Regional River Quality Monitoring & Surveillance
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Nf^-A Sv?Jt-h COa.it 2.2 fc Environmental Protection Draft Report REGIONAL RIVER QUALITY MONITORING & SURVEILLANCE RESULTS OF THE 1990/1991 BIOLOGICAL SURVEY June 1993 FWS/93/004 Author: JAD Murray-Bligh Assistant Scientist (Freshwater Biology) NRA National Rivers Authority South West Region REGIONAL RIVER QUALITY MONITORING AND SURVEILLANCE - RESULTS OF TBE 1990/1991 BIOLOGICAL SURVEY Environmental Protection Report Draft Report No. FWS/93/004 July 1993 Author: JAD Murray-Bligh Assistant Scientist (Freshwater Biology) . 1 ENVIRONMENT AGENCY 110265 REGIONAL RIVER Q U A L I T Y MONITORING AND SUKVEILIANCE - RESULTS OF THE 1990/1991 BIOLOGICAL SURVEY INTERNAL REPORT No. FWS/93/004 SUMMARY This report describes the biological river quality monitoringf programme undertaken by NRA South West Region, and the results of the 1990/1991 macro- invertebrate survey. The survey comprised 954 sites covering 4241 km of river and 29 km of canal, and was completed in two years: 502 sites were surveyed during 1990 and 449 in 1991. Two sites were not surveyed. Twenty-two key sites were visited in both years, to assess annual changes. The survey mirrored the routine chemical monitoring programme, but-included additional sites so that all reaches which had been assigned River Quality Objectives were included. Habitat features were mapped at each site using standard symbols based on the NCC river corridor survey methods. These maps are to help interpret changes in the biota in subsequent years, and to provide data for conservation assessment. Photographs ‘were taken at every site. Macrophyte species were recorded in 1991. The results of these aspects of the survey are not reported here. Macro-invertebrates were sampled three times in the year: in Spring, Summer and Autumn, using the NRA standard sampling protocols (3 minute kick plus 1 minute search with a pond-net, or in deep water, three to five throws of a medium Naturalists' dredge). , Stream width, depth,- and substrate attributes, were recorded on each visit to enable RIVPACS to be used to predict the macro-invertebrate fauna expected at each site if it was unpolluted. Biotic indices including BMWP-score, ASPT and number of BMWP-scoring families (N-taxa) were determined from the aggregated data from all three seasons' samples, as were the equivalent observed to RIVPACS-predicted ratios (« Ecological Quality Indices, EQIs) for each biotic index. The overall NRA Biological Classes were determined, as were the classes based on individual EQIs. The derivation and interpretation of the NRA Biological Classification, and EQIs are discussed in this report. The ecological quality of most rivers in the South West Region in 1990 and 1991 was good: 86$ of the river length classified (representing 3630 km of rivers) had an overall NRA Biological Classification of Class A (good quality); 8% (340 km) was moderate quality? 3% (146 km) was poor quality; and 1% (35 km) was very poor quality: 2% of river were not classified. In the. reaches that were not of good quality, toxic influences and siltation ascribed to acidic mine drainage or china clay extraction were common, as were the influences of organic pollution from agriculture, agricultural processing industries, sewage treatment works effluents, and storm overflows. The biological classifications of sites in all catchments are discussed in thi s report, with an eraphasi s on those whi ch we re not good qual i ty. The overall ecological quality indicated by the NRA Biological Classification is shown on catchment based maps. The analytical quality audit of this survey demonstrated that the data was of good quality. i ACKNOWLEDGEMENTS This report represents most of the work undertaken by the NRA South West Region's Field Control Biologists in 1990 and 1991. They undertook the initial site reconnaissances, all the sampling, and the sample processing. It also represents a substantial amount of the work undertaken by some members of the Region's Freshwater Science Section, who planned the programme, obtained cartographical, site information, proof-checked the data, and produced this report. Data was input into the National Biological database by NRA Thames Region, who also computed the results. The Institute of Freshwater Ecology undertook the quality audits, and put all samples into long-term storage at Wareham. The data evaluated in Section 3.1 .4 was prepared by Moonsoft Ltd. Especial thanks are due to the biologists of NRA Thames Region who processed 50 samples in 1990. CONTENTS Page SUMMARY i ACKNOWLEDGEMENTS ii LIST OF TABLES v LIST OF FIGURES . v 1. INTRODUCTION 1 1.1 Biological