Glyn Rhonwy Pumped Storage Development Consent Order
Appendix 7.5 Etive Ecology (2012) Glyn Rhonwy Pumped Storage Scheme: Llyn Padarn Freshwater Ecology Impact Assessment September 2012
Glyn Rhonwy Pumped Storage Final Environmental Statement Volume September Development Consent Order 3 2015
Glyn Rhonwy Pumped Storage Final Environmental Statement Volume September Development Consent Order 3 2015
This Appendix was previously submitted as part of the 2012 Environmental Statement. Where there are references to Quarry Battery Company (QBC), this now relates to Snowdonia Pumped Hydro (SPH) as this Appendix is submitted in support of the Development Consent Order (DCO) application.
Glyn Rhonwy Pumped Storage Final Environmental Statement Volume September Development Consent Order 3 2015
ETIVEECOLOGY Glyn Rhonwy Pumped Storage Scheme: Llyn Padarn Freshwater Ecology Impact Assessment
Produced by for
September 2012
Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
CONTENTS
1 INTRODUCTION 3 1.1 The Scheme 3 1.2 Purpose of this Report 3 2 METHODOLOGY 4 2.1 Desk Study 4 2.2 Consultation 4 2.3 Field Sampling 4 3 BASELINE INFORMATION 7 3.1 Site Designation 7 3.2 Designated Interest Features 8 Arctic Charr 8 Floating Water Plantain 13 3.3 Non-Designated Interest Features 15 Atlantic Salmon 15 Sea Trout (Brown Trout in Freshwater) 16 Small Quillwort 17 Otter 18 European Eel 20 Lamprey Species 21 4 CONSULTATIONS 23 4.1 Environment Agency Wales 23 4.2 CCW 24 4.3 Gwynedd Council 25 4.4 Summary 25 5 IMPACT ASSESSMENT 26 5.1 Potential Impacts 26 5.2 Assessment of Impacts: Construction 29 5.3 Assessment of Impacts: Abstraction 31 5.4 Assessment of Impacts: Operational Discharges 33 5.5 Assessment of Impacts: Decommissioning 36 6 MITIGATION 37 6.1 Construction 37 6.2 Abstraction 38 6.3 Operation 38 ETIVE ECOLOGY 1 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
6.4 Decommissioning 39 7 Water Framework Directive Assessment 41 7.1 Introduction 41 7.2 Compliance with Mitigation Measures Required Under the WFD 41 7.3 Compliance with Biological Monitoring Elements of the WFD 43 7.4 Compliance with Llyn Padarn SSSI Objectives: Arctic Charr 44 7.5 Compliance with Llyn Padarn SSSI Objectives: Floating Water Plantain 45 8 CONCLUSION 1 8.1 Summary of Impacts 1 8.2 Monitoring Requirements 3 8.3 Water Framework Directive Assessment 3 9 REFERENCES 1
Quality Assessment Record
Report Version Written by Date Reviewed by Date 1.0 Russell Grey 13 September 2012 Maddy Warriner 14 September 2012 2.0 Russell Grey 24 September 2012 Maddy Warriner 25 September 2012 and Maddy Warriner
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1 INTRODUCTION
1.1 The Scheme 1.1.1 The proposed Glyn Rhonwy Pumped Storage scheme is a small (49.9 MW) pumped hydroelectric electricity storage facility. The project plans to utilise the Glyn Rhonwy cascade of disused slate quarries to the north-west of Llanberis, Gwynedd. Electrical energy is stored in the scheme by pumping water from the lower reservoir, to the upper reservoir, converting electrical energy to gravitational energy. This energy can then be converted back to electricity when required such as during periods of sudden high demand.
1.1.2 The scheme will include the construction of two new dams, a turbine house, connecting pipework and a new spillway connecting Glyn Rhonwy to Llyn Padarn. The scheme will also abstract up to 2000m3 per day from Llyn Padarn for the initial filling of the upper reservoir (Chwarel Fawr) and subsequent topping-up only as required. The scheme will also discharge an average daily volume of up to 1200m3 into Llyn Padarn, principally during periods of wet weather. This discharge will be as a result of heavy rainfall into the system and represents the natural run-off that would normally enter the Llyn Padarn system.
1.1.3 The scheme is located immediately adjacent to the Snowdonia National Park (NP) and cascades down into the Llyn Padarn Site of Special Scientific Interest (SSSI), designated for its nationally important population of Arctic charr (Salvelinus alpinus L.) and habitats supporting floating water-plantain (Luronium natans) and small quillwort (Isoetes echinospora). The site also supports Atlantic salmon (Salmo salar), sea trout (Salmo trutta) and otter (Lutra lutra).
1.2 Purpose of this Report 1.2.1 The purpose of this report is to assess the potential impacts posed to the freshwater interest features relevant to the scheme and the surrounding freshwater environment.
1.2.2 This is done by establishing the baseline freshwater environment and data gathering, including consultations and data purchase, and identifying the sensitivities of the features present. The potential impacts of the scheme are then considered, identifying the nature and magnitude of these impacts on the interest features and the likelihood of occurrence. Appropriate mitigation measures and monitoring requirements are also considered and included in the assessment.
1.2.3 The report concludes whether there will be any likely significant impacts on any of the freshwater interest features as a result of the proposed scheme.
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2 METHODOLOGY
2.1 Desk Study 2.1.1 Llyn Padarn was identified early in the design of the scheme as a key ecological receptor, as a SSSI with a potential direct pathway linking it to the scheme, during both construction and operational phases. A desk study was therefore undertaken to identify the interest features of the site, the status of these features and to consider their sensitivities to changes in the freshwater environment.
2.1.2 The following sources of information were utilized:
Countryside Council for Wales (CCW) website (http://www.ccw.gov.uk) Snowdonia National Park Biodiversity Action Plan (http://www.eryri-npa.gov.uk) Environment Agency Wales (EAW) website (http://www.environment-agency.gov.uk) Gwynedd County Council Biodiversity Action Plan (http://www.gwynedd.gov.uk/gwy_doc.asp?cat=3426&doc=9530&language=1&p=1&c=1) North Wales Environmental Information Service (Cofnod) (http://www.cofnod.org.uk)
2.1.3 An extensive internet search was also used to identify independent and unpublished information on the various species relevant to Llyn Padarn. In addition detailed survey and assessment reports were provided by CCW and EAW and are listed in the reference section (Chapter 9 of this report). Local surveyor knowledge was also applied where appropriate.
2.2 Consultation 2.2.1 The consultation process has been on-going throughout the design process for the scheme with various statutory consultees. This process has included specific discussions with regards to the freshwater interests associated with Llyn Padarn SSSI and the potential impacts resulting from the proposed scheme.
2.2.2 The following organisations have been consulted:
CCW: G.J. Davies, Casework Officer (Scoping Opinion) EAW: Fisheries Technical Team, Environment Team, Planning Officer, Senior Development Management Officer, Permitting Support Team (Matthew Hazlewood, Victoria Briscoe, Gareth Thomas, Glyn Llewelyn Gruffudd) Gwynedd Council: Emily Meilleur, Senior Biodiversity Officer
2.2.3 A review of the issues raised during the consultation process is presented in Chapter 4 of this report. A full review of all environmental consultations undertaken in relation to the proposed scheme is found within the main Environmental Statement.
2.3 Field Sampling 2.3.1 During a meeting with the Environment Agency Wales (EAW) on 29 May 2012, the issue of background water quality was raised and the need to include appropriate information in the Environmental Statement was emphasised. As a result, water quality sampling has been undertaken at up to five locations within the Glyn Rhonwy study area to provide baseline data for consideration with the EIA process. Subsequent monitoring during and
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post-construction can then be undertake using the same sampling points to identify any changes from the baseline.
2.3.2 The following surface water sampling points have been agreed:
1. The lake in Quarry 6, at a point close to the drainage adit.
2. The pipe discharge to the manhole below Quarry 7.
3. The inflow to the manhole below Quarry 7 from the south east.
4. The lake in Quarry 7 (if accessible).
5. The lake in the small quarry between Quarry 6 and Quarry 7 (if accessible).
2.3.3 Samples were taken from locations 1, 3, 4 and 5 on 30 July 2012. Location 2 was dry at the time of sampling. The samples have been submitted to an independent laboratory and analysed for the following suite of parameters:
pH, alkalinity and electrical conductivity Metals: arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, zinc, aluminium, antimony, barium, boron, cobalt, lithium, iron, manganese, molybdenum, strontium Cyanide Calcium, magnesium, sodium, potassium, chloride and sulphate Nitrate, nitrite and ammonical nitrogen Orthophosphate Total petroleum hydrocarbons (speciated to TPHCWG, if total is greater than 0.2mg/l) PAH (16) BOD and COD
2.3.4 Results from the water sampling, indicate that the water quality at all sampling points is ‘satisfactory’ and with no obvious evidence of contamination. The analysis indicates that the water from sample point1, 3 and 5 have similar in chemistry, suggesting they are hydrologically linked. Water from sample poit4 is marginally different, suggesting a different water source.
2.3.5 An assessment of these results by a senior environmental scientist, Owen Tucker at AECOM, on behalf of QBC concluded that the quality of these waters does not pose a constraint to any of the proposed developments. Further information is provided in theChapter 8 (water resources) of the Environmental Statement.
2.4 Impact Assessment
2.4.1 The impact assessment conducted in this report follows the methodology outlined in the main ecology chapter of the Environmental Statement. Likely impacts of the scheme at each of the stages (construction, abstraction, operation, decommissioning) are predicted by assessing the changes that are likely to occur as a result of the scheme, with the environmental and ecological sensitivities of the ecological features of Llyn Padarn. The level of significance of each of the predicted impact is then obtained by comparing the magnitude of each impact with the value of the ecological receptor. Significance is
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assessed for impacts pre-mitigation and then re-assessed following the application of suitable mitigation measures. Further detail on the impact assessment methodology can be found in the Environmental Statement.
2.4.2 For simplicity, all ecological receptors in Llyn Padarn have been classed as being of high value. Although only Arctic charr and floating water plantain are the designated features of the SSSI, it is considered that all of the other fish, invertebrate and plant species are important components of the SSSI and are integral to the functioning of the site. Impacts on populations of non-SSSI species could have subsequent impacts on the SSSI features of Llyn Padarn through complex interactions of species , food resources and habitats and are therefore considered to be of high value to the functioning of the site.
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3 BASELINE INFORMATION
3.1 Site Designation 3.1.1 Llyn Padarn is designated as a SSSI for both its biological and geological interest. The lake is one of only three remaining natural localities in Wales for the Arctic charr and supports a population that is genetically different from those found in nearby Llyn Cwellyn and Llyn Bodlyn. In addition the lake provides habitats which support important flora including floating water plantain and small quillwort.
3.1.2 Although not part of the primary reasons for designation of the site, the outflow of Llyn Padarn, the Afon Rhythallt and Afon Seiont, are also known to be one of the most important spawning sites for Atlantic salmon and sea trout in North Gwynedd and the lake itself is used by otters, although surveys of the outlet showed no evidence of otters close to the discharge point.
3.1.3 Condition assessment of the site has been carried out for both the aquatic plant community interest (CCW 2006, based on EAW surveys in 2003 and 2005) and the Arctic charr population (2011). In terms of the aquatic plant interest, the site is described as Annex 1 type: H3130: Oligotrophic to mesotrophic standing water with vegetation of the Littorelletea uniflorae and/or of the Isoëto-Nanojuncetea. The condition assessment concluded that the site is currently in an overall unfavourable condition as it failed on the following attributes (targets).
Water quality (failure to maintain stable nutrient levels) Lake substrate (Natural shoreline not maintained at all locations) Sediment load (Natural sediment load not maintained) Indicators of local distinctiveness (minimal negative impacts and no fish farming) Palaeo evidence (Evidence of significant environmental change, mostly specifically eutrophication)
3.1.4 Water quality data indicates that Llyn Padarn is a circumneutral to mildly alkaline lake (mean pH 7.53) and is not at risk of acidification. However, phosphorus concentrations are moderate (mean TP 16 μgl-1) and above the 10 μgl-1 target/limit for the lake’s feature type, suggesting that Llyn Padarn is suffering from nutrient enrichment.
3.1.5 Phosphate levels have been a particular concern in recent years, with discharges from the Llanberis Sewage Treatment Works coming under scrutiny from the EAW, CCW and local angling groups. The Lanberris WWTW discharges directly into the Afon y Bala, the main inflow into Llyn Padarn at the eastern end of the lake. Phosphate stripping was introduced at the plant to help reduce nutrient inputs into Llyn Padarn, but there are still concerns that untreated inputs from storm-water discharges and from other parts of the catchment are continuing to lead to elevated phosphate levels. Despite enrichment by phosphates, nitrate enrichment is not considered to be problem, with concentrations at a relatively low and stable concentration, possibly as a result of the low amount of agricultural land use within the Llyn Padarn catchment.
3.1.6 In addition to the concerns about eutrophication, Nutall’s pondweed Elodea nuttalli , a non-native naturalised species was identified in the lake. Nutall’s pondweed was identified
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to be frequent within the lake during the 2006 condition assessment (present in 17% of vegetative samples) and considered to be locally abundant in deeper water areas in 2003 survey.
3.1.7 Similar concerns and failures relating to water quality parameters were identified in the condition assessment carried out for Arctic charr in 2011. In addition, evidence and survey work used in the condition assessment indicated periodically reduced dissolved oxygen levels in the deeper parts of Llyn Padarn. At times levels were reduced below the lower tolerance levels of Arctic charr. This, coupled with temperature spikes as a result of discharges from the Dinorwig hydro scheme was considered to be potential placing Arctic charr under significant amounts of stress at different times of the year. Assessment of the age structure and population density of the Arctic charr population was considered to be difficult to carry out and there was a lack of confidence in survey data, despite this, the condition assessment demonstrated a continuing trend of declining populations of older, spawning fish, and considered to the population to be unfavourable status.
3.1.8 A Water Framework Directive (WFD) risk assessment for Llyn Padarn, undertaken by the EAW in December 2009 assessed that the current overall potential for the lake was moderate, with an objective to achieve good ecological potential by 2027 (EAW, 2009). All biological and water quality elements except macrophytes achieved at least good status. However, many of the required measures to mitigate against water body modifications, such as management of flows and control of sediment inputs and outputs, were not in place and this was considered to reduce the lakes ecological potential. This conclusion is in contrast to the findings of the EAW report produced in 2011 which details a number of years of investigation into water quality in Llyn Padarn. That report highlights serious concerns about fish stocks and presents detailed analysis of data which is suggestive of many decades of nutrient enrichment of Llyn Padarn which is currently leading to algal blooms and decreased oxygen levels, with subsequent impacts on fish stocks.
3.2 Designated Interest Features 3.2.1 The site has two primary freshwater interest features, Arctic charr and floating water plantain. These are detailed below with information provided relating to the species’ ecology, status, distribution and sensitivity within Llyn Padarn.
Arctic Charr Ecology
3.2.2 Arctic charr is a naturally a migratory species when found in Arctic waters, although the species’ range extends into south and central Europe where it is restricted to deep mountain lakes where temperatures are sufficiently low. In these locations (including Wales), the species persists as a glacial relict from the last ice age, in non-migratory populations. Wales is at the southern extent of the species’ European distribution (Gwynedd LBAP, 2004).
