Fishtek are currently working on a fish pass at the so-called ‘Denver complex’. This is comprised of a series of large sluice structures that form a barrier between the tidal and fluvial River Ouse. The site also contains flow measuring facilities, a pipeline to deliver water to Cambridgeshire and Essex, and lock gates to maintain navigation of the South Level System. The site is considered a major priority by the Environment Agency due to large numbers of migratory species (including eels) and the problem of coarse fish that are washed out of the South Level System during operation of the various barrier structures that currently are not able to move back upstream into the Ouse when water levels reduce.
Fishtek were commissioned in May 2014 to design a suitable fish, eel and lamprey pass that would allow fish washed out of the South Level System to return. The fish pass had to be designed to avoid compromising the function of the various facilities within the Denver Complex System, as well as acting as a key monitoring point and facility for EA fisheries.
The fish pass solution that has been designed is a 2 flight larinier fish pass with an eel and lamprey pass contained within a separate channel located adjacent to the fish pass. At the upstream end of the fish pass is a 60 metre channel that is required to avoid the navigation lock gates and flow measuring sluice gates.
The construction phase of the fish pass was started in March 2015 with completion expected in August/September. A few images of the fish pass construction are given below.