East London river gets an “excellent” stamp of approval

• Channelsea River and River Lea in East London found to have ‘good to excellent’ water quality in accordance with Water Framework Directive classifications. 
• Fish are thriving in Channelsea River with latest summer 2023 survey, finding 14 fish species – a positive indicator of a healthy watercourse. 
• There have been no discharges of storm diluted sewage from Abbey Mills Pumping station since the building and commissioning of the £700 million Lee Tunnel in 2016. 
• Rating showcases what is to come for central London when Thames Tideway Tunnel is completed in 2025.

A new study of the Channelsea River and surrounding watercourses in East London has found the water quality of the rivers are improving and they can be considered a good quality urban river system. 

The report, by OHES Environmental, conducted on behalf of Thames Water, found the Channelsea and River Lea water quality can be classed as ‘good to excellent’, in accordance with Water Framework Directive classifications, which is unique for urban rivers of this type.

The study placed water quality monitoring devices, called sondes, around the Channelsea and River Lea to record dissolved oxygen, pH, temperature, electrical conductivity, and turbidity levels. These measurements were taken from November 2022 to May 2023. 

The findings form part of Thames Water’s work to understand the existing ecology in the Channelsea River as the company prepares for the commissioning of the Thames Tideway Tunnel. The water quality report also establishes a baseline for water quality, prior to the connection of the Thames Tideway Tunnel to the Lee Tunnel.

In addition, a separate summer 2023 fish survey conducted by Thames Water and environmental consultancy, Ricardo plc, has also found 14 different species in the Channelsea River, indicating it is healthy and supports a wide variety of fish. In total, 920 individual fish were captured this summer and measured using three different sampling techniques (fyke netting, seine netting and electrofishing), before being released back into the river. This follows a fish survey conducted in November 2022, by Ricardo, which found 12 species of fish in the watercourse, including a 10lb sea bass.

Tessa Fayers, Director of Waste for London at Thames Water, said: “These amazing results highlight the positive impact our investment in upgrading our sewage treatment works and the building of the Lee Tunnel has had on the Channelsea River and surrounding watercourses. We’re proud to play our part in improving urban rivers such as the Channelsea and we continue to have an unprecedented amount of investment directed towards safeguarding rivers and streams across London and the Thames Valley. The completion of the Thames Tideway Tunnel, will also deliver a huge reduction in the discharges to the tidal River Thames in London and further improve the overall health of the river.”

Joe Pecorelli, conservation programme manager at ZSL, said: “It’s vital that we continue to improve rivers in London and across the country.  Urban rivers provide unique and important habitats for wildlife in our cities, which are beneficial for the environment and local communities. The improved water quality and increases in the local fish populations in the Channelsea River is fantastic and shows that nature can recover in cities with the right planning and investment.”

Since the £700million Lee Tunnel was built by Thames Water and commissioned in January 2016, the river water quality in the Channelsea and surrounding watercourses has improved, with no discharges of storm diluted sewage from Abbey Mills pumping station into the Channelsea since 2016. 

The improvements have taken place alongside upgrades to increase the capacity of Thames Water’s five sewage treatment works, that discharge treated effluent in the tidal Thames.  The largest of the five, Beckton sewage treatment works, can now treat 27 cubic meters of sewage per second in storm conditions.  

When the Thames Tideway Tunnel is completed in 2025, it will also significantly reduce the frequency and volumes of storm discharges to the River Thames in central London, by intercepting polluting discharge points and taking the sewage to Beckton sewage treatment works, instead of flowing directly into the river.

The survey findings and information on the health of the River Lee and Channelsea River indicate there could be similar further improvements to the health and variety of wildlife in the River Thames in London, when the Thames Tideway Tunnel is fully operational.

The water quality report and the summer fish survey report can be viewed on the Thames Water website.

The Thames Tideway Improvement Scheme

First, Thames Water upgraded five Thames Water sites; Beckton, Crossness, Mogden, Dartford and Long Reach. These upgrades were completed in 2014. 

In 2016, Thames Water built the Lee Tunnel, costing £700million. It intercepts the Tidal Thames' largest combined sewer overflow (CSO) at Abbey Mills. The Lee Tunnel is a 7.2m diameter, 7km long tunnel. It runs from Abbey Mills pumping station in Stratford, to Beckton sewage treatment works in Newham. At its peak the tunnel can accept 54 cubic metres per second, preventing Abbey Mills from discharging into the small Channelsea River. 

Finally, the £4.5billion Thames Tideway Tunnel will be completed in 2025. The Thames Tideway Tunnel is 25km long and 7.2 metres wide – the width of three London Buses. It is being delivered by an independent company called Tideway.

This project, combined with previous upgrades and the building of the Lee Tunnel, will intercept 95%, of the total volume of storm flows discharged to the Tidal Thames, depending on the weather. 

Notes to Editors

1. The Abbey Mills Pumping Station Water Quality Monitoring report was conducted by OHES Environmental Limited (OHES), which is part of the Adler and Allan Group (A&A)
2. The fish surveys in Summer 2023 and November 2022 were conducted by Thames Water and environmental consultancy, Ricardo PLC, to understand the existing ecology in the Channelsea River, prior to the connection of the Thames Tideway Tunnel to the Lee Tunnel.