Natural Resources Wales releases extra water to reduce risk of fish mortality

Natural Resources Wales recently released extra water to the River Dee to reduce the risk of fish mortality during the exceptionally high temperatures experienced across Wales.

At 10am on Saturday 16 July, Natural Resources Wales (NRW) increased the discharge out of Llyn Tegid into the River Dee by 2m3/s – this was an increase in flow of 30%. This increase was timed to arrive at the tideway downstream of Chester Weir on Monday morning when the high temperatures were forecast to occur.

The additional water came from the Special Release Allocation, which is a dedicated volume of water used for environmental benefit as part of the River Dee Regulation Scheme.

This decision by NRW Officers resulted in more than double the flow entering the tideway than would have occurred under natural conditions. The decision helped lessen the impact of low water levels and high temperatures on local fish stocks.

Richard Pierce, NRW Senior Officer Fisheries, said:

“The dry weather experienced of late can result in low water levels that can impact on the health of fish stocks, by reducing oxygen levels and increasing vulnerability to disease and predators.
“To help reduce the risk of fish mortality and alleviate the threats of the warm weather, we took the decision to temporarily provide the River Dee with extra water. We would like to thank everyone for their cooperation.”

For more information and guidance about fisheries, please visit:

For more information about the River Dee Regulation Scheme, please visit: