Improving Water Quality in Loweswater
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IMPROVING WATER QUALITY IN LOWESWATER Final Report of the Loweswater Care Programme Project funded by the DEFRA Catchment Restoration Fund October 2012 – September 2015 Nov 2017 Improving Water Quality in Loweswater Project Report No. Revision No. Date of Issue Loweswater Care 001 001 17 November 2017 Programme Leslie Webb Authors: Andrew Shaw Vikki Salas Reviewed by: Stephen Maberly, CEH Vikki Salas, Assistant Director, Approved by: West Cumbria Rivers Trust Note on hyperlinking in this electronic document: The main chapter headings in the Contents are linked to the start of each chapter. The start of each chapter is linked back to the Contents page. Words in the text that are in the Glossary are italicised in blue and linked to the Glossary page. Page 1 of 89 Improving Water Quality in Loweswater CONTENTS Page Summary 9 Glossary 10 Chapter 1. Introduction 1.1 Background 11 1.2 Summary of Project programme 13 1.3 Report structure 15 Chapter 2. Reducing P inputs to Loweswater 2.1 Background 16 2.2 Farm and catchment assessments 16 2.3 Project prioritisation 16 2.4 Farm projects 2.4.1 Farm A 17 2.4.2 Farm B 19 2.4.3 Farm C 21 2.4.4 Farm D 23 2.4.5 Farm E 24 2.4.6 Use of sward slitter and lifter 25 2.4.7 Control of Himalayan Balsam 26 Chapter 3. Lake Studies 3.1 Background 28 3.2 Review of ultrasound treatment for algal control 3.2.1 Introduction 28 3.2.2 Ultrasound theory and practice 29 3.2.3 Review of previous work on ultrasound for algal control 30 3.3 Lake sediments as a phosphorus source 3.3.1 Background 32 3.3.2 Results 33 3.4 Waterfowl as a phosphorus source 37 Chapter 4. Monitoring of Becks 4.1 Introduction 38 4.2 Monitoring methods 4.2.1 Collection and measurements on water samples 38 4.2.2 Electro-fishing survey 38 4.3 Water quality monitoring results 4.3.1 EA monitoring of Dub beck inflow 39 4.3.2 WCRT monitoring of other becks 44 4.4 Electro-fishing survey results 49 Page 2 of 89 Improving Water Quality in Loweswater CONTENTS (continued) Chapter 5. Monitoring of the Lake 5.1 Introduction 51 5.2 Monitoring methods 5.2.1 Sample collection 51 5.2.2 Water quality monitoring 51 5.2.3 Phytoplankton identification and enumeration 52 5.2.4 Algal bloom monitoring 52 5.2.5 Ultra-sound treatment of Loweswater 52 5.3 Results 5.3.1 Water quality monitoring – Loweswater 54 5.3.2 Microscopy: enumeration and identification of algal populations 60 5.3.3 Algal bloom monitoring 5.4 Discussion 5.4.1 General 64 5.4.2 Ultra-sound trial 67 Chapter 6. Assessment of Project Actions and Interventions 6.1 Sources of lake phosphorus 6.1.1 Previous studies 75 6.1.2 Findings of this project 77 6.2 Mitigation from project interventions 79 6.3 Overall assessment of lake’s ecological status 80 Chapter 7. Conclusions 84 References 85 Acknowledgements 88 Appendix 89 Rainfall figures (mm) for Loweswater 2011 to 2014, Iredale Place Cottage, Loweswater Page 3 of 89 Improving Water Quality in Loweswater LIST OF TABLES Chapter 2. 2.1 Summary of farm projects Chapter 3. 3.1 Lake-scale UK studies on ultrasound Chapter 4. 4.1 Results of Environment Agency’s electrofishing surveys of four becks in 1990s Chapter 5. 5.1 Dissolved oxygen profile data from Loweswater (Goldsmith et al., 2014) 5.2 Observations of algal blooms in Loweswater, 2012, 5.3 Observations of algal blooms in Loweswater, 2013, 5.4 Results of Environment Agency’s electrofishing surveys of four becks 5.5. Chronology of ultrasound trial Chapter 6 6.1 Phosphorus loads from aerial deposition 6.2 Trophic categories based on 1982 OECD guidelines 6.3 Trophic status of Loweswater 2010 to 2015 based on OECD guidelines 6.4 WFD boundary levels for total phosphorus and chlorophyll-α for Loweswater in 2015 Page 4 of 89 Improving Water Quality in Loweswater LIST OF FIGURES Chapter 1. 1.1 View of Loweswater from the east with Dub Beck inflow at the top and outflow at the bottom 1.2 Annual means for total phosphorus, chlorophyll-a and Secchi depth from Lakes Tour Chapter 2. 2.1 Farm A - Four of the diversion drainage channels. 