According to the Natural Resources Defense Council study, boosting urban and agricultural water efficiency and reusing gray water and storm water could fill Lake Shasta, the state’s largest reservoir, three times over. That’s more water than California’s cities use in a year.
“Doing nothing in the face of our water problems is not an option,” Peter Gleick, president of the Pacific Institute and coauthor of the report, said on a conference call Tuesday morning. “We don’t say that this will be easy or fast. We do say that these are the smartest, fastest, most effective things that people can do.”
Improving agricultural water efficiency, for instance, can make a huge difference, given that agriculture accounts for about 80 percent of the state’s consumption. The report estimates that agricultural water use could be reduced by between 17 and 22 percent.
That could be achieved by switching from flood irrigation to more efficient drip and sprinkler irrigation. Better scheduling—early-morning watering to minimize evaporation, for example—also saves water, according to Bob Wilkinson, a water policy expert at the University of California, Santa Barbara.
The report says cities and businesses can improve water efficiency by between 40 and 60 percent by fixing leaks, investing in water-efficient appliances, and installing climate-appropriate landscaping. Cities like Burbank that use smart meter technologies have already reduced water losses by 2 percent, Wilkinson said.
Cities should tap gray water in a big way. “Approximately two-thirds of the reuse potential is in coastal areas where wastewater is discharged into the ocean or into streams that drain into the ocean,” the report says. “In these areas, expanding water reuse can provide both water-supply and water-quality benefits.”
The report found that capturing storm water from paved surfaces and rooftops in urbanized Southern California and the San Francisco Bay Area could increase average annual water supplies by 137 billion to 205 billion gallons (or more) annually. That would also reduce flooding and water pollution.
How much is all this going to cost? The report did not attempt to put a price tag on its recommendations. “But we do have past experience that shows it will be cost effective,” said Kate Poole, the report’s coauthor and a senior water attorney at NRDC. “Over the last decade, the state has invested $1.4 billion, and those projects have yielded about 2 million acre-feet [652 billion gallons] of water supply. So that’s a lot of bang for the buck.”