Bracing for what could be the most severe drought year of the last two decades, three states in the southwest agreed to bank more water in the rapidly shrinking Lake Mead.
Hoping to mitigate mandatory water-use cutbacks in 2022, Arizona, California and Nevada last week signed the so-called 500-Plus Plan at the annual meeting of the Colorado River Water Users Association in Las Vegas.
The agreement aims to add 500,000 acre-feet of water to Lake Mead in 2022-23, enough to supply 1.5 million households for a year.
Payments of $40 million from Arizona, and $20 million each from Nevada, California and the Central Arizona Project are expected. CAP operates canals that deliver Colorado River water in Arizona.
“There is an urgent need to minimize the impacts of drought and develop a long-term plan to facilitate conservation and economic growth, because drought doesn’t impact just one community — it affects all of us, from farmers and ranchers to city dwellers and Tribes,” said Tanya Trujillo, the U.S. Interior Department’s assistant secretary for water and science.
The Department of the Interior, which oversees the Colorado River Compact, signed onto the plan.
The cuts required by the 2019 Drought Contingency Plan could affect the credit of dozens of bond issuers in states that rely on the river to irrigate the desert landscape. Arizona, which has voluntarily stored water in Lake Mead up to this point, stands to lose about 18% of its supply.
Arizona, which has junior rights to the river, will take the most severe hit. Nearly all the reductions within Arizona will come from Central Arizona Project water users.
Given the recent intensification of the drought, deeper levels of shortage are likely in the next few years, according to CAP.
“As impacts of drought persist, additional reductions to CAP water users are likely to occur pursuant to the DCP,” the agency said. “Such reductions would include impacts to CAP water currently available to some central Arizona municipalities and tribes.”
Colorado River water distribution is dependent on two reservoirs: the Depression-era Lake Mead, behind the Hoover Dam and Lake Powell upstream, created by the Glen Canyon Dam in the 1960s.
The near-record low runoff in the Colorado River in 2021 significantly reduced storage in Lake Powell. CAP and the Arizona Department of Water Resources are the two agencies that manage the supply issues.
“ADWR and CAP are working collaboratively with Arizona stakeholders and the Basin States to deploy more adaptive measures consistent with the Drought Contingency Plan and associated agreements,” Tom Buschatzke, director, Arizona Department of Water Resources, said in an August news release. “At the same time, ADWR and CAP will continue to work with partners within Arizona and across the Basin to develop and implement longer-term solutions to the shared risks we all face on the Colorado River now and into the future.”
Based on the Jan. 1 projected level of Lake Mead at 1,065 feet above sea level, the U.S. Secretary of the Interior in August declared the first Tier 1 shortage for Colorado River operations for the coming year.
The water additions announced last week in Las Vegas are designed to keep Lake Mead from dropping below 1,025 feet, and triggering steeper cutbacks.
Total Colorado River system storage at the end of September, the 2021 water year, was 39% of capacity, down from 49% at the same time in 2020, according to the Colorado River Water Users Association.
The Colorado River supplies about 40 million people in the Southwest, and about 75% of the water in the region comes from snowmelt.
Because of climate change, snowpack in the region is expected to fall about 25% by 2050, according to a research paper in the publication Nature Reviews Earth and Environment.
By 2100, the decline is projected at 50%.
The anticipated drop coincides with rapid population growth in the region, particularly Arizona. To fuel growth of the suburbs and cities, providers are buying up agricultural water rights for residential neighborhoods. Farming is more water intensive than a residential neighborhood, where controls and conservation are often enforced.
At the Metropolitan Water District of Southern California, officials are planning on no allocation from the State Water Project.
“Climate change is creating a new normal,” Metropolitan General Manager Adel Hagekhalil said in a Dec. 1 statement. “Southern California has done a lot, but we need to do more. And we can’t do it alone. We need our state and federal partners to help accelerate these investments through a coordinated strategy for resilient, integrated and balanced water management.”
Next year marks a century since the creation of the compact that apportioned the river’s water among seven Western states. Wyoming, Colorado, New Mexico and Utah are in the upper basin.
The Colorado River Compact of 1922 is a complex set of laws governing water use in the basin and designed to conserve supply. But demand from population growth has surpassed the water available.
The Central Arizona Project was created by the Colorado River Basin Project Act, signed by President Lyndon B. Johnson on Sept. 30, 1968. In exchange for supporting the project in the 1960s, California’s congressional delegation won senior rights to the Colorado water.
According to a 2014 study by Arizona State University’s Seidman Research Institute and commissioned by the nonprofit Business for Water Stewardship, the Colorado River supports $1.4 trillion in annual economic activity and 16 million jobs across the seven states of the basin.
A drop in available water of only 10% would endanger some $143 billion in economic activity in a year, according to the study.
Ratings analysts monitor the water supplies that affect scores of credits along the river’s path.
“In many ways major water projects, such as the Colorado River Aqueduct, completed in 1941 to bring water to Southern California, and the Central Arizona Project, delivering water to Phoenix and Tucson since completion in 1994, have defined the civilization of the region,” S&P Global Ratings noted in a Jan. 6 report. “In the 21st century, though, the federal government has turned off funding for massive water projects.”