But despite the impression that this region has been left back in time, the Delta is intimately connected to both the state’s urban infrastructure and the state’s ecological health. More than 20 million Californians get at least part of their water via the Delta, from the State Water Project and federal Central Valley Project, and more than 130 species of fish and dozens of species of birds depend on the wetland habitat that has survived here.

The Predictions

The predicted one- to three-foot sea level rise in the next hundred years could knock out levees, flood islands, and create a saltwater sea stretching from Suisun Bay to Sacramento, according to a report published in 1997 by the National Environmental Trust. That salty water, in turn, could contaminate the Central Valley Project and the State Water Project, as well as wipe out the Stockton and Sacramento Deep Water channels, hundreds of miles of interstate, state, and local roads, 14 miles of the East Bay Municipal Utility District’s Mokelumne Aqueduct, and 35 natural gas fields. Even if the entire Delta isn’t inundated, changes in precipitation (i.e., less snowpack and more rainfall) could intensify floods, levee failures, and potential saltwater intrusion, according to a 2000 study by Noah Knowles, a scientist at the Scripps Institution of Oceanography.

Levee failure has always been a problem in the Delta. In the 1840s, islands were first carved for agriculture out of the Delta’s tangle of sloughs and marshes. Early levees were constructed by hand in a process that was as difficult as it was defective. High tides and storms often knocked out levees, sometimes only a year or two after they were built. In the 1870s, the invention of the clamshell dredge speeded up the building process, and made levees easier to maintain and more reliable. By the 1930s some 550,000 acres of the Delta’s fertile peat were under cultivation. Since then, all of the Delta’s islands have flooded at least once. As the islands subside farther below sea level and the levees age, the risks of collapse and flooding increase. So much is at stake in the Delta that even before the specter of global warming, massive levee failure caused by earthquake or heavy rains was a major concern. As of 1998, only 42 percent of the Delta’s 1,100 miles of levees were in compliance with FEMA standards, according to CalFed’s Levee System Integrity Program Plan. The numbers have improved but still hover above a disconcerting 50 percent. Over the next five years, CalFed plans to spend approximately $90 million for improving the levees throughout the Delta. Budget woes may reduce that number significantly, however, says David Mraz, program manager for the Delta Levee Program at the Department of Water Resources(DWR). CalFed was prompted to develop this Program Plan by a combination of three factors: heavy flooding in the 1970s and 1980s; mounting pressure to balance the competing needs of farmers, urban water users, and the environment; and growing concern about global warming.

“We’ve been talking about levee vulnerability for decades,” notes hydrologist Phil Williams. “The climate change factor doesn’t create a new risk to the levees; it just makes the existing risk worse.”

Peter Gleick, president of the Pacific Institute for Studies in Development, Environment, and Security, believes that global warming is already affecting the Delta. He has found that changes in the pattern of precipitation and run-off are resulting in declining springtime flows in the Sacramento and San Joaquin rivers, even while annual averages remain the same. “That just points to what we’ve all been talking about for the last ten years,” he says. “Winter flows are getting heavier,” which means levees could begin breaking sooner than we expect.

The Plans

Slowly but surely, state and federal agencies have begun to acknowledge the reality of global warming. ... In addition to the technical challenges in the Delta, the state also faces an educational challenge. Most Californians don’t take to heart just how central the Delta is to their own well-being. To shift into a higher gear on these projects will require great political resolve and a lot of money, two resources in which public perception plays a key role. In today’s deficit economy, the temptation (and the opportunity) for denial and delay in high places is already great. But it is enabled and bolstered by a complacent public, especially local residents who have their own natural propensity for denial.

“Is there sea level rise?” queried one realtor I talked to in Isleton. “I live right on the water and I don’t see the water rising. So no, I’m not really worried.” Walter Landi, who runs Mango, a gift store on Isleton that sells carved wooden furniture from Bali, had the same attitude. When asked if he’s concerned about sea level rise, or even seasonal flooding, he shrugged and said, “I don’t think about it. A flood once came within ten feet of my house in Rio Vista, and I still don’t think about it. That’s just the way it is on the Delta.”

Long-term environmental problems that progress in small increments are always harder to understand and take to heart than imminent threats that manifest with a bang. Of course, it is only levee weakening and sea level rise that are incremental. Massive levee failure, should it come, will be bang enough to convince everyone of the need for action . . . only too late.

Susan Davis, a freelance writer based in Alameda, reported on the Delta in Coast & Ocean’s first special issue on climate change, in 1989.