The Water Quality of the Tidal Thames Environment Agency Information Centre The Water Quality Head office of the Tidal Thames Class no .A-Report-of-the-Environment'Agency February 1997 National Information Centre The Environment Agency Rio House Waterside Drive Aztec West BRISTOL BS12 4UD Due for return LONDON : THE STATIONERY OFFICE Commissioning Organisation: Environment Agency Rio House Waterside Drive Almondsbury Bristol BS12 4UD Tel: 01454 624400 Fax: 01454 624409 © Environment Agency First Published 1997 ISBN 0 11 310125 2 Applications for reproduction should be made to: The Stationery Office Ltd., St. Crispins, Duke Street, Norwich NR3 1PD All rights reserved. N o part o f this document may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, mechanical, photocopying, recording or otherwise without the prior permission of the Environment Agency. The views expressed in this document are not necessarily those o f the Environment Agency. Its officers, servants or agents accept no liability whatsoever for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained herein. Cover photograph: Chorley and Handford Ltd., The Thames Estuary at Tower Bridge Printed on recycled paper Reprise Matt 115gsm 80% recycled content (40% pre consumer waste 40% post consumer waste) Preface----- --------- One of the Environment Agency's more important duties is to compile information in order to form an opinion of the general state of pollution of the environment. There are many ways in which such an opinion could usefully be formed, but one of the most constructive is that of looking at specific areas of the environment in an integrated way. By their very nature, estuaries are complex bodies of water, and this complexity-is greatly increased by the many activities which take place within them. It was for this reason that the National Rivers Authority embarked on a series of in-depth studies on the major estuaries of England and Wales, reporting on the Humber_in_1.993-and-on-the-Mersey~m 19957This'senerKaTbeen continued by the Environment Agency, with a first report on that most important o f estuaries, the Thames. It is a good story, but one which has yet to be completed. Quite dramatic improvements have been made in the past, but pressures on the estuary remain and these need careful management. The Environment Agency is thus working closely with others to draw up plans upon which future decisions can be sensibly made, and to ensure that plans for the river upstream of the tidal limit are linked to plans for the downstream, estuarine areas. This report provides the historic and factual evaluation upon which such plans will be based. R J Pentreath Chief Scientist and Director of Environmental Strategy Water Quality of the Tidal Thames Contents Executive Summary 8 1. An Introduction to the Thames Estuary 11 1.1 G eography 11 1.2 Hydrography 1 1 1.3 Freshw ater Inputs 13 1.4 Groundwater Inputs and Geology 13 1.5 London 15 1.6Land Use 17 1.7 Recreation and Transport 18 1.8 Conservation Status 19 The Legislative and Regulatory Framework 20 2.1 Introduction 20 2 .2 Metropolitan Board ofWorks 20 2.3 Thames Conservancy 20 2 .4 Port of LondonAuthority (PLA) 20 2.5 Pollution Prevention Acts, 1951 and 1961 20 2 .6 Pippard Report, 1961 20 2.7 Port of London Act, 1964and 1968 21 2.8 Water Act 1973 21 2.9 Control of Pollution Act 1974 21 2 .1 0 Water Act, 1989 and Water Resources Act, 1991 21 2.11 Environmental Protection Act, 1990 21 2.12 Environment Act 1995 21 2.13 International Legislation 22 2.14Paris Convention 23 2.15 North Sea Conference Declarations 23 Factors which Affect Water Quality in the Thames 24 Estuary 3.1Introduction 24 3.2 Dissolved Oxygen 24 3.3Temperature 24 3.4 Retention Time and Freshwater Flow 25 3.5 Re-Suspension and Settlement of Solids 25 3.6 Photosynthesis/Respiration and Eutrophication 26 3.7 Oxygen Absorption from the Atmosphere 26 3.8 Sewage Treatment Works and Storm Water Effects 27 3.9 Contaminants 28 The Pollution History and Clean-up 29 4.1 Introduction 29 4 .2 Cholera Epidemics 29 4.3 Metropolitan Commissioners of Sewers 1847 30 4.4 Metropolitan Board ofWorks 30 Contents 4.5 London County Council 31 6 Port of London'Authority 3 F 4.7 Thames Survey Committee and the Pippard Report 31 4.8 Recent History 1960 to 1989 ' ' ' ' 32 5. Current Quality Management of the Thames Estuary 36 _5.1 Introduction ____ ____ _ ___________________ _36 5.2 Water Quality Objectives 36 5.3 Monitoring 36 574 Water Quality Models 38~ 5.5 STW Discharges, River Flow, Storm Discharges and Operating 38 Agreem ents 5.6 Summer Conditions and Improved Operating Standards 41 for STW s 5.7 Storm Water Discharges 42 5.8 Freshwater Flow 43 5.9 Heavy Metals and Organic Micro-Pollutants 44 6. Quality Compliance of the Thames Estuary 47 6.1 Introduction 47 6.2 Dissolved Oxygen Compliance 47 6.3 Compliance with Environmental Quality Standards 49 6.4 1995 Compliance with Discharge Consents 49 7. The Biology of the Thames Estuary 51 7.1 Introduction 51 7.2 Invertebrates 51 7.3 Fish of theThames Estuary 53 7.4 Birds 56 8. Achievements, Priorities and Future Developments 57 8_. 