Western drought hurts hydropower production, California among the hardest hit states
Energize Weekly, July 14, 2021
The drought conditions smothering the West are crippling hydropower production with hydro-generation’s share of energy production forecast to be 6.5 percent this year – the lowest it has been since 2015, according to the U.S. Energy Information Administration (EIA).
In 2022, western hydropower’s share of total generation is expected to rise to 6.8 percent, but that it still below 2020’s 7.5 percent share.
California is among the hardest hit states, with 100 percent of the state in some drought condition and a third of the state in “exceptional drought,” the worst category.
In the first three months of 2021 hydroelectric generation in California was down 37 percent compared to the first three months of 2020 and 71 percent less the same period in 2019.
Driving the drought are below normal rain and snow, leading to less snowpack, along with drier soils and higher-than-normal temperatures.
“These factors lower the water supply available in the summer months.” EIA said. “Mountain snowpack serves as a natural reservoir, providing water throughout the spring and summer as it melts. However, the California snowpack was well below normal this year, and most of it melted quickly because of higher spring temperatures. Measurable snow was present at only 3 of 131 monitoring stations on June 1.”
Snow melt didn’t even reach reservoirs as it was absorbed by dry soils and streams.
The drought conditions are impacting water levels in California reservoirs and the output from hydropower plants. The state’s two largest reservoirs – Lake Shasta and Lake Oroville – are nearing historic lows. Lake Shasta only reaching 48 percent of capacity and Lake Oroville being only 40 percent full.
Lake Shasta is forecast to drop to 37 percent of capacity this summer and Lake Oroville to reach 31 percent of capacity.
As Lake Orrville’s water levels fall, it will likely force the Edward Hyatt power plant to close for the first time since it opened in 1967, EIA said.
California also saw hydropower output drop during the last drought, between 2012 to 2016, which included the state’s first-ever mandatory water restrictions in 2015. As water resource conditions improved after 2016, hydropower rebounded.
EIA’s Short-Term Energy Outlook is forecasting that overall hydroelectric generation will be 19 percent less this year than in 2020, decreasing to 13.6 megawatt-hours (MWh) from 16.8 MWh in 2020.
There are big problems in reservoirs across the West that could jeopardize hydroelectric output. The nation’s biggest reservoir Lake Mead, near Las Vegas, is at is lowest level since the Hoover Dam was built in the 1930s, creating the lake.
Lake Mead is at 35 percent of its total capacity and federal managers have trimmed the Hoover Dam hydroelectric output by 23 percent.
On average the dam has provides about four billion kilowatt-hours of electricity each year for use in Nevada, Arizona and California.
Lake Powell, which is upstream and feeds Lake Mead, is at 43 percent of capacity and is projected to reach its lowest level since it was created in 1964 as flows into the lake will be at near-record low levels.
“‘Unregulated inflows’ into Lake Powell show that 2021 will be the 2nd worst year after only 2002 going back to 1964,” Brad Udall, senior water and climate research scientist at Colorado State University, said on twitter. “This is a really grim year for runoff.”
Hydroelectric production from the Glen Canyon Dam, built to create Lake Powell, could also be impaired. The Glen Canyon powerplant generates an average of five billion kilowatt-hours a year distributed by the Western Area Power Administration to utilities in Wyoming, Colorado, Utah, New Mexico, Arizona, Nevada and Nebraska.
