The Biggest Potential Water Disaster in the United States
In California, millions of residents and thousands of farmers depend on the Bay-Delta for fresh water—but they can’t agree on how to protect it.
By David Owen
May 11, 2022
The Sacramento is California’s largest river. It arises near the lower slopes of Mt. Shasta, in the northernmost part of the state, and runs some four hundred miles south, draining the upper corridor of the Central Valley, bending through downtown Sacramento, and, eventually, reaching the Pacific Ocean, by way of the San Francisco Bay and the Golden Gate Bridge. Erik Vink, the executive director of the Delta Protection Commission, a state conservation agency, described the Sacramento to me as “California’s first superhighway.” By the eighteen-fifties, daily steamboats ferried passengers between San Francisco and Sacramento in as little as six hours. Travellers now mostly use I-80 to cover the same ninety miles, and oceangoing ships bound for the Port of West Sacramento finish their trip in a deepwater canal built sixty years ago by the Army Corps of Engineers. But the Sacramento is still important: it and its tributaries make up the state’s single largest source of fresh surface water. Most precipitation in California falls in the north, while the biggest users, including all the major metropolitan areas and the immense farms of the San Joaquin Valley, are farther south. Devising ways to move water from wet places to dry places has been the labor of generations. During the past century and a half, miners, farmers, politicians, engineers, conservationists, and schemers of all kinds have worked—together and against one another—to create one of the most complex water-shifting systems in the world.
In mid-February, I ate lunch at Bethany Reservoir State Recreation Area, a ninety-minute drive south of Sacramento, with Jay Lund, who is a co-director of the Center for Watershed Sciences at the University of California, Davis, and Peter Moyle, an emeritus professor at the same university. Lund is in his sixties, and Moyle is almost eighty. Spring was well under way—on our drive to Bethany, we’d passed hundreds of acres of blossoming almond trees with neat stacks of beehives spaced at intervals along the rows, for pollination—but the weather was still cool enough for jackets. Before we ate our sandwiches, Lund unrolled a laminated sheet on top of our picnic table. The sheet was three feet wide and so long that one end drooped almost to the ground. Its surface was covered with lines, arrows, symbols, and small blocks of text—a maze-like network that could have passed for the wiring diagram of a nuclear power plant. In fact, Lund explained, it was a schematic of the state’s water infrastructure, the inflows and outflows, both natural and man-made.
Near the middle of the picnic table, maybe three feet from the edge that represented the Oregon border, was a small label indicating “The Delta.” It marked what Lund described as the most important element of California’s plumbing: an expanse of some seven hundred thousand acres, east of the Bay Area, formed by the confluence of several rivers, the largest of which are the Sacramento and the San Joaquin. For tens of millions of Californians, the Delta—which is also known as the Sacramento-San Joaquin Delta, the Bay-Delta, and the California Delta—serves as a hydrological hub. “The Delta ties everything together,” Lund said. All the fresh water that farms and cities in the south import from the north comes from it. Not far from our picnic table, large pumping stations were sending Delta water to other parts of the state.
In 2014, while I was researching an article and a book about the Colorado River, I interviewed Pat Mulroy, who had recently retired as the general manager of the Southern Nevada Water Authority and had just become a fellow at the University of Nevada’s law school. She surprised me by saying that the condition of the Delta—which lies several hundred miles outside the Colorado’s watershed and which I’d only just heard of—posed as grave a threat to the Colorado’s long-term stability as the shockingly low water levels I’d seen in its two largest reservoirs, Lake Powell and Lake Mead. Seven Western states and Mexico divert water from the Colorado, which for decades has been depleted by drought and unsustainable use. As Mulroy and I spoke, California was already being forced to reduce its withdrawals. The Delta is crucial because, if it ever failed as a hub, the resulting water crisis in California would increase existing tensions with the Colorado’s other parched dependents. “One good earthquake would do it,” Mulroy said.
