Natural England Pollution Risk Assessment & Source Apportionment: River Mease Catchment
Total Page:16
File Type:pdf, Size:1020Kb
Natural England Pollution Risk Assessment & Source Apportionment: River Mease Catchment Natural England Pollution Risk Assessment RIVER MEASE CATCHMENT APRIL 2015 © Natural England 2015 1 Natural England Pollution Risk Assessment & Source Apportionment: River Mease Catchment BLANK PAGE 2 Natural England Pollution Risk Assessment & Source Apportionment: River Mease Catchment Natural England has engaged Westcountry Rivers Limited (the commercial arm of Westcountry Rivers Trust) to develop a method for catchment-wide pollution risk and source apportionment assessments. In addition, The Rivers Trust has been commissioned to facilitate the integration and dissemination of this work with Catchment Based Approach Partnerships. Catchment Based Approach (CaBA) was developed as a framework for improving water quality by Defra 2009. After a successful pilot phase in 2011 actions were made for the wider adoption and national roll out of CaBA from 2013. As rivers trusts now represent catchments across a large part of England and Wales, with new ones continually forming, they are responsible partner hosts for the majority of local CaBA initiatives around the United Kingdom. Key objectives of CaBA are to deliver positive and sustained outcomes for the water environment by promoting a better understanding of the environment at a local level; and to encourage local collaboration and more transparent decision-making when both planning and delivering activities to improve the water environment. The Catchment Based Approach is about much more than just complying with the Water Framework Directive. It allows local communities, businesses, organisations and other stakeholders to come together to undertake actions or develop projects which incorporate local priorities such as flood risk management, fisheries and biodiversity. The Catchment Based Approach will see issues being identified and tackled at a much more local level, giving key stakeholders and local communities the opportunity to get involved. “The introduction of the CaBA signifies a major change to land and water management. It is a key step in the right direction, but fulfilling its potential will take determination, imagination and thoughtful audit and review” (CIWEM, 2013). 3 Natural England Pollution Risk Assessment & Source Apportionment: River Mease Catchment The Rivers Trust (a company limited by guarantee and granted registered charity, 2004) provides a logical extension for the increasing level of liaison that had taken place for some time between established rivers trusts. The main aims of The Rivers Trust are, “to co-ordinate, represent and develop the aims and interests of the member Trusts in the promotion of sustainable, holistic and integrated catchment management and sound environmental practices, recognising the wider economic benefits for local communities and the value of education.” Westcountry Rivers Ltd is the commercial trading subsidiary of the Westcountry Rivers Trust (charity no. 1135007 company no 06545646). All profits generated through the consultancy are covenanted to the Trust to help secure the preservation, protection, development and improvement of the rivers, streams, watercourses and water impoundments in the Westcountry and to advance the education of the public in the management of water. Cover photo: River Mease at Croxall © Paul Williams, 2011. Published by: Westcountry Rivers Ltd. Rain Charm House, Kyl Cober Parc, Stoke Climsland, Callington, Cornwall, PL17 8PH. Tel: 01579 372140; Email: [email protected]; Web: www.wrt.org.uk © Westcountry Rivers Ltd. 2015. All rights reserved. This document may be reproduced with prior permission of the Westcountry Rivers Ltd. Document history: Revision Details of Revision Prepared By Checked By Approved By Date of Issue Issue v1 1st draft for client comment Angela Bartlett Dave Johnson Russell Smith 10/04/15 Issue v2 Final revisions Angela Bartlett Russell Smith 4 Natural England Pollution Risk Assessment & Source Apportionment: River Mease Catchment Contents Contents 5 Abbreviations 7 Executive summary 8 Introduction 11 1.1 Key contacts 12 1.2 Purpose statement 12 Methodology 13 1.3 Pollution risk assessment & source apportionment 13 1.3.1 Pollution risk modelling 13 1.3.2 Existing evidence and water quality data review 13 1.4 Intervention strategy development 13 1.4.1 Assessment of current mitigation measures in the catchment 13 1.4.2 Targeting delivery 14 1.4.3 Proposals for delivery of future intervention 14 1.5 Assessment of potential outcomes 14 1.6 Limitations and suggestions for further research 14 Catchment overview 15 1.7 Morphology & hydrology 15 1.8 Social & economic 22 1.9 Farming & land use 23 Catchment classifications