California’s ability to produce renewable energy from hydroelectric dams has been significantly hampered over the last few years because of an increasingly severe and widespread drought, the U.S. Energy Information Administration said Monday.

The drought, which began in 2011 and is now covering 100 percent of the state, is drying up the reservoirs behind hydroelectric dams. The reservoirs create power when the force of the water in them is released onto turbines. When there is less water, there is also less pressure to spin those turbines, thereby decreasing the amount of renewable electricity that can be produced.

Hydroelectric power used to account for 20 percent of California’s in-state electricity generation for the first six months of each year from 2004 until 2013, the EIA said. But during the first six months of 2014, hydropower generation was halved, making up only 10 percent of California’s in-state electricity generation.

To make up for the shortage of hydropower, California also increased its use of natural gas by 3 percent over the first six months of 2014, according to the EIA.
Partially because of the length of the drought, California’s natural gas use has increased by 16 percent overall in the last 10 years, the EIA said.

The state also boosted its use of other renewable sources of energy — wind power generation, for example, was used more than hydroelectric power for the first time this year in February and March.

California’s drought is currently so critical that “14 communities on the brink of waterlessness,” the LA Times reported this month. Hundreds of people living in rural San Joaquin Valley either have no water or are having “some kind of water issue,” according to the Porterville Recorder, causing emergency services teams to deliver rations of bottled water to the community. The heat waves that have been contributing to the drought have forced school closures across Southern California, and more than 100 schools in San Diego have been forced to shorten individual school days to protect students from high temperatures.

The most recent drought monitor for the state showed 58 percent of the state in “exceptional drought,” the most intense category. Almost the entire state is in severe drought.

The severity of the drought in California has been directly linked to climate change by Stanford University researchers, who found last month that the conditions causing California’s drought are “at least three times as likely to occur in the present climate as in the preindustrial climate.”