News stories about the Western drought often focus on the Colorado and its reservoirs. The drops in their water levels are easy to see. A little over twenty years ago, Lake Mead was full, but since then, its volume has shrunk by two-thirds. As the water has disappeared, it has left a broad band of light-colored mineral deposits, known as the “bathtub ring,” on the surrounding canyon walls. The Delta’s problems are as dire, but they receive far less public attention. (No bathtub ring.) Up close, the Delta doesn’t look like much: a huge expanse of flat agricultural land, with relatively few signs of human habitation. On Google Earth, it resembles a triangular green jigsaw puzzle. The principal puzzle pieces are five or six dozen irregularly shaped islands, which are separated from one another by seven hundred miles of sloughs and meandering waterways. The islands are actually what the Dutch called polders; they’re landforms that farmers created, beginning in the nineteenth century, by draining natural wetlands. Most of the islands cover thousands of acres. All are surrounded by dikes, which are known locally as levees; their purpose is to keep water from flooding back in. The cultivated fields inside the levees have gradually subsided, and in some places are now twenty-five feet below sea level. One consequence is that Delta farmers, in addition to siphoning irrigation water from the channels that surround their islands, have to pump water out—a chore familiar to anyone who has used a sump pump to keep a basement dry.
The main threat to the Delta is saltwater intrusion. If an earthquake caused a major levee failure, the sunken islands would flood, drawing salt water from the Pacific into waterways that are now kept fresh by the pressure of inflows from the Sacramento. “Instantly, your fresh water turns to sea water,” Mulroy said—and, at that moment, a resource that millions of Californians depend on for drinking and irrigation would be unusable. A month before my interview with Mulroy, I had met with Bradley Udall, who had just joined Colorado State University as a senior water-and-climate-research scientist. During our conversation, he described the Delta to me as “the biggest potential water disaster in the United States.” That was eight years ago. In the meantime, the drought has continued, making all the problems worse.
When the Spanish first sailed into San Francisco Bay, in the late seventeen-hundreds, the water was so clear that a sailor could look over the side of a ship and see shoals of fish swimming at the bottom. The noise made by salmon at night, as they migrated up nearby streams, was loud enough to keep people awake, and there were so many ducks, geese, pelicans, cranes, and other birds that when they took flight they darkened the sky. Elk, deer, antelope, beavers, and grizzly bears were abundant. The hills surrounding the bay were covered by ancient forests. The Central Valley—California’s most productive agricultural region, which runs much of the length of the state, between the Sierra Nevada and the Coast Ranges—was a lush seasonal wetland.
All of that began to change in 1848, when a carpenter who was helping to build a sawmill for a Swiss immigrant named John Sutter noticed something glittering in the mill’s tailrace: the beginning of the California gold rush. An emergent mining technique involved shovelling gravel and dirt into an open-ended trough, called a sluice box, then running water over it. Gold is so dense that it settles into riffles in the bottoms of the sluice boxes as the lighter material is washed away. Miners soon realized that they could get rich quicker if they built bigger troughs and increased the volume and speed of the water. They diverted mountain streams into wooden flumes and broad pipes, then used canvas hoses with iron nozzles to aim the resulting water jets at entire hillsides. That technique was called hydraulic mining. The water jets were so powerful that, according to contemporary reports, they could kill people standing two hundred feet away. Samuel Bowles, an influential New England newspaperman (who was also a friend of Emily Dickinson’s and an early reader of her poems), visited the Sierra foothills in the eighteen-sixties. “Tornado, flood, earthquake and volcano combined could hardly make greater havoc, spread wider ruin and wreck, than are to be seen everywhere in the path of the larger gold-washing operations,” he wrote. Hundreds of millions of tons of sediment were pushed downstream, burying some farmland as far away as the Delta.
