River Mole November pollution data is out! Things are getting complicated as more rainfall reduces Phosphate levels despite storm overflows increasing since low durations through Summer. Notice how the red blobs showing high Phosphate levels in June and July get smaller and lighter through to November.
After a dip through Summer, storm overflows into the river have increased every month which correlates reasonably well with rainfall.
Overall, the River Mole remains mostly moderate, poor or bad water quality status according to the data our fabulous citizen scientists collected in November.
However, for several water courses in the catchment the levels of phosphate were the lowest (least polluted) they had been since records started in May. November hotspots include Leigh Brook, Salfords Stream, Redhill Brook and downstream of Pixham sewage works in Dorking.
Phosphate levels for the whole catchment were the lowest recorded due to dilution from high river levels despite increases in untreated sewage overflows, which of course themselves are diluted. Treated effluent at low flows in summer results in worse quality than outfalls!
Downstream, from left to right, there are still pretty consistent signals that the Upper Mole below the first order streams is the most polluted. This has the "widest" area of catchment gathering water from diverse land uses including agriculture, industry and major roads.
Finally a HUGE thank you to our fantastic citizen scientists younger and older for venturing out in November weather to test our River Mole.. thank you all!
Finally a HUGE thank you to our fantastic citizen scientists younger and older for venturing out in November weather to test our River Mole.. thank you all!
Комментарии