3.2.3 Charr are similar in appearance and ecology to sea trout but in the case of Llyn Padarn, charr are non-migratory. Adult fish spawn in November to January in the relatively shallow margins of the lake, where the lake bed comprises of a stony, gravel substrate, notably at the inlet along the Afon y Bala at the eastern end of the lake. Within Llyn Padarn, Charr feed primarily on phytoplankton in deep water where temperatures are lowest and where
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there is little competition from other species such as trout which tend to feed in the shallower littoral areas (Bean, 2005). In summer charr form shoals at the surface where they feed on plankton and insects.
3.2.4 Charr are a highly sensitive species requiring a specific set of environmental conditions to survive, including variables such as water quality, nutrient level, water temperature and dissolved oxygen. Although they are relatively tolerant of a range of temperatures and oxygen levels (Baroundy, 1995) their sensitivity to nutrient levels and the effect this has on water quality and phytoplankton availability makes them potentially vulnerable in Llyn Padarn.
Status
3.2.5 The Arctic charr is listed under Section 42 (Wales) of the NERC Act (2006) as a species “of principal importance for the purpose of conserving biodiversity”. The species is also listed on the Gwynedd Local Biodiversity Action Plan (LBAP), is a Priority Species on the UK BAP and is listed on the IUCN Red List as being vulnerable (2008).
3.2.6 Prior to 2010, there were only five sites in Wales which still support Arctic charr populations, all of which are found within Gwynedd. These are Llyn Padarn, Diwaunedd, Cwellyn, Bodlyn and Ffynnon Llugwy, all of which, with the exception of Padarn, are within the Snowdonia National Park boundary (Gwynedd LBAP, 2004).
3.2.7 The Welsh populations of Arctic charr represent a distinct race Salvelinus alpinus perisii and the Llyn Padarn population is genetically different from those in Llyn Cwellyn and Llyn Bodlyn (Gwynedd LBAP, 2004). The same race also inhabited the adjacent Llyn Peris prior to the hydro-electric scheme. Subsequent habitat loss resulted in the establishment of new breeding sites in Llyn Diwaunedd and Ffynnon Llugwy as part of the mitigation for the Dinorwig hydro scheme.
3.2.8 The most recent round of Condition monitoring of the Arctic charr population in Llyn padarn was carried out by CCW in 2011 (CCW, 2011). The assessment was based on survey data collated by EAW and concluded that overall the population of Arctic charr in Llyn Padarn was in unfavourable condition. Population densities for Arctic charr were assessed as being 1075.6 fish per ha in 2007, 55.1 charr per ha in 2008 and 195.4 charr per ha in 2009. These densities exceed the target for oligotrophic lakes of 37 charr per ha. However, there is low confidence in the survey results as the hydroacoustic surveys are no able to distinguish between charr and trout (the principal species in the lake). It was therefore considered that densities would be considerably lower, and the continuing decline in densities resulted in this target being assessed as unfavourable. The second target for Arctic charr populations is that a minimum of 70% of the population must be comprised of juvenile fish species. In 2007, 2008 and 2009, 93%, 70% and 92% of the population respectively, was comprised of juveniles. Although the target was met, again there was low confidence in the results.
3.2.9 Additional parameters assessed as a result of condition monitoring relate to suitable habitat for Arctic charr and appropriate water quality. Dissolved oxygen monitoring from 2009 and 2010 found levels below the tolerance levels for Arctic charr (~2mg/l) at depths as shallow as 15 – 20m (EAW, 2011). The CCW assessment also highlighted other concerns including: high Total Phosphorus levels with the target of <10µg/l exceeded in 2009; spikes in ETIVE ECOLOGY 9 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
temperature with temperatures over 150C recorded in the upper 10m of Llyn Padarn in July 2010 and in the upper 2m in September 2010; and, toxic blue-green algae blooms between May and October 2009. Favourable aspects of monitoring included maintenance of the key spawning location at the Afon y Bala , limited disturbance to the lake through dredging and changes to the lake bed, and a lack of introduced species in Llyn Padarn.
3.2.10 In addition to condition monitoring carried out by CCW, an extensive number of investigations including fisheries surveys have been conducted on (and continue to be conducted on) Llyn Padarn, particularly when a serious algal bloom in 2009 raised concerns about the stability of the lake and its fish population to a critical level. The surveys are too numerous and detailed to present anything other than a summary here.
3.2.11 Hydro-acoustic surveys have been the key method for assessing fish populations in Llyn Padarn since 2002 with surveys conducted in summer 2002, 2003, 2005 and then annually since 2007. Hydro-acoustic surveys are limited in that they can only identify the numbers of fish and not species. However, they have been supported by a small number of fyke netting surveys (Hanks 2009, 2010) which indicate that the main fish species in the lake are brown trout and Arctic charr with a 50:50 split. This split is based on only a small number of samples and there is low confidence in the assessment.
3.2.12 Hydro-acoustic surveys are summarised in Clabburn (2011). The eastern end of Llyn Padarn has typically been identified as having higher fish densities, as well as deeper areas in the centre of the lake and some shallower areas on the south-west and central northern margin of the lake. Population levels of Arctic charr above >262mm in size since 2002 are shown in Table 3.1 below. The surveys indicate a decline in the larger age classes of fish with the densities in 2011 being the lowest ever recorded. The hydro-acoustic surveys recorded a sharp decline in the larger fish populations in 2005 possibly corresponding with the anoxic conditions in the lake which were recorded that year. However, hydro-acoustic data from 2011indicated that numbers of fish in smaller age classes were higher than in 2010, although only two of the size classes showed an appreciable increase.
Table x.x: Population Estimates of Arctic charr (fish >262mm in size) (from Clabburn, 2011)
Year Low Population Mean Population Upper Population Estimate Estimate Estimate
2002 1003 1810 2617 2003 2107 3850 5592 2005 915 1443 1971 2007 1080 2072 3064 2008 328 699 1070 2009 298 815 1333 2010 328 787 1247 2011 141 595 1049
3.2.13 Multi-beam sonar surveys have been conducted on the Afon y Bala at the eastern end of Llyn Padarn since 2008 and are reported in Clabburn et al 2011. The Afon y Bala is the main spawning site for Arctic charr and sonar surveys have been important in increasing confidence in population number estimates of Arctic charr. In 2008 a minimum of 100 Arctic charr were recorded spawning in the Afon y Bala during the sonar surveys. ETIVE ECOLOGY 10 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
However, surveys in 2008 did not commence until 9 December and only continued for 10 days and it was felt that a large part of the spawning period was missed by the surveys. In 2009 the sonar study was conducted from 2 December to 23 December. The peak count of Arctic charr was recorded as 197 fish with limited confidence. Surveys were repeated again in 2010 from 19 November to 31 January, in order to cover the entire spawning period. The peak daily movement was recorded as 327. This count was adjusted for the wider spawning area, and the total population of fish in the Afon y Bala was calculated as 2592 fish (EAW, 2011). Fyke net surveys from the same year (Hanks, 2010) indicated that 38.5% of fish were Arctic charr, giving a total of 998 fish using the Afon y Bala in 2010. The hydro-acoustic surveys conducted on Llyn Padarn in 2009 had estimated the spawning stock at 756 individuals. The estimates from the sonar and hydro-acoustic surveys are broadly similar, providing an indication that the Afon y Bala is the key, and potentially only spawning location in Llyn Padarn, with the end of November to end of December being the main spawning run, and mid-December being the peak period of the run.
3.2.14 Fyke net surveys were conducted in 2009 and 2010 (Hanks 2009, 2010) in the Afon y Bala to capture Arctic charr for translocation. Amid fears about the decline in Arctic charr, a three year plan was drafted with the aim of creating a second population of the Llyn Padarn strain of Arctic charr which could be used to re-stock the lake if necessary (EAW, 2011)
3.2.15 After a rigorous selection procedure, Llyn Crafnant was chosen as a receptor site. Charr captured during fyke net surveys in 2009 and 2010 were processed and fertilised eggs hatched and released into Llyn Crafnant with approximately 700 fish released in 2010 and a further 5000 in June 2011. Stocking of charr into Llyn Padarn took place at the end of 2011 with 800 fish being released into the lake
3.2.16 A survey by Middlemiss (2005) recorded that the south-west shore of Llyn Padarn from the Afon y Bala confluence to the Afon Goch (further west on the south shore of Llyn Padarn) could provide further suitable spawning habitat for Arctic charr. In addition the lake outflow to the Afon Rhythallt has been highlighted as a historic spawning site. Scuba diving surveys were carried out by the Environment Agency in December 2010 at seven sites around the lake shore were surveyed to a maximum depth of 8m. Although some areas of lake bed between the Afon Goch and Afon y Bala were recorded as potentially being scraped out by fish for spawning, no spawning was confirmed (EAW, 2011). No other sites were identified as having potential spawning activity. Surveyed areas included one location within 200m of the proposed discharge/abstraction location for the Afon y Bala scheme.
3.2.17 Overall the status of the Arctic charr population within Llyn Padarn is concluded to be declining and vulnerable. This decline is likely to be linked to a number of factors including eutrophication (and subsequent declines in oxygen levels) and disturbance.
Sensitivities
3.2.18 The following factors are believed to be affecting the species within Gwynedd (taken from Gwynedd SAP);
Eutrophication of Llyn Padarn plus associated blue-green algal blooms as a result of run-off from adjoining land and atmospheric deposition. Discharges of pesticides and other chemicals into the lake. Discharges from sewage outfalls and WTWs. ETIVE ECOLOGY 11 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
Fluctuating water levels as a result of water discharges and abstraction from the lake is a potential problem, particularly as the Arctic charr spawning and nursery grounds occur within its shallow marginal waters, notably along Afon y Bala. However, there are no current abstractions from the lake for potable supplies. Over-fishing is a potential problem.
3.2.19 The species is also known to be sensitive to;
Acidification. Changes in catchment management (e.g. deforestation, afforestation, etc); impacting on water quality. Engineering schemes (e.g. hydro-electric). Short-term temperature spikes have been recorded in water around Afon y Bala, coinciding with water releases from Llyn Peris, which may impact charr use of this important area (temperatures in excess of the maximum for spawning 80C and the maximum for egg development 50C were recorded in the Afon y Bala for short periods of time in December 2009 (EAW, 2011 1)).. Water abstraction and lake drainage. Introduction of coarse fish such as carp and roach. Introduction of alien invasive species such as the zebra mussel (EHSNI, 2007). Climate change.
3.2.20 After a serious blue-green algae bloom in 2009, the EAW undertook comprehensive investigations in 2010 of the pressures acting on Llyn Padarn. The work included a review of previous survey data as well as new investigations. Studies have shown that LLyn Padarn has been subject to nutrient enrichment for decades, with a paleolimnology study indicating that the diatom community of the lake was replaced by a community dominated by Asterionella formosa, a species indicative of nutrient enrichment, in the 1950s and 1960s (Bennion et al 2010). This is likely due to the increase in population, and hence increased sewage inputs from Llanberris. Phosphorus stripping was introduced to waste water treatment facilities in Llanberris in 1995 but water quality measurements still show that phosphorus levels are elevated in the lake and there are concerns that untreated stormwater discharge provides a significant contribution of phosphorus. Despite phosphorus stripping a dense bloom of the blue green algae Annabaena flosaque was recorded throughout 2009.
3.2.21 Nutrient enrichment of a normally oligotrophic lake is a significant pressure for Arctic charr. The subsequent decay of algal cells in the deeper parts of the lake significantly reduces dissolved oxygen levels, and in August 2009 levels of 1.8mg/l were recorded at a 26m depth in Llyn Padarn (EAW, 2010). This is below the lower tolerance level for Arctic charr, and even greater reductions were recorded in 2010 with dissolved oxygen levels of less than 1mg/l at depths below 20m. Under eutrophic conditions, such severely depleted dissolved oxygen levels effectively, reduce the area of the lake that is available to Arctic charr.
3.2.22 A further concern is that the problem could be exacerbated further by spikes of elevated temperature as a result of warmer discharges from the Dinorwig hydro scheme. Elevated temperatures have been recorded, co-inciding with releases from Llyn Peris as part of the Dinorwig scheme. There two issues associated with this, the first is that warmer water has a reduced dissolved oxygen capacity, and increased temperatures within the lake will ETIVE ECOLOGY 12 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
therefore further reduce dissolved oxygen in the hypolimnium (deeper parts of the lake). The second is that discharges from the Dinorwig scheme enter directly into the key Arctic charr spawning area on the Afon y Bala and have been known to raise water temperatures above 50C for short periods of time in December. Such elevated temperatures can have adverse effects on both spawning and egg development (EAW, 2011).
3.2.23 EAW, DCWW and CCW are all working on improving the quality of habitat within Llyn Padarn for Arctic charr following the catastrophic algal bloom in the summer of 2009.
Floating Water Plantain Ecology
3.2.24 Floating water plantain occurs in a range of freshwater situations, including nutrient-poor lakes in the uplands (mainly referable to Habitat 3130: Oligotrophic to mesotrophic standing waters with vegetation of the Littorelletea uniflorae and/or of the Isoëto-Nanojuncetea) and slow-flowing lowland rivers, pools, ditches and canals that are moderately nutrient-rich (JNCC, 2012).
3.2.25 The species occurs as two forms: in shallow water with floating oval leaves, and in deep water with submerged rosettes of narrow leaves. The species is apparently stoloniferous, although what appear to be stolons are in fact modified inflorescence stems which may be prostrate and creep through the substrate (Lansdown & Wade, 2003). Floating water plantain can reproduce by various means (sexual or vegetative) so the ability of any given community to flower is important in determining its long term viability as vegetative reproduction only will lead to a depleted gene-pool (Lansdown & Wade, 2003). The species is however, well adapted to vegetative dispersal along water-courses. It is tolerant of a range of pH levels (3.6-8) and appears to have a very wide range of chemical and substrate tolerances (Lansdown & Wade, 2003).
3.2.26 The plant thrives best in open situations with a moderate degree of disturbance, where the growth of emergent vegetation is held in check. Populations fluctuate greatly in size, often increasing when water levels drop to expose the bottom of the water body. Populations fluctuate from year to year, and at many sites records have been infrequent, suggesting that only small populations occur, in some cases possibly as transitory colonists of the habitat (JNCC, 2012).
3.2.27 In Llyn Padarn it was noted (CCW, 2003) to be growing in Section 11 of the lake (NGR SH 582 602) in water depths of 2-3m. This area is located approximately 1km east of the proposed discharge/abstraction point. The plant was found to be present in approximately a quarter of the vegetated quadrats that were sampled in section 1. It wasn’t however found to be present in any of the other three quadrats and therefore its presence in the lake was recorded as being rare. The location of the proposed abstraction and discharge point was not surveyed during the 2003 condition monitoring surveys and no further condition assessment has been carried out since 2003.
