“How high is the water, Mama?” croons Johnny Cash. Not high enough in both Lakes Mead and Powell, say water regulators.
Both Lake Mead on the Arizona-Nevada border and Lake Powell bordering Utah-Arizona line have recorded their lowest water levels since the reservoirs were first filled. Lake Mead, the nation’s largest reservoir and which supplies water to Nevada, Arizona and California, measured 1,040.4 feet above sea level on Aug. 7, and Lake Powell, the nation’s second-largest reservoir, hit its record low on Aug. 8 at 3,519.8 feet above sea level (a year ago, it stood at 3,551.33 feet above sea level).
Created by Hoover Dam in 1935, Mead is nearly 190 feet below being full and measured at 1,054 feet ust a year ago (it was last at full in 1983). At 895 feet, it reaches “dead pool” — a complete shutdown of Hoover’s hydropower system. Built in 1966, Glen Canyon Dam, which created Lake Powell, begins to lose its ability to generate hydropower at 3,490 feet, and reaches “deadool” at 3,370 feet
More than 40 million people rely on the Colorado River’s water supply. Under the 1922 Colorado River Water Compact, the seven states on the Colorado River divide up 15 million acre-feet of water every year. The compact allows both the Upper and Lower Basin states to each take 7.5 million acre-feet annually or 15 million over 10 years. But there’s not that much water anymore, with the entire West in the midst of what climatologists are calling a 25-year “mega drought.”
The four states of the Upper Basin have historically only about 4 million acre-feet annually, while the Lower Basin states have used about 1 million more acre-feet per year than their allocated amount. The three states have now agreed to reductions, with the Interior Department recently announcing its own plan in a final environmental impact statement (FEIS), which is being contested.
There is that optimism that a forecasted “Super El Niño” weather pattern may change things this year, but it take more than one year to turn things around.
Grand Canyon Report (by Tom Martin/Grand Canyon Private River Runners )
Running the Grand this fall or winter and wondering what the water levels might be? Read on for the latest report from Tom Martin and Grand Canyon Private River Runners…
“Still holding on… sorta. Here’s a look at what might be ahead of us for boating the Colorado River in Grand Canyon this winter.
As of today, July 29, 2026, the reservoir behind Glen Canyon Dam has lost roughly 5,600 acre-feet of water per day in the last 19 days. If this rate of decline continues, then we can expect the reservoir to reach minimum powerpool — 3,500 feet — in about 190 days, or early February, 2027.
The last 19 days show increased inflow to the reservoir due to the arrival of monsoon rains. This is true for the reservoir behind Hoover Dam as well, with increased inflow from the Little Colorado River and other tributaries to the Colorado River in Grand Canyon.
What could happen in early February, 2027.
If the level drops below 3,500 feet, dam operators will no longer be able to release water through the penstocks and hydroelectric turbines, meaning they must rely entirely on the river outlets lower on the dam for all releases. This would not only zero out the dam’s hydropower output, but could also damage the outlet tubes, since they aren’t engineered for long-term, sustained use.
In order not to damage the dam, keep the turbines doing something, and keep some water going to Mead, Reclamation may defend that 3,500-foot level, presumably even if it means going to a run-of-the-river operation.
During a run-of-the-river operation, water is released from the dam at the approximate rate that it is flowing into the reservoir, minus evaporation and seepage around the dam. Today, the evaporation amount is about 397 cubic feet per second (cfs) and the inflow from the Colorado and San Juan is 4,434cfs. Leakage around the dam is about 500cfs. This would allow a run-of-the-river release of about 3,537 cfs, less than half one-half of current releases. This may happen this winter during the motor-free river running season in the Grand Canyon.
This 3,537 cfs figure does not include bank seepage or possible decreases in the upstream releases from Flaming Gorge Dam and Navajo Dam. This means the actual run-of-the-river release from Glen Canyon Dam in February 2027 may be even less if the Flaming Gorge and Navajo releases decrease.
If — or more likely, when — this occurs, it will render Lake Powell useless as a water savings account, and reduce it to a marginal power generator. Meanwhile it will still be a silt collector and large evaporation pool. Boating will still be possible on the reservoir and rafting downstream of the dam in Grand Canyon, but most existing boat ramps on the reservoir will no longer be usable. This will lend strength for calls to drain the reservoir, either by decommissioning the dam altogether, or by building bypass tunnels that can be shut down if climatic conditions change and aridification is reversed.
I appreciate help from Jonathan P Thompson in writing this outlook.”