UNITED UTILITIES _________________________ MANCHESTER SHIP CANAL WATER QUALITY REVIEW PART 1 OF 2 (PRIMARY DOCUMENT) _________________________ FINAL REPORT September 2007 APEM REF: 410039 APEM Scientific Report 410039 CLIENT: United Utilities ADDRESS: Haweswater House, Lingley Mere Business Park, Lingley Green Avenue, Great Sankey, Warrington, WA5 3LP PROJECT No: 410039 DATE OF ISSUE: September 2007 PROJECT DIRECTOR: Dr. Keith Hendry PROJECT MANAGER: David Campbell, M.Sc. SENIOR SCIENTISTS: Dr Roger Baker Margaret-Rose Vogel Heather Webb Kathleen Beyer Riverview, Embankment Business Park, Heaton Mersey, Stockport, SK4 3GN Tel: 0161 442 8938 Fax: 0161 432 6083 Website: www.apemltd.co.uk Registered in England No. 2530851 Final Report – September 2007 ii APEM Scientific Report 410039 CONTENTS 1 INTRODUCTION .............................................................................................................................1 1.1 BACKGROUND TO WATER QUALITY WITHIN THE MSC ..............................................................1 1.2 SPECIFIC WATER QUALITY ISSUES OF THE MSC...........................................................................2 1.3 WATER QUALITY IN THE PRESENT DAY WITHIN THE MSC .........................................................3 1.4 INTRODUCTION TO DATA AVAILABILITY AND PREVIOUS WATER QUALITY REPORTS ...............4 1.4.1 Data Availability .................................................................................................................4 1.5 BACKGROUND TO PREVIOUS REPORTS REVIEWING THE WATER QUALITY OF THE MSC...........6 1.5.1 Academic reviews (1988-Present) ......................................................................................6 1.5.2 APEM Review (1990) in association with Watson Hawksley (now MWH) .......................7 1.5.3 Harper Review (2000).........................................................................................................7 2 REVIEW OF MSC WATER QUALITY DATA ...........................................................................9 2.1 BOD .............................................................................................................................................9 2.2 AMMONIA...................................................................................................................................12 2.3 DISSOLVED OXYGEN ..................................................................................................................14 2.4 SUSPENDED SOLIDS AND TRANSPARENCY..................................................................................17 2.5 NUTRIENTS (PHOSPHORUS)........................................................................................................17 2.6 BACTERIOLOGY..........................................................................................................................18 2.7 OTHER DATA ..............................................................................................................................19 2.7.1 Metals.................................................................................................................................19 2.7.2 pH.......................................................................................................................................19 2.7.3 Conductivity.......................................................................................................................20 2.7.4 Residual chlorine...............................................................................................................20 2.8 SEDIMENTS .................................................................................................................................20 2.9 KEY FINDINGS ............................................................................................................................22 3 REVIEW OF MSC BIOLOGICAL DATA....................................................................................23 3.1 HISTORICAL REVIEW OF MACRO-INVERTEBRATE DATA ...................................................................23 3.1.1 Upper MSC ...............................................................................................................................23 3.1.2 River Inputs...............................................................................................................................24 3.1.3 Salford Quays ...........................................................................................................................26 3.2 HISTORICAL REVIEW OF ALGAL DATA ..............................................................................................26 3.3 KEY FINDINGS ..................................................................................................................................28 iii Final Report – September 2007 APEM Scientific Report 410039 Foreword This report details a review of water quality within the Manchester Ship Canal and is the product of an extensive data and literature search. The primary section of the document provides a summary of important data and discusses the associated relevant issues. Detailed descriptions of the data used along with various graphs and charts are presented in an associated technical document (Appendix document). iv Final Report – September 2007 APEM Scientific Report 410039 1 INTRODUCTION The Manchester Ship Canal (MSC) was opened in 1894 creating a major freight access corridor into the heart of industrial Manchester. It extends some 35 miles (56km), from the River Mersey at Eastham to Manchester Docks. Following a decline in shipping use, Manchester Docks (now renamed Salford Quays) eventually closed as a shipping port in 1984, leading to severe urban decline in the area. Subsequent regeneration in Salford Quays from the 1987 onwards has since led to a thriving area of intense development with the Quays currently playing host to modern apartment buildings, office developments and art and cultural centres. The shift from deprivation and decline in the Quays area to its current prosperity is inextricably linked to the history of water quality within the Manchester Ship Canal. This review is specifically concerned with the changes in water quality of the MSC and Salford Quays over the past three plus decades (for which survey data were available), along with development of the ecology of the phytoplankton, periphytic diatoms, and benthic macro-invertebrate communities present in this system. It was prepared for United Utilities as part of a wider investigation into the water quality of the Manchester Ship Canal (MSC), within the context of the European Community Freshwater Fish Directive (EC FFD). Crucially, the MSC has been designated under the directive as a cyprinid fishery from the River Irwell near Salford University to the freshwater limit of the Canal at Latchford Locks (22km of the MSC). The quality of water in the MSC does not currently meet the EC FFD standards, which has ultimately been the impetus behind this study. The objective of this review is to summarise the extent of the water quality monitoring that has been conducted on the MSC and Salford Quays and to discuss the changes that have taken place in the aquatic environment of these water bodies over the preceding decades. 1.1 Background to Water Quality Within the MSC The Manchester Ship Canal has experienced poor water quality since its construction. The overriding issues driving this are two fold; one that the Mersey catchment is arguably overpopulated and two; that as a water body the MSC is essentially too small for the catchment it serves. Regarding the first of these points, the Upper Mersey catchment encompasses large densely populated areas including the cities of Manchester and Salford which generate huge amounts of anthropogenic waste. This is particularly true of the River Irwell, that flows through the centre of Manchester and directly into the MSC at its upper extent. Over 90% of the Irwell’s dry weather flow is made up of combined sewage effluent from the various waste water treatment works (WwTWs) and industrial effluents along the river. In addition, the construction of the sewer network is such that during heavy rainfall events, the sewer system is occasionally unable to cope with the large volumes of water entering it, which bring about direct spills of untreated sewage from the combined sewage overflows (CSOs) (Rees and White 1993). During a CSO event untreated sewage is washed into the MSC, adding further to the dry 1 Final Report – September 2007 APEM Scientific Report 410039 weather pollutant load. This clearly presents severe water quality issues for the Ship Canal, but further to this, not only is the inflowing water extremely polluted, but as this water enters the MSC the physical nature of the Canal exacerbates the problem. The MSC receives water from a number of arguably heavily modified but reasonably natural rivers, including the Rivers Irwell, Irk, Medlock, Mersey and Bollin, which combine to give an average total inflow of over 3000 Megalitres (Ml) per day. However, the physical structure of the Canal fundamentally changes the flow regime of these rivers by slowing the flow, which has a profound effect upon water quality. The vertical walls and deep nature of the Canal (up to 9m) dramatically changes the hydraulic regime compared to that experienced in the inflowing rivers. The high residence time in the Canal means that pollutants are not readily flushed out and particulate contaminants can settle