits and Costs Associated with the Measures for Water Body 3b

Measure

Remove weirs, take out Remove weirs but leave in straightened sections and Category straightened sections; allow leave river to reform pools river to reform pools and and riffles (as is happening in riffles naturally river already)

Net PV cost of measure -£30,000 -£100,000

Water-related environment Large benefit impact Moderate benefit

Heritage Moderate adverse impact Neutral

Landscape and Moderate beneficial impact Neutral geomorphology

Townscape Slight beneficial impact Neutral

Notes: categories taken from Proforma 11 – ratings given above follow approach set out in the guidelines that have been developed for use when undertaking an assessment

As the measures for Water Body 3b are not considered disproportionately costly, it is recommended that the river is not designated as heavily modified, but that action can be taken to improve the ecological status of the river.

For Water Body 3a, the measures are expected to be much more expensive to

38 implement and the PV benefits are also much lower (mainly due to a lack of access to the river for recreation). However, the environmental benefits are potentially very significant (rated as ‘very large benefit’ for one of the measures). This highlights an important consideration in terms of determining whether a measure which has lower PV benefits than costs but which would bring about significant other (non-quantified) benefits should be considered disproportionately costly, or not. It may also be possible to consider a phased approach, whereby the modifications considered to have the greatest impact on ecological status are undertaken first (even if this does not bring about good ecological status straight away). This may mean that further assessment of measures is required, which considers each part of a measure and the particular benefits that it may deliver. It is unlikely that such assessments could be valued in monetary terms as the differences between the small improvements made by each ‘part’ of the measure may be too similar to be represented by economic valuations. Hence, it may be necessary to develop an alternative system that can be used to assess marginal changes/improvements.

It may also be possible to consider how the net PV costs of the measure could be reduced, for example, by combining the measure with agri-environment schemes through the Countryside Management Division to encourage uptake by landowners. This could be particularly important where buffer strips are to be included as part of the measure. Such schemes may not always result in the full benefits that could be gained if the land was actively managed for conservation purposes, but could lead to cost- effective small scale benefits which, over a large area, may lead to significant improvements to ecological status in the river within the water body.

7.4 Discussion and Conclusions

[Discuss lessons learned, any problems encountered and how they were overcome

39 Table 10 – Problems and proposed range of measure to achieve Good Ecological Status on the Lagan catchment

Perceived Water Hydromorphological Benefits Associated Other Comments Proposed measures problem Body quality elements to costs ecology

Weirs and · Replacement with 3a / 3b River Continuum If Lagan Canal opens blockages to cascade/ladder to similar there will be a continuity/ dimensions, thus retaining water requirement to fish passage depths and gradients overall. ensure the maintenance of · Replacement with elongated passage for fish. cascade system – would extend gradient over a longer reach.

· Removal of weirs leading to Some rehabilitation changes in water depths & measures may gradients (would require directly impact on modelling to ascertain change in the existing value of flood risk & drainage regime) habitats e.g. removal of weirs. · By passing of weirs – construction of new salmonid – friendly channel or fish pass. Perceived Water Hydromorphological Benefits Associated Other Comments Proposed measures problem Body quality elements to costs ecology

Changes to natural hydrological Regime All

Floodplain · Manage location, extent and Hydrological does not act duration of flooding. regime/Morphological as a sediment conditions sink

loading into Hydrological regime · Installation of Sustainable urban watercourse drainage systems (SUDS)

2 Perceived Water Hydromorphological Benefits Associated Other Comments Proposed measures problem Body quality elements to costs ecology

Physical alteration to habitat · Some rehab Bed level in to measures may low. directly impact Bank profiles · Raise bed levels locally as 3a / 3b Morphological conditions on the existing steep and indicated by fluvial assessment- value of habitats regular (needs to be sustainable) e.g. removal of weirs. Buffer Lack of · Reprofile locally as indicated by Morphological conditions zones as gradient in flurial assessment-(must be correctors zone 3. sustainable) 3a / 3b · Modelling Lack of water · Recreation or artificial creation of exercise would features sustainable features & their Morphological conditions be required associated subsequent management 3a / 3b with the river · Restoration of the fishery habitat · Consider as i.e. ponds & of this reach would be possible if floodplain habitat oxbows a narrow summer flow channel rather than Morphological conditions could be established within a fishery habitat- wider channel capable of manage carrying flood flows. accordingly for wetland habitats.

