Grimwith Reservoir is at the head of the River Dibb at a point some 2.5 miles (4 km) from Appletreewick.

The name is possibly derived from the Olde English dib, a dialectical form of dip meaning hollow, or deep place pool.

[3] The river starts from the south side of Grimwith Reservoir and flows south-west through Burnett Fold Nook and then south before returning south-west to pass under the B6265 at Dibble's Bridge, which has been the scene of two coach crashes - one in 1925 when seven people were killed, and one in 1975 when 33 people were killed.

[5] The river flows for 5.2 kilometres (3.2 mi) largely over millstone grit, which overlays limestone and shales.

[8][9] A leat used to take water from a high point of the river (between the overflow of the reservoir and Dibbles Bridge) to a lead mine near to Barben Beck.