The Mendip Power Group are installing micro-hydroelectric turbines in a number of historic former watermills. GarGar weir was built on the watermills and waterfalls. The Domesday Book, compliled in 1086, records 5,624 watermills in England alone. By Carolingian times, references to watermills had become "innumerable" in Frankish records. The term is inherited from the earlier technology of mill ponds and watermills. Below the earliest medieval evidence for different types of watermills. It had a stream which could be dammed at intervals to provide power for watermills. Andover also had six watermills which ground grain to flour. All the major rivers in the county were used to power watermills. During the time watermills operate channels tend to sedimentate, particularly backwater. There were many Medway watermills in the area. Little is known about the initial distribution system for the flour produced by the watermills. It is designed to produce electricity at the sites of former watermills. One of the last few watermills in Wales producing flour is in St Dogmaels. Their final stop is one of the Isle's ancient watermills.