As significant as the gold rush, in terms of the physical and cultural transformation of California, was the passage, by Congress, of the Swamp Land Act of 1850. One of its purposes was to facilitate the conversion of Florida’s Everglades into arable land, but its provisions also applied to several other states, California among them. As frustrated forty-niners gave up on gold, they often turned to agriculture. Speculators acquired large wetland tracts, then built levees, drained marshes, and cut or burned existing vegetation. They grew potatoes, beans, corn, asparagus, cabbages, and other row crops, and riverboats carried their produce to market. They cut down so many trees, partly to provide fuel for the riverboats, that the only real surviving remnant of the region’s ancient forests is the name of the city at the eastern end of the Bay Bridge: Oakland. The enterprise was made possible by the immigration of laborers from China and, beginning in the late nineteenth century, by the use of steam-powered dredges. The modern Delta was born then.
Two days before our picnic at Bethany Reservoir, Jay Lund and I spent most of the afternoon on waterways near the Delta’s southwestern tip, in a boat owned by William Fleenor, an engineer and emeritus senior researcher at the Center for Watershed Sciences. Fleenor’s boat is fifty feet long and has a catamaran hull. We set out from the Pittsburg Marina, near the place where the Sacramento and the San Joaquin flow together. (The San Joaquin arises in mountains near Yosemite National Park, runs northward in the Central Valley, and enters the Delta from the south.) We headed up the mainstem of the Sacramento, and were soon passed by the Atlantis Discovery, a six-hundred-and-ten-foot-long bulk carrier, which was going the other way. I learned later, from a ship-tracking Web site, that it had left South Korea a month before, had unloaded cargo in West Sacramento, and was now heading back toward the Golden Gate. We gave it a wide berth.
The wind blew hard during our boat ride, as it often does in the Delta—one of California’s largest assemblages of wind turbines was just to our west, in the Montezuma Hills—so we spent most of the trip inside the boat’s enclosed bridge, snacking on grapes that Lund had brought and on chocolate cookies that Fleenor’s wife had made. The bridge’s windows were high enough that I could look over the levee of Sherman Island and see the difference in elevation between its subsided fields and the level of the river. Fleenor said that the truly unnerving view is the one you get when you stand in a subsided field and watch a ship like the Atlantis Discovery going by above your head.
Soil in the Delta has a high peat content. That’s a result of the steady accumulation, throughout thousands of years, of dead wetland vegetation—largely bulrushes called tules, which once flourished throughout the area. As the Pacific rose with the melting of the northern ice sheet, the tule marshes rose with it, and the underlying layer of submerged dead plant material thickened, creating a stratum of what is really a juvenile fossil fuel. (Peat in the Delta sometimes catches fire and burns underground.) Plowing exposes the peat to air, causing it to oxidize, and as it oxidizes, the land shrinks. Peat also compacts easily, and, when it dries, the Delta winds can blow it away. Some island fields have been sinking at an average rate of more than an inch and a half a year since the eighteen-hundreds.
Almost all the islands in the Delta have flooded at one time or another. A few are still submerged, making the Delta jigsaw puzzle appear, from above, to be missing several pieces: Big Break, which was an asparagus farm until 1928; Franks Tract, which flooded in 1937 and 1938; Mildred Island, which flooded in 1983; most of Liberty Island, which flooded in 1998. There have been many close calls. In 1980, workers on Jones Tract, a twelve-thousand acre island in the southeastern Delta, were enlarging a levee by dredging sediment from the adjacent waterway and piling it on top. “The extra weight crushed the peat foundation, and it slowly sank and failed,” Greg Gartrell, a hydraulic engineer and an adjunct fellow at the Public Policy Institute of California, told me in an e-mail. Water rushing through the breach threatened the Mokelumne Aqueduct, which carries drinking water across the Delta to one and a half million residents of San Francisco’s East Bay. The torrent would have swept away piers supporting the aqueduct had a passing train on the island railroad not gone off its tracks and partly plugged the gap.
