California’s hottest and driest drought in recorded history, from 2012 to 2016, shifted the sources of energy for electricity with adverse economic and environmental consequences. This report focuses on the period of drought from 2011 to 2014.

Under normal conditions, electricity for the state’s millions of users is produced from a blend of many sources, with natural gas and hydropower being the top two. Since the drought reduced the state’s river flows that power hundreds of hydropower stations, natural gas served as the replacement. This was an expensive change, leading to increases in electricity costs and carbon dioxide emissions.