and challenges 29 1.10 River Mease SSSI classifications 29 1.11 WFD classifications 32 Pollution risk assessment & source apportionment 33 1.12 Suspended solids 33 1.12.1 Fine sediment risk analysis 33 1.12.2 Sediment source apportionment 40 1.12.3 River corridor & landscape sediment risk assessments 42 1.12.4 Water quality sediment analysis 43 1.13 Phosphorus 46 1.13.1 Phosphorus risk analysis 46 1.13.2 Diffuse and point agricultural sources 47 1.13.3 Consented & unconsented discharges 48 1.13.4 Groundwater and in-stream sources 50 1.13.5 Phosphorus source apportionment 51 1.13.6 Surface water quality phosphorus analysis 59 1.14 Additional pollution risks to the SAC/SSSI 61 1.14.1 Pollution incidents 61 Intervention strategy development 64 1.15 Prior interventions 64 1.15.1 Natural habitats & designated sites 64 1.15.2 Previous on-farm interventions 65 1.16 Targeting delivery – FARMSCOPER modelling areas 75 5 Natural England Pollution Risk Assessment & Source Apportionment: River Mease Catchment Assessment of outcomes 78 1.16.1 FARMSCOPER analysis 78 1.17 Deliverables and costs for proposed plan 88 1.18 Increasing STW load risk 89 Conclusion 91 1.19 Delivery challenges 96 References 97 Further information & contacts 98 Appendix 1: Summary of optimisation and mitigation methods. 99 Appendix 2: List of Environmental Stewardship Scheme options with water quality benefits included in each category. 102 6 Natural England Pollution Risk Assessment & Source Apportionment: River Mease Catchment Abbreviations CaBA – Catchment Based Approach CEH – Centre for Ecology and Hydrology CSF – Catchment Sensitive Farming CSM – Common Standards Monitoring DWPP – Diffuse Water Pollution Plan ES – Environmental Stewardship HES – High Ecological Status JNCC - Joint Nature Conservation Committee LOD – Limit of detection RBMP – River Basin Management Plans SAC – Special Area of Conservation SDD – Small Domestic Discharge SRP – Soluble Reactive Phosphorus SS – Suspended Solids SSSI – Site of Scientific Interest STW – Sewage Treatment Works (or Wastewater Treatment Works WwTW) TP – Total Phosphorus UWWTD – Urban Wastewater Treatment Directive WFD – Water Framework Directive 7 Natural England Pollution Risk Assessment & Source Apportionment: River Mease Catchment Executive summary The River Mease is a lowland clay river in the Midlands area of England. The River Mease is designated as a Special Area of Conservation (SAC) under the EU Habitats Directive, and a Site of Special Scientific Interest (SSSI) under the Wildlife and Countryside Act. The River Mease which is referred to in this report includes both the designated section of the River Mease and the lower section of Gilwiskaw Brook. The River Mease SAC/ SSSI has been identified as failing to meet its water quality targets due, at least in part, to diffuse water pollution pressures. Phosphorus and sediment have been identified as the main diffuse water quality issue for the ecological health of the Mease SSSI/ SAC. Current annual mean Soluble Reactive Phosphorus (SRP) concentrations are more than double the water quality target for the Mease SSSI/ SAC at all monitoring locations and up to ten times higher than the water quality target at some monitoring locations. At a catchment scale, sources SRP are equally important from combined non-agricultural sources, including urban run-off and Sewage Treatment Works (STWs) discharges, and combined sources from arable and livestock agriculture. The main source of sediment is from agriculture; natural erosion is a minor source. Water quality monitoring, and therefore SSSI condition assessments and Water Framework Directive (WFD) status, results suggest that water quality problems are widespread throughout the catchment for SRP and sediment. However, the monitoring data has limited spatial and temporal coverage. It is possible that more targeted monitoring would support the more spatially varied pattern of risk identified by the modelling and characterisation data discussed below. Catchment management approaches have the potential to deliver significant improvements in SRP at a catchment scale, but FARMSCOPER modelling suggests improvements will not improve water quality sufficiently to achieve the water quality targets for the Mease SSSI/ SAC. Therefore, additional emphasis needs to be on the reduction of SRP from non-agricultural sources, most notably urban run-off, if conservation targets for SRP are likely to be met. It should be noted that the findings stated above originate from the SAGIS model used in this report. Some recommendations have been made within the report to improve understanding, particularly with regards to STW discharges to improve and review the SAGIS model for the Mease catchment. Measures to reduce SRP losses from point sources should be focused in the Gilwiskaw Brook sub- catchment,