In the Hounslow Green Party we have been concerned about water pollution in the Thames and the Brent / Grand Union Canal for some time. This has been associated with the recent wider awareness of the national issues highlighted by the likes of Feargal Sharkey and our very own Green peeress Jenny Jones.
At a local level we noticed a recent Hounslow Flood Risk Assessment had the lower Brent (running through Brentford) with Poor water quality. This was not a surprise to us as we have noticed reduction in nature in the area. We also noticed that that the London Plan is targeting all water bodies in London having Good water quality – although it neglects to say when this will be achieved by.
Further investigations found that whether the water quality was considered to be Poor, Moderate or Good was based on quite infrequent testing. It was also not entirely clear how they came to the one word headline (Poor, Moderate or Good) from the actual tests done.
We in the Hounslow Green Party were keen to have a better understanding of this, in order to lobby the council (and anyone else) into more action. At first we contacted a number of people with little progress.
But recently we have managed to get involved in a lot of different types of testing:
- The excellent Clean Up River Brent (CURB) have allowed us to have continuous monitoring of the quality of the water in the River Brent basin near the Island / Holiday Inn. This shows the water quality getting worse and worse during dry spells and then improving on heavy rainfalls.
- We have joined in testing with Fresh Water Watch. They have provided us with sample tubes that allow us to test for nutrients Nitrates and Phosphates. Generally the test results have shown moderate nutrient levels – which classify as Poor ecological status.
- The Rivers Trust have a six monthly Big River Watch that we have also participated in. In this we loaded their app and a number of us went to the side of the Brent river near the Cornelius bridge (the new foot bridge over the canal in Brentford) and entered our observations.
- Imperial College, in conjunction with CURB, have been doing a very large study of water pollution at 50 different bridges along the whole river Brent. We in the Hounslow Green Party are responsible for the last two at Augustus Close road bridge and the Cornelius foot bridge, Brentford. The particular focus of this study is to see how much road run off ends up in the river after heavy rain fall. So “our” bridges are of particular interest with the A4/M4 just up stream. Quite a challenge to participate in this as it has been very dry and most of the heavy rainfall has been in the middle of the night! Results from this should be coming through shortly.
The Mogden sewage works, in Isleworth, are another major source of water pollution – but I will leave that to another time.
Armed with more information, we will continue to hold the council to account and generally raise awareness of the issue and its impacts on us and the rest of the natural world.
Tony Firkins
3 May 2025