The outflow of Ennerdale Water, holding the largest population of freshwater pearl mussels in England
The Ehen leaves Ennerdale Water at its western end and runs about nineteen miles down to the Irish Sea near Sellafield, and the reason it is protected is buried in its gravel. Freshwater pearl mussels live for over a century, filter the water constantly, and breed only where the riverbed stays clean and a good head of young salmon and trout is present — the larvae spend months attached to fish gills. England’s largest surviving population is here, and it is still a fragile thing: for years very few young mussels were recruiting at all.
That is also why the lake’s outflow has been argued over. Water was taken from Ennerdale for industry and supply for decades, and the weir at the outflow was finally removed in 2023 to let the river run naturally again.
The valley above is the subject of Wild Ennerdale, a long-running project to let the forest and river do more or less as they please. Footpaths run along the water below the lake, and Egremont Castle stands on a mound above the river further down. Whitehaven Station is the nearest train.
