Traveling through the Delta on Highway 4 or 12, few of us realize we are driving across the linchpin of California’s water supply—or even that we’re on top of a levee. Many of us probably also don’t know that this man-handled, tangled web of waterways and conveyance pipes—Command Central for distributing drinking water to two-thirds of the state’s population—is in trouble, threatened by sea level rise, climate change, sinking of the land itself, population growth and suburban sprawl. But we’ve been given a warning. Last summer’s levee failure at Jones Tract, which cost the state $44 million to repair, was a hint of the disaster likely to come in our lifetimes.
Two respected UC Davis scientists, a geologist and a fisheries biologist, are sounding the alarm. Geologist Jeff Mount says there’s a forty percent chance that in the next fifty years, a hundred-year flood (those whoppers that statistically occur once in a hundred years) will cause widespread island flooding. The chance is the same that we’ll have a huge earthquake, with multiple levees failing—several active faults run along the west side of the Delta. The odds of both an earthquake and a big flood are one in six. The odds that one or the other will occur in the next fifty years? Two in three.
These predictions, says Mount, are based on CALFED and Department of Water Resources literature, his own research, and sea-level rise data from the Intergovernmental Panel on Climate Change. The predictions assume that we will continue to manage the Delta the way we have been—that is, acting as if it’s a stable landscape. What would happen if the Delta failed? Consider what it does now: massive pumps suck in water, which is piped to the Central Valley and Southern California for drinking, and closer to home, the Contra Costa Water District. If sinking and levee breaks allow salt water from the bay to enter the Delta, that water becomes unsuitable for drinking and agriculture.
Mount stresses that the failure odds he cited are actually conservative because they don’t include cascade or threshold effects. “Cascade effects in the Delta are well known but not talked about,” he says. “If an island levee fails, the likelihood that adjacent island levees will fail increases significantly. This is because once the island fills with water, its entire levee perimeter is at risk from wind waves.” When the remaining levees begin to fail, explains Mount, the process accelerates (like a cascade) because human efforts to fight the floods can’t keep up. Says Mount, “As an example, on the Jones Tract failure this past summer, there was a heroic fight to save the levee along Trapper slough. Settling of that levee, coupled with highly erosive wind waves, could have breached it. And we barely won that fight.” If a second breach had opened up on Jones Tract, says Mount, there would have been no way to drive trucks around the island to fight the flood. “Once you lose that ability,” says Mount, “everything has to be done by boat, which is too slow to win the fight.”
And though the state’s resource managers assume a steady increase in the risk of failure as sea level rises and sinking continues—much of the Delta is now twenty feet below sea level—there can be points or “thresholds” at which the risk of failure increases substantially, even abruptly. As the Delta continues to sink, the more likely it is that the levees will fail even absent earthquakes and floods, says Mount. He believes we need to worry about both sea level rise and climate change, even though they may seem slow in our eyes. “We’re looking at rises of several feet in a couple of generations,” he explains. The problem, says Mount, is that sea level rise and climate change exceed the normal human life cycle, so no one—including politicians and planners—wants to deal with those threats. “No one has thought through the ‘what if’ questions. You’ve got landscape-level threats to the Delta that operate on large space and time scales. Those tend to fall out of the sphere of influence of the typical political lifecycle.”
We’ve forgotten what the Delta really is, says Mount. “The Delta is by most definitions not a delta but an estuary. It’s a drowned river, a complex mosaic of freshwater and brackish water tidal marshes. It probably had a few moderate-elevation forested islands in a vast sea of wetlands.” Today’s islands were created by diking and draining, says Mount, activities that tried to make an evolving landscape hold still. “We’re saying to this once very dynamic landscape, ‘Don’t move! Cause if you do, it really messes things up.'”
Meanwhile, fisheries biologist Peter Moyle worries about human safety and our native fishery. Based on climate change models, Moyle predicts snow will melt earlier, the snow pack will be reduced, rain will increase, winter floods worsen, and sea levels continue to rise. These phenomena will not be a constant, he says, but will vary with storms and El Ni&o events, putting additional stress on the Delta and its levee system. All of these changes will have impacts on fish, as will the growth of California’s population—80 million people by 2050. That, says Moyle, means that there will be greater demand for water for human consumption, greater demand for storage of that water, and greater demand for the construction of more and bigger levees. Moyle predicts that as the demand for water grows and supply becomes more variable, there will be less water for fish in our streams, and more native fish will go extinct. He thinks we will see wildlife habitat decrease, our salmon fishery decline, and non-native fish increase.
How are we responding to these threats? We continue to build subdivisions in the outer Delta, without regard to the fact that it is continuing to sink. We continue to build bigger, “super” levees to protect those subdivisions, a cycle that encourages further sinking, according to the Department of Water Resources’ Chris Enright, a biologist who has studied the Delta extensively. He says the biggest lesson we are not learning is that sinking and levees are “tied at the hip. Every increment of elevation lost of the land surface is another increment of levee strength that needs to be added.”
