Last year marked a significant downturn in hydropower generation across the Western United States, reaching its lowest levels in over two decades. Preliminary data from the Energy Information Administration’s Electricity Data Browser revealed an 11 percent decline in hydropower output during the 2022–2023 water year compared to the previous year, hitting its nadir since 2001.
This decline notably impacted states stretching from the Dakotas to Texas, where 60 percent of the nation’s hydropower originates. These regions, including California, Nevada, Arizona, and New Mexico, are increasingly grappling with the effects of climate change, exacerbating water scarcity. Interestingly, typically hydropower-rich states in the Northeast were unexpectedly affected the most, attributed to extreme heat and drought conditions.
The interplay of drought and high temperatures resulted in a troubling trend: diminished hydroelectric energy output from dams. Consequently, utilities leaned more heavily on fossil fuels to compensate, escalating greenhouse gas emissions, and exacerbating climate change-induced droughts.
The Western US also faced abnormal heat during the last water year, marked by a significant heatwave in May 2023 that saw temperatures soaring 30 degrees Fahrenheit above average in the Pacific Northwest. This heatwave precipitated the rapid melting of snowpack, a critical water source during dry summer months, leading to below-average water supplies for the remainder of the year. Hydropower generation in Washington and Oregon plummeted by at least 20 percent, despite normally accounting for 37 percent of the nation’s hydropower capacity.
In contrast, California experienced relief from a prolonged megadrought that has gripped the Southwest for around two decades. Although a series of intense atmospheric river storms in 2023 replenished snow and rain in parts of the state, it also triggered destructive floods in typically arid regions. While hydropower production briefly rose in California last year, projections indicate a decline in the coming year.
Looking ahead, the Energy Information Administration anticipates a 12 percent reduction in hydropower production across the Western US in 2024 compared to the previous year. This shortfall typically translates to increased reliance on gas and coal-fired power plants, amplifying pollution levels.
Globally, 2023 witnessed a surge in energy-related greenhouse gas emissions, with an increase of 410 million metric tons, equivalent to the output of over 1,000 new gas-fired power plants. Drought-induced hydropower shortages, particularly in the US and China, contributed significantly to this rise, accounting for 40 percent of the global emissions increase, according to the International Energy Agency.
