Characteristics of Lake Mead, Arizona–Nevada

Lake Mead was formed in the 1930s by the construction of Hoover Dam on the Colorado River. Hoover Dam was one of the first multipurpose dams constructed by the federal government. Lake Mead is the largest reservoir in the United States by volume (3.5479 × 1010 m3 at full pool) and is second only to Lake Powell in surface area (637.05 km2). Water from Lake Mead is used for municipal and industrial purposes and irrigation water by approximately 25,000,000 people. The Colorado River provides approximately 97% of the inflow, with the remainder coming primarily from Las Vegas Wash and the Virgin and Muddy rivers. Flow in Las Vegas Wash more than doubled over the past 30 years as a result of the rapid population growth in Las Vegas. Lake surface elevations have dropped by about 40 m since 1999 as a result of extended drought and increasing water demands brought about by population growth. This elevation change impacted water quality and recreation and is just one of many management challenges facing the lake. The discovery of adult quagga mussels (Dreissena rostriformis bugensis) in Lake Mead in February 2007 created infrastructure management problems and raised concerns about lake biology and water quality. The impacts of this invasion are still under investigation. This manuscript provides information on the history of Lake Mead, as well as descriptions of lake and watershed characteristics, hydrology, water quality, fisheries, and recreation that lake managers can use to guide future assessment and management of Lake Mead.