U.S. hydropower drops to 20-year low as Northwest snowpack shrinks

American rivers produced less hydropower in 2023 than at any time in the past 20 years, according to data from the U.S. Energy Information Administration.

Drought and low snowpack in much of the West made it a bad year for the climate-friendly energy source, especially in Washington state, the nation’s leading producer of power from flowing water.

Washington hydropower fell 23% in “water year 2023”— the 12-month period from October 2022 to September 2023. In Oregon, the next-biggest hydro producer, it fell 22%.

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The two Northwest states saw their dams’ power output fall 10% below the previous 20-year low, set two years earlier.

Hydrologists track runoff and hydropower by “water years” instead of calendar years because autumn and early-winter snowfall typically doesn’t melt and fill streams, rivers, and dam turbines until the following spring and summer.

“The snowpack acts as a reservoir, so it stores our precipitation, so that when it melts, in our drier months, we have that water available,” said interim Washington State Climatologist Karin Bumbaco. “It's a really critical resource in our climate that has a very distinct wet season and dry season.”

Bumbaco said as the global climate has warmed, higher elevations in the Northwest have been getting more rain and less snow, with the average winter snowpack shrinking about 5% to 10% per decade since the mid-20th century.

“Hydropower supplies more than half of the electricity in Washington and Oregon,” said energy economist Lindsay Aramayo with the Energy Information Administration. When hydropower production drops, “we do see other energy sources helping meet that demand,” she said.

According to Energy Information Administration data, power plants in Washington and Oregon burned 20% more natural gas and 17% more coal in calendar year 2023 than in 2022, while wind and solar power rose just 3%, and output from the Northwest’s sole nuclear power plant fell 14%.

The increased natural gas and coal combustion generated more heat-trapping pollution, contributing to the climate change that threatens the region’s snowpack and hydropower.

River flows and hydropower that vary from year to year are “completely normal,” according to Ryan Egerdahl, a planner with the Bonneville Power Administration, a federal agency that markets hydropower throughout the Pacific Northwest. “It can be all over the map.”

“Despite these fluctuations, hydro is there when it's needed,” National Hydropower Association spokesperson Copeland Tucker said in an email.

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Hydropower industry officials say other factors besides precipitation patterns can reduce energy output, including the need to manage rivers for flood control, irrigation, and salmon migration, not just electricity.

The vast geography of the Columbia River basin, covering parts of seven states and one Canadian province, helps dampen the fluctuations of downstream dams’ output, industry officials say.

“We watch that snowpack in Canada, Western Montana closely, and just because the weather's wet in Portland doesn't mean we're going to have a very high water year and vice versa,” Bonneville Power Administration meteorologist Erik Pytlak said. “But if it's snowing in Canada, then our concern drops.”

Still, 2023’s hydropower production was the lowest of any year since 2001 in the Northwest and nationwide.

An unusual heat wave in May 2023 ate into the already-meager Northwest snowpack, sending an exceptionally large pulse of water, more than could be stored or passed through many dams’ turbines, flowing toward the Pacific.

“It's essentially fuel lost,” Aramayo said.

(In the jargon of hydropower, water is fuel.)

With the current water year less than half over, snowpack is in better shape in most of the West than a year ago, though another low-snow and low-water year is expected in the Northwest.

“It pains us greatly to say this, but El Niño has now washed the 36th Legendary Banked Slalom into 2025,” said Mt. Baker Ski Area CEO Gwyn Howat said in a Jan. 31 video announcing the cancellation of the annual snowboard and ski race.

On that day, Washington state’s snowpack was just 63% of normal.

Big winter storms in late February fluffed the mountain snowpack a bit closer to normal. At Mt. Baker Ski Area, snow doubled in depth, from under 5 feet to nearly 10 feet, in the last two weeks of February.

On Tuesday, following a week of heavy storms that dumped 5 feet of snow in parts of the Cascades and left many skiers giddy, Washington state’s snowpack was still just 73% of normal.

“This season has gone from ho-hum to the March Miracle In The Mountains,” the Summit at Snoqualmie’s snow report claimed on Monday.

Washington state statute defines anything below 75% of normal snow or water supplies as drought conditions.

According to the U.S. Department of Agriculture’s Natural Resources Conservation Service, Washington’s snowpack was in the 2nd-worst shape of any western state, with only Montana doing worse at 72% of normal.

Oregon’s snow supply was 105% of normal (in other words, 5% above normal), while Idaho was a mixed bag: 74% of normal in northern Idaho and 99% in southern Idaho.

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Bumbaco said precipitation has been a bit lower than normal this winter, but the main factor has been warmer temperatures tilting the mountains’ balance toward rain and away from snow.

“On average this winter, we've been about one to three degrees Fahrenheit above normal for most of Washington State,” she said.

While Washington’s snow and water outlook may be poor at the moment, winter isn’t over yet, especially in the mountains.

“March and April are still big snowpack building months, particularly in the upper part of the Columbia Basin,” Pytlak said. “So those deficits can get wiped out and [we] end up with a much more normal working water supply situation if March and April are wet.”

A spokesperson for Puget Sound Energy, Washington’s largest utility, declined to be interviewed for this story.