In 2002, NASA launched a satellite named GRACE into Earth's orbit. It's purpose? To monitor the availability of freshwater. What GRACE has shown us over the years is eye-opening: from October 2003 to March 2010, the Sacramento and San Joaquin River Basins collectively lost approximately thirty cubic kilometers of freshwater, which is about the full volume of Lake Mead, the freshwater lake that supplies Las Vegas. This happened because farmers were forced to start pumping groundwater than they had in previous years because of the drought. But now, the situation is worse. From 2012 to 2013, the Sacramento and San Joaquin River Basins collectively lost twenty cubic kilometers of freshwater. If we keep doing what we're doing, it's only going to get worse from here on.
What can we do about it?
In California, Governor Edmund Brown declared a drought state of emergency, drastically reducing the freshwater available to California's residents and putting a considerable 750,000 of crops at risk. Making cuts like this is difficult, yet necessary.
Work Cited: http://voices.nationalgeographic.com/2014/02/04/epic-california-drought-and-groundwater-where-do-we-go-from-here/