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Howard Humphreys Consulting Engineers in Association with Cobham Resource Consultants NATIONAL RIVERS A U TH O R ITY NATIONAL WATER RESOURCES STRATEGY: COMPARATIVE ENVIRONMENTAL APPRAISAL OF STRATEGIC OPTIONS Volume 1: Main Report Ref. 84.247.0/AW/3122/NRAEA1.R02 Howard Humphreys & Partners Ltd f .Thorncroft' '■•TX. • Manor* ■. v ,1 Dorking Road > Leatherhead Surrey KT22 8JB January 1994 WJtmw Brown & Root Civil National Rivers Authority Guildbourne House Worthing Please return this book on or before last date shown below. Renewals can be obtained by contacting the library. E n v i r o n m e n t A g e n c y NATIONAL LIBRARY & INFORMATION SERVICE SOUTHERN REGION Guildbourne House, Chatsworth Road. Worthing. West Sussex BN 1 1 1LD Howard Humphreys Consulting Engineers in Association with Cob ham Resource Consultants NATIONAL RIVERS AUTHORITY NATIONAL WATER RESOURCES STRATEGY: COMPARATIVE ENVIRONMENTAL APPRAISAL OF STRATEGIC OPTIONS Volume 1: Main Report Ref. 84.247.0/AW/3122/NRAEA1.R02 Howard Humphreys & Partners Ltd Thomcroft Manor Dorking Road Leatherhead Surrey KT22 8JB January 1994 NATIONAL RIVERS AUTHORITY NATIONAL WATER RESOURCES STRATEGY COMPARATIVE ENVIRONMENTAL APPRAISAL OF STRATEGIC OPTIONS FINAL REPORT VOLUME 1 - MAIN REPORT CONTENTS EXECUTIVE SUMMARY 1. INTRODUCTION 1 1.1 Background 1 1.2 Objectives and Tasks 2 1.3 Scope of Study 2 1.4 Limitations of Study 3 1.5 Scope of Report 3 2. IDENTIFICATION OF STRATEGIC OPTIONS 5 2.1 Selection of Strategic Options 5 2.2 Strategic Options 6 3. LITERATURE REVIEW AND UK EXPERIENCE 7 3-1 Key Findings from Literature Review 7 3.2 Key Findings From UK Experience 9 3.3 NRA Consultation Workshops 11 3-4 Key Issues 11 4. FRAMEWORK FOR ENVIRONMENTAL ASSESSMENT 17 4.1 Role of Environmental Assessment 17 4.2 Method of Environmental Assessment 20 4.3 Categories and Criteria 20 4.4 Assessment of Option Components 21 4.5 Comparison of Options 22 5 ENVIRONMENTAL IMPLICATIONS OF STRATEGIC OPTIONS 23 5.1 OPTION 1: Unsupported Severn-Thames Transfer 23 5.1.1 River Severn Downstream of Deerhurst 23 5.1.2 Bankside. Storage and Pumping Station at Deerhurst 27 5.1.3 Pipeline, Deerhurst to Down Ampney 28 Re£ S4.247.0/AW/3122/NRAEA1.R02 5.1.4 Gravel Pit Storage at Down Ampney 29 5.1.5 Restored Thames & Severn Canal 30 5.1.6 River Thames, Buscot to Egham Reach 31 OPTION 2: Craig Goch Regulation of Severn 35 5.2.1 Enlarged Craig Goch Reservoir 35 5.2.2 Tunnel Aqueduct to River Severn (Llanidloes) 38 5.2.3 River Severn, Llanidloes to Coalport 38 5.2.4 River Severn, Coalport to Deerhurst 41 5.2.5 Sevem-Thames Transfer 42 OPTION 3: Craig Goch Regulation of Wye 43 5-3.1 Enlarged Craig Goch 43 5.3.2 Tunnel to Nannerth 44 5.3.3 River Wye, Nannerth to Ross-on-Wye 44 5.3.4 Pipeline, Ross to Deerhurst 48 5.3.5 Deerhurst-Thames Transfer 48 OPTION 4: Vymwy Redeployment for Severn Regulation 49 5.4.1 Vymwy Reservoir 50 5.4.2 River Vyrnwy to Severn Confluence 50 5.4.3 River Severn, Vyrnwy Confluence to Deerhurst 52 5.4.4 Sevem-Thames Transfer 53 5.4.5 River Thames, Buscot to Egham Reach 53 5.4.6 Knock-on Resource