Hydropower output plummets in parched U.S. West with no quick end in sight

Energize Weekly, September 29, 2021

The heat wave that blanketed the western United States this summer drained the region’s hydropower output, a situation that will likely continue in 2022 and may even get worse, according to reports from multiple federal government agencies.

Among the findings in those studies are that:

• U.S. hydropower plant electricity generation will be 14 percent lower in 2021 than it was in 2020, according to the U.S. Energy Information Administration (EIA)
• Falling water levels at Lake Powell, which straddles Arizona and Utah and is the second-largest man-made reservoir in the country, could make electricity generation impossible as soon as next year, the U.S. Bureau of Reclamation forecasts
• The 20 months between January 2020 and August 2021 were the driest on record for the Southwest, and the drought will extend into at least next year, according to the National Oceanic and Atmospheric Administration (NOAA)

“Extreme and exceptional drought conditions have been affecting much of the western United States, especially California and states in the Pacific Northwest, which are home to the majority of U.S. hydropower capacity,” the EIA said.

The agency’s latest short-term energy outlook forecasts hydropower generation in the Northwest electricity region, which includes the Columbia River Basin and parts of other Rocky Mountain states, to total 120 billion kilowatt-hours (kWh) for 2021, a 12 percent decline from 2020.

For the California electricity region, the EIA expects the shortfall to be a whopping 49 percent lower in 2021 than in 2020, at 8.5 billion kWh.

California provided about 7 percent of all the hydropower in the U.S. in 2020, but this year the Lake Oroville Reservoir dropped to a historic low of 35 percent of capacity forcing the Edward Hyatt Powerplant to go offline for the first time since 1967.

The hydropower plants in the Columbia River Basin, in the Pacific Northwest, which covers parts of Washington, Oregon, Idaho and Montana, generated 136 billion kWh in 2020, 54 percent of all the hydropower generation for the year.

In 2021, the combination of a heat wave and dry conditions hit the Columbia River Basin and led to drought emergencies in counties in Washington, Oregon and Idaho. At the end of August, reservoir storage in Oregon measured 17 percent of capacity, and storage was at 34 percent of capacity in Idaho.

Reservoir storage is at or above average levels in Washington and Montana, according to the U.S. Department of Agriculture’s National Water and Climate Center.

The same can not be said for the nation’s two largest man-made reservoirs Lake Mead and Lake Powell.

In late July, Lake Powell had fallen to a record 3,554 feet in elevation – just 33 percent of capacity – according to the Bureau of Reclamation.

Five-year forecasts released in September by the bureau indicate that there is a slight chance that water levels at Lake Powell could fall low enough next year to make hydrogeneration impossible, that risk rises to 34 percent in 2023.

“The latest outlook for Lake Powell is troubling,” said Reclamation’s Upper Colorado Basin Regional Director Wayne Pullan in a statement. “This highlights the importance of continuing to work collaboratively with the Basin States, Tribes and other partners toward solutions.”

In August, Lake Mead was at 35 percent capacity, also a record low, and federal managers trimmed the lake’s Hoover Dam hydroelectric output by 23 percent.

By 2025, the projections show a 66 percent chance that Lake Mead could drop below the critical threshold of 1,025 feet above sea level.

Reservoir waters at that level would not only impair hydropower, but trigger deep cuts in water allocations to California, Arizona, Nevada and New Mexico under the Colorado River Compact, which regulates the use of the Colorado River among seven states and Mexico.

Driving the dire conditions across a six-state, Southwest region have been the lowest precipitation and third-highest daily average temperatures – for the January 2020 to August 2021 period – since instrumental climate records began being kept in 1895, according to a NOAA report.

The NOAA study looked at Arizona, California, Colorado, Nevada, New Mexico and Utah. “This exceptional drought punctuates a two-decade period of persistently warm and dry conditions throughout the region,” the report said.

The successive years of below-average precipitation appear to have come from “natural but unfavorable” variations in the atmosphere and ocean and the winter of 2021-2022 is already forecast to be drier than average.

“Taken together, even if higher annual precipitation totals occur in coming years, it will take several seasons (and potentially years) of above-average precipitation to replenish the reservoirs, rivers, streams, and soil moisture that 60+ million people depend on for their water, livelihoods, food, power, and recreation,” the NOAA study said. “This, when coupled with the La Niña forecast for the coming winter, suggests the ongoing Southwestern U.S. drought will very likely last well into 2022, and potentially beyond.”