Status
3.2.28 Floating water plantain is listed on Annex II of the Habitats Directive. The species is also
1 EAW (2003) Boat Survey transect, Section 1, Sample Points 4, 5 & 6. ETIVE ECOLOGY 13 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
listed under Section 42 (Wales) of the NERC Act (2006) as a species “of principal importance for the purpose of conserving biodiversity”. Floating water plantain is also a UKBAP Priority Species and a Gwynedd LBAP species as well.
3.2.29 The species is found only in Europe and the ‘core’ natural habitat is considered to be lakes in Snowdonia and mid-Wales. It is also a probably native species to Cumbria, whilst its other occurrences within the UK are likely to be as a result of introductions (Gwynedd LBAP, 2004). Information gathered from various sources indicates that upland oligotrophic lakes and slow-moving mesotrophic river populations throughout the UK seem relatively stable and the species continues to be discovered in new, previously overlooked sites, and to expand east into some English canals. However, the fate of the populations in lowland lakes and pools is uncertain and may be unstable or vulnerable due to a range of transient and more persistent pressures (JNCC, 2010).
3.2.30 Populations tend to be more stable at natural sites than artificial ones, but approximately half of recent (post-1980) records are from canals and similar artificial habitats. Its habitat in rivers has been greatly reduced by channel straightening, dredging and pollution, especially in lowland situations (JNCC, 2012).
3.2.31 Gwynedd is considered to be a stronghold for the species within Wales, found within many of the numerous lakes present within the area, including those within the Snowdonia National Park (Gwynedd LBAP, 2004). There has however, been a potential decline of populations in heathland pools and lakes within agricultural catchments. To counter this, a number of new sites have been identified, or created as a result of active management. Some canal populations have been designated as SACs but may be subject to development and boating pressures (JNCC, 2010).
3.2.32 Historic records for the species within Llyn Padarn exist from CCW monitoring; near the outfall in the northwest of the lake (1994), near the inlet from Llyn Peris at the east end (1965) and immediately downstream of outfall in Afon Rhythallt (1967). As described above, floating water-plantain was also recorded from ‘survey section 1’ at the eastern end of Llyn Padarn growing at water depths of between 2 –3m during condition assessments in 2003. A SCUBA diver survey was carried out by the EAW in 2011 (Thomas and Holt, 2011) principally to investigate potentially suitable spawning locations for Arctic charr in Llyn Padarn, but also included records of plant species. A location within 200m of the proposed Quarry Battery discharge/abstraction location was investigated, no floating water plantain was identified, though dense beds of Canadian pondweed were recorded.
3.2.33 In summary, the species has a restricted geographical range within the UK and has shown some evidence of decline. The factors likely to be causing that decline are still operating.
Sensitivities
3.2.34 The following factors are believed to be affecting the species within Gwynedd (taken from Gwynedd SAP);
Eutrophication of lowland lakes: fertiliser run-off leading to nutrient enrichment whereby the species cannot compete with other vegetation growth. Acidification of catchments, resulting in water quality impacts.
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Historic watercourse management such as flood defence works, dredging, straightening, canalisation, all resulting in habitat degradation. Disturbance from recreational use/crafts, resulting in habitat degradation. Introduced alien invasive species such as New Zealand pigmyweed Crassula helmsii.
3.3 Non-Designated Interest Features 3.3.1 The site supports a further six interest features, known to be present within Llyn Padarn. Four of these are listed on the SSSI citation but are not the primary reason for site designation. These are detailed below with information provided relating to the species’ ecology, status, distribution and sensitivity within Llyn Padarn.
Atlantic Salmon Ecology
3.3.2 Salmon utilise river systems for their reproductive and nursery phases, and the marine environment for adult development and rapid growth, migrating from the ocean into freshwater environments to spawn and rivers and water-bodies with suitable gravel beds. The species therefore benefits from the relatively low-risk spawning sites in rivers and the rich feeding on offer in the open sea (Hendry & Cragg-Hine, 2003).
3.3.3 After hatching, young fish spend between two and four years in freshwater before migrating to the sea to mature. Fish return to freshwaters to spawn on suitable gravel beds, mainly in autumn or winter, with a high adult mortality rate as a result of the effort involved in the spawning process. Eggs remain in the spawning site until they hatch, with the incubation period directly linked to water temperature. The stability of the spawning gravels during the incubation period is critical to the hatching rate. Juveniles will then remain in freshwater habitats whilst they mature, using a variety of in-channel micro-habitats (Hendry & Cragg-Hines, 2003).
3.3.4 The outflow of Llyn Padarn, the Afon Rhythallt, is known to be one of the most important spawning sites for Atlantic salmon within Gwynedd, where the gravel beds and stony substrates offer excellent spawning habitat in a relatively sheltered and undisturbed environment. July through to August is known to be the key period when runs of salmon occur in the river.
Status
3.3.5 The Atlantic salmon is listed in Annex II of the Habitats Directive. The species is also listed under Section 42 (Wales) of the NERC Act (2006) as a species “of principal importance for the purpose of conserving biodiversity”. Salmon are a UKBAP Priority Species and a Gwynedd LBAP species as well.
3.3.6 The Atlantic salmon is widespread in parts of the British Isles, with Scottish rivers being particularly important for the species. In Wales, breeding populations are present in most rivers, notably the larger river systems. Within Gwynedd, there are a number of rivers that have runs of salmon, including the Afon Rhythallt (Gwynedd LBAP, 2004).
3.3.7 There are recent records of salmon in the Afon Rhythalt immediately downstream of the outfall of Llyn Padarn, and within Padarn itself; near the inlet from Nant Peris and within a
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tributary running through Llanberis. Environment Agency reports indicate that there has been a decline in salmon catches in the Afon Seiont in the past five years (EAW, 2011). However, the Water Framework Directive fish classification for all waterbodies in the catchment are currently meeting good status or above, but this does not mirror Environment Agency rod catch data.
3.3.8 In 2010 the EAW undertook electrofishing surveys of key tributaries of Llyn Padarn and the Afon Seiont catchment including Caledffrwd, Afon Hwch and Afon Gafr. Survey results found either no salmon, or much lower numbers than had previously been found during surveys. The lower numbers were possibly due to the effects of a blue-green algal bloom in Llyn Padarn in 2009 restricting migration of fish into tributaries.
Sensitivities
3.3.9 Atlantic salmon are known to be sensitive to;
Water pollution, including diffuse agricultural run-off, point source pollution such as sewage discharges and mine/quarry drainage. This is as a result of direct (toxic impacts) and indirect impacts (de-oxygenation through eutrophication). Acidification of catchments. Silt erosion and in-channel deposition clogging up spawning gravels. Invasive species. Engineering works including works that result in habitat degradation, installation of barriers such as weirs and regime alteration through damming of rivers and abstractions. Angling. Climate change.
Sea Trout (Brown Trout in Freshwater) Ecology
3.3.10 The sea trout has a large native range, extending from Iceland down to Morocco, making them one of the most widespread freshwater fish in Europe. They are found in a variety of freshwater habitats, including rivers, large lowland water-bodies and upland lakes. The species has two alternative life-cycle patterns; the freshwater resident is referred to as brown trout, whilst the anadromous (sea going) form is sea trout.
3.3.11 Sea trout are like Atlantic salmon in that they migrate to sea to feed and mature before returning to freshwaters to spawn. Migration downstream from spawning grounds usually occurs between March and June, after up to two years spent in freshwater nursery habitat. They then utilise local coastal areas during their maturation stage at sea, rather than migrating long distances to specific feeding grounds. Migration back upstream by adult fish for spawning usually begins in October and continues through into December/January. Environmental factors such as water temperature and daylight hours, as well as genetic factors, determine the timing and duration of spawning in different river systems. Like salmon, spawning takes place over gravel beds with eggs laid and fertilised in a shallow pockets.
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3.3.12 Both sea trout and brown trout are present within Llyn Padarn, with the sea trout utilising the Afon Rhythallt outflow as a spawning area. Gravel beds elsewhere around the margins of the lake may also be used by brown trout for spawning (Gwynedd LBAP, 2004).
Status
3.3.13 Sea trout is listed under Section 42 (Wales) of the NERC Act (2006) as a species “of principal importance for the purpose of conserving biodiversity”. The species is also listed on the Gwynedd Local Biodiversity Action Plan (LBAP) and is a Priority Species on the UK BAP.
3.3.14 Trout have a similar geographical distribution and range to those of salmon. Within Gwynedd, sea trout are present in most rivers and streams, including the Afon Rhythallt and Llyn Padarn. Catches of migratory sea trout within Gwynedd are declining but brown trout still appear to be maintaining steady numbers.
3.3.15 In Llyn Padarn, a very important outlet spawning population of wild brown trout is suspected on the Afon Rhythallt. Outlet spawning is an indication of an ancient race, is usually restricted to old glacial lakes. Wild brown trout normally spawn on inlets, therefore if outlet spawning is confirmed in Llyn Padarn, the population of brown trout could be a genetically distinct race of trout (Gwynedd LBAP, 2004).
3.3.16 There are recent records of sea trout within Afon Rhythallt, around the outfall and within Llyn Padarn; around the outfall and the tributary inlets from Llyn Peris and Llanberis.
Sensitivities
3.3.17 As a very similar species, the sensitivities of sea trout are the same as the listed sensitivities of Atlantic salmon.
Small Quillwort Ecology
3.3.18 Small quillwort is a submerged aquatic perennial macrophyte usually found forming open stands to a depth of 2m in nutrient poor lakes over a wide range of substrates, from rocks and stones to silt and peat. It also grows in more mesotrophic water, such as coastal sea-level lakes enriched by wind-borne base salts, lowland reservoirs, slow-flowing rivers and flooded gravel- and clay-pits. The species is often associated with a few other macrophytes such as Potamogeton gramineus and Subularia aquatica, and occasionally it is found with filamentous green and blue-green algae. It often grows with lake quillwort Iseotes lacustris, and not infrequently hybridises with it (BRC, 2012).
3.3.19 The species is perennial. Copious spores mature in the autumn at the leaf-bases and embed in the tight rosette. They are only distributed when plants are dislodged by wave action or by fish or birds, and then washed up on the strand line or moved by birds (BRC, 2012).
3.3.20 The absence or rarity of the species in some areas where rock substrates appear suitable is unexplained but may be correlated with water temperatures and chemistry in early Pleistocene Britain (BRC, 2012).
3.3.21 The ecology of the species within Llyn Padarn is uncertain as there are no recent confirmed
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records of the species’ presence and the most recent condition assessment indicated that lake quillwort was present rather than small quillwort, and previous records are unconfirmed by specialists. Lake quillwort is found in the littoral zone in water depths of less than 0.5m.
Status
3.3.22 Small quillwort is widespread in Scandinavia but rare and scattered in Europe south of 55°N where it is threatened by eutrophication. The increase in records within the UK since 1962 may reflect a trend of the acidification of upland lake waters, but is more likely to be the result of more active botanical recording. It is likely that the species is still under-recorded in the UK and an accurate account of its distribution is unknown.
3.3.23 There is a single record for small quillwort within Llyn Padarn dating back to the period 1961-66. There are other records of the species within the 10km grid square but none within 5km of the site.
3.3.24 The CCW condition assessment (2006) notes the presence of lake quillwort rather than small quillwort, as stated on the SSSI citation. However, there are some subtle differences between the two species and they cannot be reliably identified without examination of megaspores. It is therefore uncertain as to which species is present within Llyn Padarn.
Sensitivities
3.3.25 The species is sensitive to competition from other species. Therefore, eutrophication as a result of fertiliser or lime runoff from pasture/agricultural fields leading to increased competition from other plants is a key risk factor. Given the preferred depth of small quillwort, any actions which result in frequent or drastic changes to water level could also affect the species through exposure and drying of key shallow habitat areas.
Otter Ecology
3.3.26 The otter is one of the UK’s largest carnivores. They are semi-aquatic and utilize every type of water-based habitat, including rivers, streams, wetlands, lakes and ponds, and estuaries. They feed mainly on fish, with amphibians forming a major part of the diet in late winter and early spring. During the day, otters lie-up in resting sites usually close to water. Typical resting sites include tree root systems (especially oak, ash and sycamore), boulder cavities, couches in wetlands, and dense scrub thickets. Otters have no fixed breeding season, but the timing of birth of the one to four cubs is probably linked to an abundant local food resource such as amphibians (SNPA, 2010).
3.3.27 Birth and early cub rearing usually take place in very secure undisturbed sites, often within several hectares of scrub, wetland or woodland. Each otter occupies a large home range, between 10 and 40Km of watercourse, and spends much time travelling to feed, defend territory and search for mates. Up to 30 resting sites distributed throughout the home range will be used by an otter, with each site being used for shelter for only one to three days at a time (SNPA, 2010).
3.3.28 Llyn Padarn is likely to offer undisturbed habitats along its northeast bank where woodland
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dominates the old mine and quarry workings and public access is limited. In contrast the southwest bank is characterised by tourism and recreational use, linked to the various amenities and attractions associated with Llanberis, and is likely to be less preferable to the species. The lake provides an excellent range of prey items including amphibians and various fish species, including salmonids.
3.3.29 It is therefore possible that Llyn Padarn is used by otter as a feeding resource whilst the more sheltered habitats found on the northeast banks may be used for places of shelter, holts or dens.
Status
3.3.30 The otter is listed on Annex II of the Habitats Directive. The species is also listed under Section 42 (Wales) of the NERC Act (2006) as a species “of principal importance for the purpose of conserving biodiversity”. Otter are a UKBAP Priority Species and a Gwynedd LBAP species as well.
3.3.31 Historically, otters occurred over most of the UK. However, persecution, habitat loss and, more recently, the impact of toxic organochlorine insecticides caused a marked reduction in the range of the species. At present, the majority of the otter population in Great Britain occurs in Scotland, with a significant proportion of this number being found in the north and west of the country. Other strong populations survive in Wales and Ireland. The otter is still scarce over much of England, where the highest concentrations are in the south-west (JNCC, 2012). However, recent surveys suggest that the otter population is recovering well and recolonising parts of its former range, but in low numbers, leaving the species vulnerable to future declines.
3.3.32 The species is relatively common on rivers throughout most of Wales with the most recent otter survey of Wales (1991-2002) showing an increase in the number of positive sites. However, this is believed to be representative of a widespread population in mid- and south-Wales, whereas in Snowdonia the animal is still relatively rare (JNCC, 2010).
3.3.33 In Gwynedd and Snowdonia NP key areas for the species exist in the Glaslyn, Gwyrfai and Seiont mountain rivers, and on the Dyfi and Dysynni catchments. Otter distribution throughout the rest of the region is patchy, with little or no otter activity on many rivers. Of the major lakes, Llyn Tegid is regularly visited by otters and they are also known to use a number of water-bodies within the Dwyryd catchment. Coastal habitat around the Llyn Peninsular and the Menai Straits is also inhabited (Gwynedd LBAP, 2004).
3.3.34 The most recent records for otter around Llyn Padarn are from 2002 in the Afon Rhythallt near Llyn Padarn. Other records for otter are from 1993, from Llyn Peris indicating that the species is still able to persist in the lower reservoir of the Dinorwig scheme.
