Hydropower generation drops in Montana, Pacific NW due to drought

Hydropower generation in the northwest, including Montana, dropped 24% in the first half of 2023 compared to the same period last year mainly because of a snowpack that melted quickly and drought conditions, the U.S. Energy Information Administration said in a recent report.

Since the region generates about half of the nation’s hydropower, the stark drop in production could have been worse for the country had it not been for California’s historic snowpack, which helped generate 94% more power in the first half of this year than the first half of 2022, according to the EIA.

The EIA last week dropped its forecast of U.S. hydropower generation by 6%, citing the drought in the Rocky Mountains and Pacific Northwest and a forecast El Niño expected to strengthen this winter. The forecast estimates 2023 will see the lowest amount of hydropower generated nationwide since at least 2015.

“Parts of the Northwest, particularly around the Columbia River Basin, have had increasingly severe drought conditions since June 2023,” EIA author Lindsay Aramayo wrote in the report. “These conditions will limit water supply, which could limit hydropower generation in the future.”

Year-to-date data on hydroelectric power generation shows an 11% drop in the amount of power generated nationwide from January through July of this year compared to the same period last year.

But the Mountain region (-18.4%) and Pacific region (-11.6%) both saw drops in power generation.

Montana (-26.1%), Idaho (-24.5%), Oregon (-26.1%) and Washington (-26.9%) all saw significant drops during the first seven months of this year compared to the same period in 2022. Those states are the same that have seen severe and extreme drought expand throughout the calendar year.

Most of Montana’s utility-scale hydroelectric plants are in the Columbia River Basin west of the Continental Divide, and five of the state’s 10 largest power plants are hydroelectric.

NorthWestern Energy, Montana’s largest utility, says about one-third of the electricity used by customers comes from hydroelectric power from its 11 hydroelectric facilities across the state. The EIA says hydropower accounted for 38% of Montana’s in-state net generation last year, and that about 70% of the electricity Montanans use is generated in-state. The rest is sent primarily to Washington and Oregon through the Western Interconnection grid, though some is sent east.

Three of the largest hydropower plants in the state – the Hungry Horse Dam, Libby Dam, and Seli’š Ksanka Qlispe’ Dam – are in the river basin and generated approximately 37% of the hydroelectric power that comes out of Montana, according to a 2020 Department of Natural Resources and Conservation report.

All three are located in northwest Montana, which has seen drought expand throughout the spring and summer. According to this week’s U.S. Drought Monitor update, all of northwestern Montana is now experiencing severe drought conditions, and most of Flathead County and parts of Lincoln and Sanders counties are seeing extreme drought at this week’s start of the water year.

The drought has shifted since this time last year, when north-central and northeastern Montana were seeing the worst drought in the state. Currently, only the upper third of Montana is experiencing drought, mostly along and north of the Hi-Line, while the rest of the state is drought free.

The Kalispell area has seen more rain in recent weeks than it did for most of the summer, but is still more than 3.5 inches below normal precipitation levels for the year, according to National Weather Service data. The weather site at Libby Dam shows it is about 2.5 inches below its normal precipitation levels for the year.

Flathead Lake levels peaked around 2,892 feet in mid-June and dropped about 2 feet into late July, prompting Montana’s governor and other officials to press the federal government, which manages the Hungry Horse Dam upstream of Flathead, to try and find a way to prop up water levels at one of the state’s main summer destinations.

The Columbia River Basin Technical Management Team declined to do so over worries about Hungry Horse Reservoir being able to refill this winter and impacts to protected bull trout.

U.S. Geological Survey data show Hungry Horse reached its peak levels this summer around 3,554 feet in early July – about 4 feet less than the peak the year before.

The year-to-date data from the EIA shows Montana generated around 430,000 megawatt hours more in the second quarter of 2022 than in the second quarter of this year, and 919,000 megawatts hours more in the first quarter of 2022 compared to the first quarter of this year. The 2.24 million megawatt hours generated in the second quarter this year is the fewest Montana has generated since 2001, according to EIA data.

California (90.85) and Arizona (6.6%) were the only western states that generated more hydroelectric power in the first seven months of this year than in the first seven months of 2022.

The EIA has now downgraded its conventional hydroelectric forecasts nationwide through the end of the year, though it projects that those power resources could rebound next year despite the El Niño, which often leads to warmer and drier winters in Montana and the Pacific Northwest.

“Water supply for the new water year, which starts on October 1, will be influenced by the El Niño conditions, which are likely to affect hydropower generation for the remainder of 2023,” Aramayo wrote in her Sept. 28 report.

The latest season drought outlook through December released Sept. 30 by the Climate Prediction Center shows drought is expected to persist in northern Montana through the end of the year.

A Sept. 14 El Niño forecast update showed a 71% chance of a “strong” El Niño that is expected to persist into March. A three-month outlook from the Climate Prediction Center shows temperatures in western Montana are expected to be slightly above-normal through the end of the year, with slightly below-average precipitation.