We spend so much electricity shipping it around the state and drawing it up from the ground that using less will save power.
From WorldChanging at The Guardian:
The virtues of water efficiency can be found in California and China - regions where water shortages have become emergencies and droughts may worsen with climate change. Conditions may become more severe in the future as consumers turn to water solutions that often require even greater energy supplies.
In California, where drought is afflicting the land for the third year in a row, the state is reducing water deliveries by 20-30 percent this winter and warns of "the most significant water crisis in its history." The water shortages are forcing farmers to cut production and lay off employees in an already sour economy.
Meanwhile, water transportation, storage, and treatment account for about 19 percent of the state's electricity, according to a 2007 California Energy Commission report [PDF]. To reach the rapidly expanding urban clusters in southern California, for instance, water is pumped 2,000 feet (610 meters) over the Tehachapi Mountains north of Los Angeles.
Mind you, hydroelectric dams create electricity -- but that won't be reduced as we use less. And as the Sierra snowpack melts away with climate change, we will likely lose most of that reservoir, the snow itself, and have to find more ways to store water in our (ostensibly) wet winters to have enough to last us through our dry, dry summers. We'll either have to build a lot more dams, or find other ways to get (and save) water, and to generate power.
California's population is burgeoning, as well. We will, as a whole, want more water, not less, in future years -- and more power. By cutting back now -- growing dry-climate and native gardens, using landscaping water to grow our own climate-adapted food rather than lawns and privet hedges, moving California's crops into areas better suited for them, controlling water use in new developments, and other water conservation measures -- we can use less of the inevitable additional water, rather than more.
(Photo from Aquifornia)