As states butt heads over Colorado River plans, water experts gauge impacts to Colorado

Colorado’s water and reservoirs are in the thick of disagreements over Colorado River management in a drier future.

All seven Western states in the Colorado River Basin agree that climate change is exacerbating conditions in the basin, and water users need sustainable, predictable water management. They agree that the current rules, which expire in 2026, didn’t do enough to keep reservoirs from dropping to critically low levels. They even agree that water cuts need to happen.

But they’re at loggerheads over how to share the pain — and have been for years. Now, the Lower Basin officials have proposed a plan calling on all basin users, including Coloradans, to make sacrifices.

“This is not a problem that is caused by one sector, by one state, by one basin. It is a basinwide problem, and it requires a basinwide solution,” John Entsminger, Nevada’s top negotiator, said during a news conference March 6.

Basin officials are negotiating Colorado River management in order to create new interstate water sharing rules that will replace the current agreements, which were created in 2007. The overburdened river system provides water to seven Western states, two Mexican states and 30 Native American tribes.

Basin states released competing proposals March 6, outlining their ideas for releasing, storing and cutting back on water use.

The Upper Basin proposal — put forward by Colorado, New Mexico, Utah and Wyoming — only includes cuts to the Lower Basin’s water use, although the four states would continue developing voluntary conservation programs.

The Lower Basin alternative — from Arizona, California and Nevada — looks at the amount of water stored in seven federal reservoirs. When that storage falls below 38% of total reservoir capacity, all seven states would conserve water to cut their collective use by 3.9 million acre-feet. One acre-foot roughly equals the annual water use of two to three households.

That’s a no-go for Upper Basin states, where water supply fluctuates yearly because it primarily relies on mountain snowpack. In 2020, a particularly dry year, the Upper Basin used 4.5 million acre-feet — much less than its legal allotment of 7.5 million acre-feet. In 2021, another drought year, the states had to cut back further.

That’s without any additional water cuts, like those proposed by the Lower Basin.

“When we’re looking at those years, like 2021 when our uses in the Upper Basin were at 3.5 million acre-feet, that represents almost a 25% cut,” Commissioner Becky Mitchell, Colorado’s top negotiator, said. “To cut further in a year like that could wreck communities and economies.”

Colorado’s role in the Upper Basin plan

The Upper Basin proposal calls for few changes in the upstream states.

The Upper Basin would keep taking steps to ensure Lake Powell, located on the Utah-Arizona border, could make its required releases downstream, and to reduce Upper Basin water use through voluntary, temporary and compensated cuts, like the system conservation pilot program.

The rest of the proposal is meant to offer guidance to the Lower Basin, Mitchell said.

In the past, officials have changed how water is stored and released at lakes Mead and Powell based on the reservoirs’ elevations. The Upper Basin plan links operations more closely to each year’s available water storage, a high priority for Colorado officials.

In years when Lake Powell is less than 20% full, the Upper Basin states suggested releasing as little as 6 million acre-feet of water downstream. Upper Basin states are legally obligated to let at least 7.5 million acre-feet flow to Lower Basin states (plus some for Mexico) annually, as averaged over a rolling 10-year period.

If reservoir storage dropped to certain trigger levels, Lower Basin states would also cut up to 3.9 million acre-feet in a year.

The approach is designed to replenish depleted water storage in reservoirs, like Mead and Powell. These two enormous reservoirs — which function like savings banks for water users — drained to a third of their volume in the early 2020s, prompting a crisis response among officials and ramping up concerns about water availability in the future.

It would also protect Lake Powell’s ability to release water downstream according to water law, Mitchell said.

“That protects Colorado users. That protects all the Upper Basin states’ users,” Mitchell said. “The rebuilt storage protects all 40 million people — that’s the way that we protect all 40 million is to have a safety net.”

A call for widespread cuts

The Lower Basin officials say that the entire Colorado River Basin — including Colorado and the other Upper Basin states — must cut water use.

