Lake Mead is a reservoir formed by the Hoover Dam on the Colorado River in the Southwestern United States.

Lloyd Joseph Hudlow, an engineer with the Bureau of Reclamation, came to Boulder City in March 1933 to assist in the survey, and ended up as the project manager.

The accumulated water from Hoover Dam forced the evacuation of several communities, most notably St. Thomas, Nevada, the last resident of which left the town in 1938.

[12] The ruins of St. Thomas are currently visible (as of May 23, 2022) via dirt road and hiking trail, due to Lake Mead's low water level.

Access from the north-west from Interstate 15 is through the Valley of Fire State Park and the Moapa River Indian Reservation to the Overton Arm of the lake.

When the lake levels are high enough, a section of the lake farther upstream from the Gregg Basin is flooded, which includes Grand Wash Bay, the Pearce Ferry Bay and launch ramp, and about 55 miles (89 km) of the Colorado River within the lower Grand Canyon, extending to the foot of 240 Mile Rapids (north of Peach Springs, Arizona).

Lake Mead receives the majority of its water from snow melt in the Colorado, Wyoming, and Utah Rocky Mountains.

Releases from Hoover Dam have been over 9 million acre-feet (11,000,000 Ml) of water each year, which has led to declining levels in Lake Mead since 2000.

[20] In these decades prior to 2000, Glen Canyon Dam frequently released more than the required 8.23 million acre-feet (10,150,000 ML) to Lake Mead each year.

[24] In 2012 and 2013, the Colorado River basin experienced its worst consecutive water years on record, prompting a low Glen Canyon release in 2014 – the lowest since 1963, during the initial filling of Lake Powell – in the interest of recovering the level of the upstream reservoir, which had fallen to less than 40% capacity as a result of the drought.

The water year begins October 1 to coincide with seasonal Rocky Mountain snowfall, which produces most of the Colorado River's flow.

[29] Drought restrictions were narrowly avoided again when the lake level rose above 1,075 feet on September 28, 2016, three days before the deadline, and the Bureau of Land Reclamation did not issue a shortage declaration.

[30][31] A reprieve from the steady annual decline occurred in 2017, when lake levels rose throughout the year due to heavier than normal snowfall in the Rocky Mountains.

[38][31] However, by mid-2021 its level fell below the trigger elevation and was projected to keep falling through 2022, which led the Bureau of Reclamation to declare a water shortage in August 2021.

[40] As a result of the decreasing water level, marinas and boat launch ramps have either had to be relocated to another area of the lake or have closed down permanently.

[48] A 2021 estimate stated that covering 10% of the lake's surface with foam-backed floating photovoltaics could result in "enough water conserved and electricity generated to service Las Vegas and Reno combined.

"[49] In December 2021, with Lake Mead at 35% of capacity, Arizona, California, Nevada, and the U.S. Department of the Interior signed an agreement to spend $200 million for 2022 and 2023 to subsidize water users who voluntarily reduce their usage or undertake capital projects to improve efficiency.

[6] Severe drought lowers the level of the lake, affording social anthropologists opportunities to study indigenous dwellings that were previously submerged.

Meanwhile, their forensic colleagues are routinely called in whenever relatively contemporary remains of people are revealed, to investigate scientifically who the deceased might have been in life, how they died, and how their bodies got to the lake.

For example, the 2020–2023 North American drought caused a series of unexplained human remains to be revealed, prompting speculation about how many more will be discovered as the water level recedes.

[60] The Desert Princess, operated by Lake Mead Cruises, is a three-level paddle wheeler certified by the U.S. Coast Guard to carry 275 passengers.

[64] Lake Mead, Hoover Dam, and the wrecked B-29 play a large role in the setting of the video game Fallout: New Vegas.