River Ashop

The River Ashop is a river in the Derbyshire Peak District, England. Its source is on the eastern slopes of Mill Hill, three miles south east of Glossop and just north of Kinder Scout.

The river flows approximately ten kilometres east, following the Sheffield to Manchester Snake Pass road through remote countryside, before emptying into Ladybower Reservoir, which itself flows into the River Derwent.

The only significant tributary of the River Ashop is the short River Alport. The flow of the Alport is partially diverted by a weir to feed into the Ashop above the impound weir built in the 1920s to increase the catchment area of the Derwent Reservoir prior to the building of the Ladybower Reservoir downstream. The weir impounded the water and fed it into an open culvert (water conduit) that was built along the side of the hill. The culvert then feeds into a siphon over the river in a 6-foot-diameter (1.8 m) iron pipe before entering a tunnel to pass through the hill to the Derwent Reservoir via an open watercourse, entering the reservoir just north of the dam wall. The concrete structure of the weir is visible when travelling up the Snake Pass route from Sheffield.