Colliford Lake is a reservoir on Bodmin Moor, Cornwall, England, United Kingdom. Covering more than 900 acres (3.6 km2), it is the largest lake in Cornwall. Between 1983 and 1984 a dam was constructed, impounding water from the River St Neot, creating a water supply bigger than all of Cornwall's other reservoirs combined. It is situated south of the A30 trunk road near the village of Bolventor, the approximate centre of the lake being at OS grid reference SX179730. Dozmary Pool outfalls into the lake and the lake's own outfall forms one of the tributaries of the River Fowey.