Sensitivities
3.3.35 The following factors are believed to be affecting the species within Gwynedd (taken from Gwynedd SAP/JNCC/SLBAP);
General declines in fish populations as a result of over-fishing, pollution and river management. Drainage of wetlands which removes amphibian food resource and potential breeding ETIVE ECOLOGY 19 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
sites. A lack of resting sites and a continuing loss of suitable tree and scrub cover for resting sites, as a result of grazing and poor bankside management. Small, scattered populations cannot sustain losses from road kills, drowning during floods etc. Use of toxic sheep dips and other chemicals. Pollution, diffuse and point source, and acidification of watercourses and the subsequent effect of this on fish populations. Disturbance from recreational users.
European Eel Ecology
3.3.36 The European eel is catadromous, living in fresh water but migrating to marine waters to breed. Within its freshwater stage, the species is found in all types of benthic habitats from small streams to shores of large rivers and lakes. It only occurs naturally in water bodies that are connected to the sea, being stocked elsewhere. Juveniles inhabit rivers, streams, lake ponds, estuaries and coastal lagoons. They live on the bottom, under stones, in the mud or in crevices. Eels are individualist in all its life-stages. Once fully mature, adult eels migrate downstream and out in estuarine waters and the open sea where they spawn. The spawning peaks between March and July. Little is known about the location or details of eel spawning. Young glass eels (elvers) return to estuaries to develop, before heading up into freshwater systems (IUCN, 2010).
3.3.37 Llyn Padarn is connected via the Afon Rhythallt, which after 2km feeds into the Afon Seiont and eventually the Menai Straits and the Irish Sea, allowing elvers to swim up to the lake where they can mature. It is likely that the rocky margins around the lake provide good habitat for foraging and sheltering eels.
Status
3.3.38 The European eel is listed under Section 42 (Wales) of the NERC Act (2006) as a species “of principal importance for the purpose of conserving biodiversity”. Eels are a UKBAP Priority Species and are listed as critically endangered on the IUCN Red List (2010).
3.3.39 There has been a 65% decline over the last 25 years in the number of 10km squares or number of water-bodies known to host the species within the UK. There is definitive evidence of species decline but little evidence of a reduction in the geographical range (JNCC, 2010).
3.3.40 There are records of eels in and around Llyn Padarn from EAW fisheries monitoring. The species was found in 2005 and 2007 at the eastern end of the lake near Llanberis and the inflow from Nant Peris. In 2005, eels were recorded at the northwest end of Llyn Padarn and in 2008 they were recorded downstream of the lake within the Afon Rhythalt. A large adult was also recorded in an old bomb store in Glyn Rhonwy (2009), indicating that the species is able to persist in isolated water-bodies such as those present within these former quarries and mines.
Sensitivities
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3.3.41 The species is sensitive to the following factors;
Changes to global weather / climatic conditions; impacting spawning, larval survival and growth rates. Overfishing for glass eels (mainly in France, Spain, Portugal and UK) and downstream migrating eels (silver eels) across Europe due to demand in Asia. According to ICES (2006) eel fisheries are currently not sustainable, and a recovery plan urgently needs to be developed for the whole stock. Parasites found in some farmed stocks, suspected to impact the ability of wild European eels to reach their spawning grounds. Dams (for hydropower and water management) are also a threat to the species by blocking migration routes and also through causing high mortality rate as the downstream migrating eels are killed by turbines. Climate change may be having an impact on the suspected breeding grounds (Sargasso Sea). Increasing numbers of predators, in particular cormorants, across Europe may also have a negative impact on this species
Lamprey Species 3.3.42 There are records of brook lamprey Lampetra planeri downstream of Llyn Padarn and lamprey species within the lake itself. Without further information or records relating the species within the lake, it is assumed for the purpose of this assessment that it is brook lamprey that are present within the catchment. However, it should be noted that it is possible that all three species are present.
Ecology
3.3.43 The brook lamprey is a primitive, jawless fish resembling an eel, and is the smallest of the lampreys found in the UK. It is a non-migratory freshwater species, occurring in streams and occasionally in lakes in north-west Europe. Like other lamprey species, the brook lamprey requires clean gravel beds for spawning and soft marginal silt or sand for the ammocoete larvae. It spawns mostly in parts of the river where the current is not too strong (JNCC, 2012).
3.3.44 Within Llyn Padarn it is possible that the species utilises the gravel and stony beds found around the lake margins and at inflow/outflows at either end of the lake to spawn.
Status
3.3.54 All three lamprey species are listed in Annex II of the Habitats Directive. River lamprey and sea lamprey are also listed under Section 42 (Wales) of the NERC Act (2006) as species “of principal importance for the purpose of conserving biodiversity” and are UKBAP Priority Species. All lampreys are Gwynedd LBAP species as well.
3.3.46 The brook lamprey is considered to be widespread and common in Britain but vulnerable in Europe. The species, has however, declined in parts of the UK, although it is still widespread. This species is the most abundant and widespread of the British lampreys and is often found in the absence of the other two species, for example above a barrier that precludes the presence of the migratory species (JNCC, 2012).
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3.3.47 There has been no targeted survey work on lampreys within Gwynedd but all three species are known to be present, having been found in various locations and catchments (Gwynedd LBAP, 2004). EAW monitoring records indicate that brook lamprey have been found within the Afon Rhythalt in 2008 and that a lamprey species was found within the eastern end of Llyn Padarn in 2005.
Sensitivities
3.3.48 Lamprey species are sensitive to the following environmental factors;
Water pollution including diffuse run-off, point source sewage discharge, drainage from mines/quarries, direct and indirect impacts. Silt erosion (from catchment management) and subsequent in-channel deposition River works leading to habitat degradation including loss silt beds and siltation of spawning gravels. River work leading to the creation of environmental barriers including weirs and dams Alterations to the flow regime which can not only change sediment deposition factors but also cause drying or loss of spawning and grounds and prevent migration upstream as a result of low flows.
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4 CONSULTATIONS 4.0 A full record of the consultation process and all relevant discussions and meeting minutes are presented in the main Environmental Statement. For the purposes of this assessment, the specific issues raised with regards to the freshwater interest features associated with Glyn Rhonwy and Llyn Padarn SSSI are considered.
4.1 Environment Agency Wales 3 January 2012, Scoping Opinion
EAW noted that an investigation into potentially contaminated land within Glyn Rhowny and the likelihood of contaminants leaching into groundwater or surface waters would be required. Monitoring of water quality would be required both during and post-construction. Concern was also raised over the potential for the works to release suspended sediments and slate fines into local watercourses. Environment Agency standards for working near watercourses must be adhered to, including Pollution Prevention Guidance 5 “ Works and Maintenance in or Near Water”. It was strongly recommended that a detailed method statement be prepared governing all works in relation to managing water on site.
29 May 2012, Meeting
EAW suggested that the proposed daily abstraction volume from Padarn (~1-2 megalitre/day) sounded acceptable, but that a ‘hands-off’ condition may be required during low-flow periods to prevent abstraction when it would be potentially damaging to the lake ecology. The impacts of abstraction and spillways must be considered within the Environmental Impact Assessment. EAW noted that abstraction from the Quarry 1 catchment would not be permitted as it is already over-subscribed. The proposed scheme may also affect flows out of the quarry and EAW were to investigate these issues further. Quarry Battery were asked to detail further their drainage requirements at Quarry 1. EAW detailed their concern regarding the residual risk of heavy metals being present within the ground around Quarry 6 and the bomb store, and whether these could be released in groundwater or surface waters during works. Monitoring would be required prior to any planning submission to establish the water quality baseline. Subsequent monitoring during the operational phase would also be required. Discharges into Llyn Padarn may only be allowed when the water level in Llyn Padarn is low enough, similar to the discharge consent for Llyn Peris. The additional flooding risk associated with Llyn Padarn is a concern for EAW and the design of the scheme needs to consider this additional flood risk with a degree of certainty. The water temperature of discharges into Padarn is also a concern to EAW. A similar issue is currently being investigated by EAW in Llyn Peris. A Water Framework Directive assessment will be required prior to planning submission. A discharge consent will be required (to cover difference in water temp and potential contaminants) under the Water Framework Directive. Quarry Battery should contact EAW fisheries and local fisheries groups for further fisheries data.
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June 2012, Email correspondence
4.1.1 EAW provided a recommended scope for water quality monitoring, including biological and algal testing/analysis. Quarry Battery queried the inclusion of biological and algal testing, rationalising that faecal content was expected anyway (due to adjacent land use including some agricultural land) and algal content was not relevant as the purpose of the testing was primarily to identify heavy metal content. These tests were excluded from the schedule of analysis.
June 2012, Email with Fisheries
4.1.2 EAW fisheries team noted that coarse fish are suspected to be present in Glyn Rhonwy, possibly trout as well, but that there are no records to support either of these assumptions. If present, the scheme could result in the transfer of coarse fish and/or their eggs/fry into Llyn Padarn, to the detriment of current fish populations including Arctic charr. EAW recommended that this issue was followed up, qualified (i.e. are coarse fish present in any of the quarries) and addressed as it would be a potential adverse effect on the SSSI.
4.1.3 The fisheries team reconfirmed that discharging water into Llyn Padarn may result in the input of water with high nutrient loads and higher temperatures. They noted that Arctic charr in Llyn Padarn are under pressure and further nutrient loading and temperature differences could exacerbate conditions. Quarry Battery will need to determine whether water releases will impact temperatures and nutrient levels in Llyn Padarn which could subsequently affect the charr population and potentially other fish species.
4.1.4 EAW Fisheries noted that water extraction via pumping from Llyn Padarn has the potential to cause entrainment of fish. Any such activity would require a fish screen to be attached on the pump inlet to prevent entrainment, with 1-2mm spacing. EAW also requested further information regarding the proposed location of the inlet for the pumps and the likely size of the pumps.
4.2 CCW January 2012, Scoping Opinion Response
4.2.1 In relation to Llyn Padarn SSSI, the main concerns relate to the following potential impacts;
Polluted water from the scheme entering the lake (directly or indirectly), and/or impacts from heated water (used within the operational process) being discharged in the lake and resulting in increased water temperatures. These occurrences could impact on Arctic charr and mitigation measures would be required. The accidental introduction of non-native invasive species a Bio-security Risk Assessment should be undertake to assess the level of risk of non-native introductions.
4.2.2 In relation to statutory protected species, the following relevant comment was made;
In addition to legally protected species the EIA should consider the impacts to habitats and species listed under Section 42 of the Natural Environment and Rural Communities (NERC) Act (2006) and the Gwynedd Local Biodiversity Action Plan (LBAP).
4.2.3 CCW also made the following comment regarding a Bio Security Risk Assessment; “The EIA should include an Invasive Non-Native Species (INNS) bio-security risk assessment. This will ETIVE ECOLOGY 24 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
need to consider INNSs already present on and immediately adjacent to the site, together with measures that prevent accidental or deliberate introductions onto site. The assessment should also consider and address any risks posed by INNSs to statutory protected species, habitats or sites.”
4.3 Gwynedd Council January 2012, Email correspondence
4.3.1 Discussions with the senior biodiversity officer at Gwynedd Council regarding the scheme related to the ecological issues and sensitivities of the site area within Glyn Rhonwy, rather than those relating specifically to Llyn Padarn SSSI.
4.3.2 Those issues raised related primarily to terrestrial ecology but did include reference to the presence of eel with Glyn Rhonwy and the need for the ecological assessment to consider species and habitats listed on the Gwynedd LBAP and the Section 42 lists of the NERC Act 2006.
4.4 Summary 4.4.1 The key issues identified during the consultation were;
Potential for contamination to groundwater and/or surface waters within Glyn Rhonwy. Water quality monitoring will be required pre-application, during construction and post-construction. Sensitive working in relation to water-courses will be required and should be detailed in a construction method statement. Abstraction at ~1 megalitre/day is likely to be acceptable but abstraction will not be permitted when levels in Llyn Padarn are low. Pumped abstraction from Llyn Padarn will require fish screens to prevent fish entrainment. Abstraction from Quarry 1 will not be permitted. Discharge regime into Llyn Padarn will need to consider the flood risk potential, the water temperature and water quality of discharged waters. Potential impacts on fish populations in Llyn Padarn will need to be assessed if coarse fish are present within Glyn Rhonwy and they are allowed to enter Llyn Padarn as a result of the scheme. A Water Framework Directive assessment will be required for the scheme pre-application. Ecological appraisals of the scheme should consider Gwynedd LBAP species and NERC habitats and species. A Bio Security Risk Assessment will be required for the scheme.
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5 IMPACT ASSESSMENT
5.1 Potential Impacts 5.1.1 Based on the desk study data presented Chapter 3, and considering the potential ecological sensitivities of the ecological receptors in Llyn Padarn against the scheme description, it is possible to predict the potential scheme impacts on this waterbody. If consented, the scheme will progress in a number of stages including:
Construction: Including stabilisation and lining of the quarries, construction of the dams construction of the pipeline and turbine house, and construction of the abstraction point and pump house. Abstraction: Filling of the quarries will take place, with an abstraction from Llyn Padarn being used to fill the quarries over a period of approximately one year. Operation: Once operational the scheme will operate as a closed system with water cycling between the upper and lower quarries over a 24hour period. Occasional discharges will occur via a spillway during periods of heavy rainfall. Decommissioning: The scheme will be decommissioned at the end of the consented period, which is expected to be 100 years. 5.1.2 The potential impacts of the scheme relevant to Llyn Padarn SSSI are shown in Table 5.1 below.
