The Bureau of Reclamation is keeping the option open to use reservoirs, including Blue Mesa in Colorado, to stabilize Lake Mead and Lake Powell if their water levels fall dangerously low.
The rules that govern how water is stored and released at lakes Mead and Powell, the two largest reservoirs in the Colorado River Basin, are set to expire in 2026. The federal government, basin states, Mexico and 30 tribal nations are navigating high-stakes negotiations in a multi-year effort to establish new rules.
Colorado water officials argued for the feds to take Blue Mesa and its two sister reservoirs, Navajo and Flaming Gorge, off the negotiating table — especially if releases end up supporting excessive water use in the Lower Basin states, including Arizona, California and Nevada. But Reclamation is still considering several options that could include the reservoirs in future Colorado River operations, according to a 389-page scoping summary released Thursday.
“My concern with those Upper Basin reservoirs is the slow creep of federal authority,” Commissioner Becky Mitchell, Colorado’s lead negotiator, told the Colorado River Drought Task Force on Oct. 12. “We need to stand together and say that’s not what these are for — sustaining the use that we’re seeing in the Lower Basin now is not what those are for.”
Colorado and other Upper Basin states calculate that the Lower Basin overdrew from the Colorado River Basin by more than 1 million acre-feet each year between 2019 and 2021.
One acre-foot can provide a year’s worth of water for about two typical urban households.
The soon-expiring rules date back to 2007 and govern how water is stored in and released from Lake Powell, on the Utah-Arizona border. Powell releases water to Lake Mead, on the Arizona-Nevada border, which manages its releases to provide for Lower Basin water users.
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The two massive reservoirs are part of a system of dams and reservoirs built along the 1,400-mile river that can store up to 58.48 million acre-feet of water. Together, lakes Mead and Powell make up about 92% of that storage with a combined capacity of 53.9 million acre-feet.
If the water drops too low, dam infrastructure can be damaged, or at certain levels, the dams cannot release water downstream — which would negatively impact ecosystems, crop production, electricity production and water security for millions of people.
The scoping summary released last week is one step in the long effort to establish operating rules for lakes Mead and Powell after 2026, a process that started earlier this summer. It outlines what options the federal government is keeping on the table as it and the basin states negotiate the final rules for reservoir operations after 2026.
The scoping summary will be used to create a draft plan, which could be completed by the end of 2024. The final version of the plan could be available in early 2026 and will go into effect in 2027, according to a news release.
Future emergency operations
One idea that Reclamation will consider is using upstream reservoirs, like Blue Mesa, in temporary, emergency water releases to stabilize Mead and Powell if their water levels fall too low, according to the scoping summary.
Blue Mesa, located on the Gunnison River in Colorado, a tributary of the Colorado River, is operated by the federal government as part of the Aspinall Unit, which also includes Crystal and Morrow Point dams.
The unit was originally built to generate electricity, increase water storage capacity and regulate streamflows. The reservoirs are also popular recreation spots, which helps support local economies.
Drought-response contingency plans, which also expire in 2026, assigned another duty to the Aspinall Unit: providing emergency releases of water to stabilize Lake Powell’s water levels.
In 2021 and 2022, Mead and Powell teetered on the edge of a crisis when water levels reached historic lows, and the river system’s total water storage fell to 35% of its capacity.
In response, Blue Mesa sent 36,000 acre-feet of water, and Flaming Gorge, a reservoir on the Utah-Wyoming border, sent 588,000 acre-feet downstream to shore up Powell’s depleted water levels.
In November 2021, the reservoir held about 220,000 acre-feet of its 941,000 acre-foot capacity; in November 2022, 282,000 acre-feet.
The emergency releases in 2021 set back some local businesses around Blue Mesa, particularly during the dry 2022 season. This year’s wetter conditions boosted morale, local businesses and the reservoir closer to its capacity, according to the Gunnison County Chamber of Commerce.
Blue Mesa stored about 608,000 acre-feet as of Sunday and peaked around 765,000 acre-feet in late June, according to federal data.
The Bureau of Reclamation attributed water supply insecurity in the Colorado River Basin to prolonged drought conditions, lower than usual runoff from rivers into reservoirs, and climate change that is causing aridification in the scoping summary. Officials in Colorado — part of the Upper Basin along with New Mexico, Utah and Wyoming — argue that overuse by Lower Basin water users is another key factor.
Reclamation said it will consider “upstream or downstream actions needed to protect critical reservoir elevations,” like temporary emergency response operations at upstream Colorado River dams, as long as the operations stay within the rules that already govern each dam.
Staff members at the National Park Service recommended against using the Aspinall Unit in future drought-response procedures — or if the dams are used, aligning water releases with the needs of endangered fish species, according to comments submitted during the scoping process.
The 2021 and 2022 emergency releases “decimated” the local recreation season by forcing the marina to close and contributing to an algal bloom, Mitchell said during an Aug. 29 Upper Colorado River Commission meeting.
If the basin plans to release water from upstream reservoirs, like Blue Mesa, as part of a Drought Response Operations Agreement, then the water should be used to help stabilize critical elevations at Lake Powell, she said.
“The reality is that half of our DROA water sent from those upstream reservoirs to Lake Powell was ultimately released,” Mitchell said.
“Total system storage”
When it comes to protecting critical water elevations at Mead and Powell, Reclamation also said it will consider “total system storage in all major Colorado River reservoirs” to decide operations at the two key reservoirs.
That idea puts some Colorado officials on edge.
Under current agreements, Upper Basin states have more say in operations at Lake Powell and upstream dams, like Blue Mesa and the Aspinall dams, Flaming Gorge and Navajo Reservoir, on the Colorado-New Mexico border, all of which are part of the federal Colorado River Storage Project.
If the water storage in upstream reservoirs is lumped into the calculations with the Mead and Powell storage that govern reservoir operations, Colorado officials would be concerned that it would be a sign of federal authority expanding, and would benefit the Lower Basin to the detriment of Upper Basin water users and economies.
In a letter to the Bureau of Reclamation, Colorado and the other Upper Basin states argued that the rules “cannot modify” operations or records of decision for Aspinall, Flaming Gorge and Navajo reservoirs, in part, because Reclamation said it would focus only on operations at Mead and Powell when it launched this planning process.
Some Colorado officials were also concerned that in times when the Lower Basin used too much water, Aspinall, Flaming Gorge and Navajo reservoirs could basically be drained down, which could impact local recreation and economies.
Not everyone shared the same concerns. Bart Miller, healthy rivers director at Western Resource Advocates, an environmental organization, supported the idea of including the upstream dams in total system storage calculations.
“Looking at the basin as a whole provides Reclamation more flexibility in how and where it keeps water,” he wrote, adding that more holistic management should also benefit environmental resources like the Grand Canyon.
Other water managers in Colorado are keeping a close eye on these developments, like the Colorado River Water Conservation District and the Southwestern Water Conservation District, which together cover the entire Western Slope. Steve Wolff, general manager of Southwestern, did not have concerns about the scoping summary.
“I think Reclamation is really just trying to leave the door open to a creative solution that the seven states might be able to come up with,” Wolff said. “Maybe some alternative that the seven states can come up with might have some component of upstream storage or downstream storage within it, and they don’t want to preclude that this early in the process.”