But this year did not bring much-needed precipitation to the river basin. The latest report from the US Bureau of Reclamation shows Lake Mead at just over 1,040 feet above sea level in July, having dropped nearly 10 feet in just two months, and is currently at just 27% of its maximum capacity.
More critically, the bureau predicts the reservoir will be at nearly the same level, around 1,041 feet, come January.
If that forecast holds in next month’s report, which is what federal officials will use to determine cuts for 2023, the Southwest will be subject to a Tier 2 water shortage — and the fresh cuts that come with it — starting in January.
At 1,050 feet, a Tier 2 shortage is declared, further decreasing the amount of water Arizona, Nevada and Mexico can use from the Colorado River. If the forecast is below 1,045 feet, which the latest forecast would suggest, then parts of California would be forced to cut its Colorado River water consumption, too.
At Tier 3 — something the forecast suggests is possible starting in January 2024 — water cuts could be deep enough to extend beyond agriculture and impact household and industrial water use.
An ‘optimistic’ bias
Importantly, the Bureau of Reclamation’s studies are based on historical data from the 1990s — a much wetter period in the West, said Eric Kuhn, a retired former manager of the Colorado River Water Conservation District.
“This means that the ‘most probable’ 24-month study should be considered to have a wet or ‘optimistic’ bias,” Kuhn told CNN, which suggests that it’s likely the actual levels will run a bit below what the bureau is predicting.
“Individual La Nina years can be wet or dry” for the Colorado River basin, Kuhn said. “But in consecutive La Nina years there is a very clear trend toward drier years. The combination of dry soils, a third La Nina and critically low reservoirs levels is a major concern.”
And what happens upstream is of critical importance to Lake Mead. The reservoir’s forecasts are also now accounting for the falling water level — and the government’s emergency actions — at Lake Powell, Mead’s upstream neighbor and the country’s second-largest reservoir.
Without those emergency steps, the government estimated there was about a 25% chance the Glen Canyon Dam, which generates power for as many as 5.8 million homes and businesses across seven states, would have stopped producing energy by the end of this year.
There is some opportunity for the Colorado River to pick up more inflow between Lake Powell and Lake Mead, from springs and small creeks in the Grand Canyon — but drought and climate change have been reducing these flows, as well.