Organised in Barnet, but carried out by two Pauls both sides of the Thames. The Great UK Water Blitz, part of EarthWatch, seeks to find out about levels of nitrogen and phosphates in our water.

The south London bit was done by Paul B in Lewisham on the River Quaggy, part of the Ravensbourne catchment which flows into the Thames at Deptford. Levels of both nitrogen and particularly potassium were much higher than when the survey was last done in May.