3 Perceived Water Hydromorphological Benefits Associated Other Comments Proposed measures problem Body quality elements to costs ecology

Changes to land use /planning All Lack of low intensity · Creation of buffer strips/planting/carr riparian land Link with N.I targets use · Link with established delivery to determine Past loss of mechanise catchment targets B.A.P Assessment required to produce a Lack of information wetland water level management plan. on required water habitats & levels for specific species wetland habitats

4 8 Definition of Maximum Ecological Potential (6 pages)

[Please discuss, to the extent possible at this stage, the maximum ecological potential (MEP) of the water body that is achievable (see WFD Annex II, 1.3 "Establishment of Type-Specific Reference Conditions for Surface Water Body Types", with reference to WFD Annex V, Table 1.2.5 "Definitions for Maximum, Good and Moderate Ecological Potential for Heavily Modified or Artificial Water Bodies" giving the normative definitions of ecological potential). Identify any areas requiring further clarification.]

8.1 Determining Maximum Ecological Potential

It is difficult to make a judgement on the ecological potential of this water course as most of the modification have been long term. However, the following is a discussion of possile ecological potential

In the freshwater sections of the River Lagan (Zones 3a and 3b) the Maximum Ecological Potential is that for a medium sized, moderately deep, alkaline river as defined in the WFD Annex V, Table 1.2.5. However, in accepting this definition it ignores the significant hydraulic impact associated with the weirs, absence of a natural riparian buffer strip and canalisation due to management. It is difficult to quantify the effects of these physical limitations in terms of their biological consequences for the flora and fauna of the river. In this respect the WFD definition is perhaps, unhelpful in its current wording. Advice needs to be given as to the effects of the modifications and how these can be meaningfully and consistently estimated and interpreted.

In the context of the Lagan the flora and fauna can be compared directly with high quality reaches that are hydromorphologically similar. It is unlikely to be the case in other HMWB in mainland Europe. Pollution pressures from a variety of sources further confound the effects of modification and this is particularly evident in the Lagan case study.

In the specific instance of the River Lagan it might be argued that the flow regime and general hydromorphological characteristics correspond to conditions elsewhere (see 8.3) but this ignores the level fluctuations that are a consequence of the weir impondments under high and low flows.

In accordance with Annex II clause 1.3 (iii) type specific reference conditions can be either spatially based or based on models, or may be derived using a combination of the methods. Where this is not possible expert judgement may be used. In the context of the proposed heavily modified sections of the mid- and lower sections of the River Lagan it is proposed to use all three approaches in defining Maximum Ecological Potential.

Data for benthic macroinvertebrates and macrophytes are available for the River Lagan below Magheralin and into the saline reaches (Zones 3a and 3b), which can underpin the current status of the system. Using the UK River Invertebrate Prediction and Classification system (RIVPACS) it is possible to generate predicted invertebrate assemblages for the freshwater sections using hydromorphological data (see Table ** in 8.3) if the individual reaches were in their natural state (Appendix 1, Armitage et al, 1983). The level of deviation can hence be quantified objectively even if it is not possible to estimate the proportion of these differences that are the direct result of the modifications.

Comparisons can be made with the flora and fauna of rivers of similar typologies in other parts of Northern Ireland although ideally this should be augmented using data for similar rivers in other parts of the ecoregion. These approaches are elaborated in the following section

Benthic infauna

Water body 4 – This stretch is dominated by organic enrichment indicators such as oligochates, spionids and capitellids and chironomids. A reduction in organic enrichment may result in a reduction in the abundance and biomass of opportunists accompanied by a moderate increase in diversity. An improvement in water quality may result in some colonisation of bivalve molluscs, particularly in the higher salinity part of the impoundment closer to the Lagan Weir.

Water body 5 – Improvements in water quality in this water body would also be associated with an increase in diversity and a reduction in the abundance and biomass of opportunists. These changes would be expected in the areas which are not as vulnerable to the constant physical disturbances of the high speed ferries, such as the epifauna species on hard structures and in the benthic infauna in the more quiescent areas.

