Last month we posted some images of the construction works of a Larinier fish pass and eel pass at North Molton weir on the River Mole, North Devon. The works have since been complete and the pass looks great! See the images and video below of the completed works.
The combined fish and eel pass was designed by Fishtek and built by Castleford Engineering and has vastly improved habitat connectivity in the lower Mole and provided better access to spawning and juvenile habitat upstream. The fish pass will allow for the free migration of resident brown trout and large migratory salmonids, whereas the eel pass will cater for elvers and yellow eels.
Previously, a leat channel that runs from above the weir to approximately 500 m downstream abstracted all the water at low flows, which created a long deprived reach below the weir. The pass was carefully designed to ensure an approximate 50/50 flow split between the fish pass and the leat at low flows, in order to maintain the existing abstraction whilst replenishing the weir pool at all times, therefore preventing stagnation of the deprived reach.