Table 5.1: Potential Impacts of the Quarry Battery on Freshwater Receptors of Llyn Padarn
Scheme Stage Element of Scheme Potential Impacts Potentially Affected Ecological Receptors Construction Stabilisation and lining Siltation and pollution of SSSI Features: of quarries and Llyn Padarn as a result of Arctic Charr: Silting of spawning beds, construction of dams construction activities. decreased oxygen. and pipeline Floating water plantain: Reduced light levels and silting of habitats. Non-SSSI Features: Atlantic Salmon, Sea trout, Brown trout and lamprey: potential silting of spawning habitat Macro-invertebrate fauna and macrophytes including small quillwort: silting of habitat and smothering of species. Construction of Disturbance of protected Non-SSSI Features: pumphouse species on shoreline of Otters: disturbance to shelters or foraging Llyn Padarn. habitat. Siltation or other SSSI Features: pollution of Llyn Padarn Arctic Charr: Silting of spawning beds, as a result construction decreased oxygen. activities. Floating water plantain: Reduced light levels and silting of habitats. Non-SSSI Features: Atlantic Salmon, Sea trout, Brown trout and lamprey: potential silting of spawning habitat Macro-invertebrate fauna and macrophytes including small quillwort: silting of habitat and smothering of species Construction of Disturbance of protected Non-SSSI Features: Otters: Disturbance to off-take and discharge species on shoreline of animals and/or damage to shelters pipe from Llyn Padarn Llyn Padarn. Damage to an area of SSSI Features: lake bed approximately Arctic Charr: Potential disturbance/loss of 30m long and 5m wide spawning and feeding habitat. ETIVE ECOLOGY 26 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
Scheme Stage Element of Scheme Potential Impacts Potentially Affected Ecological Receptors Floating Water Plantain: Potential loss of habitat and plants. Non-SSSI Features: Atlantic Salmon, Sea trout, Eels, Lamprey species, Brown trout: Potential disturbance/loss of spawning and feeding habitat. Macro-invertebrate fauna and macrophytes including small quillwort: Potential loss of habitat including plants and invertebrates. Abstraction First Fill of Quarry Draw down of Llyn SSSI Features: System from Llyn Padarn and subsequent Arctic Charr: Exposure of spawning beds Padarn – approximately exposure of shoreline. during draw-down. 2000m3 per day over a Floating Water Plantain: Exposure and period of one to two drying out of suitable habitat years. Non-SSSI Features: Atlantic Salmon, Brown trout, Sea trout and lamprey: potential exposure and drying out of spawning or feeding habitats. Entrainment of fish within SSSI Features: Arctic charr the off-take pipe. Non-SSSI Features: Atlantic salmon, Brown trout, Sea trout, European Eel, Lamprey. Changes in water quality SSSI Features: as a result of draw-down Arctic Charr: Increased nutrient levels and of the lake. depleted oxygen levels affecting fish growth and population. Floating Water Plantain: Eutrophication leading to increased competition from other plant species. Non-SSSI Features: Atlantic Salmon, Brown trout, Sea trout, Lamprey Species, European Eel: : Increased nutrient levels and depleted oxygen levels affecting fish growth and population. Small quillwort: Increased competition from other species as a result of eutrophication. Macro-invertebrates: Shift in macro-invertebrate fauna as a result of eutrophication. Operation Cycling of water around No impacts on Llyn N/A the system Padarn – water is cycled in a closed system Occasional discharge Water level fluctuations SSSI Features: into Llyn Padarn and flooding on the lake Arctic charr: Flooding or wash out of margins. gravels. Floating Water Plantain: Changed in depth of water affecting plant ecology. Non-SSSI Features: Atlantic salmon, lamprey species, European eel, brown and sea trout: Potential flooding or wash out of spawning habitats and potential impacts on migratory watercourses. Plant species: Changed water depth and potential wash out of habitats affecting plant ecology. Macro-invertebrates: Potential change in invertebrate communities as a result of changed lake bed habitat, changed water depths etc. Changes in water quality SSSI Features: due to differences in the Arctic charr: direct toxic effects and chemistry of the potential effects on fish development and
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Scheme Stage Element of Scheme Potential Impacts Potentially Affected Ecological Receptors discharge and the lake. fecundity. Floating water plantain – competition impacts from other plant species as a result of increased nutrients and potential direct toxic impacts. Non-SSSI Features: All features – as above. Localised changes in SSSI Features: water temperature as a Arctic Charr: Impacts on fish growth, result of differences in development and survival as a result of temperature between the changed temperatures. Increased stress discharge and the lake. on fish as a result of increased temperatures and decreased oxygen levels Non-SSSI Features: Atlantic salmon, Brown trout, sea trout, lamprey and European eel: As above. Potential algal blooms as SSSI Features: a result of the quarry Arctic Charr: potential positive impacts discharge ‘seeding’ Llyn through increased food source, countered Padarn. by likely decrease in oxygen levels. Floating Water Plantain: Reduced growth and survival due to decreased light levels. Non-SSSI Features: Atlantic Salmon, brown and sea trout, lamprey and European Eel: As for Arctic charr. Macrophytes including small quillwort: Reduced growth and survival due to decreased light levels. Scour and wave action as SSSI Features: Floating Water Plantain: a result of the discharge disturbance of rooting habitat. pipe causing disturbance Non-SSSI Features: Other macrophytes: to the lake bed. As above. Introduction of alien SSSI Feature: Arctic charr and Floating species and coarse fish water plantain – potentially adverse into Llyn Padarn SSSI. impacts through competition for resources and space, and introduction of disease. Non-SSSI Feature: All features – as above. Decommissioning Draining of quarry Changes in water quality Similar impacts to operational discharge system as a result of draining the but on a greater scale. quarry system into Llyn Padarn Water level changes as a Similar impacts to operational discharge, result of draining the but on a greater scale quarries into Llyn Padarn. Changes in water Similar impacts to operational discharge temperature as a result of but on a greater scale. draining the quarries into Llyn Padarn Removal of pumphouse Siltation or other SSSI Features: structure and pipeline pollution of Llyn Padarn Arctic Charr: Silting of spawning beds, as a result of decreased oxygen. decommissioning Floating water plantain: Reduced light levels and silting of habitats. Non-SSSI Features: Atlantic Salmon, Sea trout, Brown trout and lamprey: potential silting of spawning habitat Macro-invertebrate fauna and macrophytes including small quillwort: silting of habitat and smothering of species. Disturbance of protected Non-SSSI Features: species during Otters: disturbance to shelters or foraging decommissioning habitat.
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Scheme Stage Element of Scheme Potential Impacts Potentially Affected Ecological Receptors activities.
5.2 Assessment of Impacts: Construction Siltation and pollution of Llyn Padarn as a result of construction of the quarries, pipeline, pumphouse and abstraction/discharge point
5.2.1 The quarries and pipeline route that the scheme outline is based on, are not in close proximity to, or connected to any watercourses. However, the scheme will require suitable drainage of construction works which will eventually discharge into the surface water system, although the exact details of this drainage design are not known. The works in Llyn Padarn to lay the pipeline, and on the shoreline of the lake for the construction of the pump-house, both have the potential to generate silt and suspended sediments, and unlike the construction of the quarry and the pipeline, these works will be directly connected to, or in close proximity to Llyn Padarn.
5.2.2 Generation and release of suspended solids and silts into Llyn Padarn has the potential to cause short to medium term negative impacts on the SSSI features of the lake (Arctic charr and floating water plantain) as well as non-SSSI features including Atlantic salmon, brown and sea trout and macro-invertebrate fauna. Impacts of elevated suspended solids entering the lake could include:
Smothering of spawning gravels and substrate Smothering of macrophytes and macro-invertebrates as a result of deposition of suspended solids directly on to these features Reduced oxygen levels as a result of the biological oxygen demand of decay of silt and suspended solids Increased turbidity and low light levels affecting growth of macro-invertebrates
5.2.3 Pollution could also result from non-organic sources potentially including accidental spills of substances such as fuels, lubricating oils and cement.
5.2.4 Impacts could potentially be substantial in magnitude depending on the nature of any incident and therefore there could be large or very large significant effects on both ecological features of the SSSI as well as non-SSSI ecological receptors. However, the likelihood of such impacts occurring is reduced through the scheme design including industry standard water protection measures, with specific reference to the Environment Agency Pollution Prevention Guidance. It is thought that with the application of appropriate working methods and water pollution prevention measures, the chance of such impacts occurring is negligible. Impacts are therefore considered to be no greater than slight in magnitude and of slight/moderate significance for all receptors. Further detail on pollution prevention measures is provided in Chapter 6.
Disturbance of protected species as a result of construction activities on Llyn Padarn shoreline
5.2.5 An initial survey of the shoreline in the proximity of the proposed pump-house and pipeline has been carried out to assess the potential for the presence of protected species (Cambrian Ecology Partnership, in AECOM, 2012)). The survey considered that the shoreline was too ETIVE ECOLOGY 29 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
disturbed by wave action and human activity to be suitable for water vole, and despite a detailed search, no evidence otter or shelters of the species were found. Searches of the woodland around the proposed pump-house location were conducted and no signs of badger or their setts were found.
5.2.6 Despite the lack of survey evidence it was considered that otters are likely to periodically use the shoreline for foraging and movement, and that badgers may also use the shoreline woodland for foraging. Some disturbance of foraging activity of these two species may therefore occur during the construction period.
5.2.7 The disturbance as a result of construction will be short term, lasting only as long as the construction period. All of the construction activity will take place during daylight hours, out-with the key periods of activity for the two species and disturbance due to noise and human activity is expected to be of slight magnitude. A risk may potentially occur as a result of badgers and otters entering the construction area during the night, and coming into contact with exposed trenches or harmful construction materials.
5.2.8 Without appropriate mitigation these impacts may potentially be significant resulting in harm or injury to protected species. However, the scheme design has included for good practice construction measures detailed in Chapter 6 and any impacts are likely to be negligible in magnitude, having impacts of only slight significance.
Damage to lake bed as a result of construction of the off-take/discharge pipeline
5.2.9 The pipeline which will be connected to the shore-line pump-house and used for both the abstraction during the fill period and periodic discharges during the operational period will consist of two pipelines, being approximately 30m in length and taking up an area no more than 5m wide. The pipeline will be constructed on the lake shoreline and then floated out and sunk in the required location. It will be connected to the lake bed by approximately ten concrete collars. A small amount of trenching may be carried out close to the shoreline to bury and hide the pipeline below ground level for aesthetic purposes.
5.2.10 The laying of the pipeline along the lake bed, and minor trenching works may will create localised disturbance to the lake bed and cause the loss of a small area of habitat as a result of the footprint of the pipeline. The disturbance, principally including sediment disturbance and siltation, will be short term in duration, whereas habitat loss will be permanent for the duration of the scheme.
5.2.11 Detailed surveys of the lake bed in the location of the pipeline have not been undertaken for this survey. However, it is known that the preferred spawning location for Arctic charr is some 1km to the east on clear gravels at Afon y Bala close to the old connecting watercourse between Llyn Peris and Llyn Padarn. Arctic charr are also know to use the deeper central areas of the lake for feeding, rather than shoreline habitat as a result of competition for foraging resources between charr and trout (SNH in Charrnet et el, 2005). Impacts on Arctic charr as a result of pipeline construction are therefore likely to be negligible.
5.2.12 The most recent survey of floating water plantain which has been carried out by the Environment Agency Wales (condition monitoring surveys 2003) did not identify this particular location as being a key area for the plant species. The plant was only identified some 1km east of this location. Based on the most recent surveys, it would seem that
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there would be no effect on the species. However, the EAW survey methodology only includes spot samples, so it cannot be concluded that the species is absent from the lake bed in this location.
5.2.13 The expected area of habitat disturbance and loss is no greater than 5m x 30m. In the context of Llyn Padarn, which is approximately 3km in length and 0.5km wide, this is a very small scale effect. However, in terms of the areas of the lake that are suitable for or support floating water plantain, even loss of a small area of habitat could be significant if floating water plantain were found in the construction area, despite what is apparently a small scale effect.
5.2.14 Impacts on other ecological receptors which are not included in the SSSI citation are likely to include:
Disturbance and loss of a small amount of lake bed and the macrophyte and macro-invertebrate fauna this area supports. Potential loss and disturbance of a small area of fish spawning habitat (though it is not known if this particular location is used for spawning). Potential localised siltation during construction.
5.2.15 The potential siltation impacts will be short-term during construction, whereas the loss of habitat will be a permanent effect of the scheme.
5.2.16 Impacts on Arctic charr and other fish species are therefore considered to be of slight significance and impacts on floating water plantain and small quillwort of neutral significance if their presence is not identified during pre-construction surveys and of large to moderate significance if the species are found during pre-construction surveys. Impacts on all non-SSSI receptors are considered to be of slight significance.
5.3 Assessment of Impacts: Abstraction Draw-down of lake and shoreline exposure as a result of abstraction
5.3.1 A planned daily abstraction rate of 2000m3 per day from Llyn Padarn is planned to take place for a period of approximately one to two years. This abstraction rate is the recommended maximum rate advised by the Environment Agency Wales and is currently predicted to result in a draw-down in Llyn Padarn of not more than a few millimetres per day in the absence of any other top up of the system. This would result in <0.75m of total draw-down if all of the water required was abstracted at once. In practice this is unlikely to occur due to the length of time that the abstraction will occur over and due to influxes of water (including rainfall) into Llyn Padarn.
5.3.2 Modelling of the effect of this draw-down on the size and extent of the exposed lake shoreline has not been carried out. However, it is likely that there will be an area of shoreline normally submerged, which will become exposed as a result of draw-down. These areas are likely to be quite limited as CCW bathymetry data indicates that much of the shoreline area becomes rapidly deep (8 – 9m) with the main shallow zones in the north-east of the lake and a few shallower areas along the eastern and south-west shore. The effect is likely to be most pronounced during dry periods, and not necessarily restricted to summer and the shallow marginal areas of the lake are most likely to be affected.
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5.3.3 Exposure of shoreline areas could result in a number of impacts. Specifically in relation to the SSSI features, there may be drying or loss of floating water plantain communities, although in practice, this is unlikely as the species is currently found in water depths of 2 – 3m. However, reduced water depth due to draw-down may mean the species is present in shallower than usual water, reducing its growth rate or increasing plant stress. The second key potential impact is the drying of key areas of spawning substrate used by Arctic charr. The effects are likely to be most severe during dry weather and during key spawning periods for Arctic charr, particularly November and December. The shallow spawning gravels at Afon y Bala may therefore be particularly vulnerable to draw down during December. Similar impacts may result on non-SSSI species including brown trout, other fish and macrophyte species and macro-invertebrates principally as a result of the contraction of marginal areas.
5.3.4 For mobile species (fish and invertebrates) there is likely to be some adaption to the lower water level. The rate of draw-down will be very low and will allow invertebrates to move with the water level. Fish may lose some, but not all spawning habitat and there may be increased competition for spawning sites and foraging resources including competition within and between species. Plant species which are not mobile will be less able to adapt.
5.3.5 Despite this, the draw-down should be no more significant than a dry year, and re-colonisation and readjustment will occur quite rapidly after the period of abstraction. Impacts are considered to cover the short to early medium term, with the potential for a full recovery in the medium to long-term. If the draw-down occurs in a dry year the impacts are likely to be more severe and recovery may be more difficult due to areas of the lake bed drying out and becoming hardened. Without appropriate mitigation, the impacts on Arctic charr and other fish species could be moderate in magnitude, particularly if low water levels in November and December coincide with abstraction this would result in an effect of moderate to large significance. Impacts on floating water plantain, other plant species and macro-invertebrates are likely to be lower in magnitude, with a predicted slight magnitude and slight to moderate significance.
Entrainment of fish in the abstraction pipe
5.3.6 During abstraction there is potential for fish to become entrained within the abstraction pipe. Without mitigation this could result in a loss of or harm to the various fish species that are present in Llyn Padarn including Arctic charr, Atlantic salmon, sea trout, brown trout lamprey species and eel. This effect would only occur during the time period it would take to fill the quarry system, currently anticipated to be a year. It is impossible to quantify the number of fish that might be lost, however given the current status of Arctic charr in Llyn Padarn any loss of fish and subsequent reduction in recruitment is likely to be a significant negative effect.
5.3.7 The effect of entrainment is considered likely to have moderate magnitude impacts on all fish species in Llyn Padarn. Although only a small proportion of fish in the lake would be affected, any losses will have significance on the overall lake populations, impacts are therefore considered to be of moderate to large significance without application of suitable mitigation.
Changes to Water Quality as a Result of Abstraction Draw-Down ETIVE ECOLOGY 32 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
5.3.8 Detailed water quality modelling has not been carried out as part of the assessment. The daily abstraction rate is planned to be a maximum of 2000m3 per day, compared to a volume of approximately 15 million m3 in Llyn Padarn. As discussed above, this rate of abstraction is not expected to yield more than a a few millimetres of draw-down each day, and subsequent recharge by rainfall will counteract this effect. This scale of effect through draw-down, although potential important in terms of exposure of shoreline, is not expected to lead to significant impacts on water quality due to the large volume of the lake itself. Impacts on all receptors are therefore predicted to be of negligible magnitude and slight significance.