Macrophytes

The main limiting factor on the settlement of macrophytes in this stretch of the River is the vagaries of the salinity regime imposed by the management of this section of the river. It is difficult to see how macrophytes could be used as a robust measure of ecological potential.

The situation is similar in the inner harbour area. However, in the outer harbour area, water quality improvements should result in a higher algal sepcies diversity and a

2 reduction in the occurrence of opportunistic green algae and a more similar flora to that of outer Belfast Lough.

Fish Water body 4 – Without the physical structure of the Lagan Weir, a fish population similar to that in water body 5 might be expected, with an increase in the number of truly estuarine species. Despite the water quality problems in the harbour area, this water body supports a diverse fish population. In determining maximum ecological potential, a the fish fauna could be compared with another fish impingement site about 7 miles away at Kilroot Power station in outer Belfast Lough.

Phytoplankton

Determining the ecological potential of this quality element will be subject to the same problems expressed for macrophytes, where the main stressor on the systmen is the artificial salinity regime.

8.2 Measures for Achieving MEP

[Description of measures that would theoretically have to be undertaken in order to allow comparison with the closest comparable water body. How has the appropriate level of mitigation been defined?]

Water Body 3 Mitigation measures that can theoretically be undertaken to reinstate the River Lagan have been considered in detail. The key elements for the freshwater sections (3a and 3b) would involve the removal of the system of weirs, changes in bridge construction, reduction in the degree of canalisation (3a), reinstatement of the riparian buffer zone etc. However, many rivers of this type in Northern Ireland are degraded to a greater or lesser extent due to some or all of these influences and hence for comparative purposes an approach using the “best of their type” in terms of the quality of the biological elements is adopted.

Water body 4 Although the impoundment of the estuarine part of the River has improved the aesthetic appearance of this stretch, the Weir has not reduced the cause of the water quality problems in the impoundment. Mitigation measures to maximise ecological potential are outlined below. It is essential that all of these mitigation measures are combined with good water quality monitoring to inform management decisions.

3 Reduction in inputs of nutrients A reduction in the volume discharged from combined sewer overflows into impounded stretch of the River is planned. Urban pollution studies have been undertaken to identify the weakest points in the Victorian sewerage system in parts of Belfast. A £6 billion project is currently being planned by the Water Service to upgrade the sewerage system of Belfast. In addition, the designation of a sensitive area under the UWWTD will reduce nutrient inputs from waste water treatment works and industry. This combination of measures is expected to dramatically improve water quality.

Direct Aeration of the Water Column The aeration system in this section of the Lagan is invaluable in that it destratifies the water column and directly introduces oxygen. As outlined above, there were many teething problems in the establishment of the aeration system, but most of these have now been resolved. The aeration system was originally copied from that of an aeration system in a sewage treatment works. This system was very prone to physical damage from large objects coming down the river which would be screened out in a sewage works situation. In addition, the original aeration system transversed the river at two points. The system has now been modified to run longitudinally along the River which has been demonstrated as being more effective. The aeration system is currently linked to the monitoring of dissolved oxygen to ensure that the dissolved oxygen concentrations will always allow the passage of migratory fish. This quality objective has been agreed with the managers of the impoundment.

Flushing of the Impoundment A further measure to ensure that there is adequate dissolved oxygen in the impoundment is to flush with sea water on a high tide. This measure is used regularly during periods of high temperature, low flow or both and has been found to be effective. Close co-operation between EHS and the river managers (Laganside Co-operation) during this process. Dredging Periodic dredging of water body 4 is an essential management measure. Even with the reduction in inputs from CSOs, WWTWs and industry, there will still be considerable inputs of leaf material and silts from the riverine stretch of the Lagan and it’s tributaries. It is recommended that dredging activity is carried out over the winter period to reduce the potential for deoxygenation of the water column on the disturbance of the organically enriched sediments. Dredging on a ‘little and often’ basis is preferable to large dredging operations in this sensitive water course.