A different levee failure on Jones Tract drenched the entire island in 2004. Dealing with that break was complicated by the kinds of conflicts that, for decades, have derailed efforts to address climate change and other environmental threats. Because the Jones Tract levee was “non-project”—meaning that it wasn’t part of a federal flood-control program and hadn’t been built under federal supervision—the Army Corps of Engineers could not help until they had received a formal request. By then, the fields were underwater. The Corps eventually did help to rebuild part of the levee, citing the need to protect State Route 4, which skirts the island, but the repair was done with dredged material that turned out to be contaminated by toxic metals. At the time, California’s Department of Water Resources believed the flooding might have been confined to just half of the island, but the Burlington Northern Santa Fe Railroad refused its request to block an opening under a trestle. Drying out Jones Tract took months and cost an estimated ninety million dollars, lawsuits not included.
That Jones Tract failure occurred not during an earthquake or a torrential rainstorm but on an otherwise ordinary day in early June—an unsettling thought. Rising seas will cause the Delta’s waterways to press harder against the levees, and the continued sinking of the fields will make them more vulnerable. A number of levees have been raised or reinforced in recent years, but many haven’t, and no single regulatory body is responsible for all of them. A perennial challenge to effective planning in California is that water management is divided among hundreds of jurisdictions, from the federal government down. There are so many agencies, overlapping constituencies, interest groups, and simmering historical antagonisms that implementing comprehensive remedies to the biggest problems has, so far, proved to be impossible, even as those same problems have grown more dire. Farmers in the Delta sometimes worry that farmers in the San Joaquin Valley and homeowners in Los Angeles are out to screw them, and vice versa. Politicians act as though they hope disaster will hold off until the day after they’ve left office. In 2011, a report published by the Public Policy Institute offered a grim diagnosis: “The result is often a game of ‘chicken,’ where the management of a declining resource becomes deadlocked.” Lund, who co-wrote that report, told me, “Everybody is watching this thing decay, but nobody wants to be the first to offer a compromise, because that weakens their negotiating position.” The ocean, meanwhile, continues to rise, and the fields continue to sink.
The Delta’s main defense against saltwater intrusion has always been the Sacramento River. Throughout the decades, waterways among the islands have been channelized, diverted, and, on occasion, partially blocked, in order to make them more effective both as salt impediments and as freshwater conveyances. During our boat ride, we saw a temporary salt barrier, which the state’s Department of Water Resources had placed across the West False River, an eight-hundred-foot-wide channel. The barrier was a small dam, made of stone, whose purpose was to impede the flow of ocean water into canals that carry water to the south, for irrigation and domestic use. The greatest danger had passed, and the D.W.R. had recently removed the center of the barrier. I also visited the Delta Cross Channel, a mile-long diversion canal on the east side of the Delta, built in 1951. A dam-like structure at its mouth has gates that can be closed during floods, to reduce the likelihood that salty water will reach the pumping stations.
Many other defenses have been tried or proposed. In 1929, John Reber, an actor, screenwriter, and theatre producer, suggested building two immense dams across San Francisco Bay, roughly where the Bay Bridge and the Richmond-San Rafael Bridge are today, to disconnect the Sacramento almost entirely from the Pacific Ocean. Reber wasn’t an engineer; in fact, he hadn’t gone to college. But he was an avid amateur hydrologist and an effective promoter. In 1950, Congress appropriated two and a half million dollars to study his and other ideas, and the Army Corps of Engineers built a functioning scale model of the entire region. The model, which was completed in 1957, still exists. I went to see it, at the Bay Model Visitor Center, in Sausalito. It consists of two hundred and eighty-six concrete sections weighing five tons each, and it covers about two acres, inside a warehouse in which liberty ships were outfitted during the Second World War. It still has working tides, which turn more than a dozen times an hour. Linda Holm, the park ranger who showed me the model, said that tests conducted by the corps of engineers in the early sixties proved that the Reber Plan, if implemented, would have caused “flooding of Biblical proportions” and doomed the Delta’s salmon, among other species, by blocking their migration to and from the ocean.
