By every measure, it’s been dry

Nature is pulling a triple whammy on Southern California this year. Whether it’s the Sierra, the Southland or the Colorado River Basin, every place that provides water to the region is dry.

It’s a rare and troubling pattern, and if it persists it could thrust the region into what researchers have dubbed the perfect Southern California drought: when nature shortchanges every major branch of the far-flung water network that sustains 18 million people.

Usually, it’s reasonably wet in at least one of those places. But not this year.

The mountain snowpack vital to water imports from Northern California is at the lowest level in nearly two decades. The Los Angeles area has received record low rainfall this winter, contributing to an early wildfire season that included Friday’s blaze in the Hollywood Hills. And the Colorado River system remains in the grip of one of the worst basin droughts in centuries.

“I have been concerned that we might be putting all the pieces in place to develop a new perfect drought,” said UCLA geography professor Glen MacDonald, who has researched drought patterns in California and the Colorado River Basin over the last 1,000 years.

“You have extreme to severe drought extending over Southern California and also along the east and west slopes of the Sierra, and then you have it in the Colorado [basin], particularly Wyoming.”

That, coupled with wet winter weather patterns in the southern Great Lakes region and the Northeast, MacDonald said, “is extremely similar to the last time we had a perfect drought, which was the late 1980s, early 1990s.”

Thanks to a bountiful Sierra snowpack in the spring of 2006, the state’s reservoirs are in good shape. Southern California water managers say they have ample supplies in reserve and are better prepared for a prolonged dry spell than they were two decades ago.

“We’re watching this. We’re not pleased. We’re not worried, either,” said Jeffrey Kightlinger, general manager of the Metropolitan Water District of Southern California, the region’s major water wholesaler. “If it does continue, we have prepared ourselves for a multiple-year drought.

“It used to be we thought that geographic diversity was enough” protection, he added. “In 1990 or so, we realized it really wasn’t.”

Since then, the water district has constructed a large reservoir in Riverside County and is storing more water underground.

The region’s water agencies have also promoted conservation and recycling during the last two decades, steps that have helped Los Angeles keep water demand relatively flat at the same time the city added 1 million more people.

“We believe we will be able to meet the needs of the city for the coming year and beyond,” said Thomas Erb, director of water resources at the Los Angeles Department of Water and Power, which gets about half of its supplies from the Eastern Sierra.

The snowpack there is shaping up to be one of the lowest since the start of record-keeping in 1940. Twice during the 20th century -- in the late 1950s and the early 1980s -- drought strained all three regions that supply Southern California, said Scripps Institution of Oceanography hydrologist Hugo Hidalgo, who has studied drought patterns with MacDonald. “These events have been relatively rare.”

They usually last for four or five years. But “the scary part,” MacDonald said, is that ancient tree ring records indicate they can go on for a couple of decades -- much longer than anything experienced in modern times.

“We believe that there were much more severe and prolonged simultaneous droughts in those regions during the period 1300 AD to about 900 AD,” he added. “Once you start looking back in time, you realize that what we’ve seen in the historical record -- the last 100, 150 years, where we have good measurements -- that’s really nothing compared to what nature can throw at us here.”

MacDonald agreed that the state’s large water districts “are actually doing a good job in terms of planning for a five- to seven-year drought.”

But, he warned, “if you went into a decade or longer of persistent drought that affected the Sacramento [River Basin], the Los Angeles area and the Colorado, you would end up basically taxing all of the those water storage facilities, from the dams on the Colorado to what we have here, to beyond the breaking point.”

The big reservoirs in the Colorado system, which last year provided the Metropolitan Water District with 30% of its deliveries, are roughly half empty as a result of a drought that began in 2000. Federal officials have said that within a few years they may be forced to cut Colorado deliveries, although Arizona and Nevada would be hit before California, which has senior water rights in the lower basin.

As a result of this spring’s skimpy Sierra snowpack -- it’s at 46% of the normal statewide average -- the State Water Project will reduce deliveries of Northern California water to the central and southern parts of the state, but not dramatically.

“One year a drought does not make, especially the way our system is plumbed. We have ample storage,” said Arthur Hinojosa, chief of the hydrology branch for the California Department of Water Resources.

But he acknowledged that if the Sierra snowpack is poor again next winter, that “would probably create a lot of angst.”

Maury Roos, the state’s chief hydrologist, said that both groundwater and surface reservoir supplies were currently above average because of recent wet years -- 2004-05 was the second-wettest year on record in Los Angeles. However, that “cushion won’t be there for next winter” if the dry spell continues, he added.

“These dry years come often in pairs,” Roos said. “There is a reasonable chance of that happening. Hopefully not.”

Bill Patzert, the climatologist at NASA’s Jet Propulsion Laboratory in La Canada Flintridge, has said the Pacific is in an “El Nino-repellent” pattern that will favor drought in Southern California for years.

MacDonald said scientists have found that periods of simultaneous drought in Southern California, Northern California’s Sacramento River Basin and the Colorado typically have been marked by cold water in the eastern Pacific off the North American coast -- a condition that existed this winter.

A 2004 study by a team of researchers concluded that the western mega-droughts that occurred between 900 and 1300 took place during a warming period that drove up temperatures in the western Pacific, producing an upwelling of cool waters in the eastern Pacific that caused drier La Nina conditions to prevail. The researchers warned that global warming could promote severe drought in the West.

“This is the billion-dollar question,” MacDonald said. “Will global warming push us into another prolonged perfect drought?”

bettina.boxall@latimes.com

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How dry we are

The reservoirs have ample supplies, but it’s clearly a low-water year for Southern California, which relies on the Sierra snowpack, the Colorado River and local precipitation for water. Here’s a look at the statewide picture.

[See microfilm for full chart information]

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Precipitation

Partial water year, from July 1 to last Sunday

*--* % of Inches Average Eureka 30.58 93 Redding 18.61 67 Sacramento 9.99 57 San Jose 7.98 61 Fresno 4.80 50 Bakersfield 2.44 45 Los Angeles 2.47 18 San Diego 3.39 36

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Sources: California Department of Water Resources Division of Flood Management, U.S. Bureau of Reclamation

Graphics reporting by Cheryl Brownstein-Santiago