The forecast for spring-summer runoff in the Colorado River has taken a nosedive due to sharply decreased snowpack and total precipitation in April compared to earlier months.
The federal forecast for 55% of normal April to July runoff into Lake Powell means this year’s runoff could be the second lowest in the past six years. The prediction was made Wednesday by the federal Colorado Basin River Forecast Center, a branch of the National Oceanic and Atmospheric Administration.
It comes as various river experts were already warning that another crisis is looming for the river’s supply as water levels in its reservoirs trend lower, following a rebound from record low levels in 2023 and 2024 due to good precipitation and snowpack.
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It also comes at a crucial time in the seven-state negotiations over future Colorado River operations, as the Lower Basin states including Arizona are deadlocked with the Upper Basin states over how to cut water use to bring the overused river’s supply and demand into balance.
The forecasted runoff into Lake Powell and the actual rainfall and snowpack totals for the lands upstream of the lake are important for residents of the Lower Basin states of Arizona, Nevada and California, because Powell supplies water directly to Lake Mead downstream.
Mead is the direct source of drinking water for Tucson and Phoenix through the Central Arizona Project, as well as for city residents in the Los Angeles and Las Vegas areas and farmers and tribes along the Lower Colorado River.
Specifically, the river forecast center said in a webinar on Wednesday:
— Snowpack in the mountains above Lake Powell was 71% of normal in early May, compared to 125% of normal in December.
— Precipitation in the area above Powell was 60% of normal in April, compared to 88% of normal for the entire period of October 2024 through April 2025.
— As a result, the May forecast runoff of 55% of normal was 19% lower than the April forecast of 67% of normal. The May forecast is the last major forecast for the river for the spring.
Asked to comment, longtime river expert and scientist Jack Schmidt focused on the water elevations in various river reservoirs including Powell and Mead.
Using the metaphor of a checking account, Schmidt said the runoff is “income” for the account. Water that is used or lost from the river due to evaporation and other forces represents “expenses” from the account. The amount of water stored in the reservoirs represents the checking account balance, said Schmidt, director of Utah State University’s Center for Colorado River Studies.
Lake Mead in Nevada, shown here in an aerial photo, is the direct source of drinking water for Tucson and Phoenix through the Central Arizona Project’s canal system. The bleak forecast for Lake Powell is important to Tucson because Powell supplies water directly to Lake Mead downstream.
The total storage today in all 46 river reservoirs is the same as in August 2021 and total storage in Powell and Mead today is the same as in October 2021, he noted. Around that time, the U.S. Bureau of Reclamation was declaring the first shortage on the river — a shortage curtailing supplies to Central Arizona farmers — and news stories were proclaiming a crisis on the river, Schmidt said.
“Thus, the prediction of a low inflow year in 2025 comes at the same time that we already have a low balance in the checking account. We’re in the crisis right now; it never ended,” Schmidt said in an email to the Star on Wednesday.
The negotiations between the Upper and Lower Basin states have been stalled for months mainly because the Upper Basin states refuse to take any more cuts in their river water supplies and say the Lower Basin states should take all the cuts, which the Lower Basin states refuse to do. The Upper Basin states are New Mexico, Colorado, Wyoming and Utah.
Sarah Porter, director of an Arizona State University water research center, said this year’s low flows on the Colorado may create stronger incentives for the states to come to an agreement.
“It forces people to get serious. In a really good year on the river, that takes the pressure off and buys time,” allowing negotiators to delay dealing with the issue, said Porter, director of the Kyl Center for Water Policy.
