WATER POLITICS

The deadline is rapidly approaching for the Colorado River Basin states to come up with a plan for divvying up the river’s waters and operating its reservoirs and other plumbing infrastructure after 2026. But a recent report warns that even if the states do make the November deadline — and it’s looking more and more likely they won’t — it won’t be soon enough to avert a crisis in the coming 12 months if the region experiences another dry winter.

Their analysis found that a repeat of the 2025 water year, which ends at the end of this month, will result in consumptive water use in the basin exceeding the Colorado River’s natural flow by at least 3.6 million acre-feet. That would potentially use up the remainder of the “realistically accessible storage” in Lake Mead and Lake Powell, constraining reservoir operations as early as next summer.

“Given the existing limitations of the river’s infrastructure,” they write, “avoiding this possible outcome requires immediate and substantial reductions in consumptive use across the Basin.”

The authors of the paper acknowledge that, despite a plethora of available data, it can be “difficult to see the water forest amid all the data trees.” Interpreting the data is rife with complexity, and translating snow water equivalents at hundreds of SNOTEL sites into streamflow forecasts is an uncertain science. However, it is abundantly clear that for the last quarter century, the collective users of the Colorado River have consumed more than the river offered, leading to a deep drawdown of the basin’s “saving accounts,” i.e. Lake Powell, Lake Mead, and a dozen smaller federal reservoirs.

As of Sept. 14, Lake Powell contained about 6.85 million acre-feet of water², which is less than one-third of what was in the reservoir on the same date in 1999 (23.23 MAF). Lake Mead held about 8 MAF, or 32% of capacity. Equally striking is that in just the last year, Lake Powell has lost about 2.4 MAF of its water — or about 30 feet of surface elevation — to downstream releases and evaporation. The savings account is rapidly draining.

The authors assume that next year’s natural flow on the Colorado River will be the same as in 2025, or 9.3 MAF³, which they describe as a “realistic and conservative, but not overly alarmist, projection” based on the Bureau of Reclamation’s own forecasts. And, also based on Reclamation reports, they assume total Colorado River consumptive use in the U.S. and Mexico will be 12.9 MAF.

That makes for a deficit of 3.6 MAF that will have to come from the reservoirs’ dwindling storage, potentially putting the elevation of Lake Powell at 3,500 feet by this time next year. And, due to the infrastructure’s limitations, Glen Canyon Dam would have to be operated as a “run of the river” (ROR) facility, meaning it couldn’t release more water than is coming into the reservoir at any given time, severely reducing downstream flows in the Grand Canyon and causing an even more rapid drawdown of Lake Mead.

Lake Powell inflows this August totaled about 268,000 acre-feet, while releases were 761,000 acre-feet, meaning under the ROR scenario the monthly release volume would be cut by nearly 500,000 acre-feet. Even more alarming is that instead of sending between 9,000 and 12,000 cubic feet of water per second into the Grand Canyon, late summer streamflows below the dam could fall as low as 2,000 cfs, affecting aquatic life and making river running significantly less predictable (and more like the pre-dam days?, save for the amount of sediment in the water). I’d be curious to see Crystal rapid or Lava Falls at 2,000 cfs. Any insight on that one would be appreciated.

While this scenario could be delayed by essentially draining upstream reservoirs such as Flaming Gorge in Utah and Wyoming or Blue Mesa in Colorado, it would only offer a temporary reprieve. Two consecutive dry years would certainly render Glen Canyon Dam essentially useless, and leave Lower Basin users high and dry. Which leaves the folks relying on the river with a couple of choices: They can pray for a lot of snow and hope someone’s listening, or they can slash consumption significantly and rapidly