Autumn has been very busy with fish pass builds happening all over the country, many of which have being designed and managed by Fishtek. Particularly noteworthy is the construction of Culham hydroelectric scheme on the River Thames, which comprises three large Archimedes screw turbines and a co-located Larineir fish pass and eel pass. The water level at the site is heavily managed for navigation and flood prevention by a series of weirs, locks and sluice gates that prevent upstream fish passage and also create a head of water that can be exploited to create green energy.
Fishtek were commissioned by Mannpower Consulting to carry out a Fisheries Impact Assessment and to design and gain approval of the fish pass according to the abstraction licence. The impact assessment, along with designs for a two-flight 3 m wide Larinier fish pass and separate 0.5 m wide eel pass channel received formal Environment Agency approval in May of this year. The developers wasted no time and began constructing the scheme in the summer. Fishtek fabricated the Larinier baffles and supplied the eel crawling substrate that were installed into the reinforced concrete channels. The works are now almost complete and the fish and eel pass are looking great!
The fish pass is built according to best practice guidelines and discharges >5% of the maximum turbine abstraction and is co-located with the turbines to further increase attraction flow. It will serve a wide range of potamodromous and catadromous fish species and is the largest fish pass in the UK specifically designed for non-anadromous species. The scheme has significantly improved habitat connectivity, whilst also protecting existing fish habitat and creating additional habitat in the upstream channel, as well as creating the potential to generate 400 kW of green energy that can be used by the local community or exported to the grid. The project is a great example of a win-win scheme!
A) Fish pass entrance co-located with the turbine outfall
B) Larinier fish pass (left) and eel channel with specialised crawling substrate (right)
C) View of the upstream end of the fish and eel pass and the turbine head-race channel
D) Installation of the Larinier baffles and eel tiles (Fabricated and supplied by Fishtek)