Many of California’s reservoirs have been filled with nearly capacity this year due to adequate snowman runoff in the Sierra Nevada. However, the situation varies widely along the Colorado River. The Colorado River is another important source of water in Southern California, where extremely arid springs have reduced the amount of runoff that flows into the reservoir.
The latest forecast from the federal Colorado Basin River Forecast Center shows that the river flows to Lake Powell will likely be around 46% of the average over the next three months.
“We’ve noticed a low runoff, and there’s no doubt about that,” said Luke Gingerlich, a peasant who grows peaches near the Palisade river in Colon.
Snowmen in the Upper Colorado River reached a median of 89% on April 1, but the outlook has deteriorated over the past two months as past dry, warm temperatures and arid soil absorbed some of the runoff.
“This is another year that won’t help the long-term water crisis in the Colorado Basin. It’s going to make things worse,” said UCLA climate scientist Daniel Swain. “This year will again put more stress on the Colorado system.”
Utah – Lake Powell on the Arizona border is located at 33% of its capacity. Lake Meade, downstream near Las Vegas, is 32% full.
With a slight thaw, the country’s two largest reservoirs will likely drop even further this year, and will approach very low levels that will require additional reductions in water supply over the next few years.
Representatives from California and six other states are negotiating long-term plans to reduce water use since 2026, when rules expired to address the ongoing shortage. However, disagreements over competing proposals have created deep clefts between the three states in the river’s lower basin, California, Arizona and Nevada, and four states in the upper basin – Colorado, Utah, Wyoming and New Mexico.
The latest forecast from the U.S. Burial Service, which manages river dams, is that the rest of 2025 will be “a very dry year, and the results will be important,” authors and water researchers Eric Coon and John Fleck wrote in a blog post.
Kuhn and Fleck revealed that the latest federal figures include programs that pay farmers who agree to temporarily dry parts of their fields despite ongoing conservation efforts, but that further declines in the reservoir are expected. According to recent estimates, “We have not reconstructed reservoir storage again,” they write. “We’re draining the system.”
The Colorado River provides water to cities from Denver to San Diego, and offers 30 native tribes and farmland from the Rocky Mountains to northern Mexico.
The river has been held in the whole for a long time, and its reservoirs have been decreasing badly since 2000. The average river flow has shrunk by about 20% since 2000, and scientists estimate that the decline was caused by global warming caused by burning of fosil fuels and rising levels of greenhouse gases.
In recent years, the state has adopted a series of progressive water saving plans to prevent reservoirs from reaching dangerously low levels. Sometimes, they express fears that inaction will ultimately drive Lake Mead into a “dead pool.”
There are other risks at very low reservoir levels. The states in the Upper and Lower Basin have made conflicting interpretations of certain provisions of the 1922 Colorado River compact, as described by Koon and Fleck as the looming “tripwire” that could trigger a legal battle, as a possible way to cause a legal battle.
This year’s low runoff highlights the need for a new set of river management guidelines from 2026 onwards, according to John Berglen, Regional Policy Manager for Resource Advocates for the nonprofit Western.
“What we’re looking at is the importance of a new set of guidelines over another 20 years, actually responding to climate change, actively preparing for these shortages, and stabilizing the system,” Berggren said.
Southern California uses more water from the Colorado River than any other state, providing cities and farmland. While local water shortages are likely to continue to promote conservation efforts, the Metropolitan Water District of Southern California has recorded moisture in its reservoirs and underground storage areas, benefiting from the supplies it has provided over the past three years in California.
In the Colorado River Basin, April and May were extremely dry. Warmer temperatures than average for some areas contribute to reduced runoff.
“The rise in temperatures over the last few decades has had a major impact on the runoff,” Bergglen said.
“Unfortunately, we’ll see more and more. We need a snow pack well above average to get closer to the average runoff due to temperature,” Bergglen said. As the reservoir is at a low level and the inflow shrinks, he said:
Drought conditions in the western United States
About 51% of the west experienced at least moderate drought on May 27th.
There is no drought
It’s abnormally dry
Moderate drought
Serious drought
Extreme drought
Exceptional droughts
US drought monitor
Los Angeles Times
Scientists have determined that the past 25 years have been perhaps one to two hundred years in western North America’s most a driest quarter century, and that the serious megadorates that research has shown are being strengthened by rising temperatures.
As of this week, the US drought monitor website shows that around 51% of the 11 western states have experienced some drought, indicating that parts of the Colorado River basin are in severe or extreme drought.
Southern California is classified as drought, but Northern California is not.
Lake Shasta, the state’s largest reservoir, is 92%. The second largest reservoir, Lake Oroville, is located at 99% of its capacity.
Sierra Nevada has had above average snow for the past three years, but this year the snow pack has quickly melted due to dry conditions and warm average temperatures, especially the warm nighttime temperatures in the mountains.
“Almost every basin melted really quickly,” Swain said.
“We have previously melted snow in the western mountains, especially at low to medium elevations,” he said.
The latest seasonal forecast from the National Oceanic and Atmospheric Administration predicts that temperatures that are likely to continue this summer, including the Colorado River Basin and California.
Early snowmelt in many areas probably means that mountain soils and vegetation will dry out faster and more risk of wildfires in the coming months, Swain said.
“In the past few years, California has been so high elevation, so the snow bands have not actually been fire season,” Swain said. “So I think we’ll see more fire activity this summer as a result of this summer compared to the past few years in the mountains.”
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