Development in North West Region 53 OPTION 5: South West Oxfordshire Reservoir Regulating Thames 53 5.5.1 South West Oxfordshire Reservoir 54 5.5.2 River Thames, Culham to Egham Reach 55 OPTION 6: Canal Transfer, Severn-Thames 57 5.6.1 Pipeline, Severn (Coalport) to River Penk 59 5.6.2 River Penk to River Sow Confluence 59 56.3 River Sow to Trent and Mersey Canal 59 5.6.4 Trent and Mersey Canal, Great Heywood Junction to Fradley Junction 59 5.6.5 Coventry Canal, Fradley Junction to Hawkesbury Junction 62 5.6.6 Oxford Canal, Hawkesbury Junction to Isis Lock 63 5.6.7 River Thames Downstream of Oxford Canal 64 OPTION 7: Severn to Trent Transfer 65 5.7.1 Severn Upstream/Downstream of Coalport 65 5.7.2 Pipeline, Coalport to Lower Drayton on River Penk 67 5.7.3 River Penk, Lower Drayton to Confluence • with River Sow 68 5.7.4 River Sow, from River Penk Confluence to River Trent Confluence 70 M.247.0/AW/J122/NRAEA1.R02 5.7.5 River Trent Downstream of River Sow Confluence 71 5.8 OPTION 8: Great Bradley Reservoir with Ely Ouse- Essex Scheme 73 5.8.1 Great Bradley Reservoir 73 5.8.2 Ely Ouse Downstream of Denver 75 5.8.3 River Stour Downstream of Reservoir 79 5.8.4 River Pant/Blackwater 82 5.9 OPTION 9: Unsupported Trent to Essex Transfer 84 5.9.1 River Trent Downstream of Torksey Intake 85 5.9.2 Fossdyke Navigation from Torksey to River With am 87 5.9.3 River Witham 89 5.9.4 Pipeline Witham - Ely Ouse 91 5.9.5 Ely Ouse-Essex Scheme 91 5.9.6 River Stour 92 5.9.7 River Pant/Blackwater 95 5.10 OPTION 10: Broad Oak Reservoir 97 5.10.1 Broad Oak Reservoir 98 5.10.2 River Stour, Downstream of Intake at Plucks Gutter 98 5.10.3 Sarre Penn, Downstream of Reservoir 102 5.11 Other Options 104 5.11.1 Surface Water Schemes 104 5.11.2 Groundwater Schemes 106 5.11.3 Alternative Transfer Options 109 5.11.4 Desalination 111 COMPARISON OF OPTIONS AND KEY ISSUES 113 6.1 Alternative Strategies 113 6.2 Thames Region 115 6.3 Severn-Trent Region 117 6.4 Anglian Region 118 6.5 Southern Region 119 6.6 Discussion 120 FURTHER STUDY REQUIREMENTS 122 7.1 Strategic Studies 122 7.2 Option Specific Studies 123 CONCLUSIONS AND RECOMMENDATIONS 124 8.1 Review of Literature and Existing UK Schemes 124 8.2 Development of Environmental Assessment Methodology 124 8.3 Results of Environmental Assessment , 125 8.4 Requirements for Further Studies 127 Bcfi &4.247.0/AW/ 3122/ NRAEA1-R02 TABLES Alter Page No. 4.1 River/Canal Framework for Assigning Sensitivity 22 4.2 Reservoir/Pipeline Framework for Assigning Sensitivity 22 4.3 River/Canal Framework for Assessing Risk of Significant Impact 22 4.4 Reservoir/Pipeline Framework for Assessing Risk of Significant Impact 22 5.1 Option 1 Environmental Assessment 23 5.2 Option 2 Environmental Assessment 35 5.3 Option 3 Environmental Assessment 43 5.4 Option 4 Environmental Assessment 50 5.5 Option 5 Environmental Assessment 54 5.6 Option 6 Environmental Assessment 58 5.7 Option 7 Environmental Assessment 65 5.8 Option 8 Environmental Assessment 73 5.9 Option 9 Environmental Assessment 85 5.10 Option 10 Environmental Assessment 98 6.1 Advantages and Disadvantages of Strategic Options 114 