Water Body 5 Reduction in inputs of nutrients and contaminants The reductions outlined for water body 4 are expected to dramatically improve water quality in the Port area. In addition, improved knowledge of the industrial processes and

4 subsequent consenting practises in the Port area will reduce inputs of contaminants to the Harbour. Dredging The area is subject to regular maintenance dredging and occasional capital dredging. The disposal of dredged material from this process is licensed by EHS under the Food and Environment Protection Act (1985). Dredged material is usually disposed of at a sea disposal site out of Belfast Lough but some material has been refused for sea disposal as it has been too contaminated. All the dredging operators employed by the Belfast Harbour Commissioners follow a code of good dredging practice to minimise resuspension of sediment into the water column.

8.3 Comparison with Comparable Water Body [Describe how a comparable water body was identified - what selection strategy was defined based upon typological (physico-chemical and hydromorphological) parameters. Was biological data used as part of the selection process? Was the ecological condition of the water body comparable to the HMWB?]

Mitigation measures that can theoretically be undertaken to reinstate the River Lagan have been considered in detail. The key elements for the freshwater sections (3a and 3b) would involve the removal of the system of weirs, changes in bridge construction, reduction in the degree of canalisation (3a), reinstatement of the riparian buffer zone etc. However, many rivers of this type in Northern Ireland are degraded to a greater or lesser extent due to some or all of these influences and hence for comparative purposes an approach using the “best of their type” in terms of the quality of the biological elements is adopted.

Comparisons with comparable water bodies are only valid for quality elements not impacted by the modification, e.g. it is not valid to compare the benthic infauna of a regularly dredged channel with any other water body but it may be valid to examine fish fauna.

8.4 Discussion and Conclusions

[Discuss lessons learned, any problems encountered and how they were overcome.]

5 9 Definition of Good Ecological Potential (6 pages)

9.1 Determination of Good Ecological Potential

[Describe the ecological potential to be achieved in the medium and long term. Refer to paper 3 ver 3, nr.3. How has slight deviation from the MEP been defined? Has the definition of good ecological potential been influenced by the practicability of the mitigation measures?]

9.2 Identification of Measures for Protecting and Enhancing the Ecological Quality

[In this chapter, please describe the options for measures designed to protect and if necessary enhance the ecological quality of the water body. WFD Article 11 requires the establishment of a programme of measures, distinguishing between basic and supplementary measures.]

9.2.1 Basic Measures

[See Art. 11.3, which also refers to Art.10 and part A of Annex VI. How has the link between the good ecological potential and any possible measures been determined?]

9.2.2 Supplementary Measures

[See Art. 11.4 and part B of Annex VI. Can supplementary measures contribute to delivering environmental improvement?]

9.3 Discussion and Conclusions

[Discuss lessons learned, any problems encountered and how they were overcome.]

6 PART III

7 10 Conclusions, Options and Recommendations (5 pages)

10.1 Conclusions

[Highlight the "lessons learned" concerning the treatment of heavily modified water bodies in the Water Framework Directive. Discuss applicability of results in other river basins in the same ecoregion (of your country).]

10.2 Options and Recommendations

[Recommendations should be of general nature and pertain to the objectives of the European project on heavily modified water bodies. In particular, items for consideration in the harmonised and consistent implementation of the Water Framework Directive should be discussed. Highlight any clarifications of Annexes or guidelines that may be needed or helpful.]

8 11 Bibliography

Armitage, P. D., Moss, D., Wright, J. F., and Furse, M. T (1983). The performance of a new biological water quality score system based on macroinvertebrates over a wide range of unpolluted running-water sites. Water Research 17: 333-347. Haslam, S.M (1987). River Plants of Western Europe. Cambridge University Press.

9 12 List of Annexes

Sillees River in Co. Fermanagh

RIVPACS III+ PREDICTION OF FAUNA 512

Environmental data used:

Latitude 54 degrees 33 minutes N Longitude 5 degrees 56 minutes W Altitude 10 m Distance from source 72.4 km Discharge category 6 Mean width 11.0 m Mean depth 40.0 cm

Substratum composition: Boulders + cobbles 10 % Pebbles + gravel 75 % Sand 5 % Silt 10 % mean substratum (phi) -2.31

