Leat

Leat is a man-made watercourse or ditch used to divert water from a natural source, such as a river or spring, to a mill, mine, or water supply. The term comes from Old English leat, meaning a channel or way of letting water flow.

Leats are typically dug along a slope, with an intake at a reliable headwater, a channel often lined with stone or turf, and, where necessary, a culvert or aqueduct crossing obstacles. They incorporate sluices or gates to regulate flow and may be linked to a headrace, tailrace, or tail end near the mill or mine.

Historically, leats were especially important in Britain from the medieval period onward. They powered watermills by delivering a steady head of water, and in mining districts such as Cornwall and Devon they supplied water to ore processing works and to deep mines, permitting hydraulic arrangements and ore dressing.

Notable concentrations of leats exist in Cornwall, often termed "Cornish leats," with some extending many miles from upland sources to coastal towns or mines.

Today many leats survive as historic features. Some are preserved as cultural heritage and some still convey water for agriculture or urban use; others have disappeared or become overgrown. Conservation efforts by local authorities and heritage organizations document and manage them as part of industrial archaeology.