The western half of the reservoir lies in Derbyshire and the eastern half is in Sheffield, South Yorkshire; the county border runs through the middle of the reservoir, following the original path of the River Derwent.

The works involved constructing a temporary village at Birchinlee, or "Tin Town", for the workers, a temporary railway line from the main line at Bamford, construction of a link aqueduct to the Derwent Dam.

The dam is of solid masonry construction, and 117 ft (36 m) tall, 1,080 ft (330 m) long, and impounds 1,900,000 imp gal (8,600 kl) of water, from a catchment area of 5,155 acres (2,086 ha).

The workers who died during the construction of the dam were buried in St John the Baptist's Church, Bamford.

This is not to be confused with the more well-known Featherbed Moss on the Pennine Way between Kinder Scout and Bleaklow.