Country diary: the power of water in the valley

St Dominic, Tamar valley: Rainfall may have destroyed the weir, but there are still old methods present to pump water back uphill

The beat of a hydraulic ram reverberates along the deep ditch, running fast with spring water towards a little tributary originating from beneath Viverdon Down. The water joins other streams along the incised course through steep woods and pastures before meeting the tidal Tamar, more than two miles downstream. Last month's exceptional run-off along this network of streams contributed to the destruction of the National Trust's weir, which channelled water along a leat to Morden Mill's historic water wheel and the more recent hydroelectric plant.

Hydro-rams used to be common in the dissected hilly countryside. They used the water's momentum to pump a proportion of the flow uphill to storage tanks or reservoirs, which then gravity-fed farmsteads and field drinking troughs. Mains water supplies gradually ousted these slow, but low-maintenance, machines.