Water Quality
Monitoring the Deben

If this goes on, we will lose everything that we treasure about the Wye. It will turn a horrible, ugly green every time it gets sunny. The fish will go, and they will be followed by our kingfishers, our dippers and our herons. It is very, very worrying.

Simon Evans (Wye and Usk Foundation)

There are multiple sources of P (phosphate) pollution but source apportionment modelling suggests that 60-70% of the total phosphate load now comes from agriculture. Phosphate contains valuable nutrients (phosphorous) essential for plant growth and development and is a key ingredient in all fertilisers. When too much nutrient enters the river it causes eutrophication leading to excessive growth of algae and plants which adversely affects the quality of the water as well as damaging the local ecology.

Wye soils are also more P-leaky than many other soils because of their poor ability to hold onto applied P in fertilisers and manures, and pose a high risk of P loss to draining streams.

The Scale of the Problem

“Phosphate limits are already being exceeded at 31 points in the river catchment, with further failures likely in the future.” (River Wye Nutrient Management Plan – Phosphate Action Plan, 2021)

Data, collected by the Friends of the Upper Wye Citizen Science project, with guidance from Cardiff University water quality scientists, found that 46 per cent of 1,993 samples collected from 73 sites along the Upper Wye throughout 2022 contained “high” levels of phosphorus, with 15 per cent “very high”.

In Wales NRW have been able to undertake more sampling and have found that of the 42 sections of the Wye tested 28 had failed their WFD (Water Framework Directive) limits.