Climate change is drying up the Colorado River and will impose new rules on users


SALT LAKE CITY — Water managers across the Colorado River Basin are gearing up to negotiate new rules to apportion the river’s shrinking flow and share the pain of growing scarcity.

They adapt the centenary Colorado River Compact to a river that bears little resemblance to the abundant gushing that negotiators from seven states and the federal government in 1922 thought — or hoped — would bless the Southwest forever. The stakes rise with every foot that Lake Mead and Lake Powell fall, as the states and water users within them recognize that they are due to tighter pressure.

Arizona gets more than a third of its water from the river, growing bountiful crops around Yuma and homes around Phoenix and Tucson. The Las Vegas area gets most of its water from the river and has built a deeper pipe into Lake Mead to ensure its continued access. Late-developing states like Wyoming use the water for ranching and energy development, and hope to continue to expand there.

“We’re all going to lose,” John Entsminger, chief executive of the Southern Nevada Water Authority, told his counterparts across the watershed Friday at a river law symposium at the University of Utah. . Wallace Stegner Center for Lands, Resources and the Environment.

His warning was less a lament than a call to action on behalf of a river that some 40 million people use from headwaters in Wyoming and Colorado to the delta in Mexico.

“We’re up for the challenge because we have no choice,” said Entsminger, whose agency in Las Vegas embraced water austerity by banning most new lawns and golf courses. and limiting new pool sizes.

Drought:Lake Powell water levels plunge to new low, sparking concern

Rethinking the flow of the river

Before states, indigenous communities and water districts can agree on a new plan to divide the water more conservatively, they will need to agree on the level of the river.

Negotiators in 1922 asserted that the river could provide more than the 15 million acre-feet divided among the seven states that share it, with some remaining to drain into Mexico. 2022 negotiators are wondering if they should budget for just 11 million acre-feet because Entsminger’s agency in Nevada has already listed its water safety plans.

In Arizona today, one acre-foot of 326,000 gallons is about enough to supply three households for a year.

Since 2000, the river has delivered an average of 12.3 million acre-feet per year, typically a few million less than the region has used. Consequently, the giant reservoirs that were full at the time collapsed, Lake Mead at about a third of its capacity, Lake Powell at a quarter.

Although the pact assigned specific shares to the upper and lower basins of the 1,450-mile river, the U.S. Department of the Interior’s Bureau of Reclamation agreed in 2007 with states on an adaptive plan that reduces deliveries of certain users when the reservoirs dip beyond certain thresholds. States, including Arizona, have relied on these rules, sometimes paying tribes and other users to keep water in Lake Mead. But the guidelines expire at the end of 2025, and states, tribes and water districts will spend the next few years debating a new, likely tougher plan.

A shortage declared by the federal government based on the 2007 rules has already hit some users hard who are not at the top of the river’s first credit list, like farmers in central Arizona.

Planning for a steady supply of just 11 million acre-feet would erase long-held assumptions about how much water some or all users thought they were entitled to for future growth. Contingencies at this level could significantly limit growth potential in the upper basin, where Wyoming, Colorado, New Mexico and Utah are far from fully developing their collective share of 7.5 million acre-feet. described by the pact.

These states are required to send an average of 7.5 million additional acre-feet downstream to the lower basin states of Arizona, Nevada, and California, with an additional 1.5 million acre-feet promised in Mexico. If the States and water users agree, the Lower Basin could profoundly reduce its already developed share, which, according to many observers, would distribute the suffering more equitably. Failure to agree would leave the decision solely to the US Secretary of the Interior or to the courts if the states sue each other.

A buoy lies on the ground on a closed boat launch on Lake Mead in the Lake Mead National Recreation Area near Boulder City, Nevada, August 13, 2021.

“You have to plan less”

While the water experts who gathered in the courtroom at SJ Quinney College of Law know they need to plan for less water, some aren’t ready to publicly commit to a figure that will alarm users. water at home. Arizona Department of Water Resources Director Tom Buschatzke, for example, needs legislative approval for any deal he might make.

