As the effects of the drought worsen, two persistent water myths are complicating the search for solutions. One is that environmental regulation is causing California's water scarcity. The other is that conservation alone can bring us into balance. Each myth has different advocates. But both hinder the development of effective policies to manage one of the state's most important natural resources.
Let's consider the first myth, that water shortages for farms are the result of too much water being left in streams for fish and wildlife. Claims are circulating that California's farms have lost 4 million acre-feet annually because of environmental policies, and some have even suggested that the severe, long-term declines in groundwater levels in the San Joaquin Valley are a result of environmental cutbacks.
Since the early 1990s, efforts to improve environmental conditions have indeed reduced water supply reliability, particularly for San Joaquin Valley farmers who rely on exports from the Sacramento-San Joaquin Delta. But blaming these efforts for today's critical supply issues vastly overstates the role of environmental regulations.
By our calculations, restrictions on Delta exports, coupled with new restrictions on flows on the San Joaquin River, have cost San Joaquin Valley farmers no more than 1.5 million acre-feet per year in reduced water deliveries - a sizable amount, but far less than 4 million acre-feet. During the current drought emergency, environmental restrictions have been significantly relaxed to make more water available for farms and cities, with most of the remaining Delta outflows dedicated to keeping water in the Delta fresh enough for local farmers.
And while reduced surface water has likely accelerated groundwater overdraft in the Valley - especially since new Delta pumping restrictions in the late 2000s - the notion that environmental restrictions are the origin of overdraft is unfounded.
According to the U.S. Geological Survey, farmers in the Valley have been mining groundwater at an average annual rate of 1.5 million acre-feet per year since long before Richard Nixon signed the Endangered Species Act in 1972. Nothing seems to change this overall pattern, including construction of the State Water Project. Water demand in the San Joaquin Valley simply exceeds available supply. What's more, the Valley's water demands are likely increasing with the shift to permanent orchards and vineyards - now more than 40 percent of total irrigated farm acreage.
What about the second myth? Can conservation really create abundant "new" water? Of course, new technology and changing water use habits have yielded long-term declines in per capita water consumption in California, and this drought is likely to spur more reductions. New irrigation techniques and better crop varieties, along with rising commodity prices, have helped California's agricultural industry steadily increase production and profits. Farmers have become more economically efficient in using their water.
Some claim that potential dramatic yields of more than 10 million acre-feet of new water - equivalent to 10 full Folsom Reservoirs - can be had from conservation measures that draw half from agricultural and half from urban users. But this is just not credible.
In fact, conservation does not always yield new water, because the water saved is often not wasted in the first place - it is already reused. This is especially true in agriculture.
Irrigation water that is not consumed by crops flows back into rivers or seeps into groundwater basins. Indeed, the single largest source of groundwater recharge in the Central Valley is irrigation. Studies from around the world consistently show that increased irrigation efficiency often does not decrease net water use. Indeed, these technologies often encourage farmers to plant more crops, worsening long-term declines in groundwater availability. The only way to generate reductions in water use on the scale imagined is to fallow several million acres of farmland.
In the urban environment, steady reductions in per capita water use since the early 1990s have allowed total urban use to remain steady at about 8.5 million acre-feet annually, despite the addition of 7 million new residents. Further savings - especially from more drought-tolerant landscapes - will be needed. But because about a third of urban water already gets reused - it also returns to rivers or groundwater basins - it's simply not possible to achieve the level of new water that some have imagined.
The reality is that conservation is a valuable and necessary part of a portfolio of approaches to water supply management, but it will not produce vast quantities of new water for California.
As the late Sen. Daniel Patrick Moynihan said, "Everyone is entitled to his own opinion, but not to his own facts." Californians need to make continued progress in managing our scarce water resources to get through this drought - and future droughts - while protecting the state's economy, society and environment. This requires a common understanding of the causes of water scarcity, and practical, reasoned solutions - not blame games and wishful thinking.
Jay Lund is director of the Center for Watershed Sciences at UC Davis and an adjunct fellow at the Public Policy Institute of California. Jeffrey Mount and Ellen Hanak are senior fellows at PPIC.