Hydroelectric generation is forecast to fall by 14 percent in 2021, the result of persistent drought, the Energy Information Administration said Sept. 23.
The picture for reservoir storage in the Columbia River basin is mixed, the agency said. Figures from the Agriculture Department's National Water and Climate Center show reservoir storage in Washington and Montana is at or above average, but storage at the end of August in Oregon was measured at 17 percent of capacity, well below the historical average of 47 percent. In Idaho, storage was reported at 34 percent, below the historical average of 51 percent.
Hydropower in Washington, Oregon, Idaho and Montana produced 136,000 GWh in 2020, 54 percent of U.S. hydropower generation for that year.
In California, Lake Oroville's storage hit a historic low of 35 percent in August, the EIA said.