Ongoing drought conditions in California have caused its hydroelectric power production to plummet to 10% of the state's total generation, according to data released by the U.S. Energy Information Administration.
EIA said that on average, hydropower accounted for about 20% of California's in-state generation through the first six months of each year from 2004 through 2013, but has fallen given the state's drought that began in 2011.
U.S Department of Agriculture data shows 58% of the state is classified as experiencing "exceptional drought", which is the agency's most severe drought category.
The shortage of hydropower has caused California to rely more heavily on natural gas-fired capacity, with natural gas production 16% higher from January to June this year compared to the average from the past decade.
Other renewables are also filling the gap left by hydro, with wind and solar generation growing. EIA said California's wind generation surpassed its hydro generation in both February and March for the first time.
Drought remains a significant issue through much of the American Southwest, with the U.S. Bureau of Reclamation reporting that Nevada's Lake Mead had dipped to its lowest levels since the Hoover Dam was completed in the 1930s.
HydroWorld.com also reported in September that wildfires had forced the temporary closure of several California hydroelectric projects.