Analysis finds 14 million acre-feet in untapped water supply in California


Pacific Institute and the Natural Resources Defenses Council released an analysis finding an additional 14 million acre-feet in water supply that can be used to fill the gap between water supply and water demands in California.

The issue brief, The Untapped Potential of California’s Water Supply: Efficiency, Reuse, and Stormwater, includes a discussion of the gap between water supplies and water demands in California.  While the gap is difficult to measure or estimate, indicators are present, especially in the crisis in the Delta and in groundwater overdraft.  The Delta serves key environmental, local farming and water export purposes—but with the State Water Resources Control Board finding that diversions exceed a sustainable level by almost 5 million acre-feet—it is stressed to the point where all of its purposes are jeopardized.  With groundwater providing nearly 40% of the state’s water supply in an average year and 60% in a drought, it is a significant source of supply—but pumping chronically exceeds annual recharge in some areas, leading to host of problems, including land subsidence, which damages infrastructure, dry wells, water quality degradation, and stream flow depletion.

After giving the bad news about the gap between water supply and demand, Pacific Institute and NRDC identify solutions “that are cost-effective, technically feasible, more resistant to drought than the current system, and compatible with healthy river and groundwater basins.”  They focus on four strategies—which when combined could provide 10.8 million to 13.7 million acre-feet per year, with agricultural conservation and efficiency contributing 5.6 million to 6.6 million acre-feet, urban conservation and efficiency contributing 2.9 million to 5.2 million acre-feet, expanded water reuse contributing 1.2 million to 1.8 million acre-feet and stormwater capture providing the remaining 0.4 million to 0.6 million acre-feet.

Each of the strategies—which have additional benefits, including effective drought responses, improved water supply reliability, reductions in energy use and greenhouse gas emissions, reduced need to build new infrastructure and elimination of pollution from stormwater and wastewater discharges—are used to some extent already, but the authors argue “much more can be done.”

Robert Wilkinson a professor from the University of California, Santa Barbara and co-author of the report said, “We have an unprecedented opportunity to do more with less – and we need to take every possible step to do so. By rethinking water management strategies so we work in harmony with the environment and our economy, we’ll be rewarded with dramatic water savings that will offer us local and more sustainable supply for decades to come.”

Both Peter Gleick, President of Pacific Institute, and Kate Poole, Senior Attorney of NRDC’s water program, say that we need to retune our thinking to meet the challenges presented by the current water crisis.

“We know that traditional water solutions have failed to solve California’s water problems,” said Gleick. “The good news is that there are broad, cost-effective, environmentally sound options that work and that can help us during the current drought and far into the future.”

“While there’s no silver bullet to solving this water crisis, efficiency, reuse, and stormwater provide a tremendous water-saving blueprint we can realize if we take collaborative action now, backed by government and community leadership,” said Poole. “This is a critical moment for all water users to step up and implement robust solutions that will make a lasting difference.”

Access the Issue Brief, along with an infographic and other supporting materials at: or

Written by Marta Weismann