“I won’t say 11,” Buschatzke joked from the symposium stage, “because I might get arrested when I get off the plane in Phoenix tonight.”

Climatologists who study and project Colorado’s flows as the region warms think that even 11 million acre-feet could be wishful thinking. Some studies suggest that the consequences of heat on water supply will cause the river to drop to just 9 million acre-feet in the coming decades, said Brad Udall, a researcher at Colorado State University. which has been focusing on the river for 20 years.

“I could live with 11” as a planning guideline, albeit an optimistic one, Udall said. This projection is stark enough to require bold action that water managers could build on later. It would follow the trajectory that scientists like Udall say represents the heat-induced aridification of the region, as opposed to temporary drought.

Others think it would be wise to plan for contingencies to protect a river that may only deliver 9 million acre-feet. Without adjustments to the Lower Basin Guaranteed Deliveries, a river that is consistently this small would leave the Upper Basin less than half of what it currently withdraws.

“We have to plan less,” said Colorado River District General Manager Andy Mueller, who represents water users in western Colorado. “You don’t plan a system on hope or politics.”

Colorado River:Dry boat ramps and exposed rocks at Lake Powell reveal the cost of a long drought

The expanded role of tribes

Tribal officials and lawyers said federal and state negotiators need to include Indigenous perspectives in these talks, far more so than in previous rounds. The original pact, in particular, did not take into account the needs of the tribes who now hold or, in some cases, expect to hold sufficient water rights to make essential contributions to climate adaptation and conservation. storage tank conservation.

Everyone who shares the river should use it responsibly and in a way that protects a semblance of nature and harmony, said Nora McDowell, a member of the river’s Water and Tribes Initiative and former president of the Fort Mojave Tribe on the lower Colorado.

“We have a responsibility to change what we have learned over the past hundred years of putting this pact in place,” McDowell said. Tribes need a voice to ensure the river itself is no longer an afterthought, she said. “It’s time.”

Regardless of the volume chosen and planned by the parties, those in the upper basin will want to modify the strict requirement that they deliver a set amount of water to the states below the Glen Canyon Dam, near the border between Arizona and Utah. And some in the lower basin admit they will likely have to bow to that provision to reach a deal.

Entsminger told The Arizona Republic that water users in the upper and lower regions will have to comply or they won’t reach a deal. Asked if this meant that the lower basin might have to reduce enough to allow future flows to be evenly split with the upper basin, he said he was not ready to discuss how to split the water.

“A 50-50 split would go a long way to solving the problems,” said Amy Haas, who leads Utah’s Colorado River Authority.

That’s certainly true for his state, but an even split would likely compound the pain in Arizona, where the state has already maxed out the river and would have to cut further to allow for upstream development. Arizona’s Buschatzke, like Nevada’s Entsminger, didn’t put numbers on a preferred rationing plan, but said all river users should share the benefits and the pain.

“We need a discussion about fair shares of the river,” said Udall, the Colorado State researcher. The Upper Basin states are still using less than two-thirds of what they were promised in 1922, and could not have foreseen at the time how climate change would penalize them for their slower development.

Still, he told The Republic, states will likely have to agree on a deal that doesn’t force an equal divide on the lower basin, where California and Arizona have the largest watershed populations. .

In the coming weeks, the Bureau of Reclamation will be soliciting suggestions on what the new guidelines should take into account, and it will launch a formal environmental review next year. The agency must balance the needs of seven states and 30 tribes while honoring treaty obligations with Mexico during, said agency program manager Carly Jerla, and will need those partners to pull together. elbows.

“Our job here has never been harder,” Jerla said.

Brandon Loomis covers environmental and climate issues for The Arizona Republic and Join it at [email protected] or follow on Twitter @brandonloomis.

Environmental coverage on and in the Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow The Republic’s environmental reporting team at and @azcenvironment on Facebook, Twitter and Instagram.

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