Slope 1.3 m/km Alkalinity 117.2 mg/l CaCO3

Probability of group membership

512 7 95.6% 6 2.0%

10 RIVPACS III+ PREDICTION OF FAUNA

512 "Spring", "Summer" and "Autumn" combined

Predicted BMWP families in decreasing order of probability of capture

100.0% Gammaridae (incl. Crangonyctidae & Niphargidae) 100.0% Chironomidae 100.0% Baetidae 100.0% Oligochaeta 100.0% Ancylidae (incl. Acroloxidae) 100.0% Elmidae 99.9% Caenidae 99.7% Sphaeriidae 99.7% Hydrobiidae (incl. Bithyniidae) 99.5% Lymnaeidae 98.3% Asellidae 93.6% Simuliidae 93.4% Polycentropodidae 93.2% Dytiscidae (incl. Noteridae) 93.1% Glossiphoniidae 91.8% Planorbidae 91.1% Corixidae 87.2% Ephemerellidae 87.1% Limnephilidae 86.2% Haliplidae 86.0% Leptoceridae 80.9% Hydropsychidae 80.1% Hydrophilidae (incl. Hydraenidae) 79.9% Gyrinidae 74.5% Heptageniidae 71.2% Planariidae (incl. Dugesiidae) 67.7% Tipulidae 65.2% Piscicolidae 65.0% Gerridae 64.9% Erpobdellidae 64.2% Valvatidae 61.4% Rhyacophilidae (incl. Glossosomatidae) 57.5% Sialidae 53.7% Lepidostomatidae 53.2% Psychomyiidae (incl. Ecnomidae) 51.3% Coenagriidae 44.8% Notonectidae 40.3% Leptophlebiidae 38.8% Physidae 35.4% Nemouridae 34.8% Perlodidae 33.4% Sericostomatidae 32.9% Capniidae 32.4% Calopterygidae 31.9% Dendrocoelidae 22.6% Leuctridae 20.7% Taeniopterygidae 19.1% Phyrganeidae 15.4% Hydroptilidae 14.8% Chloroperlidae 13.8% Goeridae

11 13.4% Ephemeridae 6.5% Unionidae 6.4% Siphlonuridae 6.4% Hydrometridae .7% Beraeidae .2% Perlidae .2% Aphelocheiridae .2% Hirudinidae .1% Astacidae

BMWP Statistics.

512 "Spring", "Summer" and "Autumn" combined

Exp(E)

BMWP score 189.1

No. taxa 34.6

ASPT 5.46

12 RIVPACS III+ PREDICTION OF FAUNA 519

Environmental data used:

Latitude 54 degrees 31 minutes N Longitude 6 degrees 0 minutes W Altitude 20 m Distance from source 64.4 km Discharge category 6 Mean width 23.0 m Mean depth 48.3 cm

Substratum composition: Boulders + cobbles 75 % Pebbles + gravel 15 % Sand 10 % Silt 0 % mean substratum (phi) -6.10

Slope .5 m/km Alkalinity 115.7 mg/l CaCO3

Probability of group membership

519 7 90.9% 6 6.1% 5 2.5%

13 RIVPACS III+ PREDICTION OF FAUNA

519 "Spring", "Summer" and "Autumn" combined

Predicted BMWP families in decreasing order of probability of capture

100.0% Gammaridae (incl. Crangonyctidae & Niphargidae) 100.0% Chironomidae 100.0% Baetidae 100.0% Oligochaeta 100.0% Ancylidae (incl. Acroloxidae) 100.0% Elmidae 100.0% Caenidae 99.5% Sphaeriidae 99.5% Hydrobiidae (incl. Bithyniidae) 99.3% Lymnaeidae 96.5% Asellidae 93.9% Simuliidae 93.8% Dytiscidae (incl. Noteridae) 93.4% Glossiphoniidae 93.4% Polycentropodidae 91.9% Planorbidae 89.8% Corixidae 87.9% Ephemerellidae 87.8% Limnephilidae 86.7% Leptoceridae 86.6% Haliplidae 81.8% Hydropsychidae 80.9% Gyrinidae 80.0% Hydrophilidae (incl. Hydraenidae) 75.8% Heptageniidae 69.0% Tipulidae 68.8% Planariidae (incl. Dugesiidae) 64.1% Gerridae 63.2% Piscicolidae 62.9% Erpobdellidae 62.6% Rhyacophilidae (incl. Glossosomatidae) 61.6% Valvatidae 55.0% Sialidae 54.7% Lepidostomatidae 53.9% Psychomyiidae (incl. Ecnomidae) 49.0% Coenagriidae 42.9% Notonectidae 40.1% Leptophlebiidae 37.9% Physidae 37.7% Nemouridae 35.5% Perlodidae 32.7% Sericostomatidae 32.2% Capniidae 31.8% Calopterygidae 30.3% Dendrocoelidae 25.6% Leuctridae 21.7% Taeniopterygidae 18.2% Phyrganeidae 17.8% Hydroptilidae 15.7% Chloroperlidae 14.1% Goeridae 13.9% Ephemeridae

