I also got this from Kevin Nash of the Environment agency when I sent in a queery about Sankey brook and the river Glaze.
Hi Martin
Sorry for the delay in responding to your queries about Sankey Brook and the River Glaze.
You are quite right that both rivers hold fish, and the River Glaze is particularly productive and supports a good head of coarse fish in the main river upstream of the Manchester Ship Canal. I think Pennington Flash is particularly helpful in this respect as it can act as a 'nursery area' for small fish who are then protected from high flows that often push fish downstream.
The ability of these watercourses to support fish are limited not only by their water quality but also by the shape of the river channels and presence of subsequent habitat. In effect good fish habitat is often lost where flood defences are needed to protect properties. This is particular true of an urban river like the Sankey.
With regard to water quality, both catchments suffer from a variety of polluting influences. The most significant are Agriculture, Urban run-off, Storm Sewage Overflows, Contaminated Land & Minewaters. The influence of these sources is best seen in our own invertebrate databases which show that the 'bugs' of the river are typical of polluted waters and are not as diverse as they should be. However the actual details of water quality varies locally depending on current and historical landuse, and this will also effect fish distribution at the local level.
With regard to a pollution event on the Sankey near Newton Le Willows. I have been informed by our local Environment Officer that an unsubstantiated report of dead fish was recieved and investigated by both an EA Fisheries
Officer and the local angling club. In both cases no dead fish could be found and any polluting sources could not be identified. The report did however come in during a period of high flows and it is quite possible that fish were killed and then washed away during sudden releases of dirty flood waters (e.g. from urban surface water or Combined Sewage Overflows (structures that release flood waters from the drains to stop sewage works from flooding)).
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