Electricity generation from hydroelectric power plants in the U.S. will grow by 4% in 2020 from 2019 levels, to 280 billion kWh, despite current drought conditions and extensive wildfires in parts of the country, according to the U.S. Energy Information Administration’s latest Short-Term Energy Outlook (STEO).
States in the Pacific Northwest, home to the Columbia River Basin, are the largest hydroelectric power producers in the U.S. Idaho, Montana, Oregon and Washington generated 47% of all U.S. hydroelectric power in the first half of 2020. As such, drought conditions in these states can have noticeable impacts on overall U.S. hydroelectric generation, especially if the drought is severe or long-lasting.
Many factors affect how much water is available to generate hydroelectric power, including precipitation levels in current and previous years. Seasonal precipitation for the 2020 water year (October 2019 to September 2020) has been mixed in the Columbia River Basin. Most of the stations in the eastern half of the basin have reported 70% to 130% of normal precipitation, and some stations in the western half have reported less than 50% of normal precipitation.
As of September 2020, 14 counties in Oregon and four counties in Idaho have issued drought emergency declarations. This year’s droughts, however, aren’t expected to have noticeable impacts on hydroelectric power production because reservoirs in the region have stored water from near-normal to above-normal precipitation in recent years.
According to data from the U.S. Department of Agriculture’s National Water and Climate Center, which produces a database on water supply conditions (including reservoir storage), reservoirs in most of the states in the Pacific Northwest have been able to retain precipitation from recent years. As of the end of August 2020, reported reservoir storage levels were at or higher than the 30-year (1981 to 2010) normal in Washington, Idaho, and Montana. In Oregon, reported reservoir storage was at 37% of maximum capacity, lower than the historical average of 45%.
So far this year, monthly hydropower generation in these states has been within the 10-year (2010 to 2019) historical range, with the exception of April’s hydropower generation in Oregon, which was 10% lower than the 2010 to 2019 monthly range. If the 2021 water year has near-normal precipitation levels, impacts from this drought could be minimal.