The Environment Agency’s £12 million flagship project, the country’s largest fish pass in the Colwick Country Park, has been officially opened in Nottinghamshire.

Colwick Fish Pass Credit: Jackson Civil Engineering

The fish pass has opened up the River Trent and its tributaries for coarse and migratory fish, including salmon and trout, as well as eels.

The Environment Agency said the direct environmental benefits of the fish pass will be £18.6 million. This includes 60 kilometres of river improvement from poor to good status for fish, as well as 60 kilometres of new spawning habitat immediately upstream of the barrier. It will also aid interconnectivity with numerous other fish passage schemes previously constructed upstream by the Environment Agency. 

The Colwick fish pass has been completed as part of the Environment Agency’s work to improve fish passage across the country. It is 200 metres long, 6 metres deep and 6.5 metres wide.

Fish can now navigate past the Environment Agency-owned Holme Sluices that were built in the 1950s. It forms part of a large-scale flood defence scheme and helps to protect Nottingham from flooding.

The fish pass includes a 2-metre-high fully automated radial gate which constantly monitors the water levels and flow rates in the River Trent. The pass will then open and close based on the differing water levels throughout the year.

The pass is divided into 20 ascending chambers into which water flows through narrow slots. Fish of all species can swim upstream to lay their eggs in the gravel riverbeds of the Trent tributaries such as the River Dove and the River Derwent. They will be able to pass through these slots and rest in the chamber above before continuing.

The decline of migratory fish in the Trent catchment dates back to the Industrial Revolution, when large weirs were built to open up the river for trade. While some fish were able to overcome these barriers not all of them could.

Steve Lawrie, Area Environment Manager at the Environment Agency said:

“We have held the official opening of this major project with our partner Nottingham City Council, at the site of the fish pass in the council’s Colwick Country Park.

“The fish pass provides a significant step in restoring the River Trent catchment to its former glory for salmon and other coarse and migratory fish. It also includes an eel pass to help support the critically endangered European eel.”