1 Achievements _= = . _. 57, 8.2 Local Developments 5 7 8.3 National Developments 57 8.4 The Future 58 8.5 Conclusion 59 Bibliography 60 Glossary of Terms 61 Glossary of Abbreviations 63 Water Quality of the Tidal Thames Appendices 64 Appendix 1: Dangerous Substances Surface Water Regulations 64 1989 and 1992 Appendix 2: Natural Environmental Quality Standards for List II 65 Metals for the Protection o f Salt Water Life Appendix 3: U.K. Red List 66 Appendix 4: Annex 1A Substances 67 Appendix 5: Fish Species of the Thames Estuary 68 Acknowledgements Plate 1.1 TheThames Estuary Plate 1.3 TheThames Estuary at Canary Wharf Plate 1.4 Thames Estuary at Queen Elizabeth II Bridge Cover photograph All reproduced by permission of Chorley and Handford Ltd. List of Plates Cover Plate TheThames Estuary atTower Bridge cover Plate 1.1 T h eT h am es Estuary 10 Plate 1.2 TheThames Barrier 12 Plate 1.3 Thames Estuary at Canary Wharf 16 Plate 1.4 Thames Estuary at Queen Elizabeth II Bridge 17 Plate 1.5 Angling on theThames Estuary 18 Plate 4.1 Monster Soup 29 Plate 4.2 Faraday giving his card to Father Thames 30 Plate 4.3 TheThames Bubbler 35 Plate 7.1 Oligochaete worm 52 List of Figures Figure 1.1 Map ofThames Estuary showing main features 11 Figure 1.2 Annual Mean Abstraction fromThe River Thames 14 1 8 9 0 -1 9 9 4 Figure 1.3 Water Level Changes in the Chalk and Basal Sands Aquifer 14 Figure 3.1 Chloride Profile of theThames Estuary showing Saline 25 Intrusion for High and Low Flow Conditions Figure 3.2 Typical Oxygen Sag Curve Showing the Critical Point 27 Figure 4. la Decrease in Polluting Load Discharged to the Estuary 33 Figure 4.1 b Dissolved Oxygen Levels in the Tidal Thames between 33 1950 and 1980, April-September mean Figure 4.2 Dissolved Oxygen Profiles of the Estuary before, during 3 4 and after a storm event in 1977 Figure 5.2 Effective Oxygen Load from the Freshwater Thames in 40 Relation to the Flow for 1995 6 Figure 5.3 The Percentage Load Contributed to the Tideway by the 41 _ . — Fresh waterThames, Mogden , Grossness and Becklon:^. STWs in a High and Low Flow Period Figure 5.4 Modelled Effect of Reduced Abstraction on Dissolved 43 O xygen Figure 5.5 Dissolved Oxygen Profile, May-September mean, 4 4 showing improvement since 1989 Figure 5.6 ThamesTideway Pollution Incidents between [989 ___ _____ .46 and 1995 " Figure 6.1 Dissolved oxygen compliance for each quarter of 1995 4 7 -4 9 __Figure.7.. 1___Mean Macroinvertebrate Species-Number from-Thames -------- 5-2 Estuary Benthic Programme in 1994 Figure 7.2 Cumulative Fish Species Recorded inTidal Thames 54 (Fulham-Tilbury) 1964-1989 Figure 7.3 Confirmed Annual Returns of Salmon in theThames 55 Estuary 1979-1995 List of Tables Table 1.1 Riverine Inputs to theThames Estuary 1 3 Table 1.2 Population of London 15 Table 1.3 Population Density 16 Table 5.1 Standards and Water Quality Objectives for the Reaches 3 7 of theThames Estuary Tabl e5 .2 L oadsD isch argedfrom STWs 3 9 Table 5.3 Industrial Inputs____________________ _______________________ 39 Table 5.4 Freshwater Inputs 40 Table 5.5 Consent Standards for STWs in theThames Estuary 42 Table 5.6 Loads of Organic Micro-pollutants in Sewage and the Estuary 45 between 1991 and 1995 Table 6.1 Mean Concentration of List I Substances in theThames 50 Estuary, 1995 Table 6.2 Mean Concentrations of List II Metals in theThames 50 = Estuary, 1995 Table 6.3 Compliance with the bathing water directive 1991-1995 50 Water Quality of the Tidal Thames Executive Summary TheThames Estuary is now considered to be one of the cleanest metropolitan estuaries in the world. A great number of articles and papers have been written for books, journals, conferences and other local and international forums on the clean-up of theThames. This report, by the Environment Agency aims to bring together the various aspects of the historical and current water quality management of the Thames Estuary into one document. The report focuses on the success of the Environment Agency and previous regulatory bodies in achieving a water quality in the Estuary which sustains a thriving fish population and other biological life.