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October Test results are in!


River Mole River Watch October pollution test results are in! Overall catchment phosphate levels were down due to dilution in higher river discharge but water quality still mostly poor or moderate. Some spikes in pollution occurred in tributaries notably Redhill Brook and the the streams draining from Hookwood fields under the A217. In contrast to previous month, apart from the spikes mentioned, the Lower Mole experienced higher pollution levels than the Upper Mole.

High river flows through the latter part of October provided a significant dilution effect which lowered Phosphate levels at most test sites.

Despite dilution effects 87% of water courses in the catchment tested as moderate or poor water quality. Fortunately this month none were tested as Bad quality status.

Pollution hot spots include Redhill Brook 2.26ppm, Hookwood Common Brook and Spencers Gill both 1.6ppm. Suprising hot spots raised from previous tests include Bookham Brook, a strong candidate for chalk stream status and the river through the Mole Gap, both scoring >1.00ppm.


The latter half of October was very wet with 164mm of total rain at Charlwood official wx station. River levels were therefore high contributing to dilution.


1000 hours of storm discharges occured during October.. that's 5 weeks of untreated sewage draining into the River Mole. (actual EDM = 949 hours but there were 1600 hours offline so assuming some offline activity would exceed 1000 hours)


Finally, a huge thank you to our fantastic River Mole River Watch citizen science volunteers who braved inclement weather to get all the tests done and in over last weekend.



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Caroline Cardew-Smith
2023年11月08日

Brilliant report thank you Simon, it’s so exciting to see the results over the last six months of testing building a picture of just how dire the Mole catchment is. With the facts and data we can formulate a strategy to talk to various polluters and work with them., which does include resident actions! We all want the same ultimately, a beautiful clean river Mole!

いいね!
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