We’ve started our project on the River Teise to make a weir passable for fish migration.
Weirs were introduced years ago to help control the flow of water, allowing our ancestors to operate mills. Nowadays many remain in rivers despite no longer being required.
Weirs are a barrier to fish passage and leave the habitat fragmented with fish populations isolated. In the event of pollution or other presures like climate change, these isolated populations are at greater risk with nowhere to escape to.
Although being a barrier to fish migration is a significant problem, weirs also interrupt the natural flow of rivers, resulting in a degradation of habitat. Upstream of weirs, water is slowed down which causes silt to drop out and accumulate in the channel.
This image from the Wild Trout Trust explains the effects of weirs on fish habitat:
Funded through Defra’s Catchment Partnership Action Fund, we’ve started works on a weir on the River Teise – where Olly and Rosie carefully removed a number of boards from the top of the weir.
After removing the boards, the impounded water levels upstream dropped noticeably, revealing many natural features of the river which had been drowned out when the weir was put in place.
Some of the diverse new habitat revealed by lower water levels above the weir
The next phase of the project is to remove the impoundment and enable full fish passage and habitat restoration, so watch this space!