Creating an efficient fish pass whilst having minimal effect on flood risk can be challenging, particularly at flow control structures in the tidal area of a watercourse. Fishtek have recently completed the design and installation of a new fish pass at Fulney Lock on the tidal limit of the River Welland in Spalding, Lincolnshire. Many factors were taken into account in the design phase such as flood risk, effects of saline ingress on riverine ecology, boat navigation, lock operation and fish pass efficiency.
Before the fish pass was installed, the structure created a complete barrier to fish migration when the downstream gates close as the tidal level exceeds the upstream water level. The fish pass, an aperture created in the downstream gate of the lock structure – see photos below, enables fish to pass upstream after the gates close, creating a route for migration over the whole tidal cycle. The aperture has been fitted with a surface-mounted penstock so it can be closed off during exceptionally high tides, reverting the gates into their original operating condition.
The new fish pass at Fulney Lock plays a vital role in the connectivity and efficiency of further fish passes that have been constructed upstream. The Environment Agency have been monitoring the operation of the fish pass in conjunction with lock gates and we are pleased to report that everything is working well.