Sevier Lake, body of water in Millard county, western Utah, U.S. The lake is about 25 miles (40 km) long and up to 7 miles (11 km) wide. Located in the Pahvant Valley at an elevation of about 4,500 feet (1,370 metres), in an ecological transition zone between the Colorado Plateau and the Basin and Range geological province, it receives the Sevier River from the north; there is no outlet and its waters are strongly saline, a characteristic that has given rise to local halite and potassium sulfate manufacturing facilities.