A California drought will increase the carbon footprint of electricity used to charge EVs, according to a new report from the Energy Information Administration (EIA).

The drought has cut the state's hydropower generating capacity nearly in half compared to normal conditions, forcing California to rely on more carbon-intensive sources for a greater amount of its grid mix, according to the EIA.

Hydropower typically produces 15% of California's electricity with normal levels of precipitation, but that shrinks to an estimated 8% in a drought year, according to the report, which analyzed six California hydropower facilities representing 22% of the state's hydropower capacity.

Electrify America charging site

Electrify America charging site

Hydropower is typically the third-largest source of electricity in California, the EIA noted. But its availability is heavily dependent on snowpack that forms in winter. That snowpack was 40% below normal levels as of April 1, according to the EIA.

The agency expects the decrease in hydropower generation to lead to an 8% increase in California's electricity generation from natural gas, a 6% increase in energy-related carbon dioxide emissions in the state, and an average 5% increase in wholesale electricity prices throughout the West.

Any shift away from green energy could increase the carbon footprint of EVs, which are only as clean as the grid they're plugged into. However, this momentary lapse shouldn't overshadow the fact that, over a decade, the national power grid has become much cleaner. And as a 2019 study pointed out, the Midwest stands to gain more in the transition to clean power than California.

San Diego Gas & Electric substation

San Diego Gas & Electric substation

The state has already made great progress in cleaning up its grid. California in April reached a brief time in which the state's grid was powered entirely—or nearly so—by renewable energy.

The California grid could still use some improvements to ensure EVs can be charged cleanly and reliably, though. Last year's heat waves prompted alerts about EV charging habits.

Top utilities from the state have also said that the grid will need massive upgrades to be fit for shifting entirely away from the sale of gasoline vehicles by 2035.