Where Does Lake Mead Get its Water From

The great Colorado River, and subsequently its reservoirs, are not what they once were because the basin states have been affected by a megadrought that has gripped the southwest of the U.S. for two decades lowering water levels of Lake Mead, threatening the population of the region who depend on it.  Where does lake mead get its water from?

Lake Mead is fed by the Colorado River and three smaller tributaries: the Virgin and Muddy Rivers and Las Vegas Wash. Gregg Basin and Temple Basin are fed by the mainstream of the Colorado River, which now enters Lake Mead at the northern end of the Gregg Basin, nearly 60 miles upstream of Hoover Dam.

Lake Mead’s water level has risen over the winter months due to rainfall and particularly cold weather hitting parts of the U.S. bringing short-term relief but long-term planning is needed as most officials believe drought will once again dictate.

Where Does Lake Mead Get its Water From


The Colorado River system over 1400 miles long is incredibly dynamic.  In recent years, drought conditions have reduced snowfall in the Rocky Mountains, and the demand for water has increased, dramatically lowering water levels in the lakes of the southwest region. The Narrows, Virgin River, Zion National Park • James Kaiser

The Colorado River has been flowing for millions of years and is a well-established, huge, and naturally-replenished source of water flowing through the harshest environments of the country. But the trillions of gallons of water that fill these reservoirs do not originate in Nevada or Arizona; in fact, they have traveled hundreds of miles to get there.

The Colorado River provides approximately 97% of the inflow to Lake Mead, with the remainder coming primarily from Las Vegas Wash and the Virgin and Muddy Rivers

Snowpack contributes around 90% – As warming temperatures melt this snowfall, water runs downhill and begins its journey down the Colorado River.  The Colorado River begins as a tiny mountain stream, but as it picks up more and more of the melted snow, it swells into a coursing river.

This snow melt mixed with precipitation will end up in Lake Mead and Lake Mohave begins as precipitation in the Rocky Mountains, slowly moving a long way to go before reaching these lakes. Along the way, the Colorado River flows across cold mountain meadows, sweeps along rocky rapids, and carves its way through granite and sandstone landscapes. Eventually, after snaking through the Grand Canyon, the river empties into the eastern end of Lake Mead.

  • Virgin and Muddy Rivers converge in the lake’s Overton Arm flowing from the north
  • Las Vegas Wash contributes a mere 3% of Lake Mead’s water comes from stormwater urban runoff from the Las Vegas area-more during flood run-off




What is the Lake Mead Water Level Today?

Continuing a 22-year downward trend, water levels in Lake Mead stand at their lowest since April 1937, the water level at Lake Mead in Nevada, USA, was 1052.78 feet above sea level and  166.82 feet below Full Pool as of its last reading on 05/22/2023.…………………………………….read more


The Muddy River, 32 miles long formerly known as the Moapa River, is a short river located in Clark County, in southern Nevada, United States.

The Virgin River is a tributary of the Colorado River in the U.S. states of Utah, Nevada, and Arizona. The river is about 162 miles long It was designated Utah’s first wild and scenic river in 2009, during the centennial celebration of Zion National Park.

California, Arizona, Nevada, Utah, Wyoming, New Mexico, Colorado, and northern Mexico. During the early 1900s, lower basin states were experiencing rapid development, resulting in growing demands for water.

Because of this, in 1922, the Bureau of Reclamation, the government agency that manages water in the US, divided the river among two groups of states: the upper basin and the lower basin.

  • The upper basin includes Utah, Wyoming, Colorado, and New Mexico, and the
  • The lower basin comprises California, Nevada, and Arizona.

This progress threatened slower-developing northern states that were worried about their future rights to water. The threat was intensified by states such as Arizona and California requesting federal support for the construction of dams and other flood control structures to protect valuable croplands.

The need for a water treaty between states was imminent and resulted in the unprecedented Colorado River Compact of 1922. This Compact endeavored to ensure everyone’s fair share of the river and would be the first in many treaties, agreements, laws, and court decisions collectively known as the “law of the river.”


Is Lake Mead Natural or Man-Made?

Unlike many lakes and other large bodies of water, Lake Mead is not a natural lake It was created & started filling up in 1934, at the same time as the Hoover Dam was built. Initially, Mead was established so that it could provide a source of water for the booming Southwest.…………………………………………read more


Lake Mead Overview figure 1, showing the location of the lake in Nevada and Arizona.


Lake Mead is fed by the Colorado River and three smaller tributaries: the Virgin and Muddy Rivers and Las Vegas Wash. Gregg Basin and Temple Basin are fed by the mainstream of the Colorado River, which now enters Lake Mead at the northern end of the Gregg Basin, nearly 60 miles upstream of Hoover Dam. Inflows to the lake are largely moderated by the upstream Glen Canyon Dam at Lake Powell. Lake Powell is formed by the Glen Canyon Dam, which lies in Northern Arizona, near the border with Utah.

The Virgin and Muddy Rivers flow into the Overton Arm and then travel 25 miles under current conditions to merge with Colorado River water in the Virgin Basin. The combined flows from the upper end of the lake enter the east end of Boulder Basin at the Narrows. Las Vegas Wash enters Las Vegas Bay at the west end of Boulder Basin.


Is Lake Mead’s Water Level Rising?

Yes-While heavy precipitation & snow melt will help with irrigation & water-saving efforts for residents & businesses in the dry southwest region of the U.S., Lake Mead has been helped very little & the Bureau of Reclamation anticipates that the water levels ………………………………………read more


JimGalloway Author/ Editor 



Newsweek  Lake Mead: Where Does It Get Its Water and Is It Filling Up?

National Park Sevice-Lake Mead



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