5.4 Assessment of Impacts: Operational Discharges Changes in Water Quality as a Result of the Discharges
5.4.1 As the Quarry Battery system will be filled initially by abstraction from Llyn Padarn and incidental rainfall, the only potential sources for changes in water quality are:
Leaching of contaminants from ground water and surface water flow with the system and adjacent catchment area. Accumulation of nutrients in surface water run-off from the quarry catchment. Chemistry changes within the quarry system itself.
5.4.2 Initial water quality investigations have indicated that there is no residual contamination of the quarry systems with heavy metals or other contaminants. Further details on water quality sampling are provided in Chapter 8 (Water Resources) of the Environmental Statement. These early sampling results indicate that there is likely to be no effect on the water chemistry of Llyn Padarn as a result of contaminated water discharges from the quarry system.
5.4.3 Much of the surrounding catchment for the quarries is dominated by the remnants of old slate mines and quarries. The system is not therefore expected to receive surface water run-off which is rich in nutrients which principally would result in agricultural catchments. Levels of phosphates , which are currently a cause for concern in Llyn Padarn, are therefore not expected to be any higher than the background levels in SSSI.
5.4.4 The continual circulation of water within the quarry battery system will result in a discharge which is sufficiently aerated. Combined with the current data which suggests that the quarry system is not affected by heavy metal or other contamination, and situated in a catchment which is not expected to receive high nutrient inputs, it is expected that the discharge from the system is highly unlikely to have significant impacts on the water quality of Llyn Padarn. Furthermore, the volume of the expected average daily discharge (1200m3 (maximum) though variable over the year in response to rain-fall and storm events) compared with the volume of Llyn Padarn (15 000, 000m3) further reduces the likelihood of significant impacts. It is therefore considered that any changes in water chemistry will be of negligible magnitude and slight significance for all receptors as a result of operational discharges into Llyn Padarn.
Changes in Water Levels as a Result of Discharges into Llyn Padarn
5.4.5 During periods of wet weather, it is expected that there will be routine discharge from the Quarry Battery system into Llyn padarn to prevent the system becoming inundated. On ETIVE ECOLOGY 33 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
average the discharge is expected to be a maximum of 1200m3 per day although this will vary and discharges will be carried out in response to rain-fall and storm events. Details on the water level fluctuation as a result of this discharge are provided in Chapter 8 of the Environmental Statement, however, the expected daily change in water depth as a result of discharges is expected to be no more than a few millimetres a day. The effect will be more pronounced if discharges occur during periods of wet weather and flooding.
5.4.6 The scale of the discharge when compared to the volume of Llyn Padarn (15 million m3) is small, equating to approximately 0.013% of the lakes volume based on an 800m3 discharge volume, or 3.6% of the Q95 flow along the Afon Seiont as measured at Peblig Mill. Given that the discharge is water that would normally have naturally entered the catchment during rainfall events, it is unlikely that the discharge will have any discernible impacts on water level or shoreline flooding. Impacts are therefore considered to be negligible in magnitude and overall the impacts on ecological receptors in Llyn Padarn are considered to be of slight to neutral significance.
Temperature Changes in Llyn Padarn
5.4.7 Arctic charr are the least tolerant of salmonids to increased temperatures and the most tolerant to low temperatures (Baroudy, 1995)). In experiments, Arctic charr have been found to have the highest growth rates in water temperatures between 120C and 160C (Maitland, 1992)). Increased temperatures can have negative impacts on salmonid fish species including Arctic charr, Atlantic salmon and trout species, principally through reducing the dissolved oxygen levels within the waterbody, which subsequently places salmonid species under stress as without exception they require high oxygen levels.
5.4.8 Due to the potential issue of temperature spikes in Llyn Padarn as a result of the routine discharges from First Hydro’s Dinorwig scheme, the Quarry Battery scheme has been designed to be low friction and fundamentally different from the Dinorwig scheme. The Quarry Battery will be a closed system with Q6 (Quarry 6) being the bottom reservoir, not Llyn Padarn (as is the case for Dinorwig). The scheme has also been designed to be low friction, minimising the warming of water used in the system.
5.4.9 It is difficult to predict the temperature range of water that will be held within the pumped storage system and which will be discharged into Llyn Padarn. Water temperatures will vary diurnally and seasonally and will be moderated by the bathymetry of the reservoir, the operation of the plant/mixing and the altitude of the quarries. However, it is not considered that the temperature of the water within the system will vary significantly from that within Llyn Padarn. Should there be slight differences in temperature, the relatively low rate and volume of any overflow will be buffered by the much larger volume of water in Llyn Padarn. The expected daily discharge from the scheme is in the region of a maximum of 1200m3 compared with a volume of Llyn Padarn that is approximately 15 million m3. Compared to the scale of the Llyn Padarn, the discharge could only ever have a localised effect on water temperatures. Given what is known about spawning in the lake, with most fish spawning in the shallows of Llyn Padarn, any localised temperature affect at the outfall is unlikely to have a significant effect on fish species. Further details on temperature modelling are found in Chapter 8 of the Environmental Statement.
5.4.10 Given the predicted temperature of the discharge (Chapter 8)) and the scale of the discharge in comparison to Llyn Padarn, the impacts are considered to be negligible in magnitude. ETIVE ECOLOGY 34 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
Significant impacts of increased temperatures of Llyn Padarn are therefore considered highly unlikely to occur and for all ecological receptors are considered to be of slight to neutral significance.
Potential for ‘algal’ seeding of Llyn Padarn
5.4.11 The potential for occasional discharges to result in the ‘seeding’ of Llyn Padarn with algal blooms was raised by consultees. Algal blooms, apart from being unsightly and a recreational hazard, can seriously reduce light and oxygen levels within water bodies, and would subsequently have a deleterious effect on both SSSI and non-SSSI ecological receptors.
5.4.12 Algal growth is mainly influenced by water composition, temperature and light intensity. Algae also require a stable water column; largely still, calm impoundments can often have problems with algal blooms, particularly where nutrient inputs are high. Any actions which disturb, aerate and mix the water column will significantly inhibit the growth of algae and physical measures such as the blowing of compressed air through tubes or using methods including pumps to recirculate water are often used as measures to prevent or treat algal blooms in reservoirs (http://www.fwr.org/drnkwatr/algaltox.htm).
5.4.13 A key aspect of the Quarry Dam scheme is the continuous disturbance and movement of water over a twenty-four hour period. Water is passed by pipes from the top dam, through turbines into the bottom dam and then pumped back to the top dam, all over a twenty-four hour period. Under such ‘agitated’ conditions it is considered highly unlikely that algal blooms will be able to develop within the closed dam system. The risk of Llyn Padarn being seeded by algae from the scheme is considered to be negligible and there should be no change to the algal status of Llyn Padarn as a result of the operation of Quarry Battery and therefore no impacts on any of the ecological receptors.
Scour and Wave Action Damaging the Lake Bed
5.4.14 Even low velocity discharges from incorrectly designed outfalls have the potential to cause scour and disturbance to a lake bed. It is considered unlikely, given the location of the discharge pipe and what is currently known about the distribution of the designated plant communities in the lake (Luronium and Isoetes communities), that the discharge pipe will affect habitat supporting these species. The discharge point which will be located some 30m out in to the water and submerged to a depth of approximately 5m, meaning that it will also be unlikely to affect spawning habitat of Arctic charr, trout, and Atlantic salmon, all of which prefer shallow waters to spawn. Significant impacts on SSSI features are therefore unlikely to occur, and although there may be some localised disturbance of benthic macro-invertebrate communities, fish feeding and plant communities the potential impacts are likely to be negligible magnitude with slight to neutral significance.
Introduction of Alien Species and Coarse Fish into Llyn Padarn
5.4.15 By connecting water-bodies which have not previously been joined, or transferring water from one catchment to another carries the risk of transferring non-native alien species between waterbodies. In this case the risk is of transferring alien species in the discharge water from the Quarry Battery system into Llyn Padarn. Introduction of new species in the lake could lead to a range of impacts including competition between the introduced and
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naturalized species for space and resources, and the spread of disease.
5.4.16 A key concern of the Environment Agency Wales is the potential for the introduction of coarse fish into Llyn Padarn. This risk, along with that of introducing non-native plant species, invertebrates and disease, arises despite the system being filled by water from Llyn Padarn, as both the upper and lower dams currently contain a low level of water which will be retained within the system. Water from the lower dam will be transferred to the upper dam, and the abstraction from Llyn Padarn will be used to top this up. It is therefore feasible that any species currently present within the dams, could be introduced via the discharge overflow into Llyn Padarn.
5.4.17 Detailed surveys of the fauna and flora in the dams have not been conducted, although the Environment Agency Wales believe it probable that coarse fish are currently present in the lake. At this stage it is therefore difficult to assess the magnitude and significance of impacts. As a precautionary approach the worst-case scenario is assumed, whereby a species could be introduced into Llyn Padarn with the potential to reduce the viability of the populations of fish and plant species within the SSSI. In this case the un-mitigated effect would be substantial in magnitude with impacts of large to very large significance.
5.5 Assessment of Impacts: Decommissioning 5.5.1 A number of impacts could possibly occur as a result of decommissioning including:
Changes in water quality, water levels and water temperature as a result of draining the quarry system into Llyn Padarn. Siltation or other pollution of Llyn Padarn as result of decommissioning activities Disturbance of protected species as a result of decommissioning activities.
5.5.2 The anticipated time period for the consent for the scheme is 100 years. At this stage it is therefore very difficult to determine the exact magnitude and significance of any impacts, as the baseline status of Llyn Padarn and the quarries themselves may have altered. However, it is likely that without appropriate detailed pre-decommissioning survey and mitigation design that the impacts on SSSI and non-SSSI ecological receptors could be significant with the return of water from the quarries having the potential to have large significant impacts on the Llyn Padarn system without appropriate consideration and mitigation. The requirement for further survey and protective measures is discussed further in Chapter 6 of this report.
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6 MITIGATION 6.0 The mitigation required at each of the scheme stages in described below.
6.1 Construction 6.1.1 Key potential impacts identified during the construction period included the potential risk of siltation or pollution incidents, the potential for disturbance of protected species and the potential to damage lake bed habitat supporting important plant species. In all instances, simple but effective mitigation measures can be employed to reduce impacts.
6.1.2 As required by the EAW, all construction works will have due regard to the EA Pollution Prevention Guidelines. A formal method statement outlining drainage, water management measures and pollution control measures will be written and agreed with the Local Authority and Environment Agency Wales prior to the start of construction. The method statement and construction methods will include appropriate ways to control and manage silts including measures to separate clean and dirty water, measures to trap and remove silt from construction run-off and comprehensive drainage design plans, highlighting early on where key drainage risk areas are and what capacity and nature of drainage system will be required to deal with silty water discharges. Similar method statements will be produced for other pollutants. Key requirements will include:
Safe and secure storage of all chemicals and fuels at least 50m from watercourses. Provision of spill kits at key locations across the site and training of staff on how to use spill kits. Installation of wheel-wash facilities for construction vehicles. Concrete wash out facilities and clearance and removal of all concrete contaminated waste from site. Installation of appropriate silt treatment, water pollution prevention measures and drainage across the site including silt lagoons, catch pits, silt fencing and check dams where appropriate, and monitoring and maintenance of drainage. Use of high quality capping material for all road surfaces to reduce the generation of silt fines. Establishment of a visual and water sampling monitoring programme at strategic locations within the construction site and within Llyn Padarn.
6.1.3 Pre-construction surveys will be carried out for otter and badger along the shoreline area of Llyn Padarn. If shelters are identified within 150m of the proposed pump-house and pipeline location appropriate mitigation and a European Protected Species licence might be required. Shelters are not currently identified as being present, however the following mitigation measures are recommended:
Pre-construction surveys and tool-box talks to all contractors working within the vicinity of Llyn Padarn to highlight the potential presence of, and risks to, protected species at the site (including more generally the importance of Llyn Padarn SSSI). Safe storage of all chemicals and fuels in a locked and secured container at least 50m from the shore of Llyn Padarn. Covering of, or inclusion of an egress ramp in, all overnight excavations to allow for the escape of entrapped mammals.
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Covering of the end of stored pipes to ensure that animals do not become trapped within pipework. No lighting of or working in, shoreline construction areas overnight.
6.1.4 Pre-construction surveys of plant flora will be undertaken in the proposed pipeline location in Llyn Padarn. If plant species including either floating water plantain and/or small quillwort are found during the pre-construction surveys, CCW and the EAW will be contacted for advice on mitigation. It is anticipated that in the unlikely incidence of either species being found the effect could be mitigated through micro-siting of the pipeline, assuming that a micro-siting tolerance in the region of 75m is included in the planning consent. If this is not possible, options for ‘transplanting’ plant material from this location to a nearby locality within the lake will be investigated.
6.2 Abstraction 6.2.1 Key potential impacts as a result of abstraction include the potential for fish to become entrained within the off-take pipe and the potential for reduced water levels to have adverse impacts through changes in water quality and exposure of some areas of shoreline habitat.
6.2.2 Abstraction rates have been discussed and provisionally agreed with EAW. The proposed abstraction rate of 2000m3 per day is considered to be appropriate and the assessment of impacts indicate that the resultant draw-downs will have limited impact on the hydrology and water quality of Llyn Padarn. Despite this, the impacts are likely to be greater and magnified during a dry year and could also have greater impacts on SSSI features (particularly Arctic charr) during the key spawning period (November – December). A ‘hands-off’ limit will therefore be set for the abstraction and included as a planning condition. This ‘hands-off’ limit will be determined and agreed with the EAW and is likely to be based on both critical rainfall rates and the water level within Llyn Padarn. In particular, the water level and shoreline exposure of the spawning gravels around Afon-y-Bala will be important in determining hands-off limits, particularly during November and December. An appropriate monitoring regime will be undertaken to observe monthly changes in water depth and shoreline exposure at key locations around Llyn Padarn.
6.2.3 The abstraction pipe will be fitted with a screen of no greater than 2mm size. The screen will be an effective method of preventing entrainment of fish into the Quarry Battery system. The abstraction pipe should also be positioned slightly above the lake bed and a sill should be used to prevent the entrainment of silts and sediment from the lake bed.
6.3 Operation 6.3.1 Potential impacts on water levels, water quality and water temperature in Llyn Padarn as a result of the operational discharge of Quarry Battery were not considered to be significant. Despite this, it is recommended that a robust routine monitoring system is established to assess the continued balance of the system. The monitoring programme will be agreed with the Environment Agency Wales and should include the following on at least a monthly basis:
Water quality monitoring of the upper and lower dams, discharge and strategic points within Llyn Padarn (i.e. at the point of discharge and a control distant from this point).
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Parameters will be similar to those measured during the initial water quality investigations described in this report. Dissolved oxygen and temperature profiling of the upper and lower dams and a strategic location within Llyn Padarn. Algal monitoring of the upper and lower dam. Monitoring of water levels within Llyn Padarn or assessment of Environment Agency Wales data.
