Lake Powell

Lake Powell is a large reservoir on the Colorado River, straddling the Utah–Arizona border within Glen Canyon National Recreation Area. It was formed by the Glen Canyon Dam, construction of which began in 1956 and was completed on September 13, 1963; the reservoir first reached its full pool of 3,700 feet on June 22, 1980 — sixteen years after the dam was finished. The lake is named for John Wesley Powell, the Civil War veteran who first descended the Colorado in three wooden boats in 1869. At full pool, Lake Powell holds 24,322,000 acre-feet (3.0×10^10 m3) of water, making it the second-largest reservoir in the United States by capacity. It extends roughly 186 mi (299 km) in length, reaches a maximum width of 25 mi (40 km), and a maximum depth of 583 ft (178 m). Its shoreline, complicated by hundreds of side canyons, measures approximately 1,900 mi (3,057 km). The reservoir lies primarily in southern Utah, with a smaller portion in northern Arizona, spanning Garfield, Kane, and San Juan counties (UT) and Coconino County (AZ). It is managed jointly by the U.S. Bureau of Reclamation, which operates the dam, and the National Park Service, which administers the Glen Canyon National Recreation Area established in 1972.