California’s Levees Are in Sorry Shape

The threat is well known. A big quake rumbles across the Sacramento-San Joaquin Delta, knocking out dozens of the primitive levees that guard the state’s main water crossroads. A key source of water for nearly two out of three Californians and the nation’s biggest fruit and vegetable garden is shut down for months, maybe even a year or two.

Can the state avert such a scenario?

The watery calamity that befell New Orleans has highlighted the sorry state of delta levees, prompting calls from Gov. Arnold Schwarzenegger and California congressional leaders for federal money for levee repairs.

The delta’s vulnerabilities have also prompted some experts to dust off an idea they believe might be more practical: building a canal that would route water around the delta to agricultural and urban consumers in Central and Southern California. For though it may be technically possible to armor the delta, many experts doubt it is economically feasible.

Schwarzenegger last week asked the federal government for $90 million to improve some of the most critical levees in the delta and the Central Valley. But that is a fraction of the $1.3 billion in repairs officials say it will take just to bring the delta levee system up to basic standards. And that would do little to protect it from earthquake damage. The state Department of Water Resources can’t even say how many billions more it would cost to do the seismic work.

“To make them basically earthquake-proof, you would probably have to start over with a brand-new levee system,” said Les Harder, acting deputy director of the department and an engineer who helped put together a 2000 state analysis of the delta’s seismic risk. “I think it’s going to be unlikely we would ever make the whole delta today earthquake-proof.”

That -- coupled with projections of rising sea levels that would stress the fragile levee system even without a major quake or flood -- is reviving talk of a politically charged alternative to delta water shipments: the Peripheral Canal. Rejected by California voters in 1982, the canal would have drawn water from the Sacramento River and carried it around the delta to federal and state aqueducts supplying the Central Valley and the Southland.

“The idea that you can fix this so that [massive earthquake failure] won’t happen is nonsense,” said B.J. Miller, an environmental engineering consultant who represents some of the Central Valley’s largest irrigation districts. “You can’t dig out the peat soil the levees are resting on. There is no economic way to do that.

“Everybody knows what the solution is,” he said. “Build a canal around the delta.”

The Peripheral Canal died largely because of fears that it would become a giant straw through which Southern California could suck more of the north’s water. Though the concept remains highly controversial, Miller is not the only one raising it. Former Interior Secretary Bruce Babbitt mentioned it recently at a hearing on the CalFed program he helped set up to improve water delivery from the delta. And even some environmentalists are broaching the idea of a smaller pipeline around the delta that would ferry some -- but not too much -- water south.

Overall, the delta levee system is in far worse shape than the levees that so dramatically failed in New Orleans. They have collapsed for no apparent reason in good weather. Dozens could fall apart if a major earthquake or flood were to strike, not only imperiling water supplies but also flooding thousands of acres of farmland as well as highways and railroads that cross the delta.

And though the more than 400,000 people who live in the delta reside mostly on its edge rather than its more flood-prone interior, growth is encroaching, bringing more people closer to the levee system.

The threat of an earthquake is by no means the only concern. There is a growing recognition that given rising sea levels, an inadequate levee system, natural disasters and the ongoing subsidence of delta islands, the delta is not going to stay the same.

“There is a very strong likelihood that the delta as we know it today is not sustainable over the long term,” Harder said. “We’re going to have to take a look at what we need most and where.”

Change has been a constant in the delta since Gold Rush settlers started draining and dredging the vast tidal marsh created thousands of years ago by the confluence of two of the state’s biggest rivers, the Sacramento and the San Joaquin, as they flowed into San Francisco Bay.

Using shovels and wheelbarrows, laborers began building what became a 1,100-mile maze of earthen levees that keeps the water out of the dozens of islands that were planted with crops after they rose from the drained marshland.

The drainage and farming have turned the delta, which is bigger than Orange County, into California’s Holland, making for a constant battle between land and the more than 700 miles of waterways that wreathe the islands.

Cultivation has broken down the deep peat soils, causing them to blow away and oxidize, turning to gas. Through soil loss, the islands sink ever lower. Some areas are now as much as 20 to 30 feet below sea level.

The subsidence probably will be accentuated by an expected rise in sea level tied to global warming. Scientists say the ocean off California could rise roughly a foot over the next 50 years and perhaps as much as 3 feet over the next 100 years.

