California utilities are being forced to use natural gas plants to create electricity as drought cuts down on hydropower generation. Lakes and dams where hydropower is used are sometimes less than 50% full. Without ample water, the energy can’t be created.
Increasingly, utilities are using natural gas power plants as fallbacks. However natural gas creates more emissions than hydro and is also more expensive. California has an ambitious plan to generate 33% renewable in-state energy by 2020. A continued dry spell will certainly impact those plans, even if California doesn’t count big hydro as renewable energy. (This odd distinction is probably due to political considerations. If big hydro isn’t renewable, then big solar and big wind projects must be built, and will have captive buyers. How cozy is that for big money?)
In 2011 hydropower account for 18.2% of California energy. In 2012 it plunged to 11,7% 2013 numbers haven’t been released yet but are probably even worse.