2.2 Farm A – Head of beck before re-construction 2.3 Farm A – Head of beck, after reconstruction and new fencing 2.4 Farm A – New fencing along both sides and new water-gate at lower end 2.5 Farm B – Existing cattle yard 2.6 Farm B – new cattle shed 2.7 Farm B – new fencing 2.8 Farm C - Roofing over yard adjacent to slurry tank 2.9 Farm C - Slurry tank before roofing and enlargement 2.10 Farm C - Roofing over slurry tank before enlargement and installation of slatted floor 2.11 Farm C – new cattle shed with slatted floor after completion 2.12 Farm C – new bale pad 2.13 Farm D - Before crossings constructed, whole beck and location of upper crossing 2.14 Farm D – After crossings constructed, whole beck and upper crossing with new water tank 2.15 Farm D – new shed for over-wintering sheep 2.16 Farm E – Existing area with no fencing and with new fencing/gates 2.17 The Opico Sward Slitter (in front) and the Sward Lifter (behind) 2.18 Demonstration of Sward Slitter and Lifter 2.19 Demonstration of test hole 2.20 Volunteers pulling Himalayan Balsam in Dub Beck catchment, August 2015 Chapter 3. 3.1 Sound frequency range and applications 3.2 Variation of temperature and dissolved oxygen (DO) with depth in 2009 for Loweswater 3.3 Simple mass balance for Loweswater 3.4 Bathymetry of Loweswater showing location of short cores and surface sediment samples 3.5 Total phosphorus content of short sediment cores in Loweswater 3.6 Calculated phosphorus fluxes over time for four sediment cores taken in 2013 (lows 3-6) and one taken in 1999 (LOWS1) Page 5 of 89 Improving Water Quality in Loweswater LIST OF FIGURES (continued) 3.7 Phosphorus content of surface sediments in Loweswater at different water depths 3.8 Loweswater phosphorus mass balance 3.9 Nutrient loading from wildfowl in Loweswater, 1995 to 2010 Chapter 4. 4.1 Monitoring locations around Loweswater. 4.2 Seasonal variation in Alkalinity in Dub Beck inflow and Loweswater, 2013 and 2014. 4.3 Seasonal variation in pH values in Dub Beck inflow and Loweswater, 2013 and2014. 4.4 Seasonal variation in water temperature in Dub Beck inflow and Loweswater, 2013 and 2014. 4.5 Seasonal variation in specific conductivity in Dub Beck inflow and Loweswater, 2013 and 2014. 4.6 Seasonal variation in Oxygen concentrations (%) in Dub Beck inflow and Loweswater, 2013 and 2014. 4.7 Seasonal variation in Nitrate-nitrogen concentrations in Dub Beck inflow and Loweswater, 2013 and 2014. 4.8 Seasonal variation in SRP concentrations in Dub Beck and Loweswater, 2013 and 2014. 4.9 Seasonal variation in Total Phosphorus concentrations in Dub Beck inflow and Loweswater, 2013 and 2014. 4.10 Seasonal variation in Chlorophyll-a concentrations in Dub Beck inflow and Loweswater, 2013 and 2014. 4.11 Monthly rainfall, Iredale Place, Loweswater, 2013 and 2014. 4.12 Range and mean temperatures for Loweswater becks, July 2013 to December 2014. 4.13 Range and mean pH levels for Loweswater becks, July 2013 to December 2014. 4.14 Range and mean conductivities for Loweswater becks, July 2013 to December 2014 4.15 Range and mean DO levels for Loweswater becks, July 2013 to December 2014. 4.16 Range and mean turbidity levels for Loweswater becks, July 2013 to December 2014. Chapter 5. 5.1 One of the two rafts deployed on Loweswater; the solar panel generated power for the ultrasound equipment and charged a battery for reserve power. 5.2 Google Earth aerial photograph of Loweswater, showing the location of the two rafts in the lake. 5.3 Seasonal variation in Alkalinity in Loweswater, 2011 to 2014. 5.4 Seasonal variation in pH values in Loweswater, 2011 to 2014. 5.5 Seasonal variation in surface water temperature in Loweswater, 2011 to 2014. 5.6 Seasonal variation in specific conductivity in Loweswater, 2011 to 2014. Page 6 of 89 Improving Water Quality in Loweswater LIST OF FIGURES (continued) 5.7 Seasonal variation in dissolved oxygen (%) in Loweswater, 2011 to 2014 5.8 Dissolved oxygen profile data from Loweswater (Goldsmith et al., 2014). 5.9 Seasonal variation in concentrations of SRP in Loweswater, 2011 to 2014. 5.10 Seasonal variation in concentrations of nitrate-nitrogen in Loweswater, 2011 to 2014. 5.11 Seasonal variation in concentrations of TP in Loweswater, 2011 to 2014. 5.12 Seasonal variation in concentrations of phytoplankton chlorophyll-a in Loweswater, 2011 to 2014. 5.13 Seasonal changes in depth of Secchi disc in Loweswater, 2011 to 2014. 5.14 Seasonal changes in four diatoms, Asterionella, Aulacoseira, Urosolenia and Cyclotella in Loweswater, 2011 to 2014. 5.15 Seasonal changes in four cyanobacteria, Planktothrix, Woronichinia, Snowella and Anabaena in Loweswater, 2011 to 2014. 5.16 Seasonal changes in Cryptophytes (including Chroomonas), Chrysophytes, Dinophytes and Chlorophytes in Loweswater, 2011 to 2014. 5.17 09 June 2103, Thick white scum along shoreline at Watergate end of lake. 5.18 17 July 2013, Heavy algal scum on the NW shore. 5.19 22 August 2013, Dark blue-green bloom. 5.20 27 July 2013, Bands of very blue-green algal blooms along the shoreline at Watergate end of lake.