Nice to see an example, for once, of a positive outcome for nature and wildlife ...
Lost watercourse flows again in Somerset after more than 60 years
Restoration of unnamed tributary of River Chew offers new habitat for rare wildlife.The half-kilometre tributary of the River Chew, which runs from the Mendip Hills down to the River Avon, was severed by a dam in 1956, when the valley was flooded to form the Chew Valley Lake reservoir to supply water to Bristol and Bath.
Downstream, the ecosystem withered into a dry ditch and died. An important ecological corridor was lost for aquatic creatures which had been using the route since the last ice age. Instead, an occasional spill from the reservoir was diverted into a concrete spillway, bypassing the old riverbed and destroying the central linking piece of the route’s ecological jigsaw.
The water has now been redirected as part of a restoration project by Bristol Water, with Bristol Avon Rivers Trust and other partners. The river’s revival has included dramatic re-engineering of reservoir overflows, redirecting water along its former path.
The restored route meanders through an abandoned 1950s poplar and alder plantation. Dense thickets of bramble and shady canopy have been opened up to encourage river wildlife, bringing in light and encouraging aquatic plants, and the channel has been reshaped with berms, riffles and pools so undesirable silt buildup is scoured out by the natural energy of a faster current, opening up fish and invertebrate spawning areas.
Vulnerable populations of water voles, eels, and white clawed crayfish should be able to weave their way upstream and recolonize the area. Fish likely to return include salmon, trout, chub, perch, bream, carp, pike, minnow and stickleback.
Otters, kingfishers, barn owls and rare bats already hunt close by. Spring forest floor flowers have reappeared on the river banks. Chattering green woodpeckers and orange-tip butterflies flash through fresh sunlight among primroses, wild garlic and bluebells.
https://www.theguardian.com/environment/2019/apr/12/lost-river-returns-somerset-70-years-after-dried-up