A different approach to the salt threat was championed by Jerry Brown, who was the governor from 1975 to 1983, and again from 2011 to 2019. In his first stint, the state legislature approved a plan to build the Peripheral Canal, a longer and bigger version of the Delta Cross Channel, to divert some Sacramento River water around the outside of the Delta’s eastern edge. In 1982, voters killed the plan in a veto referendum, and the canal was never constructed. In his final term, Brown proposed a similar idea—to move water not around the Delta but under it, through a pair of earthquake-resistant concrete tunnels. (Pat Mulroy told me that a tunnel was essential, when I spoke with her in 2014.) The two-tunnel idea attracted strong opposition, from environmentalists, from Delta farmers, from taxpayers, from others. A scaled-down, one-tunnel idea hasn’t gone much further.
One of many arguments made by environmentalists against tunnels in the Delta is that building and operating them would harm endemic species. The best known is the Delta smelt—a tiny, slender, iridescent fish that lives there and nowhere else—which was abundant until the early eighties. In 1993, based on data that Moyle had compiled, the U.S. Fish and Wildlife Service listed the Delta smelt as threatened, and since then extraordinary amounts of money have been spent to preserve it, and equally extraordinary amounts have been spent on campaigns devoted to publicizing its preservation. Those campaigns have been created not just by environmental groups but also by the enemies of environmental groups—which, in a perverse way, are also heavily invested in its continued survival, because efforts to save it have been such an easy target for derision. (In 2009, at a hearing, the Republican Congressman George Radanovich referred to it as a “worthless little worm.”) All of that may change soon, since growing evidence suggests that the Delta smelt is now effectively extinct in the wild.
Every Delta-related water issue has been complicated by the ongoing Western drought. (Tree-ring analysis shows the past two decades were the driest in more than a thousand years.) Under ideal circumstances, surface water and groundwater are complementary resources: in dry years, increased groundwater pumping makes up for the lower surface flows, while in wet years heavy precipitation allows subterranean aquifers to recharge. But the drought has changed all that, by stressing all resources at once. It has also hugely increased the challenge of maintaining water quality in the Delta hub. As less water flows down the Sacramento from the north, controlling salinity inevitably requires reducing exports to farmers in the south. Those farmers, who are the biggest users of Delta water, feel forced, in turn, to pump more groundwater, which is rapidly becoming as scarce as snowpack in the mountains. (Parts of the San Joaquin Valley have sunk more than islands in the Delta.) Every problem makes every other problem worse.
People who don’t know much about water tend to suggest the same handful of remedies for California’s difficulties. One is to build a big pipeline from Oregon or Washington. (“Wouldn’t have to be that big,” Donald Trump told me during a telephone conversation, in 2015. “A lot of water would come down, I can tell you that. They have nothing but water.”) Another is desalination. (During the same conversation, Trump said, “Or you could do something with the sea, with the—what do they call it?”) Another is to prevent the Sacramento and other rivers from reaching the ocean. (In a speech to farmers in Fresno in 2016, Trump ridiculed environmentalists for “taking the water and shoving it out to sea.”) Another is to build new reservoirs or enlarge existing ones. (In a speech in 2020, Trump promised “a lot of water, a lot of dam, a lot of everything,” in part via a proposal to raise Shasta Dam, at the top of the Sacramento’s watershed, by eighteen and a half feet.)
Moving water over mountain ranges involves a huge amount of disruptive infrastructure, including reservoirs, pumping stations, tunnels, and hundreds of miles of aqueducts—and anything like the pipeline Trump proposed would require not only many billions of dollars in federal and state funding but also the support of voters in two, if not three, states. The largest ocean-water desalination plant in the country is in Carlsbad, California. (It supplies drinking water to part of San Diego County.) Desalination is energy-intensive; replacing Delta water entirely with desalinated ocean water would require the construction of many dozens of Carlsbad-size plants, plus enough new power generation to supply them. Trump isn’t the only politician who has ever believed that allowing rivers to flow into oceans is stupid. Herbert Hoover, in 1926, said, “Every drop of water that runs to the sea without yielding its full commercial returns to the nation is an economic waste.” Human needs aside, coastal ecosystems depend on inflows of fresh water. A good example is the Sea of Cortez, at the northern end of the Gulf of California. It’s the natural outlet of the Colorado River, but the Colorado is so overdrawn that it has reached it only once in the past two decades, and even then only in a relative trickle. The Colorado’s natural delta, in northern Mexico, which used to be a two-million-acre wetland, is now almost entirely a desert.