6.3.2 Results will be compiled into a monthly report highlighting any concerns or recommended changes to the management of the regime. The report will be submitted the Local Authority, Environment Agency Wales and CCW.
6.3.3 To reduce the risk of scour and wave action from the discharge, suitable guidance on the installation of drainage points should be followed (SEPA, 2008, Engineering in the Water Environment Good Practice Guide, Intakes and Outfalls; or similar). Unlike the abstraction pipe, the outfall pipe should sit flush with the lake bed, and if considered necessary an energy dissipating structure will be installed at the end of the outlet. The depth of the outfall will be approximately 5m reducing any impacts from wave action.
6.3.4 A key concern of both the EAW and CCW was the potential for the scheme to introduce non-native species and course fish into Llyn Padarn. As the water to fill the system will mostly come from Llyn Padarn and collection of incidental rainfall, this risk arises due to the re-use of water from the bottom dam to fill the top dam, and the transfer of fauna and flora during that process.
6.3.5 Detailed fish, plant and invertebrate surveys have not been conducted on the lower dam at this stage. A full detailed bio-security risk assessment is not therefore possible at this stage. Despite this, certain steps can be taken to reduce the risk of transfer of species. Prior to commencement of work on the dams, full surveys should be carried out, including fish survey, plant survey and invertebrate survey. The aim of the work will be to identify if the dam supports a fish population and to identify if any non-native plant and invertebrate species are present in the dam.
6.3.6 If fish are identified in the lake, regardless of species, it is recommended that a licenced process of draw-down, electro-fishing and removal of all caught fish to a receptor site is carried out prior to transfer to the upper dam. The abstraction pump should also be fitted with a 2mm screen to prevent transfer of young fish and eggs during the draw down process.
6.3.7 It is considered unlikely that non-native plants and invertebrates will have colonised the dam. However, surveys will be undertaken (the specification of which will be agreed with CCW and EAW) and if non-native species are found, an assessment of the risk of transfer of these species to Llyn Padarn will be carried out. If it is concluded that the risk of transfer is high, the lower dam system will be drained and water transferred to a suitable and agreed site, rather than to the upper dam. Following draining, clearance and construction will effectively sterilise the dam.
6.4 Decommissioning 6.4.1 Potential impacts associated with decommissioning of the Quarry Battery include changes in
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water quality, water levels and water temperature as a result of de-watering the system into Llyn Padarn. It is considered that the impacts of de-watering can be minimised to a non-significant level through monitoring, designing and implementing an appropriate de-watering regime.
6.4.2 Baseline water quality, flow and temperature monitoring will have been collated over the duration of the scheme for the Quarry Battery System and for Llyn Padarn and on the basis of this data it will be possible to establish whether, without mitigation there will be significant impacts on Llyn Padarn as a result of quarry de-watering. If impacts are identified as being likely there are several options to mitigate these to a non-significant level including:
Establishing a discharge rate which, like the initial abstraction rate, will be set to minimise the change in water levels and temperature within Llyn Padarn. This may mean emptying the system slowly over a period of many years. Employ methods to treat the discharge water and strip it of any potential contaminants or reduce levels of key nutrients for example through the use of phosphate stripping. Where significant impacts are identified, consider the options for emptying the system to another surface water system outside the Llyn Padarn catchment area or maintaining the quarry system as a non-operational pumped storage system.
6.4.3 Other possible impacts as a result of decommissioning include the potential for siltation and pollution incidents as a result of construction and demolition activity, and the potential to disturb protected species as a result of these activities. These impacts will be dealt with in a similar way to the impacts of construction. Pre-construction protected species surveys will be carried out to identify the presence of any places of shelter of protected species. If protected species are identified and are likely to be affected by activities, appropriate mitigation will be designed and a European Protected Species licence will be obtained for the works. Water pollution prevention measures will be put in place during demolition works and will follow the same principles as those outlined for construction, following relevant EA guidance. A Decommissioning Method Statement will be written and agree with the Environment Agency Wales in advance of works proceeding. As with the construction phase, this documents will outline all water management and pollution prevention procedures and the measures that will be in place to protect the aquatic environment, particularly that of Llyn Padarn.
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7 Water Framework Directive Assessment
7.1 Introduction 7.1.1 The Water Framework Directive (WFD) sets a number of different objectives. The environmental objectives for surface waters including lakes are:
Prevent deterioration in status for water bodies Achieve good ecological and good surface water chemical status in waterbodies by 2015 For water bodies that are designated as artificial or heavily modified, aim to achieve good ecological potential by 2015 Comply with objectives and standards for protected areas where relevant Reduce pollution from priority substances and cease discharges, emissions and losses of priority hazardous substances.
7.1.2 The Directive sets a target of aiming to achieve at least ‘good status’ in all waters. There are two separate classifications for water bodies; ecological and chemical and for a waterbody to achieve overall good status, both classifications must attain at least good condition. Ecological status is recorded on a scale of high, good, moderate, poor and bad whilst chemical status is recorded as good or fail.
7.1.3 Llyn Padarn is designated as a Heavily Modified Water Bodies on account of the engineering and morphological changes that have taken place in and on the lake margins for water storage. Whilst good ecological status is defined as a slight variation from conditions in natural water bodies, heavily modified water bodies are unable to achieve natural conditions. Heavily modified water bodies are therefore given the target of achieving good ecological potential whilst makes sure their ecology is protected as far as possible.
7.1.4 All new schemes which will affect a waterbody must be compliant with the requirements of the WFD and must not prevent waterbodies achieving their target under the WFD. For Llyn Padarn the target is to attain good ecological potential by 2027. For the Quarry Battery scheme to be compliant with the target:
The scheme needs to be compatible with the list of mitigation measures set out by the EAW to improve the status of Llyn Padarn; The scheme should not prevent deterioration or failure to improve for those biological, chemical or morphological parameters relevant to the Llyn Padarn; and The scheme must also be compliant with the objectives of the SSSI objectives for this water body.
7.1.5 The following sections assess whether the Quarry Battery scheme is likely to be compliant with the WFD requirements for biological quality elements.
7.2 Compliance with Mitigation Measures Required Under the WFD 7.2.1 Table 7.2 below assesses each of the mitigation measures required under the WFD, the Quarry Battery scheme’s compliance with these and whether additional control measures are required to ensure compliance.
Table 7.2: Quarry Battery: Compliance with WFD Mitigation Measures
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Measure Required by the Water Potential Effect of the Quarry Battery Required Mitigation Measures to be Framework Directive Scheme Compliant with the Water Framework Directive Ensure the thermal regime in waters The temperature of discharges from As a precautionary measure thermal down-stream of the impounding works Quarry Battery are unlikely to be monitoring should be carried out in is consistent with good status significantly different from those in the upper and lower dam, discharge conditions. Llyn Padarn (see Chapter 8 of the and Llyn Padarn in the vicinity of the Environmental Statement) discharge point. Ensure that good status of dissolved Continual circulation and agitation of As a precautionary measure oxygen levels is being achieved water within the Quarry Battery dissolved oxygen profiling should be down-stream of impounding works. system will result in a well oxygenated carried out in the upper and lower discharge which should not affect the dam and a selected point in Llyn dissolved oxygen levels in the outflow Padarn and on the Afon Seiont. (Afon Seiont). Provide appropriate flows to move The scheme does not involve the Appropriate design of the intake pipe sediment down-stream. impoundment of a natural so it is lifted above the lake bed and watercourse. Loss of a natural has a sill to prevent silt entrainment. sediment load will not occur. Design of the outfall flat to sit flush Sediment from the bed of Llyn Padarn with the lake bed and provision of could become entrained within the energy dissipating structures to reduce in-take pipe or scoured by the out-fall. scouring. Ensure the rate and range of any A maximum abstraction of 2000m3 per In addition to agreement of a artificial draw-down is appropriately day from Llyn Padarn will occur for a maximum daily abstraction rate, a managed to maintain aquatic plant period of one to two years. The hands-off water level will be set as and animal communities in the shore expected draw-down rate is expected part of the planning condition. The zones of water storage and supply to be a few millimetres a day up to hands-off level will be linked to critical with gently shelving shore zones. <0.75m over the entire year, although water levels, river flows and rainfall this is unlikely to be realised as a result required to maintain marginal of top up by rainfall. If the spawning and vegetation habitat in draw-down occurs during a dry period Llyn Padarn. the impacts will be more severe and could affect plants in marginal areas of Monthly water level, rainfall and flow Llyn Padarn and shallow spawning data will be collated and analysed to habitats of several fish species monitor draw-down and impacts. including Arctic charr. Any impacts however, will be short-term and will not affect the long-term ambition of attaining good ecological status by 2027. Ensure there is an appropriate As described above, draw-down A maximum abstraction and discharge baseline flow regime down-stream of impacts of the scheme will be limited. rate will be agreed with the EAW. A the impoundment However, abstraction during hands-off limit based on water levels Ensure the seasonal pattern of water particularly critical periods such as the in Llyn Padarn will also be set. The levels during each year is managed so November – December spawning hands-off limit will have due regard to as to enable the establishment and period for charr or during dry spells. seasonal considerations for SSSI retention of aquatic plant and animal Similarly, although smaller in scale the species, in particular Arctic charr, but communities in the shore zone of the daily operational discharge of the also when dry periods occur, floating impoundment. scheme (expected to be in the region water plantain. Water levels, base of a maximum of 1200m3 per day but flows and rainfall will be measured and variable in response to rainfall and assessed on a routine basis. storm events) could have impacts including ‘flooding’ of spawning habitat and habitat for marginal and emergent aquatic plants. Given the scale of the abstractions and discharges, the impacts were not considered to be significant although specific consideration to the charr spawning periods and dry periods was considered necessary. Manage the risk of fish entrainment in Risk of entrainment of fish including Install a screen on the abstraction intakes for hydro-power turbines or Arctic charr during the initial intake of a maximum of 2mm size. water resources or pumping stations abstraction period. where there is down-stream fish migration. Structures or other mechanisms in No impacts. The scheme is not No mitigation required.
ETIVE ECOLOGY 42 www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis place and managed to enable fish to located on a watercourse and the access waters upstream and dams will not ‘block’ a natural downstream of the impounding works. migration route.
7.3 Compliance with Biological Monitoring Elements of the WFD 7.3.1 Four biological elements of Llyn Padarn are monitored under the WFD:
Chironomin and littoral invertebrates Macropphytes Phytobenthos (diatoms) Phytoplankton
7.3.2 Although different methods are used to monitor each element, the principles of monitoring and subsequent assessment are essentially the same that the type of plant, invertebrate (including chironomids), diatom and phytoplankton species that are present indicate the level of nutrient enrichment of the lake. Although, a gross simplification of the assessment method, each species of each of the groups has a different tolerance to nutrient levels and each is assigned a score according to that sensitivity. Different calculations of things such as the average scores, total scores or total numbers of species can then be used to assess the level of and impacts of nutrient levels within Llyn Padarn, when compared against a reference site with similar environmental characteristics but without nutrient enrichment. Although monitoring the species, distribution and abundance of invertebrates macrophytes, diatoms and phytoplankton can often give an indication of other influences occurring within a lake, assessment methods to monitor organic and nutrient enrichment have been selected for use in WFD monitoring.
7.3.4 Chapter 5 of this report identified the key impacts likely to occur as a result of the scheme and Chapter 6 identified mitigation measures to reduce these impacts. The key impacts that required mitigation included draw-down impacts, physical impacts as a result of installation of a small section of pipeline along the bed of Llyn Padarn and the potential impacts of introduction of invasive species. Nutrient enrichment was not identified as a key potential effect of the scheme, as the surrounding catchment of the Quarry Battery is predominantly comprised of old quarries and slate mines. Nutrient inputs will therefore be low, and the chemistry of the water from the initial in-fill from Llyn Padarn is unlikely to be changed significantly. It was also considered that due to the turbulent nature of the system, algal ‘seeding’ of Llyn Padarn would be highly unlikely.
7.3.5 Given the lack of nutrient enrichment impacts as a result of the scheme and given that impacts as a result of draw-down will be short-term and mitigated, impacts on the lake bed will be small scale and the introduction of invasive and non-native species can be prevented through implementation of appropriate mitigation, it is concluded that there would be no significant impacts on invertebrate, macrophyte, diatom and phytoplankton communities.
7.3.6 Furthermore, for Heavily Modified Water Bodies, the potential ecological status achieved from monitoring of aquatic macrophytes is not used to calculate the overall ecological potential of the lake (EAW, 2011). This is because macrophytes are sensitive to a range of environmental pressures, including changes in water level which tend to limit the physical habitat where macrophytes might occur. Because of this response, in Heavily Modified
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Waterbodies where water level fluctuations frequently occur, macrophytes are not used to determine the overall class.
7.4 Compliance with Llyn Padarn SSSI Objectives: Arctic Charr 7.4.1 Potential impacts of the Quarry Battery scheme on Arctic charr, the effect of this in terms of achieving SSSI objectives and the required mitigation are outlined in Table 8.2 below.
Table 7.2: Compliance with Llyn Padarn SSSI Objectives: Arctic charr.
SSSI Objective Potential Impact of the Quarry Mitigation Required to Ensure Battery Scheme Compliance with the SSSI Objectives Abundance of Arctic charr: In Chapter 5 of this report identified the Application of industry standard oligotrophic waters fish densities key potential concerns relevant to pollution prevention measures during which fall below a level of 37 Arctic charr as being: construction and implementation of individuals per ha are considered to be water quality monitoring. in unfavourable condition. For *Siltaton during construction mesotrophic a density of 520 *Entrainment of fish during Installation of a screen over the individuals per ha is the appropriate abstraction abstraction intake to prevent threshold. *Draw-down and exposure of gravels entrainment of fish as a result of abstraction. Maximum abstraction rates set and Although all three impacts would be agreed with the EAW and linked to a temporary in duration the impacts hands-off water level in Llyn Padarn to could persist in the longer term, ensure spawning gravels are not affecting abundance of Arctic charr. exposed by additional draw-down. Population Demographic Structure: As above. As above. To achieve favourable condition Arctic charr populations should have 70% of individuals in the juvenile (0+/1+) age class. Water Quality: Oxygen levels in the Circulation of the water in the Quarry No mitigation required however hypolimnium should exceed 4mg/l Battery system will maintain oxygen routine monitoring of the oxygen levels in the discharge water. profiles in the upper and lower dam and Llyn Padarn should be carried out along with measurements of dissolved oxygen in the discharge. Water Quality: pH should be Chapter 8 (Water Resources) of the No mitigation required, however maintained at >5.5 and Total environmental statement did not routine monitoring of the water Phosphorus should be no greater than identify any likely significant quality of Llyn Padarn, the upper and 20µg/l. differences in the water chemistry of lower dam of the Quarry Battery the discharge compared with that of system and the discharge water should Llyn Padarn. be carried out on a regular basis. Natural Hydrology Regime: The As identified above, abstraction during Maximum abstraction rates set and natural hydrology regime should be November and December, particularly agreed with the EAW and linked to a maintained during the key spawning if coinciding with dry periods could hands-off water level in Llyn Padarn to period. result in exposure of spawning gravels. ensure spawning gravels are not exposed by additional draw-down. Physical Structure of the Lake Bed: A small section of lake bed will be The discharge and abstraction pipeline The physical structure of the lake bed disturbed / lost as a result of will be designed to industry standard used by Arctic charr should be construction of a pipeline along the with appropriate siting and design to maintained. bed of Llyn Padarn. Arctic charr in reduce impacts such as entrainment of Llyn Padarn are known to use deeper silt and scour of the lake bed. water in the lake for feeding and the shallows around Afon y Bala for spawning. The pipeline will be laid to a maximum depth of 5m and is located at least 1km from key spawning habitat. Significant impacts on lake bed used by Arctic charr are not anticipated. Invasive Species: Favourable condition Chapter 5 of this report identified that Detailed survey of the aquatic fauna is dependent on there being no transfer of invasive or non-native and flora of the lower quarry. introductions or transfer of any fish species into Llyn Padarn could occur
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SSSI Objective Potential Impact of the Quarry Mitigation Required to Ensure Battery Scheme Compliance with the SSSI Objectives species, including Arctic charr, from through the routine discharges of If fish species are found, electro-fish other localities water from the system into Llyn and remove any fish to another site Padarn. during the draw-down.
