Earthwatch Water Blitz

Nitrates 10 and Phosphates 0.5

The second Water Blitz of the year - coordinated by EarthWatch - was undertaken during 2.10.17, at locations along the Hogsmill river similar  to those of the May Blitz. Starting with Knights Park TQ18536872, the nitrate level was high - scoring 10 in the sample tubes from the kits that are issued to us. All sites went on to score 10 for nitrates unless otherwise stated.

Hogsmill SW outfall
Just below the outfall at the Hogsmill Sewage Works TQ19156857, phosphate levels were the lowest of the survey at 0.1. Is this the result of phosphate stripping? The highest phosphate level was achieved at the Channel of Cess (CoC), the small stream entering the Hogsmill at TQ19866831.

Sewage fungus
In addition to the highest (therefore the worst of the chemical readings) there was a strong odour, milky colouration, sewage fungus and fresh rag lined the channel. This type of chronic pollution can be  reported to the Environment Agency on 0800807060 and is given a reference number in this case NIRS 01559048.

Tomato plant in a culvert
As we walked upstream towards another pollution hotspot at Green Lane Recreation Ground TQ20056788, a tomato plant was seen growing out of a culvert. Tomatoes and figs often indicate the presence of sewage, as tomatoe seeds pass intact through the gut. Phosphates scored 0.2-0.5

new habitat creation

Despite all the instream habitat improvements at the A240 Tolworth - see previous posts - the is still an unhealthy outfall and an amount of sewage fungus around its environs. True to form the scores equalled the CoC.

Currently, there are over 1800 data points collected across the Thames Catchment undertaken with volunteer effort. A new mapping application allows you to visualise, analyse and download all the data collected during the different WaterBlitz .

The map can be access through the Freshwater Links here:


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