KLAS: Study looks at ‘realistically available’ water in Lake Mead, Lake Powell a year from now

LAS VEGAS (KLAS) — “Immediate and substantial reductions” in Colorado River water use could be needed much sooner than anyone predicted, according to a study published last week.

The problem: People are using more water than the amount that has been coming down the river, and it could reach a tipping point by the end of next summer. That’s the conclusion of a study involving research and collaboration among four universities — the University of New Mexico, Utah State University, Arizona State University, and the University of Colorado.

That means hard choices are ahead unless a very wet winter rescues 40 million water users along the river.

A repeat of conditions this year — near-average snowpack (91% of normal), but streamflow levels projected at 52% of average — could put new pressure on the river.

That 3.6 million acre feet, the study said, equates to about half of the realistically available water stored in the nation’s two largest reservoirs, Lake Mead and Lake Powell.

The study aimed to show the current situation with the Colorado River. It’s an important snapshot of real conditions as the Colorado Basin states formulate a new agreement on how to manage the river. The current agreements expire at the end of 2026.

Last week, Democratic Nevada Rep. Susie Lee held the third annual Southern Nevada Water Summit. Lee commented today on the study:

“This report reflects what Nevadans know all too well — our water is a precious resource. It’s crunch time for interstate negotiations regarding the future of the Colorado River. I’m confident in Nevada’s negotiators’ ability to represent our state’s interests, and I stand ready to assist at the federal level however needed. There’s one place we can all agree: the best deal is one reached by the Basin states, not one imposed on the West from Washington,” Lee said.

Dire predictions about water supplies aren’t new, but this study is noteworthy in how it identifies “realistically accessible” stored water in Lake Powell and Lake Mead. Most studies are based on active storage, but that method ignores known engineering limitations that have prompted federal government decisions to keep both reservoirs from getting so low that there’s a risk of damaging pipes and turbines that produce electricity.

• LAKE POWELL: If the reservoir’s surface drops below 3,500 feet, there’s a high risk of damage to the dam’s generation of electricity. That leaves about 130 feet of water in Lake Powell (deadpool level is 3,370 feet above sea level) unavailable for use. If the federal government wanted to access that water, it would have to use pipes lower in the dam known as the “river outlet works,” but those pipes are too small to carry enough water downstream to meet contractual demands.
• LAKE MEAD: If the surface of Lake Mead drops below 1,035 feet, only five of the 17 turbines in Hoover Dam will be operated due to concerns about damaging the dam’s pipes, the U.S. Bureau of Reclamation has indicated. That leaves 140 feet of water at Lake Mead unavailable for use (deadpool level is 895 feet).

Of the active storage that adds up to 15.1 million acre feet at the two reservoirs, only 6.3 million acre feet is realistically accessible, according to the study.

For perspective, California gets 4.4 million acre feet, Arizona gets 2.8 million acre feet and Nevada gets 300,000 acre feet. Those allocations are modified under the current Tier 1 water shortage in the Southwest. Arizona’s allocation is cut by 18% (512,000 acre feet), Nevada loses 7% (21,000 acre feet) and California gets its full 4.4 million acre feet because the state holds senior water rights.

The study relied on numbers that came out Aug. 15 in the U.S. Bureau of Reclamation’s 24-month study. Reclamation released its latest version of that outlook today. Also, the study focuses on the “minimum probable” levels at the reservoirs, claiming that those reports have projected lake levels more accurately than the “most probable” levels.

The August 24-month study (minimum probable) projected Lake Mead dropping to 1,023.59 feet and Lake Powell at 3,468.75 feet in July 2027, well below the level required to generate power. The Sept. 15 update released today shows Lake Mead at 1,022.77 feet and Lake Powell at 3,489.88 feet. The reports don’t summarize changes in the projections, but the Lake Mead outlook is worse than it was a month ago.

The most probable projections show expectations for Lake Mead that are nearly 3 feet higher than they were just a month ago. Last month, the lake level for July 2027 was projected at 1,037.21 feet; this month, July 2027 is projected at 1,040.06 feet.

New projections in the study for August 2027 show Lake Mead at 1,021.91 feet and Lake Powell at 3,484.82 feet.

As of noon today (Sept. 15) Lake Mead was at 1,057.00 feet. The lowest level recorded since the reservoir filled in the 1930s came on July 27, 2022.