If other species of non-native fauna and flora are identified. Assess the risk of transfer and the risk to Llyn Padarn and determine whether residual water in the quarries should still be used in the system or disposed of/removed to another site.
7.5 Compliance with Llyn Padarn SSSI Objectives: Floating Water Plantain 7.5.1 Potential impacts of the Quarry Battery scheme on floating water plantain, the effect of this in terms of achieving SSSI objectives and the required mitigation are outlined in Table 7.3 below.
Table 7.3: Compliance with Llyn Padarn SSSI Objectives: Floating Water Plantain.
SSSI Objective Potential Effect of the Quarry Battery Mitigation Required to Ensure Scheme Compliance with the SSSI Objectives Presence of Characteristic Species: Floating water plantain occurs at Pre-construction surveys of the lake including floating water plantain and depths of 2 -3m and typically occurs in bed in within a 75m buffer of the no loss of the identified species. water that is intermediate between proposed pipeline will be undertaken oligotrophic and mesotrophic waters. with the objective of identifying if Condition monitoring carried out by floating water plantain is present. the EAW in 2009 indicated that the species was present in the lake If identified as being present, approximately 1km each of the micro-siting of the pipeline route will discharge point. Chapter 5 identifies be used as the preferred option for key potential impacts on the plant avoiding and reducing impacts on the species as being limited to the species. potential loss of the species if it is found to be present during surveys of If necessary transplanting plants to the proposed pipeline route in Llyn other parts of Llyn Padarn will be Padarn. Other impacts were discussed with EAW and CCW. discounted as the preferred depth of the plant means it is unlikely to be significantly affected by draw-down or discharges, and, changes in water chemistry such as nutrient enrichment are not predicted to occur as a result of the scheme. Potential impacts of invasive species are addressed below. Non-native species: should be absent Chapter 5 of this report identified that Detailed survey of the aquatic fauna or present at low frequency. transfer of invasive or non-native and flora of the lower quarry. species into Llyn Padarn could occur through the routine discharges of If fish species are found, electro-fish water from the system into Llyn and remove any fish to another site Padarn. during the draw-down.
If other species of non-native fauna and flora are identified. Assess the risk of transfer and the risk to Llyn Padarn and determine whether residual water in the quarries should still be used in the system or disposed of/removed to another site. Algal dominance: Cover of benthic and Chapter 5 of this report identified that No mitigation is required. Routine epiphytic filamentous algae should be the scheme is unlikely to promote the monitoring of algae in the upper and
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SSSI Objective Potential Effect of the Quarry Battery Mitigation Required to Ensure Scheme Compliance with the SSSI Objectives less than 10%. growth of algae as a result of the lower dam and an appropriate location periodic discharges into Llyn Padarn. in Llyn Padarn should be carried out. Discharges are not expected to vary significantly in nutrient loading from Llyn Padarn and all discharges will be well oxygenated as a result of continual circulation of the system. Algal presence: No excessive growth As above. As above. of cyanobacteria or green algae. Characteristic zones of vegetation: Draw-down imapcts will occur as a No mitigation required. Water level Should be present and maximum short-term effect due to abstraction. monitoring in Llyn Padarn should be depth zones maintained. In the longer term there will be carried out during the abstraction and occasional daily discharges from the operation period to assess the need to system during periods of wet weather. implement hands-off limits for None of these impacts were identified abstraction or maximum discharge as being significant, with a maximum limits. potential draw-down of 73cm being countered by rainfall and changes in water level as a result of discharges being limited to no more than 2mm based on the daily discharge. No long-term significant impacts on vegetation zones are considered likely. Water quality: Stable nutrient levels Chapter 8 of the environmental No mitigation required, however appropriate to lake type. statement did not identify any likely routine monitoring of the water significant differences in the water quality of Llyn Padarn, the upper and chemistry of the discharge compared lower dam of the Quarry Battery with that of Llyn Padarn. system and the discharge water should be carried out on a regular basis. Water quality: Stable pH and ANC Chapter 8 of the environmental No mitigation required, however appropriate to lake type. statement did not identify any likely routine monitoring of the water significant differences in the water quality of Llyn Padarn, the upper and chemistry of the discharge compared lower dam of the Quarry Battery with that of Llyn Padarn. system and the discharge water should be carried out on a regular basis. Water quality: Adequate dissolved Circulation of the water in the Quarry No mitigation required however oxygen levels for health of Battery system will maintain oxygen routine monitoring of the oxygen characteristic fauna. levels in the discharge water. profiles in the upper and lower dam and Llyn Padarn should be carried out along with measurements of dissolved oxygen in the discharge. Hydrology: There should be a natural Chapter 5 of this report identified that No mitigation required. However, hydrological regime. there will be short-term changes as a monitoring of water levels in Llyn result of abstraction and draw-down Padarn, base flows and rainfall should and longer term impacts as a result of be carried out in order to implement a daily discharges. Impacts were not hands-off flow limit when water expected to be high magnitude and should not be taken due to potential given that floating water plantain has a detrimental impacts on habitat for preferred depth of 2 – 3m, the levels floating water plantain and spawning of draw down (<0.75m) and discharge habitat for Arctic charr. were not considered likely to have significant impacts on the species. Sediment Load: Maintain a natural The scheme does not involve the Appropriate design of the intake pipe sediment load. impoundment of a natural so it is lifted above the lake bed and watercourse. Loss of a natural has a sill to prevent silt entrainment. sediment load will not occur. Design of the outfall flat to sit flush Sediment from the bed of Llyn Padarn with the lake bed and provision of could become entrained within the energy dissipating structures to reduce in-take pipe or scoured by the out-fall. scouring. Lake Substrate: Maintain the natural A small section of lake bed will be The discharge and abstraction pipeline shoreline and substrate of the lake disturbed / lost as a result of will be designed to industry standard with minimal negative impact from construction of a pipeline along the with appropriate siting and design to artificial structures. bed of Llyn Padarn. Arctic charr in reduce impacts such as entrainment of Llyn Padarn are known to use deeper silt and scour of the lake bed.
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SSSI Objective Potential Effect of the Quarry Battery Mitigation Required to Ensure Scheme Compliance with the SSSI Objectives water in the lake for feeding and the shallows around Afon y Bala for spawning. The pipeline will be laid to a maximum depth of 5m and is located at least 1km from key spawning habitat. Significant impacts on lake bed used by Arctic charr are not anticipated.
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8 CONCLUSION
8.1 Summary of Impacts 8.1.1 Following application of the mitigation described in Chapter 6 it is anticipated that all impacts on ecological receptors in Llyn Padarn can be reduced to a level of slight significance or less. Survey is still required to determine the exact impact in relation to the potential for transfer of invasive species and the potential for loss of habitat as a result of construction of a pipeline in Llyn Padarn. However, the mitigation in Chapter 6 describes measures to be undertaken that would reduce impacts to a non-significant level in the event of invasive species being identified or floating water plantain and/or small quillwort being recorded in the pipeline area.
8.1.2 Table 8.1 summarises the potential impacts, pre- mitigation significance and post- mitigation significance.
Table 8.1: Summary of Impacts and Significance of Impacts on Llyn Padarn
Potential Impact Magnitude Significance on Mitigation Post-Mitigation SSSI / non-SSSI Significance Features (SSSI/non-SSSI Features) Construction Siltation and Slight Slight – Construction Method Slight for all pollution impacts magnitude Moderate Statements and features. significance for implementation monitoring all features and management of water pollution prevention measures as part of the standard scheme design. Disturbance or harm Negligible Slight Pre-construction surveys. Slight - Neutral to protected species magnitude significance Safe storage of materials, ramping of excavations and restrictions on night time lighting. Disturbance and Negligible Large – Pre-construction surveys for Slight – neutral permanent habitat magnitude moderate aquatic plants. dependent on loss in Llyn Padarn significance or survey findings. due to pipe neutral Micro-siting of the pipeline to installation significance for reduce loss of habitat and floating water species. plantain (depending on Good practice construction its presence) measures to reduce the and slight generation of silt and potential significance for pollution incidents all other features. Abstraction Abstraction: Draw Moderate Moderate to Inclusion of a hands-off limit for Slight significance down impacts magnitude for large abstraction linked to critical for all receptors. Arctic charr and significance for flows, levels and time periods. other fish Arctic charr and species. Slight other fish Monitoring of water levels, magnitude for species. draw down and rainfall to all other Slight – accurately access impacts and
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Potential Impact Magnitude Significance on Mitigation Post-Mitigation SSSI / non-SSSI Significance Features (SSSI/non-SSSI Features) receptors moderate draw-down. significance for all other receptors Abstraction: Changes Negligible Slight Water quality monitoring will Slight in water quality magnitude be carried out in Llyn Padarn during the abstraction period. Abstraction: Moderate Moderate to Installation of a screen on the Slight to neutral Entrainment of Fish magnitude for large abstraction pipe. significance. all fish species significance Design and installation of the pipe to follow good practice. Operation Changes in water Negligible Slight to Neutral Routine monitoring of water Slight to neutral quality significance quality in the quarry system, significance. discharge and Llyn Padarn Changes in water Negligible Slight to Neutral Routine monitoring of water Slight significance level significance levels and rainfall in Llyn Padarn and the quarry catchment
Set lake levels when discharges cannot occur as part of planning conditions Changes in water Negligible Slight to Neutral Routine monitoring of water Slight to neutral temperature significance temperatures and dissolved significance oxygen profiles in the quarry system, discharge and Llyn Padarn Scour and wave Negligible Slight to Neutral Install the discharge pipe flush Neutral action as a result of significance to the bed and include an significance the discharge. energy dissipating structure if required Potential for Algal No change Neutral Routine monitoring of algae in Neutral ‘seeding’ of Llyn significance the quarry system significance Padarn. Potential for Substantial Large / very Pre-construction surveys to Neutral introduction on magnitude for large identify invasive species. significance invasive flora and all receptors significance fauna. (precautionary) (precautionary) Electro-fishing and removal of fish species.
De-water the lower quarry to a suitable permanent receptor site if required. Decommissioning Disturbance of Pre-construction surveys and design and implementation of mitigation Not significant protected species under licence if required. Siltation and Detailed construction method statements and drainage design. Not significant pollution impacts Implementation, monitoring and management of appropriate during pollution pollution prevention measures. impacts Changes in water Analysis of results to determine and design an appropriate Not significant quality, temperature de-watering regime. De-water elsewhere or disconnect the system if and water levels as a impacts are considered likely to be significant. result of
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Potential Impact Magnitude Significance on Mitigation Post-Mitigation SSSI / non-SSSI Significance Features (SSSI/non-SSSI Features) de-watering.
8.2 Monitoring Requirements 8.1.3 Pre-construction surveys are required, to include:
Surveys for otter and badger in the woodland and along the shore within 150m of the proposed pipeline and pump-house. Aquatic plant surveys including boat and shoreline transects within a 75m buffer of either side of the proposed pipeline route in Llyn Padarn. Fish, aquatic plant and freshwater invertebrate surveys of the upper and lower quarries to determine what species are present and whether these pose a risk to Llyn Padarn.
8.1.4 The scope and method for all surveys will be agreed in advance with EAW and CCW.
8.1.5 In addition to pre-construction surveys, routine monitoring is an important aspect of the Quarry Battery Scheme and will ensure that the system is constantly monitored and kept in balance. Monitoring will also be important in determining the exact details and impacts of decommissioning and will include the following elements:
Daily visual inspections and weekly water quality monitoring at key locations within the system, nearby watercourses and Llyn Padarn during the construction phase. Water quality monitoring of the upper and lower dams, discharge and strategic points within Llyn Padarn. Parameters will be similar to those measured during the initial water quality investigations described in this report. Dissolved oxygen and temperature profiling of the upper and lower dams and a strategic location within Llyn Padarn. Algal monitoring of the upper and lower dam. Monitoring of water levels within Llyn Padarn or assessment of Environment Agency Wales data.
8.1.6 A monthly report will be produced discussing the results and any requirements for environmental management within the system. The report will be issued to the Local Authority, EAW and CCW.
8.3 Water Framework Directive Assessment 8.3.1 Given the low magnitude of impacts as a result of the quarry battery scheme and the potential for these to be mitigated, this assessment concludes that the scheme is unlikely to have any significant effect on the BQEs of Llyn Padarn achieving good ecological status by 2027. Impacts of the scheme as a result of construction and abstraction were considered to have impacts that were short-term in duration and low in magnitude provided appropriate controls and mitigation were in place and therefore progression towards the longer-term target in the Water
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Framework Directive is unlikely to be affected.
8.3.2 All of the lacustrine biological monitoring focuses on scoring and assessment methods which are sensitive to changes in nutrient levels, rather than other environmental factors. Changed nutrient status of the lake is highly unlikely to occur as a result of the scheme operation as the surrounding catchment of the Quarry Battery is predominantly comprised of old quarries and slate mines. Nutrient inputs will therefore be low, and the chemistry of the water from the initial in-fill from Llyn Padarn is unlikely to be changed significantly. It was also considered that due to the turbulent nature of the system, algal ‘seeding of Llyn Padarn would be highly unlikely. The assessment therefore concluded, that although there might be small magnitude changes in the flora and fauna in the vicinity of the discharge, the overall status of biological parameters measured under the WFD will not be changed.
8.3.2 In both Chapters 5 and Chapter 7 the assessment has identified and assessed that the scheme will not have significant impacts on SSSI features and will not prevent achievement of SSSI objectives provided the appropriate mitigation listed in section 8.1 and 8.2 is applied.
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ETIVE ECOLOGY www.etiveecology.co.uk Glyn Rhonwy PS Freshwater Ecology Assessment Llanberis
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Middlemiss, W. (2005). The thermal impacts of Dinorwig pumped storage power station on Llyn Padarn Arctic charr (Salvalinus alpinus). MSc Cranfield University.
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Thomas, Rh. and Holt, R. (2011). Diver observations on Arctic charr (Salvelinus alpinus (L.) spawning grounds in Llyn Padarn SSSI. CCW Staff Science Report in press. www.fwr.org/dmkwater/algaltox.htm.
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