14 6.5% Unionidae 6.1% Siphlonuridae 6.1% Hydrometridae 1.8% Beraeidae .5% Aphelocheiridae .5% Hirudinidae .4% Perlidae .1% Astacidae

BMWP Statistics.

519 "Spring", "Summer" and "Autumn" combined

BMWP score 189.7

No. taxa 34.5

ASPT 5.49

15 RIVPACS III+ PREDICTION OF FAUNA 523

Latitude 54 degrees 30 minutes N Longitude 6 degrees 5 minutes W Altitude 25 m Distance from source 53.4 km Discharge category 5 Mean width 20.0 m Mean depth 106.7 cm

Substratum composition: Boulders + cobbles 0 % Pebbles + gravel 5 % Sand 0 % Silt 95 % mean substratum (phi) 7.44

Slope .5 m/km Alkalinity 117.3 mg/l CaCO3

Probability of group membership

523 7 100.0%

RIVPACS III+ PREDICTION OF FAUNA

523 "Spring", "Summer" and "Autumn" combined

Predicted BMWP families in decreasing order of probability of capture

100.0% Gammaridae (incl. Crangonyctidae & Niphargidae) 100.0% Chironomidae 100.0% Baetidae 100.0% Caenidae 100.0% Hydrobiidae (incl. Bithyniidae) 100.0% Oligochaeta 100.0% Lymnaeidae 100.0% Elmidae 100.0% Ancylidae (incl. Acroloxidae) 100.0% Sphaeriidae 100.0% Asellidae 93.3% Polycentropodidae 93.3% Simuliidae 93.3% Dytiscidae (incl. Noteridae) 93.3% Glossiphoniidae 93.3% Planorbidae 93.3% Corixidae 86.7% Ephemerellidae 86.7% Limnephilidae 86.7% Leptoceridae 86.7% Haliplidae 80.0% Hydropsychidae 80.0% Gyrinidae 80.0% Hydrophilidae (incl. Hydraenidae) 73.3% Heptageniidae 73.3% Planariidae (incl. Dugesiidae) 66.7% Tipulidae

16 66.7% Piscicolidae 66.7% Gerridae 66.7% Valvatidae 66.7% Erpobdellidae 60.0% Rhyacophilidae (incl. Glossosomatidae) 60.0% Sialidae 53.3% Psychomyiidae (incl. Ecnomidae) 53.3% Lepidostomatidae 53.3% Coenagriidae 46.7% Notonectidae 40.0% Leptophlebiidae 40.0% Physidae 33.3% Nemouridae 33.3% Perlodidae 33.3% Capniidae 33.3% Dendrocoelidae 33.3% Sericostomatidae 33.3% Calopterygidae 20.0% Leuctridae 20.0% Taeniopterygidae 20.0% Phyrganeidae 13.3% Chloroperlidae 13.3% Ephemeridae 13.3% Hydroptilidae 13.3% Goeridae 6.7% Unionidae 6.7% Siphlonuridae 6.7% Hydrometridae

BMWP Statistics.