monitoring in the South West Region 1 1.2 Aim of the routine biological river quality monitoring programme 1 2. METHODS 2 2.1 Survey design 2 2.2 Site location 2 2.3 The collection of site data 3 2.4 Macro-invertebrate methods 7 2.4.1 Sample collection 7 2.4.2 Sample processing 9 2.4.3 Sample storage 10 2.4.4 Analytical quality audit 10 2.4.5 Data archiving and analysis 12 2.4.6 The derivation of the NRA biological classifications of ecological quality based on macro-invertebrates 12 2.4.7 Biological classification based on less than three season's data 16 2.4.8 Interpreting environmental quality from the biological classification 17 2.4.9 Comparing the NRA Biological Classification with chemical classifications 20 3. THE ECOLOGICAL QUALITY OF RIVERS IN THE SOUTH WEST REGION 1990/1991 22 3.1 Overview 22 3.1.1 Survey overview 22 3.1.2 Quality audit results 22 3.1.3 Overview of the ecological quality of the Region's watercourses- 24 3.1.4 The relationship between the NRA Biological Classification and the NWC (chemical) Classification of rivers in the South West Region in 1990 26 3.2 The ecological quality of individual catchments 28 3.2.1 Interpreting the tables and maps 26 3.2.2 River Lim Catchment Catchment-1 31 3.2.3 River Axe Catchment Catchment-2 34 iii CONTENTS cont. Page 3.2.4 River Sid Catchment Catchment-3 37 3.2.5 River Otter Catchment Catchment-4 * 40 3.2.6 River Exe Catchment Catchment-5 43 3.2.7 River Teign Catchment Catchment-6 53 3.2.8 River Dart Catchment Catchment-7 57 3.2.9 River Avon Catchment Catchment-8 60 3.2.10 River Erme Catchment Catchment-9 63 3.2.11 River Yealm Catchment Catchment-10 66 3.2.12 River Plym Catchment Catchment-11 ^ \ 68 3.2.13 River Tavy Catchment Catchment-12B, 12C & 12D 72 3.2.14 River Tamar Catchment Catchment-12E to 12P inclusive 75 3.2.15 River Lynher Catchment.. Catchment— 12R & 12Q 83 3.2.16 River Seaton Catchment Catchment— 13 86 3.2.17 River Looe Catchment Catchment-14 89 3.2.18 River Fowey Catchment Catchment-15 .92 3.2.19 Rivers Par and Crinnis Catchments Catchments-16 & 17 95 3.2.20 St Austell and South Cornwall Stream Catchments Catchment-18 99 3.2.21 River Fal Catchment Catchment-19A (part), B, C, D & E 102 3.2.22 Helford and Lizard Peninsula Catchments Catchment-19A 106 3.2.23 River Cober Catchment Catchment-20 109 3.2.24 Lands End Catchments Catchments-21 & 22a (part) 112 3.2.25 River Hayle Catchment Catchment-22 (part) 115 3.2.26 Red River, Portreath, Bplingey and Perranporth Catchments Catchment-23 118 3.2.27 River Gannel Catchment Catchment— 24 122 3.2.28 Porth, Gluvian and Menalhyl Catchments Catchment-25A (part) 125 3.2.29 River Camel Catchment Catchment-25A (part), B, C & D 128 3.2.30 Valency and Crackington Streams Catchments Catchment- 26 131 3.2.31 Rivers Strat and Neet Catchments Catchment-27 134 3.2.32 Hartland Streams Catchments Catchment-28 137 3.2.33 River Torridge Catchment Catchment-29 140 3.2.34 River Taw Catchment Catchment 30 144 3.2.35 North Devon Coastal and Lyn Catchments Catchments 31 & 32 148 4 REFERENCES 151 APPENDIX 1 Changes in the definitions of class bands for BMWP-score 153 APPENDIX 2 The National Water Council river classification system 154 a p p e n d i x 3 Biological sites not classified in 1990/1991 156 iv # LIST OF TABLES Page 2.1 Discharge categories 7 2.2 The biological quality classes based on EQIs 13 2.3 The bands of the EQI values (based on 3 season's data) covering each biological class ' ■ 15 2.4 RIVEACS suitability codes 16 2.5 EQI bands defining the biological classes when derived from single and two seasons combined data 17 2.6 Simplistic interpretation of type of pollution indicated by classes based on EQIs for ASPT and N-taxa 18 3.1 Summary of the quality audit results 22 3.2 Number of sites in each NRA Biological Class compared to each NWC Chemical Class 26 3.3 Mismatches between the NRA Biological Classification and the NWC Classification 28 3.4 Season codes 30 Al Bands of EQIs for BMWF-score defining the NRA Biological Classes as originally defined independently, and as currently defined arithmetically, from the corresponding bands for the EQI ASPT and EQI N-taxa 153 LIST OF FIGURES 2.1 Stamdard sample data form used to record field data 4 2.2 Standard symbols used for habitat maps in the routine biological river quality surveys in 1990 and 1991 5 2.3 ' An example of a habitat map drawn for the 1990/1991 biological river quality survey 6 2.4 Standard site registration form used to record site information 8 2.5 Standard sample data form used to record macro invertebrate sample data, and to calculate BMWP-score, ASPT and N-taxa 11 2.6 The determination of class bands for 3 seasons GQI ASPT 14 i 3.1 Number of 'gains', 'losses' and 'omissions' in successive.