Utah Lake, the largest natural freshwater lake in Utah, just west of Provo and about 30 miles (48 km) south of Salt Lake City. Utah Lake has an area of 150 square miles (388 km2) and is 23 miles (37 km) long, with an average width of about 8 miles (13 km). It is fed by streams from the Wasatch Mountains lying east of it, and drains through the Jordan River into Great Salt Lake 30 miles (48 km) northwest. Utah Lake is a natural reservoir for waters used to irrigate the Salt Lake Valley.