In March, the Environmental Protection Agency approved $2.2 billion in financing for a new off-stream reservoir about seventy miles from Sacramento. The stated purpose of the project—which was first proposed in the nineteen-eighties—is to store Sacramento River water during wet years and release it during dry ones. Even if the reservoir gets built, it’s unlikely to change much. As I heard Lund say to someone else, “There are fifteen hundred reservoirs in California right now. If you build a new one, you will be building it in the fifteen-hundred-and-first best location.” A better, cheaper idea might be to store water in the ground, by recharging depleted aquifers, a technique that southern Nevada and Arizona have used successfully for years—but you can’t store water you don’t have. The real problem in California and the rest of the West isn’t a shortage of water storage; it’s a shortage of water.
One morning in Sacramento, I had breakfast at the downtown Holiday Inn with Michael George, whose title is Delta watermaster. His position was created by the state legislature in 2009, as part of the Delta Reform Act—which doesn’t appear to have reformed much yet—and he’s now in the fourth year of his second four-year term. His responsibility, according to a state Web site, is “overseeing the day-to-day administration of water rights,” a job for which he was prepared by all his previous occupations: water lawyer, water-company C.E.O., public-utility executive, investment banker, college guest lecturer. His principal function as watermaster, though, has usually been as a mediator and facilitator. “The biggest shortage in the water system in California is trust,” he told me.
George believes that, because of the water issues, there’s no alternative to fallowing large amounts of farmland in the San Joaquin Valley. Urbanites will have to cut back, too—the vegetation that most Angelenos think of as the natural flora of their delightful region, including the palm and citrus trees, is both irrigation-dependent and non-native—but the only way to make truly meaningful reductions is to limit water use by agriculture. If that happens, it would be hard on farming communities (and on those of us who, at least occasionally, try to eat the way Michael Pollan and Alice Waters say we should), but the monetary impact within the state would be smaller than most people might guess, since agriculture accounts for no more than about two per cent of California’s economy. George also believes that conservationists need to be realistic about which Delta species can be saved and which can’t, and that salmon, for example, are better candidates for preservation than smelt. In other words, any credible plan for the Delta will entail significant losses by all parties, the nonhuman ones included.
All of these notions provoke angry reactions in one quarter or another, and none of them is easy to build a public campaign around. But George, when he talks about them, sounds almost optimistic. “Nobody believes in durable solutions,” he told me. “And I think that’s great because as soon as you conclude that there’s no silver bullet, and that no one thing that will save you, then maybe you will be willing to negotiate temporary solutions with people you hate and have hated for generations. Because, unless you can get together with those people, everyone is cooked.”
During a drive along the southern and eastern parts of the Delta, I saw a house whose owners had created a terraced garden and sitting area by digging into the levee directly outside their back door—a potentially catastrophic home improvement, and not just for them. After breakfast with me, George was going to look into a similar issue, at the edge of a mostly middle-class suburb called the Pocket, five miles from downtown. The Pocket lies directly across the Sacramento from the northwestern tip of the Delta, and the river semi-encircles it. It’s especially vulnerable to flooding, because the shortest path from upstream to downstream during high water is through the neighborhoods. A group of homeless people had built an encampment by digging into the side of the levee facing the river. In any flood, the encampment would be washed away, and, because of the weakened levee, the houses on the inland side would be in danger, too. (Every problem makes every other problem worse.) George, who had first noticed the encampment from his boat, was going to investigate, and try to explain.