New Report Calls Attention to Untapped Water Savings Within California
State could save up to 13.8 million acre-feet of water a year through water-saving and recycling strategies
By now, most Californians know that we are in a serious drought. We’ve seen the headlines, heard the calls for voluntary (and sometimes mandatory) reductions in water use, and have started to think twice about leaving the water running while brushing our teeth, or taking those long, relaxing showers.
Photo by Robert Couse-Baker
What has been less clear, however, is how California is planning for a drought-resistant future, or whether Sacramento-based policymakers will take advantage of the current heightened water awareness to initiate broad changes in how we think about water in the Golden State. A new report, released yesterday by the Natural Resources Defense Council (NRDC) and the Pacific Institute, aims to motivate statewide action by calling attention to water-saving methods that lie within arms reach.
By adopting agricultural and urban water saving strategies, as well as increasing stormwater capture and water recycling efforts, California could save anything from 10.8 to 13.8 million acre-feet of water per year, inspiring the report’s title: “The Untapped Potential of California’s Water Supply.”
“To give you a sense of how much 11 to 14 million acre-feet is, all of the cities in California combined use less than 10 million acre-feet of water annually today,” explains Kate Poole, a senior water attorney at NRDC and co-author of the report. “Fourteen million acre-feet is also enough water to fill Lake Shasta, which is California’s largest reservoir, more than three times over.”
The agricultural industry is by far the biggest water user in California, using roughly 80 percent of California’s developed water supply, so it makes sense that the greatest water savings elaborated in the report stem from improved efficiencies on California farms. In particular, big savings can be gained by transitioning flood irrigated fields to drip and sprinkler systems; expanding use of irrigation scheduling, which uses local weather and soil information to inform watering; and initiating regulated deficit irrigation, in which certain crops — like wine grapes, almonds, and pistachios — receive less water during drought-tolerant growth stages.
“We find that there is still significant untapped agricultural water use efficiency potential, [even] while maintaining current irrigated acreage and current crop mixes,” says Bob Wilkinson, adjunct associate professor at University of California, Santa Barbara. “Agricultural water use efficiency can be improved by between 5.6 million and 6.6 million acre-feet per year. That is a 17 to 22 percent improvement.” These potential improvements in the agricultural sector account for roughly half of the total savings outlined in the report.
Urban users account for the other 20 percent of California’s developed water use. The report’s authors estimate that combined savings from all urban uses — indoor, outdoor, residential, and commercial — could total anywhere between 2.9 and 5.2 million acre-feet per year. Savings potential varies by region depending on current water use. Currently, the San Francisco Bay Area has one of the lowest per capita water use rates in the state at 170 gallons per capita per day, while some dry inland areas in Southern California have average use rates above 300 gallons per capita per day. Regardless of region, urban savings can be made through a variety of changes, including increased use of water efficient technologies and fixtures and conversion to water-efficient yards and landscaping.
In addition to these demand-side strategies, the report also outlines two supply-side measures that could increase water resources within the state: greater water reuse, also known as water recycling, and improved stormwater capture. Although California already reclaims roughly 670,000 acre-feet of water per year, the report estimates that an additional 1.2 million to 1.8 million acre-feet could be reclaimed each year, primarily by expanding water reuse in coastal areas where wastewater is discharged into the ocean. And as far as stormwater capture goes, increased groundwater infiltration and rainwater capture could increase water supplies in the San Francisco Bay Area and urbanized Southern California by 420,000 to 630,000 acre-feet per year.
The report does not go so far as to estimate the costs of these various supply and demand strategies, or to suggest specific policy strategies for implementing statewide changes, leaving room to wonder exactly where the money to implement changes would come from. “We do not say that capturing all of these demand reductions or supply expansions will be easy or fast,” says Peter Gleik, president of Pacific Institute, and co-author of the report. “Some of them could be. We do say that these are the smartest, fastest, most effective things the state and local agencies can do.”
What policy-makers will do with the report remains to be seen. What is clear, however, is that something has to be done, and fast. “We’ve hit the wall in California. We are past the point of peak water, where we have exceeded the limits on the water that is available from our rivers and from our groundwater,” adds Gleik. “And we know we are in a severe drought now, but even in a normal year or a wet year we are overextended. We take too much water out of the system. And pretty much everyone knows this.”