FIGURES 2.1 River Severn Regulation Options 6 2.2 Severn-Trent Transfer and South West Oxfordshire Reservoir Options6 2.3 Sevem-Thames Canal Transfer and Severn Trent Transfer Options 6 2.4 Trent-Essex and Great Bradley Reservoir Options 6 4.1 Environmental Assessment Framework 20 6.1 Environmental Assessment of Strategic Options Summary Matrix 114 M.247.0/AW/3I22/NRAEA1.R02 NATIONAL RIVERS AUTHORITY NATIONAL WATER RESOURCES STRATEGY COMPARATIVE ENVIRONMENTAL APPRAISAL OF STRATEGIC OPTIONS FINAL REPORT VOLUME 2 - APPENDICES CONTENTS TERMS OF REFERENCE LITERATURE REVIEW - THE AQUATIC IMPACTS OF INTER-BASIN TRANSFER AND RIVER REGULATION SCHEMES 1. International Perspective 2. Physio-Chemical Changes 2.1 Hydrology 2.2 Water Quality 2.3 Geomorphology 3. Biological Responses 3.1 Aquatic Ecology 3.2 Fisheries 4. Summary EXPERIENCE FROM EXISTING UK SCHEMES 1. Introduction 2. Evidence from NRA Regions 3. Impacts of Selected Existing UK Schemes 3*1 Ely Ouse to Essex Transfer 3.2 Kielder Regulation and Transfer 3-3 River Dee Regulation 3.4 River Tywi Regulation 3.5 West Berkshire Groundwater Scheme 3.6 Shropshire Groundwater Scheme 4. Summary 84 .2 47.0/AW/ 3122/ NRAEAAPP. R02 APPENDICES CONTENTS (Com.) ENVIRONMENTAL ASSESSMENT OF OPTION COMPONENTS 1. EA Methodology 1.1 Categories and Criteria 1.2 General Character/Landscape 1.3 Water Quality 1.4 Fisheries 1.5 Aquatic Ecology 1.6 Agriculture 1.7 Archaeology and Cultural Heritage 1.8 Terrestrial Ecology Component Assessments BIBLIOGRAPHY SUMMARY SHEETS FOR UK SCHEMES BIOLOGICAL BANDING M.247.0/WF/3122/NRAEAAPP.CON EXECUTIVE SUMMARY INTRODUCTION This report summarises the findings of a preliminary high level environmental assessment overview of strategic water resource development options identified by the NRA for meeting regional marginal water supply deficits in England and Wales up to a planning horizon of 2021. This assessment has involved the following tasks: • A literature review of the environmental issues and known impacts associated with water resources development schemes, including the effects of river regulation, inter-basin transfer and changes to residual flows to estuaries; • A review of the impacts of existing UK schemes to identify the lessons to be learnt for future schemes; • The development of a framework for assessment of individual schemes and objective comparison of strategic development options, taking account of EC and UK environmental assessment regulations; © An assessment and comparison of the environmental implications of ten strategic options representative of the range of likely water resource developments, taking account of the results of hydrological modelling of specific schemes. It is emphasised that this assessment is a starting point for environmental assessment of the strategic water resource development options collating, summarising and analysing the work carried out to date and identifying the key issues, constraints and benefits. The approach, methodology and preliminary conclusions will be subject to progressive modification and development as more detailed studies and investigations are undertaken.