Works on stone weir help fish habitat on the River Thame

Waterstock Mill new weir
Waterstock Mill new weir

Fish in the River Thame can now explore parts of the waterway they haven’t been able to reach since possibly Norman times, thanks to improvement works.

The River Thame Conservation Trust, in partnership with the Environment Agency, have made improvements to a stone weir at Waterstock Mill to help fish navigate the historic structure they were unable to swim over.

Waterstock Mill - the weir before

Waterstock Mill - the weir before

Natalie Breden, from the trust, said: “When habitats which were once continuous are divided by weirs, it restricts the movement of many fish and insect species, separating them from their food sources and the variety of habitats they need to complete their life cycles. This can badly affect their survival and some species can disappear altogether in some stretches of river.

“It’s made worse here on the Thame as our river has had some big pollution incidents over recent decades when thousands of fish have been killed. Blockages in the river prevent fish and other mobile species from moving away from the pollution and being able to re- colonise after the events.”

The Waterstock Mill project has restored more than half a mile of river and also received funding from the Thames Rivers Trust Restoration Fund. The project also had great support from the local landowner who allowed the work to take place on his land.

The River Thame Conservation Trust hope to carry out similar projects in the coming years to gradually improve passage and habitats across the river catchment.

Channel at Waterstock Mill

Channel at Waterstock Mill

Natalie added: “In the past humans have changed natural river systems for our own uses, for agriculture, building developments, navigation or water supply. Fish evolved in rivers long before humans had this influence and fish species are not adapted to the changes we’ve made over time, such as dredged river bottoms, straightened channels and blockages such as weirs and sluices which dissipates the flow of water and block movement.

“The River Thame and it’s tributaries have many such blockages along its length, most of which are associated with watermills – signs of a time when the river was a major source of power in the rural economy and weirs were important to help provide that power to the mills.”