According to a new report from the U.S. Energy Information Administration (EIA), U.S. hydropower generation will increase by 7.5 percent in 2025, but will remain 2.4 percent below the ten-year average.

Hydropower generation in 2024 fell to 241 billion kilowatthours (BkWh), the lowest since at least 2010. ”In 2025, we expect generation will be 259.1 BkWh,” said the report. “This amount of generation would represent 6% of the electricity generation in the country. “

About half of the hydropower generating capacity in the country is in the western states of Washington, Oregon, and California, so EIA closely monitors precipitation patterns in this region to inform its hydropower outlook.

Precipitation conditions have been mixed across the western United States since October. According to the “WestWide Drought Tracker,” more precipitation than normal has fallen in northern California, Oregon, and the eastern half of Washington state. Some areas in southeastern Oregon received record precipitation between October 2024 and April 2025. In contrast, precipitation was below normal in parts of Washington, Montana, Idaho, and Southern California.

“Accumulation from winter precipitation tends to peak by April 1,” said the EIA. “The snowpack accumulation at higher elevations serves as a natural reservoir that melts gradually as temperatures rise in the late spring and early summer, leading to increased waterflow through dams.”

Northwest and Rockies

The EIA expects hydropower generation in the Northwest and Rockies region to be 125.1 BkWh, which is a 17 percent increase compared with 2024 and four percent less than the ten-year average. EIA’s hydropower forecast is informed by the water supply outlook from the National Oceanic and Atmospheric Administration’s “Northwest River Forecast Center (NWRFC).

On May 1, NWRFC released its latest April–September water supply forecast for the Pacific Northwest, part of the larger Northwest and Rockies region as modeled in the STEO. The NWRFC forecasts the region will have a below-normal water supply compared with the past 30 years in the northern portion of the basin, which includes the Upper Columbia River Basin, and above- to near-normal water supply in the southern portion, which includes the Snake River Basin. Water supply conditions at The Dalles Dam, located near the mouth of the Columbia River on the border between Washington and Oregon, reflect those of the upstream Columbia River system. The forecast at The Dalles Dam as of May 1 was 85 percent of normal for the same period.

California

EIA forecasts hydropower generation in California to be 28.5 BkWh in its May STEO, which is six percent less than last year’s generation. This total would be 15 percent more than the ten-year average.

As of April 1, reservoir levels in most major reservoirs in California were above the historical average for this time of year. The two largest reservoirs in the state, Shasta and Oroville, were at 113 percent and 121 percent of the historical average, respectively. According to the California Department of Water Resources, snowpack conditions as of April 1 were at 118 percent of normal for the Northern Sierra Nevada, 92 percent for Central Sierra, and 83 percent in Southern Sierra Nevada regions. Warmer-than-normal temperatures in April led to some early snowmelt across the state. As of the beginning of May, snowpack conditions were at 81 percent of normal for the Northern Sierra Nevada, 73 percent for Central Sierra, and 53 percent for the Southern Sierra portion.