An epic rainstorm brought mudslides, flooding and road closures to Southern California recently, but it did little to ease the state’s four-year drought.
The fierce squalls that struck north of Los Angeles on Oct. 15 and 16 delivered a likely preview of what’s shaping up as a very wet winter in much of California. It also showed the limitations of rainfall as a drought remedy, particularly in Southern California, and demonstrated the difficulty of predicting how much relief El Niño will provide.
For all its fury, the recent storm brought “a very, very, very tiny drop of water in (terms of) drought relief,” said engineer Mark Pestrella, chief deputy director of the Los Angeles County Department of Public Works. “It is an infinitesimal amount.”
Pestrella said some of the water seeped into ground, while other experts said much of it probably wound up in the ocean in the form of storm runoff. One thing is certain: Precious little got captured in Southern California’s reservoirs or aquifers.
The pattern could well repeat itself this winter, as California’s water experts warn that one of the strongest El Niños on record is unlikely to mean the end of the drought. The recent storms weren’t believed to have been caused by El Niño but might have foreshadowed the sort of weather California can expect.
“The unfortunate truth is we may lose a lot of the runoff to the ocean and we may see a large amount of flooding,” said Noah Garrison, a geologist at UCLA’s Institute of the Environment and Sustainability.
With winter storms expected to begin in earnest in January, some agricultural groups are developing pilot projects to temporarily flood their fields with storm runoff as a means of replenishing the overpumped aquifers of the Central Valley. Nonetheless, many experts say California isn’t equipped to take full advantage of this winter’s precipitation.
The problem revolves around El Nino’s typical behavior and the lopsided nature of California’s mostly man-made plumbing system.
El Niño often drenches Southern California, and this winter should be no exception. Forecasters at the National Oceanic and Atmospheric Administration, or NOAA, said the southern half of the state stands a 50 percent to 60 percent chance of receiving above-average precipitation this winter.
Unfortunately, about 75 percent of the state’s reservoir capacity lies north of Fresno, where the chances of heavy rain are decent but not as certain. Southern California has reservoirs, too, plus more than two dozen “spreading ground” facilities for recharging aquifers. But compared to Northern California, the south state lacks water-storage infrastructure, and as a result this winter could be disappointing to Californians pining for an El Niño miracle.
In its latest winter outlook, NOAA said El Niño should bring “drought improvement” but not “drought relief” for the state.
All experts agree that the best possible outcome is ample snowfall in the northern Sierra Nevada. A heavy snowpack would replenish California’s main reservoirs and canals with gradually melting runoff well into next summer. But the forecast for snow is iffy. While Northern California has a 34 to 40 percent chance of above-average precipitation this winter, NOAA said much of it is likely to fall as rain instead of snow because of expected warm temperatures, likely undermining El Niño’s effectiveness as a drought remedy.
“This is no drought buster,” said Bill Patzert, a climatologist at NASA’s Jet Propulsion Laboratory in La Cañada Flintridge. “Too much of it will run into the ocean in the coastal communities, (and) not be captured.”
The prospect that much of El Nino’s waters could disappear into the ocean has become a bit of a political issue. The 14 California Republicans in the House of Representatives sent a letter last week to President Barack Obama and Gov. Jerry Brown demanding to know how government agencies will capture this winter’s precipitation. The letter repeated the complaint from farmers and other critics that environmental regulations have stifled the delivery of water to the San Joaquin Valley and Southern California.
“How do Federal and state agencies intend to overcome these obstacles to maximize water exports to central and southern California?” the letter asks.
Agency officials acknowledged that California’s capacity to take advantage of El Niño is limited, but they argued that environmental regulations aren’t the problem.
Nancy Vogel, spokeswoman for the California Natural Resources Agency, said the federal and state water agencies will “work together to maximize the capture of storm runoff,” as they have in previous winters. But she said those efforts are limited by the capacity of the state and federal pumping stations in the Sacramento-San Joaquin Delta, which deliver water south to farms and cities. If the precipitation falls mainly as rain and water rushes into the Delta too quickly, she said some will surely spill into the ocean.
“If we get all rain and little snow, you take what you can get when the water’s high,” she said.
Shane Hunt, a spokesman for the U.S. Bureau of Reclamation, said the agency has contributed millions of dollars in recent years to help regional water agencies build groundwater storage projects in California. While some will be ready for this winter, others are still in development.
“They take a little bit of time to plan and build,” Hunt said.
Not content to wait, some farmers and conservationists are working on small-scale test projects to flood farm fields with stormwater this winter, in order to replenish Central Valley aquifers.
“The more fields we find, the more farmers we find who are willing to participate, the more water can be recharged during these very short windows,” said UC Davis hydrologist Helen Dahlke. With funding from the Almond Board of California, her team plans to flood three small almond orchards in Stanislaus, Merced and Fresno counties.
The concept has been tried before, with some success. During the last wet winter, in 2011, Don Cameron built temporary dirt barriers around 600 acres of vineyards, pistachio trees and tomato fields on his ranch southwest of Fresno. The goal: grabbing overflow water from the Kings River.
“It worked great,” Cameron said. Between 7,000 and 9,000 acre-feet of water percolated into the ground, he said. An acre-foot is 326,000 gallons. Cameron expects to repeat the project this winter, assuming the weather cooperates, and is working on getting funding for an expanded project in future years.
Other farmers are warming to the idea but are worried about swamping their fields and orchards with too much water. Excess water can lead to mildew problems for table-grape growers, for instance.
“We have to demonstrate that it’s feasible, affordable, and that there’s no adverse impact on the crop,” said Daniel Mountjoy of Sustainable Conservation, a San Francisco nonprofit recruiting San Joaquin Valley farmers to flood their fields this winter.
The Laguna Irrigation District is already working on a project in Fresno County. Crews have begun digging a groundwater recharge pond on 54 acres the district owns near the Kings County border. The $1.2 million project is being funded by the state and a corporate sponsor, Coca-Cola, which makes grants for environmental programs.
Scott Sills, general manager at Laguna, said the pond could store up to 30,000 acre-feet of water if the winter rains persist. He said the project could be a shot in the arm for an area that, like much of the San Joaquin Valley, has overpumped groundwater during the drought.
“It would probably take two good years to overcome what’s happened in the last four,” Sills said. “But one good El Niño year, where we could shut the wells off, put water in the ground ... we have a lot of opportunities.”
The problem with aquifer recharge systems is that they generally require a steady, moderate flow of water in order to seep into the ground. With the ground as dry as it is, a sudden deluge, like the Oct. 14-15 rainstorm in Southern California, will often overwhelm the basin and disappear as runoff.
Location matters a lot, too. If the Southern California storm had struck a little further south, Pestrella said more of the water could have been captured in some of the public works department’s “spreading grounds.” Those are giant fields, generally in the southern part of Los Angeles County, where water percolates into aquifers.
As it happened, most of the rain fell too far north. Big water agencies such as the Metropolitan Water District of Southern California, the giant umbrella agency that serves 19 million customers, saw no significant uptick in water.
“We really (didn’t) get any kind of bump in supply,” said Metropolitan spokesman Bob Muir.