As the land sank during the past century, the levees got higher. But they weren’t built up according to sophisticated engineering standards. Mechanical dredges simply scooped up the muck from the adjoining sloughs and tossed it on top of the old berms. Beneath the levees lie loose sand and silt that can liquefy in an earthquake.

Of the roughly 1,100 miles of delta levees, 385 are maintained by federal and state agencies and are in somewhat better shape than the rest, which are overseen by small delta reclamation districts. In general, however, experts say the levee system is a disaster in the making.

Concern for the levees was sharpened with the recent prediction by a pair of UC Davis scientists that there is a two-in-three chance that a major earthquake or flood will hit the delta in the next 50 years, causing widespread levee failure.

“New Orleans lost the battle with the inevitable, and we will suffer the same fate in some form here in California,” said geologist Jeffrey Mount, one of the Davis researchers.

Multiple levee breaks could draw San Francisco Bay’s salt water toward the enormous federal and state pumps that siphon water from the south delta and send it to the cities of Southern California and millions of acres of San Joaquin Valley cropland.

If that happened, water managers would have to shut the pumps down. For how long would depend on where and when the levee breaks occurred.

Breaches in levees in the western delta, near the bay, would let more salt water in. If levees collapsed in the summer, agencies would either have to release a rush of water from upstream reservoirs to flush out the system or wait until the following spring, when high natural flows would do the flushing for them.

Massive levee failure could easily shut down delta water exports for months, and, in a worst case, for a year or two. “That’s one of the scenarios they’re looking at,” said David Mraz, delta levees program manager for the state water department.

Over the last three decades, the state has spent $210 million on delta levees. The Army Corps of Engineers has spent additional millions on repairs. Last year’s reauthorization of CalFed included $90 million in federal funding for levee repairs. But none of that has been appropriated, and total CalFed levee spending has lagged behind projections. Moreover, the program has yet to adopt a promised fee system under which delta users would help pay for projects they benefit from, such as levee work.

“There have been a lot of improvements of levee sections. [But] nothing has yet happened in a meaningful way to reduce the seismic risk, and that is a Damocles sword for California,” said Ray Seed, a professor of civil engineering at UC Berkeley who has been evaluating the delta levee system for the last 20 years. “There are lots of people who know how to fix it. The issue is it’s too expensive.”

Even if it costs too much to seismically reinforce all 800 miles of levees that are the most critical to maintaining water quality, Seed said selected levees could be upgraded. He suggested there are simple, relatively inexpensive things that could be done to speed repairs when disaster strikes. The state could stockpile the big rocks needed to plug holes and store on islands the plastic sheeting and sandbags that can slow erosion after a levee break.

Other proposals include taking islands out of farming to slow the subsidence, flooding some islands with fresh water to combat a saltwater intrusion during levee failure and erecting barriers that would force fresh water toward the pumps in the event of flooding.

The state has begun a two-year, $6-million analysis of risk to delta levees that will include ways of dealing with a major saltwater intrusion to try to avoid a long shutdown in water shipments.

In the meantime, some politicians are looking warily at another delta trend: creeping urbanization. Though most of the delta’s 738,000 acres are farmed, some of California’s fastest-growing areas are pushing into delta lowlands.

Symbolic of that growth is the little town of Lathrop, on the delta’s southeastern perimeter. It plans to expand from 12,000 to 80,000 residents over the next 25 years. About 35,000 of those newcomers would move into a master-planned community the town has approved for a now-empty delta island known as the Stewart Tract.

Town officials say they will require the developers to pay for levee construction that will guard against a 200-year flood. But critics say that could just push floodwaters elsewhere.

“I am very concerned about the urbanization of the delta,” said Assemblywoman Lois Wolk, a Davis Democrat who has been pushing legislation -- thus far unsuccessfully -- to give the state Delta Protection Commission more muscle to restrict delta growth.

“For me, it’s part of a larger issue which I believe has become very clear with what’s happened in Louisiana. That is the foolhardiness of building in a flood plain. We continue to do that and ... we need to have a statewide approach to restricting that growth. If local government won’t do it, then the state has to do it.”

More than the delta, the Central Valley is seeing thousands of houses sprout in areas that have flooded in recent decades. Those areas are protected by a river levee system that is also in need of extensive repairs, although it is generally thought to be in better shape than the delta’s aging system.

Pointing to new development in Lathrop, as well as north of the delta near Sacramento and in Sutter County, Wolk said: “All of these are built in areas that should have remained in agriculture. It should be expected that there will be a flood. You simply can’t make the levees strong enough.”