The Chew Valley is an affluent area in North Somerset, England, named after the River Chew, which rises at Chewton Mendip, and joins the River Avon at Keynsham. Technically, the area of the valley is bounded by the water catchment area of the Chew and its tributaries; however, the name Chew Valley is often used less formally to cover other nearby areas, for example, Blagdon Lake and its environs, which by a stricter definition are part of the Yeo Valley. The valley is an area of rich arable and dairy farmland, interspersed with a number of villages.