Fish Barrier on Isle of Lewis removed
RAFTS, in partnership with SEPA’s Water Environment Fund and the Outer Hebrides Fisheries Trust has successfully project managed the removal of a significant barrier to fish migration on the Western side of Lewis.
The following photos tell some of the story:
The barrier, a culverted burn crossing, was impossible for fish to navigate at both high and low flows due to its design. Low flows saw an impassable downstream shallow step up into culverts that were also collapsing. High flows saw high pressure jets of water issuing from the downstream end of the culverts due to the ‘dam’ effect of the structure.
Stone won from the removal of the structure was reused to armour the banks and create the rock steps that ensure a stable channel remains. This photo is taken at very low flows and so although some water is percolating through the steps, during spate conditions (when fish run this system) the design will work well. Some finer material transported from upstream will also fill the gaps in each rock step.
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