In this Monday, April 13, 2015, file photo, members of the board committee of the Metropolitan Water District, MWD moved forwards on a proposal that would cut regional water deliveries by 15 percent beginning this summer, during a meeting in Los Angeles. A major Southern California water agency has declared a water supply alert for the first time in seven years, Tuesday, Aug. 17, 2021 and is asking residents to voluntarily conserve. Credit: AP Photo/Damian Dovarganes

A major Southern California water agency has declared a water supply alert for the first time in seven years and is asking residents to voluntarily conserve.

The Los Angeles Times reports that the board of the Metropolitan Water District of Southern California took the step Tuesday, hoping to lessen the need for more severe actions such as reducing to member agencies.

The move comes a day after U.S. officials declared the first-ever water shortage on the Colorado River, a key water source for Southern California.

"This is a wake-up call for what lies ahead," said Deven Upadhyay, for the district that supplies water to 19 million Californians.

"We cannot overstate the seriousness of this drought," he said. "Conditions are getting worse, and more importantly, we don't know how long it will last."

California Gov. Gavin Newsom last month asked Californians to scale back water use and many of the state's counties, mostly in Central and Northern California, are already under a state of drought emergency.

Concern about water supplies spread to the state's heavily-populated southern region following a winter of low precipitation and shrinking reservoirs throughout the West.

This March 26, 2019 photo shows the water level of the Colorado River, as seen from the Hoover Dam, Ariz. A major Southern California water agency has declared a water supply alert for the first time in seven years, Tuesday, Aug. 17, 2021 and is asking residents to voluntarily conserve. Credit: AP Photo/Richard Vogel, File

Newsom on Tuesday said he may put mandatory water restrictions in place in the coming months, the East Bay Times reported.

"At the moment, we're doing voluntary," he said. "But if we enter into another year of drought—and as you know our water season starts Oct. 1—we will have likely more to say by the end of September as we enter potentially the third year of this current drought."

The Metropolitan Water District of Southern California receives about half its water from the Colorado River and State Water Project.

Water levels in Lake Mead, the largest reservoir on the Colorado River, were at about 35% of capacity on Tuesday. The State Water Project, which collects water from rivers and tributaries, has already reduced the Southern California district's allocation to 5% and next year the amount could be zero, officials said.

  • In this Aug. 13, 2021, file photo, a person looks out over Lake Mead near Hoover Dam at the Lake Mead National Recreation Area in Arizona. A major Southern California water agency has declared a water supply alert for the first time in seven years, Tuesday, Aug. 17, 2021 and is asking residents to voluntarily conserve. Credit: AP Photo/John Locher, File

  • In this Wednesday, Aug. 4, 2021, file photo, signs alert visitors to the severe drought in Mendocino, Calif. A major Southern California water agency has declared a water supply alert for the first time in seven years, Tuesday, Aug. 17, and is asking residents to voluntarily conserve. Credit: AP Photo/Haven Daley, File

  • In this Aug. 14, 2021, file photo, houseboats rest in a channel at Lake Oroville State Recreation Area in Butte County, Calif. At the time of this photo, the reservoir was at 24 percent of capacity and 34 percent of its historical average. A major Southern California water agency has declared a water supply alert for the first time in seven years, Tuesday, Aug. 17, and is asking residents to voluntarily conserve. Credit: AP Photo/Noah Berger, File

  • In this Feb. 28, 2014, file photo, Santa Monica, Calif., resident Josephine Miller stands next to her 200-gallon water storage tank that collects rain from her home's roof to water her garden. A major Southern California water agency has declared a water supply alert for the first time in seven years, Tuesday, Aug. 17, 2021 and is asking residents to voluntarily conserve. Credit: AP Photo/Reed Saxon, File

  • In this May 23, 2021, file photo, a home destroyed in the 2020 North Complex Fire sits above Lake Oroville, in Oroville, Calif. California officials say the drought gripping the U.S. West is so severe it could cause one of the state's most important reservoirs to reach historic lows by late August, closing most boat ramps and shutting down a hydroelectric power plant during the peak demand of the hottest part of the summer. Credit: AP Photo/Noah Berger, File

  • In this May 22, 2021, file photo, water drips from a faucet near boat docks sitting on dry land at the Browns Ravine Cove area of drought-stricken Folsom Lake, in Folsom, Calif. The Metropolitan Water District of Southern California declared a water supply alert for the first time in seven years and is asking residents to voluntarily conserve Tuesday, Aug. 17, 2021, hoping to lessen the need for more severe actions such as reducing water supplies to member agencies. The Metropolitan Water District of Southern California receives about half its water from the Colorado River and State Water Project. Credit: AP Photo/Josh Edelson, File

Scientists say has made the American West much warmer and drier in the past 30 years and will keep making weather more extreme.

Glen MacDonald, a University of California, Los Angeles distinguished professor of California and the American West, said even if precipitation returned it would not likely be enough to keep pace with the loss of water through evaporation due to rising temperatures.

That has the potential to not only turn California lawns brown but could also affect the nation's food supply, which relies heavily on the state's farmlands, MacDonald said.

"We are living in the perfect drought, right now," he said. "It's unfortunate, but we kind of have seen this coming."