Slow The Flow (STF) Calderdale was set up to look scientifically at the issue of why and how the Calder Valley floods and to look at natural flood prevention measures and solutions to slow the volume of water which comes down the hillsides into the River Calder.

Hardcastle Crags, a local National Trust site, is the home of Slow The Flow’s most successful project on the ground to date, with 250+ woody leaky dams built, and counting!  Since November 2016, STF volunteers have been working with the incredible team of rangers and land managers at The National Trust, The Environment Agency, Calderdale Council, Nathan the working horse, and many others, to build leaky woody dams across streams with large logs, and stuff deep gullies with smaller branches.

They also created several larger areas where water will be temporarily stored during a storm. These comprise a series of leaky dams blocking water courses that pass through relatively level areas of woodland. The water pools and slows, to the extent it is stationary during the storm event – wetting up the woodland floor, which provides additional environment benefits.