US hydropower generation is expected to rise about 5% in 2026 but remain below long-term averages due to snow drought conditions in parts of the country, the US Energy Information Administration said in a Tuesday note.
In its latest outlook, the agency projected hydropower generation will reach 259 billion kilowatt-hours in 2026, accounting for roughly 6% of total US electricity generation. That would mark an increase from 245 BkWh in 2025, which itself was about 4 BkWh higher than 2024, the lowest year on record.
Despite the gains, the 2026 generation is expected to remain about 1.8% below the 10-year average, reflecting reduced water availability tied to unusually warm winter conditions in several western states.
Seasonal precipitation, including both rainfall and snowpack accumulation, remains a key driver of hydropower output. Adequate precipitation helps maintain soil moisture and preserve snowpack, which serve as natural reservoirs that feed rivers and dams during warmer months.
Data from the Western Regional Climate Center show precipitation across much of the western US has been near normal. However, record warm winter temperatures have contributed to widespread snow drought conditions.
A March heat wave accelerated snowmelt in parts of California, the Southwest, and the Pacific Northwest, likely reducing water supplies during peak spring and summer demand.
In the Northwest, the Columbia River Basin, which holds more than one-third of US hydropower capacity and supplies electricity to over four million homes, is expected to see notable changes. The EIA forecasts generation in the Northwest and Rockies region will total 125 BkWh in 2026, up 17% from 2025 but still about 4% below the 10-year average.
Unusually high hydropower output in December 2025 and January 2026, driven by a series of atmospheric rivers that caused severe flooding, contributed to the year-over-year increase. The agency said its forecast draws in part on water supply projections from the National Oceanic and Atmospheric Administration's Northwest River Forecast Center.
In California, hydropower generation is projected to fall to 28.5 BkWh in 2026, down 6% from the previous year but still 15% above the 10-year average.
Reservoir levels in the state remained strong as of Apr. 1, with major reservoirs exceeding historical averages. The state's two largest reservoirs, Shasta and Oroville, stood at 114% and 124% of their historical levels, respectively. California also experienced three consecutive weeks without drought conditions.
However, snowpack levels remained well below normal, according to the California Department of Water Resources, with the Northern Sierra Nevada at 7% of average, the Central Sierra at 25%, and the Southern Sierra at 39%.
Warmer-than-normal temperatures in March further accelerated early snowmelt, potentially limiting water availability later in the year.
The EIA said these combined factors are expected to weigh on hydropower generation despite overall improvements from recent lows.