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State's Levees Vulnerable in Quake

Experts say a major temblor in the Sacramento-San Joaquin Delta would devastate agriculture and cut water supplies.

November 02, 2005|Bettina Boxall | Times Staff Writer

A major earthquake in the Sacramento-San Joaquin Delta could cause widespread levee failure and flooding, costing the state more than $30 billion in long-term losses and tens of thousands of jobs, a state official warned Tuesday.

In testimony before a joint legislative committee in Sacramento, Lester Snow, director of the Department of Water Resources, said a magnitude 6.5 earthquake in the western delta could tear 30 breaches in the levees that protect water supplies for 22 million Californians and some of the nation's most productive farmland.

The resulting delta flooding would shut down water shipments to Southern California cities and San Joaquin Valley croplands, rupture natural gas and oil pipelines and topple electrical transmission towers.

David Mraz, the delta levees program manager who prepared the earthquake scenario presented by Snow, said it could take five years and billions of dollars of work to restore full water deliveries from the delta. In the meantime, vegetable production in the San Joaquin Valley would dry up, cities would be forced to adopt stringent water conservation measures and some farm communities would permanently wither.

"I think there would be portions of the economy that would not fully recover," Mraz predicted. "I think we would be a changed society in some senses."

He added that job losses, primarily in agriculture, could exceed 30,000 and the cost to the state's economy could total $30 billion to $40 billion, much of it in lost crop production in the first five years after the earthquake.

Mraz said farmers would turn to groundwater to sustain their more valuable crops, such as fruits and nuts, straining already depleted groundwater supplies.

Snow's testimony was the latest warning about the perilous state of the levee system that protects the delta, a maze of reclaimed agricultural islands and waterways that provide nearly two out of three Californians some portion of their water.

Snow said that in an earthquake many of the earthen levees are expected to fail, flooding 3,000 homes, 16 delta islands and letting saltwater from San Francisco Bay rush toward the big pumps that send water south through the State Water Project and the federal Central Valley Project. The pumps would have to be shut down during repairs to key levees to block the saltwater.

The Metropolitan Water District of Southern California, the region's major water wholesaler, has a six-month emergency supply and also gets water from other sources such as the Colorado River. But smaller water agencies don't have such fallbacks. And even after a year of emergency repair work, only limited water deliveries would resume by rerouting water from the San Joaquin River.

"We know from running out the scenario that in this type of event we will not be able to get the water supply system up and running at full capacity for a number of years," Mraz said.

Even without an earthquake, the delta levees are vulnerable. They were haphazardly constructed by farmers and local reclamation districts, rest on decaying peat soil and have failed for no apparent reason in good weather. The state estimates it would take $1.3 billion to bring them to basic standards, a cost that does not include seismic strengthening.

The state is conducting a two-year delta risk study, but officials are already saying that Californians will have to pick which benefits they most want from the delta and be prepared to forego some of the other uses. Rising sea levels will compound the levee problems and the delta's environmental troubles are growing despite a multibillion-dollar government restoration program called CalFed.

"We have to decide -- what can we save and what do we want to save -- and put the resources together to try to do that," said Les Harder, acting deputy director of the water resources department.

There has been discussion of issuing a state infrastructure bond that would include money for levee repairs. Efforts have also been made -- thus far unsuccessfully -- to adopt a fee program that would require water users who rely on the delta to help pay for levee improvements.

And there is talk of reviving some version of an old proposal to ship water supplies around the delta rather than through it, thereby avoiding the potential for saltwater contamination.

"It may be time to consider moving a certain percentage of the water around the delta," Mraz said. "I don't think you want to do 100% of the [shipments] around the delta, but maybe 50% is a good number, maybe 30% is a good number -- something so that the folks south of the delta have a secure water supply."

Delta advocates worry that if all water shipments were diverted around the delta, efforts to protect the delta ecosystem would be abandoned.

A proposal to build a canal around the delta was defeated by voters in 1982 amid concerns that it would let the south take more water from Northern California. Such a system remains controversial, and it would cost $5 billion to $10 billion and take at least four years to construct.



Flood of trouble

State water officials say a magnitude 6.5 earthquake in the Sacramento-San Joaquin Delta could have a devastating effect on farmland and water supplies.

* 30 breaches in delta levees

* Flooding of 3,000 homes, 16 delta islands and 85,000 acres of cropland

* Delta water shipments to Southern California and San Joaquin Valley farms halted

* Natural gas and oil pipelines ruptured

* Delta highways, electrical transmission lines and railroads damaged

* 30,000 jobs lost and $30 billion to $40 billion cost to the state economy over the long term


Source: California Department of Water Resources

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