Thames Water Fish Survey 2023

07 December 2023

Fish are thriving in Channelsea River says latest 2023 fish survey by Ricardo

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 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 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 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 Ricardo plc, has also found 14 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 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, which we’ll take over running in 2025, 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.” 


Curt Williams with a juvenile sea bass

Calum Wyatt with a thin lipped grey mullet



Ryan Forshaw with an adult sea bass, and Calum Wyatt
The Ricardo river survey team

Read Thames Water's full press release