The installation of a 2-metre-high radial gate will mark the next stage in construction of the Colwick (Holme Sluices) fish pass.
The radial gate is two metres high, and weighs a little over 4 tonnes, which is the same as an Asian elephant, or an adult male hippopotamus.
The gate has been constructed off site and has been lifted into place in the fish pass in one piece, using a 40-tonne crane.
Once the fish pass is in operation, the radial gate system will be fully automated, constantly monitoring the water levels and flow rates.
When readings drop below the tolerance level, the gate will close within 8 minutes to maintain the navigable levels on the River Trent.
The Colwick (Holme Sluices) fish pass is 200m long, 6m deep and 6.5m wide.
It is the first scheme of the ambitious Trent Gateway Partnership which aims to remove all barriers to fish migration along the River Trent.
Once complete in September 2023, it will open up the River Trent for fish and eels.
Simon Ward, Fisheries Technical Specialist at the Environment Agency, said:
“By installing a fish passage, it will become easier for salmon and other fish to reach their spawning and feeding grounds.
“We are working with partners to improve the situation and hope that the Colwick Park fish pass will serve as a catalyst for other Trent Gateway projects, which will in turn enhance the river and boost the local economy.
“We will work with Nottingham City Council to make Colwick Country Park in Nottingham the hub for Trent Gateway. Plans could include a visitor centre telling the story of the Trent, its history, ecology and how it has shaped communities along its length for centuries.
“The benefits of the new fish pass include enabling access to additional spawning habitat upstream, with the potential to increase the number of fish species in the River Trent, promote awareness of fish passes and river equality, provide educational and engagement opportunities, and attract more visits by anglers to the area and boost the local economy.”