In their proposal, Lower Basin officials said they would take responsibility for the structural deficit, which refers to water losses from factors like evaporation, by cutting back on their water use by 1.5 million acre-feet in some years.

The Colorado River Basin covers 245,000 square miles in the West. (Agri-Pulse)

In years when the total storage in the system drops below 38%, the Lower Basin says the Upper Basin states need to help out so the basin as a whole can cut 3.9 million acre-feet.

If this plan had been in place since 1971, the states would have started taking cuts around 2000. For most of the past 24 years, the Lower Basin would have taken annual cuts of 1.5 million acre-feet. The Upper Basin would only have faced shortages in 2020 and 2021, according to Lower Basin officials.

“It’s very easy to craft an alternative that doesn’t require any sacrifice, but that’s not what the Lower Basin alternative does,” said JB Hamby, California’s top negotiator, during a March 6 news conference. “The Lower Basin is home to three-quarters of the Colorado River Basin’s population, most of the basin’s tribes, and the most productive farmland in the country. Our proposal requires adaptation and sacrifice by water users across the region.”

What would the Lower Basin option mean for Colorado?

Officials have released written plans, but it will take modeling out many different water supply scenarios to understand the impacts of each proposal, according to water experts.

But under the Lower Basin plan, Colorado could be on the hook for cutting its use by hundreds of thousands of acre-feet, said Colorado water expert Eric Kuhn.

In one hypothetical low-storage scenario, the Lower Basin would cut its use by 1.5 million acre-feet, then the two basins would each conserve an additional 1.2 million acre-feet, Kuhn said.

If Colorado took on a third of the Upper Basin’s obligation — and this is a big “if” — it would mean cutting water use by nearly 400,000 acre-feet.

“If Colorado ever agreed to absorb a certain percentage of the final … cuts, it’ll have a big impact on the state,” Kuhn said. “It’s not theoretical; it would be quite significant.”

For reference, all of the cities, towns and industries in Colorado use a combined total of about 380,000 acre-feet per year from multiple water sources, including the Colorado River, according to the 2023 Colorado Water Plan.

Mandated cuts could even send states into litigation, which is the worst outcome, said one Colorado official. Once the issue moves to the courts, state officials can’t talk to each other, and their future could be in the hands of U.S. Supreme Court justices who may not have expertise in the complex realm of Western water law.

“We’ll talk 1-to-1 cuts when they’re down to 4.5 million acre-feet,” said Steve Wolff, general manager of the Durango-based Southwestern Water Conservation District, referring to the average amount of water used by Upper Basin states. “When you’re still using twice as much as us, why should we agree to a 1-to-1 cut?”

Peter Ortego, general counsel for the Ute Mountain Ute Indian Tribe, said basin tribes that have made agreements to share in future shortages could be impacted. Most tribal nations have senior water rights, which get water first in dry years and should be protected from most water cuts, he said.

Environmental groups say more needs to be done to protect rivers and freshwater resources, which provide vital habitat for wildlife in the arid West.

In recent, very dry years, Colorado trout fisheries, like the Yampa River, have been shut down because of low flows and warmer water temperatures in mid-to-late summer. If modeling shows that federal or state plans would leave less water in the rivers, that would be concerning, said Jennifer Pitt, Colorado River Program director for the National Audubon Society.

Going forward, Pitt and other water experts will be watching for updates from the Bureau of Reclamation’s analysis. That’s when they’ll know more about possible impacts to Colorado.

Until then, Coloradans need to keep one thing in mind, Pitt said.

“This is not Colorado against the rest of the West. This is Colorado, part of a river basin that is shared,” she said. “All those parties need each other to get through some challenging conditions in the future.”

This story originally appeared in the Colorado Sun, a partner to Water Education Colorado in publishing Fresh Water News to cover water stories of critical importance to Colorado and the West.

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