Scammonden Reservoir is a water reservoir in West Yorkshire, England. Its water surface area when full is 42 hectares (0.16 sq mi). The level of the bellmouth overflow above sea level is 252 metres (827 ft). The reservoir holds 78,000,000,000 litres (1.7×1010 imp gal; 2.1×1010 US gal). Its length is 1.4 kilometres (0.9 mi).