Water quality – nutrients, sedimentation and algal growth

Healthy rivers require clean water. A reduction in pollution reaching the rivers and canals in the Kennet catchment will improve the whole ecology. We can see elevated levels of both Nitrate and Phosphate throughout the catchment. These nutrient levels result in algal growth, which smothers green macrophytes. Other pollutants include sediment from farmland and toxic chemicals disposed of through the drainage network.

Read Thames Water’s Autumn 2022 Water Quality Update – Kennet and Tributaries. Thames Water will circulate updates quarterly to keep you updated with the latest water quality data from the catchment.

Surface Water Summary

There has been no metaldeyde at sample points between December 2021 and November 2022, and TW do not expect to see any detections going forward as metaldehyde is now banned for outside use.

Elevated levels of propyzamide (>0.1 μg/l) we seen in the Enborne in February and March. TW have not seen significant amounts of propyzamide at any of the sample points since March.

No carbetamide was detected at any of the sample points in the Kennet catchment between January and November 2022, apart from a low detection of 0.027μg/l in the Enborne in September.

Groundwater Summary

Nitrate concentrations in groundwater have remained consistently below the DWS in the abstractions in the Ogbourne, Axford, Hungerford and Leckhampstead catchments in the last year. Marlborough recorded a concentration of 63.96mg/l in January 2022; however, TW believe this result is anomalous, and concentrations have been below the DWS since. Ashdown Park and Fognam Down have consistently recorded concentrations of 45-52mg/l from December 2021 to August 2022, with Ashdown Park recording above the DWS from February to May 2022. This has decreased since September 2022, with no abstraction recording concentrations >45mg/l.



Only rain down the drain!

Everyone has a part to play in reducing pollution, this campaign reminds people that storm drains drain to rivers and are only for rain (not paint, cigarette butts, litter, oil, dog mess …)

Schools, community groups, businesses and individuals have taken part in our only rain down the drain project to raise awareness about surface water drainage, which goes straight into the river – not to the sewage treatment works.

Keep an eye on our events page for upcoming volunteering opportunities.