The water to do that comes from the Sierra Nevada mountains, the eastern boundary of the Valley. Normally, the Sierras collect snow during the winter and release the moisture over the course of the spring and summer as it melts. Lower down, it's collected in lakes and ponds that are controlled with dams; local farmers sit on boards that decide when to release water for their crops and how much. It's not exactly a precise system, but it is one that works within narrow boundaries.
For more than a year now, the state of California has been experiencing an historic drought. Since Gov. Jerry Brown (D) took office in January 2011, the number of Californians living in regions affected by drought has gone from 0 to 100 percent; the number living in an area with the highest level of drought measured by the National Drought Mitigation Center has topped 25 million.
On Wednesday, Brown announced unprecedented, mandatory water restrictions for the state. "Today we are standing on dry grass where there should be five feet of snow,” Brown said when making the announcement from a mountain near Lake Tahoe. Measurements taken earlier this week found that the snowpack statewide was at about 5 percent of normal levels. That snow accounts for 30 percent of the state's water supply, according to the Los Angeles Times. Less snow means less snowmelt. Less snowmelt means less water.
The measures aim to reduce water consumption by 25 percent, in part by enforcing conservation pricing. There are other measures, too, like increasing drought-tolerant landscaping and asking big water users -- like golf courses and cemeteries -- to cut back. Agricultural users will have to report use to regulators. "We are not seeing the level of stepping up and ringing the alarm bells that the situation warrants," State Water Resources Control Board chairwoman Felicia Marcus said to the Times.
The bleakest part of the current scenario is that it might be glimpse of California's new normal. The current drought has been linked to unusual wind patterns in the Pacific, but projections of the long-term effects of climate change suggest that more, deeper droughts will become the norm in California and throughout the Southwest in the future. When he was sworn in for his (second) second term in January, Brown focused on climate change, pledging to cut gasoline usage and increase the amount of electricity the state gets from renewable sources. (Last month it was reported that the state got 5 percent of its power from solar.)
Wednesday's announcement was another escalation in California's attempt to maintain life as close to normal as possible. The success of the effort won't be seen until a few months from now, when the snow in the mountains is almost all gone, Los Angeles is trying to figure out how much water it can access, and the walnut trees need to be flooded again.