One example is an 11,000-home subdivision/mixed-use development called River Islands, approved by the city of Lathrop in 1996. The project, still awaiting its permits from the state Reclamation Board and the US Army Corps of Engineers, will include a 300-foot-wide “super levee” to protect it from the theoretical 200-year flood. The odds are that it will get those permits, says the Sierra Club’s Eric Parfrey, whose group sued three times over the project and finally settled out of court in exchange, in part, for funding for agricultural conservation easements. “When I started counting up the amount of development in the outer Delta, I realized that few people are looking at the cumulative effects of all of this,” says Parfrey. According to his calculations, there are 94,000 homes planned for southern San Joaquin County (including Tracy, Lathrop, Manteca, and West Stockton)—enough housing for almost 300,000 people. In eastern Contra Costa County (Brentwood, Oakley, Antioch, and Pittsburg), approximately 75,000 homes are under construction or in the planning stages. “This is a dangerous period for the Delta,” says Parfrey.
While environmentalists battle suburban sprawl, the Delta’s plumbing is the hot topic among scientists and state bureaucrats. Mount and Moyle, among others, have been using “the P word”—the dreaded peripheral canal— as a possible solution to the threat of levee breaks and Delta sinking. While the notion of a peripheral canal revives fears that Southern California will suck Northern California dry—a fear that led to several statewide voter defeats in the 1980s—some scientists are saying it’s time to look at such a canal with fresh eyes. “The reality of the Delta is that it is subsided,” says Enright, who adds that most farming operations in the Delta today are marginal with farmers lacking money to maintain the levees. If we don’t build some kind of peripheral canal that bypasses the Delta and its water delivery system, says Enright, we will have to make massive levee improvements to protect water supply and quality. On the other hand, if we do build a canal, he says, “The need for levee integrity to protect water supply goes away, and the likelihood of fundamental landscape change increases—that is, a future with thousands of acres of open water habitat.” In other words, islands would be submerged, creating a new ecosystem of open shallow water. The ultimate environmental consequences, says Enright, are unknown, except that “there would be fish where there is now air. The Delta would be relatively more salty, with a greater tidal prism and stronger tidal currents.”
If we are going to build a canal, says Parfrey, sooner would be better since the Delta is getting so built out, particularly as you go towards Stockton. Acquiring already developed land would make building a canal prohibitively expensive.
Department of Water Resources Deputy Director Jerry Johns warns that we need to “take one step back and come up with a comprehensive strategic plan before we do anything else.” Johns has faith that the CALFED process—the state/federal effort to ensure water supply while at the same time restoring Bay-Delta watersheds—will come through with solutions. “That’s what the CALFED finance plan is settling in on,” says Johns. “It’s trying to develop a funding strategy—but before we go out and put a whole bunch of hard dollars into what we need, let’s figure out what it is we need.”
In the interim, says Johns, we know that if certain islands—Sherman or Twitchell for example—were to fail, there would be drastic impacts on the state’s ability to deliver water. “Those kinds of places we need to stabilize,” he says.
Johns isn’t convinced all the data is in on the Delta. “The nice thing about the Delta is that it is not as seismically active as some parts of California.” Although he doesn’t believe the Department of Water Resources should take the lead on a new peripheral canal—”We shouldn’t be afraid to look at it, but we shouldn’t push it either”—he thinks scrutiny of future impacts on the Delta needs to be a priority. “If what we’re doing now isn’t going to work long-term, shouldn’t we know now?” he asks. “I don’t think moving water in California is going to stop being important. We ought to be willing to ask what’s sustainable on a long-term basis. Otherwise, I don’t think we’re doing our kids any favor.”
But will we be doing our native fish a favor by building a new pipe? While some species might benefit from a pipe—particularly if it reduced the amount of water sucked by the Delta’s giant pumps—the EPA’s Bruce Herbold, another fisheries biologist, is worried that Sacramento River winter- and spring-run salmon and steelhead, could be at greater risk from fish screens on a pipe farther upstream. “If you have too big a facility the screens get too big for the fish to get by, then you have to start salvaging them—collecting and trucking them around,” he explains. “It all depends on how big the canal would be—once you make those decisions, you can start talking about what the impacts on fish would be.”
Herbold says that at the very least we need to start talking. “Do we plan on losing the Delta and start building something environmentally safe or safer now? Or do we try to keep everything the way it is, keep ag happy, recognize that we’re running the risk that we’re going to lose [the Delta] and that we’re going to have backhoes out there trying to get water to Southern California in an emergency situation, with no consideration of the best way to do it, no environmental review?”
While our memories of natural disasters mimic our life spans, negative ideas about the peripheral canal—or the necessity to supply water to Southern California—may outlive us all. “People’s perceptions are really strong—you can talk to people who don’t really know what the canal was, but they still have strong opinions about it,” says Herbold. It may be time to get beyond those opinions and reexamine the topic if we are to keep our heads above water. “There’s convincing evidence that California’s climate is changing,” says Herbold. “And that’s likely to increase flooding. I’m being nudged toward a canal. All I want is for everyone to say ‘I don’t know,’ so we can start talking about it again. Since we have the luxury of planning fifty years ahead—unlike the tsunami victims—let’s put some brains to work.”