It’s interesting to compare the results from the water quality monitoring that we, and the Environment Agency have been carrying out at Sheep’s Green in the 2024 and 2025 bathing seasons
The graph above shows the Environment Agency results for E.coli at sheeps Green in red, Cam Valley Forum’s results in Green, and the rainfall in blue. (Click here for a larger copy of the graph)
The Bathing Water Quality during the 2024 season was rated as “Poor”, with ALL readings above the threshold of 900 E.coli/100ml. (Although the actual way of calculating the classification for the season is quite complicated, if more than a few test results are above 900 E.coli/100ml, the classification for the season is likely to be “Poor. This webpage explains it in more detail)
Encouragingly for swimmers, during the 2025 season, the water quality was mostly well within the “Good” range often having just 200-300 E.coli/100ml. However the overall classification was still “poor” because of a few high readings above the threshold.
We wondered if Anglian Water had done anything to cause this improvement, but they tell us that they think it is just because it rained less….
The graph above shows rainfall as a blue line. Looking at the data, we note that it rained for an average of 2mm/day in the 2024 “bathing season” but only 0.7mm/day in the 2025 “bathing season”.
As the average summer rainfall for Cambridge is 1.6mm/day, it’s clearly unacceptable to have a sewage system that only provides reasonably safe bathing water when we have an exceptionally dry summer.