Another Dry Year May Cause “System Crash” Of Colorado River Basin, Says Study

A 2026 study has found that if the Colorado River Basin experiences another dry year similar to 2025, it’s likely that water storage in Lake Powell and Lake Mead would be mostly depleted. Even if the basin were to experience a very wet year, it would only provide about two years of cushion before a similar depletion occurred.

The last time the Colorado River reservoir system was almost full was in 1999. Lake Powell and Lake Mead lost 52 percent of their combined active capacity between fall 1999 and January 1, 2005, according to the study. By March 2023, water storage in the basin was down to 27 percent of what it had been in 1999. The overall decrease has been driven primarily by drought and continued over-allocation of the river.

The Bureau of Reclamation’s most recent forecasts for reservoir storage indicate that basin-wide annual consumptive use continues to exceed annual natural supply, meaning more water is being used than is entering the basin, with the inevitable result that water supplies are dwindling. The study points out that Water Year 2026 is shaping up to be one of the lowest runoff years on record, most likely with “an even greater gap between natural supply and consumptive use and loss.”

The study’s researchers found that, in the event of another dry winter and with low projections of consumptive use, there would be a gap of 2.59 million acre feet between natural supply and basin use. In such a situation, they say, there’s a risk of the basin’s water storage system crashing. For the purpose of the study, a system crash is defined as a situation in which the major reservoirs drop to elevations that risk damage to the dam infrastructure and are operated as “run-of-the-river” facilities, where a reservoir has little to no usable storage capacity and thus primarily releases downstream only the inflow it receives.

The researchers point out that a system crash would have a significant impact on agricultural water use, but it does not mean that municipal taps will run dry, as many cities can fall back on replacement water supplies such as ground water, local rivers, and reclaimed water.

Upper and Lower Basin states that rely on the Colorado River Basin have been searching for a solution regarding how to update a century-old compact governing who gets to access the river’s water, but there has been little progress in negotiations. Greatly dependent on the outcome of negotiations are nine National Park System units found along the river, particularly Glen Canyon National Recreation Area and Lake Mead National Recreation Area. 

The Park Service "has developed a plan and funding to support identifying, monitoring and protecting cultural sites as they emerge from the waters of Lake Powell and become exposed on dry land,” a spokesperson from the Park Service told the Traveler in January. “The National Park Service is also working with the Bureau of Reclamation to identify agency responsibilities in managing cultural and natural resources as the waters of Lake Powell recede.”