A few years ago a group of researchers used computer modeling to put California through a nightmare scenario: Seven decades of unrelenting mega-drought similar to those that dried out the state in past millennia.
"The results were surprising," said Jay Lund, one of the academics who conducted the study.
The California economy would not collapse. The state would not shrivel into a giant, abandoned dust bowl. Agriculture would shrink but by no means disappear.
Traumatic changes would occur as developed parts of the state shed an unsustainable gloss of green and dropped what many experts consider the profligate water ways of the 20th century. But overall, "California has a remarkable ability to weather extreme and prolonged droughts from an economic perspective," said Lund, director of the Center for Watershed Sciences at the University of California, Davis.
The state's system of capturing and moving water around is one of the most expansive and sophisticated in the world. But it is based on a falsehood.
"We built it on the assumption that the last 150 years is normal. Ha! Not normal at all," cautioned paleoclimate expert Scott Stine, a professor emeritus of geography and environmental science at California State University, East Bay.
"The weather record that we tend to depend on in California for allocating water ... is based on about 150 years of really quite wet conditions when you look back at, say, the last 8,000 years or so," Stine said.
He found evidence of two extreme droughts in ancient tree stumps rooted in the state's modern lake beds. The trees could have grown only when shorelines beat a long retreat during medieval mega-droughts lasting a century or more.
Curious about how the nation's most populous state would fare under such chronically parched conditions, Stine, Lund and other researchers imposed a virtual, 72-year drought on modern California. In their computer simulation, annual runoff into rivers and reservoirs amounted to only about half the historical average. Most reservoirs never filled.
Under that scenario, experts say, irrigated farm acreage would plunge. Aquatic ecosystems would suffer, with some struggling salmon runs fading out of existence.
Urban water rates would climb. The iconic suburban lawn would all but disappear. Coastal Californians would stop dumping most of their treated sewage and urban runoff from rain storms into the Pacific and instead add it to their water supply.
"Cities largely did OK aside from higher water costs, since they have the most financial ability to pay for water," Lund said, referring to the study findings.
"They did more water conservation and wastewater reuse, a little ocean desalination, and purchased some water from farms," he added. "So the predominant part of the population and economy felt the drought, but was not devastated by it."
Mega-drought "doesn't mean no water," said Peter Gleick, president of the Pacific Institute, an Oakland think tank. "It will mean using what we get more effectively."
In Southern California, withering decades would speed up the region's move to expand local water sources and reduce dependence on increasingly erratic supplies from Northern California, the Eastern Sierra and the Colorado River.
"This is a situation that we're likely to be dealing with for a long period of time, whether it's 25 years in a mega-drought or repeatedly any number of years over the next 25 years," said Nancy Sutley, chief sustainability and economic development officer for the Los Angeles Department of Water and Power. "We have to look at all the sources of water that are potentially available to us."
The DWP is planning to build an expensive treatment system to cleanse industrially contaminated groundwater in the San Fernando Valley. It is reviving plans to replenish the local aquifer with highly treated wastewater -- something that has long been done in Orange County and southeast Los Angeles County but was shot down in L.A. years ago by "toilet to tap" opponents.
If conditions got bad enough, Los Angeles could use its existing drought ordinance to ban landscape irrigation completely. But former DWP Commissioner Jonathan Parfrey doubts the city would go that far.
"On the one hand, you need to send a clear signal for conservation," Parfrey said. "On the other hand, you don't want to give Los Angeles a reputation of being in dire circumstances and sacrifice, because that could suppress economic activity."
Instead, he said, the DWP should use its rate structure to make high water use extraordinarily expensive. "The days of making mini-Versailles around Los Angeles, I think, are over."