523 "Spring", "Summer" and "Autumn" combined

BMWP score 189.0

No. taxa 34.7

ASPT 5.44

17 RIVPACS III+ PREDICTION OF FAUNA 526

Environmental data used:

Latitude 54 degrees 27 minutes N Longitude 6 degrees 15 minutes W Altitude 30 m Distance from source 40.1 km Discharge category 5 Mean width 12.0 m Mean depth 73.3 cm

Substratum composition: Boulders + cobbles 30 % Pebbles + gravel 20 % Sand 10 % Silt 40 % mean substratum (phi) .43

Slope 1.5 m/km Alkalinity 85.8 mg/l CaCO3

Probability of group membership

526 7 99.5%

RIVPACS III+ PREDICTION OF FAUNA

526 "Spring", "Summer" and "Autumn" combined

Predicted BMWP families in decreasing order of probability of capture

100.0% Gammaridae (incl. Crangonyctidae & Niphargidae) 100.0% Chironomidae 100.0% Baetidae 100.0% Oligochaeta 100.0% Ancylidae (incl. Acroloxidae) 100.0% Elmidae 100.0% Caenidae 100.0% Hydrobiidae (incl. Bithyniidae) 100.0% Lymnaeidae 99.9% Sphaeriidae 99.8% Asellidae 93.4% Simuliidae 93.4% Polycentropodidae 93.4% Dytiscidae (incl. Noteridae) 93.3% Glossiphoniidae 93.1% Planorbidae 93.1% Corixidae 86.7% Ephemerellidae 86.7% Limnephilidae 86.7% Leptoceridae 86.6% Haliplidae 80.1% Hydropsychidae 80.0% Gyrinidae 80.0% Hydrophilidae (incl. Hydraenidae) 73.5% Heptageniidae

18 73.0% Planariidae (incl. Dugesiidae) 66.8% Tipulidae 66.4% Gerridae 66.4% Piscicolidae 66.4% Valvatidae 66.4% Erpobdellidae 60.2% Rhyacophilidae (incl. Glossosomatidae) 59.7% Sialidae 53.3% Psychomyiidae (incl. Ecnomidae) 53.3% Lepidostomatidae 53.1% Coenagriidae 46.4% Notonectidae 40.0% Leptophlebiidae 39.8% Physidae 33.6% Nemouridae 33.5% Perlodidae 33.3% Capniidae 33.2% Sericostomatidae 33.2% Calopterygidae 33.2% Dendrocoelidae 20.3% Leuctridae 20.1% Taeniopterygidae 19.9% Phyrganeidae 13.5% Hydroptilidae 13.5% Chloroperlidae 13.5% Ephemeridae 13.4% Goeridae 6.7% Unionidae 6.6% Siphlonuridae 6.6% Hydrometridae .2% Beraeidae

BMWP Statistics.

526 "Spring", "Summer" and "Autumn" combined

BMWP score 189.0

No. taxa 34.7

ASPT 5.45

19 RIVPACS III+ PREDICTION OF FAUNA 747

Environmental data used:

Latitude 54 degrees 21 minutes N Longitude 7 degrees 43 minutes W Altitude 50 m Distance from source 30.0 km Discharge category 5 Mean width 10.0 m Mean depth 85.0 cm

Substratum composition: Boulders + cobbles 1 % Pebbles + gravel 29 % Sand 66 % Silt 4 % mean substratum (phi) .62

Slope .5 m/km Alkalinity 98.7 mg/l CaCO3

Probability of group membership

747 7 87.0% 5 11.7% 6 1.2%

RIVPACS III+ PREDICTION OF FAUNA

747 "Spring", "Summer" and "Autumn" combined

Predicted BMWP families in decreasing order of probability of capture

100.0% Gammaridae (incl. Crangonyctidae & Niphargidae) 100.0% Chironomidae 100.0% Baetidae 100.0% Oligochaeta 100.0% Ancylidae (incl. Acroloxidae) 100.0% Elmidae 100.0% Caenidae 99.9% Hydrobiidae (incl. Bithyniidae) 99.9% Lymnaeidae 98.0% Sphaeriidae 95.6% Asellidae 94.2% Simuliidae 94.1% Dytiscidae (incl. Noteridae) 94.1% Polycentropodidae 92.2% Glossiphoniidae 88.4% Ephemerellidae 88.4% Limnephilidae 86.3% Planorbidae 86.3% Leptoceridae 86.3% Haliplidae 85.9% Corixidae 82.6% Hydropsychidae 78.7% Gyrinidae

