Phoenix among those voluntarily losing Colorado River water

The city of Phoenix this week outlined how it will voluntarily contribute water to a regional plan to shore up the country’s largest reservoir that delivers Colorado River water to three states and Mexico.

The river cannot provide seven Western states the water they were promised a century ago because of less snow, warmer temperatures and water lost to evaporation. Water managers repeatedly have had to pivot to develop plans to sustain it for the long-term.

Phoenix, the nation’s fifth-largest city, is among entities in the river’s lower basin that are part of the "500+ Plan" meant to delay further mandatory shortages. All pieces of the plan haven’t been finalized, but farmers and Native American tribes are expected to play a big role.

The Colorado River serves more than 40 million people in Arizona, Nevada, New Mexico, Colorado, California, Wyoming, Utah and Mexico. Lake Mead and Lake Powell store the water and are used to gauge the river’s health.

The 500 + Plan will be implemented as Arizona, Nevada and Mexico take the first-ever mandatory cuts from the Colorado River and while water users decide what to do after current rules for managing the river expire in 2026.

What's the 500+ Plan?

The plan announced in December provides funding for states in the lower Colorado River basin — Arizona, Nevada and California — plus the U.S. Bureau of Reclamation to find ways to leave 500,000 acre feet in Lake Mead over the next two years.

The risk in not meeting the goal is the lake dropping further absent much precipitation, leading to more painful mandatory water cuts.

The plan is projected to boost the water level of Lake Mead, which has hit record lows, by about 16 feet (4.8 meters). The reservoir straddles the Nevada-Arizona border.

Water managers want to keep the lake from falling to 1,020 feet (311 meters) above sea level. That’s the point at which they believe that the reservoir, with just one more dry year, could hit 950 feet (289 meters) and no longer have the capacity to deliver water to Arizona, California and Mexico.

Nevada has an extra layer of water security with a pipeline it built years ago to draw water below that level.

Water users crafted the 500+ Plan within months to create more certainty in the Colorado River supply.

Who's contributing water?

The plan anticipates Arizona contributing 223,000 acre feet and California 215,000 acre feet. An acre-foot of water is enough to serve 2-3 households annually.

In Arizona, Phoenix and the neighboring cities of Glendale, Scottsdale and Tempe, irrigation districts, water agencies, state entities and others have said they’ll chip in.

The Metropolitan Water District in California will work through existing partnerships with irrigation districts and seek new ways to conserve water, said Colorado River resources manager Bill Hasencamp.

The district recently signed an agreement with the Quechan Tribe along the Arizona-California to pay farmers and the tribe not to plant crops in the hotter months when water use is highest. That could leave 6,000 acre feet of water in Lake Mead a year for two years, Hasencamp said.

"Yeah, it’s a small piece but an important piece of this plan that’s needed to make the Colorado River sustainable," Hasencamp said.

Nevada will contribute money because it doesn’t have water to give, said Southern Nevada Water Authority spokesman Bronson Mack. The Colorado River supplies southern Nevada with 90% of its water.

"We’re already pretty tight as it is with 300,000 acre feet," Mack said.

The Bureau of Reclamation is expected to contribute about 62,000 acre feet.

Native American tribes will be the biggest players in the plan because they tend to have larger and more secure rights to water that isn’t fully being used. The Gila River Indian Community and the Colorado River Indian Tribes have signed on to the 500+ Plan.

"We see this as a win-win for everybody because we have solutions, we can offer solutions, we can offer ways to save the river," said Colorado River Indian Tribes Chairwoman Amelia Flores. "I’m glad that others are looking at tribes in that way, that we can be an asset and not calling on us at the last minute."

Who's funding the plan?

The states are required to put up $100 million, and the federal government will match that amount for a total of $200 million.

Phoenix will receive nearly $4.2 million for the 15,977 acre feet it is contributing, which works out to $260 an acre foot. The city will leave that water in Lake Mead rather than store it underground near Tucson as it had planned, said Cynthia Campbell, the city’s water resource management adviser.

Phoenix will use the money for rebate programs for residents to switch to low-flow toilets, smart irrigation control systems and improving the efficiency of cooling towers, Campbell said.

The Metropolitan Water District will pay up to $1.6 million to farmers on the Fort Yuma reservation and the Quechan Tribe to leave fields dry.

The tribe’s water counsel, Jay Weiner, said the tribe is gauging interest among farmers.

"It’s really a piece of Quechan trying to be as entrepreneurial as possible, figuring out ways that it can continue to benefit from its water rights for the good of the tribe and its members," he said.

What happens next?

Arizona, Nevada and Mexico will lose water this year in the first federally declared water shortage. In Arizona, that reduction largely falls on Pinal County farmers who plan to cut the acreage they farm and increasingly rely on groundwater.

The Colorado River basin states will start negotiating soon on a new set of guidelines to replace the current ones that expire in 2026.

Lake Mead and Lake Powell upstream on the Arizona-Utah border haven’t been full in more than 20 years. As they fall, it impacts water deliveries, hydropower and recreation at the popular tourist spots.

Lake Mead was at 1,066 feet (324.9 meters) this week, or about 34% full. Lake Powell was at 3536 feet (1,077 meters), or 27% full.

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