20 78.5% Hydrophilidae (incl. Hydraenidae) 76.8% Heptageniidae 70.8% Tipulidae 65.0% Rhyacophilidae (incl. Glossosomatidae) 64.2% Planariidae (incl. Dugesiidae) 60.5% Gerridae 60.4% Piscicolidae 60.1% Valvatidae 58.5% Erpobdellidae 53.1% Psychomyiidae (incl. Ecnomidae) 52.3% Sialidae 51.3% Lepidostomatidae 46.5% Coenagriidae 41.7% Nemouridae 41.2% Leptophlebiidae 40.7% Notonectidae 37.5% Perlodidae 35.1% Physidae 33.1% Capniidae 29.5% Sericostomatidae 29.3% Calopterygidae 29.0% Dendrocoelidae 28.2% Leuctridae 23.7% Taeniopterygidae 18.3% Hydroptilidae 17.9% Chloroperlidae 17.5% Ephemeridae 17.4% Phyrganeidae 15.7% Goeridae 7.8% Unionidae 5.9% Beraeidae 5.8% Siphlonuridae 5.8% Hydrometridae 2.0% Perlidae

BMWP Statistics. 747 "Spring", "Summer" and "Autumn" combined

BMWP score 189.9

No. taxa 34.3

ASPT 5.52

21 RIVPACS III+ PREDICTION OF FAUNA 748

Environmental data used:

Latitude 54 degrees 22 minutes N Longitude 7 degrees 47 minutes W Altitude 50 m Distance from source 21.0 km Discharge category 4 Mean width 15.0 m Mean depth 125.0 cm

Substratum composition: Boulders + cobbles 20 % Pebbles + gravel 0 % Sand 10 % Silt 70 % mean substratum (phi) 4.25

Slope .5 m/km Alkalinity 98.8 mg/l CaCO3

Probability of group membership

748 7 94.9% 5 5.1%

RIVPACS III+ PREDICTION OF FAUNA

748 "Spring", "Summer" and "Autumn" combined

Predicted BMWP families in decreasing order of probability of capture

100.0% Gammaridae (incl. Crangonyctidae & Niphargidae) 100.0% Chironomidae 100.0% Baetidae 100.0% Caenidae 100.0% Ancylidae (incl. Acroloxidae) 100.0% Oligochaeta 100.0% Elmidae 100.0% Lymnaeidae 100.0% Hydrobiidae (incl. Bithyniidae) 99.1% Sphaeriidae 98.3% Asellidae 93.7% Simuliidae 93.7% Dytiscidae (incl. Noteridae) 93.7% Polycentropodidae 92.8% Glossiphoniidae 90.3% Planorbidae 90.3% Corixidae 87.4% Ephemerellidae 87.4% Limnephilidae 86.5% Leptoceridae 86.5% Haliplidae 81.0% Hydropsychidae 79.3% Gyrinidae

22 79.3% Hydrophilidae (incl. Hydraenidae) 74.7% Heptageniidae 69.6% Planariidae (incl. Dugesiidae) 68.4% Tipulidae 64.1% Gerridae 64.1% Piscicolidae 64.1% Valvatidae 63.3% Erpobdellidae 62.0% Rhyacophilidae (incl. Glossosomatidae) 56.9% Sialidae 53.2% Psychomyiidae (incl. Ecnomidae) 52.3% Lepidostomatidae 50.6% Coenagriidae 44.3% Notonectidae 40.5% Leptophlebiidae 38.0% Physidae 36.7% Nemouridae 35.0% Perlodidae 33.3% Capniidae 31.6% Sericostomatidae 31.6% Calopterygidae 31.6% Dendrocoelidae 23.3% Leuctridae 21.5% Taeniopterygidae 19.0% Phyrganeidae 15.2% Hydroptilidae 15.2% Chloroperlidae 15.2% Ephemeridae 14.4% Goeridae 7.2% Unionidae 6.3% Siphlonuridae 6.3% Hydrometridae 2.6% Beraeidae .9% Perlidae

BMWP Statistics. 748 "Spring", "Summer" and "Autumn" combined

BMWP score 189.3

No. taxa 34.5

ASPT 5.48

23 Annex 2 – Proformas for HMWB designation tests and economic assessments

24