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California’s next flood could destroy one of its most diverse cities. Will lawmakers try to save it?

Climate change could submerge Stockton beneath 10 feet of water. The city's aging levees aren't prepared


By Jake Bittle - Grist

In early 1862, a storm of biblical proportions struck California, dropping more than 120 inches of rain and snow on the state over two months. The entire state flooded, but nowhere was the deluge worse than in the Central Valley, a gash of fertile land that runs down the middle of the state between two mountain ranges. In the spring, as melting snow mixed with torrential rain, the valley transformed into “a perfect sea,” as one observer put it, vanishing beneath 30 feet of water that poured from the Sacramento and San Joaquin Rivers. People rowed through town streets on canoes. A quarter of all the cows in the state drowned. It took months for the water to drain out.


More than 150 years later, climate scientists say the state is due for a repeat of that massive storm. A growing body of research has found that global warming is increasing the likelihood of a monster storm that could inundate the Central Valley once again, causing what one study from UCLA and the National Atmospheric Center called “historically unprecedented surface runoff” in the region. Not only would this runoff destroy thousands of homes, it would also ravage a region that serves as the nation’s foremost agricultural breadbasket. The study found that global warming has already increased the likelihood of such a storm by 234 percent.


In the crosshairs of that storm is the Stockton metropolitan area, which sits at the mouth of the San Joaquin River. Stockton and its neighboring suburbs are home to almost 800,000 people, and they rank among the most diverse places in the country — as well as some of the most economically distressed places in California. Thanks to decades of disinvestment, the city’s only flood protection comes from decades-old, leak-prone levees. If a major rain event caused enough runoff to surge down the mountains and northward along the San Joaquin, it could burst through those levees, inundating the city and flooding tens of thousands of homes. One federal study found that much of Stockton would vanish beneath 10 to 12 feet of water, and floods in the lowest-lying areas could be twice as deep. The result would be a humanitarian disaster just as costly and as deadly as Hurricane Katrina.


The “atmospheric river” rainstorms that rolled into California from the Pacific Ocean this month have underscored the Golden State’s vulnerability to floods, but experts insist that the destruction of Stockton isn’t inevitable. As is the case in flood-prone communities across the country, local officials know how to manage water on the San Joaquin River, but they’ve struggled to obtain funding for Stockton and other disadvantaged cities along the waterway. Even as California lawmakers have plowed money into drought response in recent years, they’ve left flood measures by the wayside, and the federal government has also been slow to fund major improvements.


“Areas like Stockton that don’t have political clout … often get bypassed terms of consideration for funding,” said Mike Machado, a former California state senator who has long advocated for better flood management in the Central Valley. “Even if any funding is available, Stockton is usually at the bottom of the list.”


Even as Stockton’s infrastructure decays, the city’s flood risk is only increasing thanks to climate change, which will cause more severe rains in the San Joaquin Valley and further stress the city’s levees. The city has grown at a rapid pace over the past two decades, but state and local officials have been more focused on protecting local agricultural irrigators from drought than on protecting the city’s residents from flooding. When the next big storm hits, it is Stockton’s communities of color, which make up more than 80 percent of the city’s population, that will see the worst of the damage.


“We are at the bottom of the bowl,” said Barbara Barrigan-Parrilla, the executive director of Restore the Delta, a Stockton-based environmental nonprofit. “We’re the drain. And they don’t value us.”


The Central Valley’s flood protection system has never been equal. During the nineteenth and early twentieth centuries, farmers and ranchers constructed a hodgepodge of levees along rivers like the San Joaquin, piling sand only high enough so that water would flood someone else’s land rather than their own. The levees were owned and maintained by local districts, rather than any centralized governing body, so wealthier areas ended up with stronger defenses.


As the region’s flood protection system expanded, the San Joaquin region fell behind. To protect the state capital of Sacramento in the 1920s, the federal Army Corps of Engineers built a diversion system called the Yolo Bypass that funnels water away from the city, but Stockton never saw any similar investment. Local authorities couldn’t raise as much money to bolster levees as their counterparts around Sacramento, and money from the state and the federal government never filled the gap.


This is in part because lawmakers have overlooked Stockton’s vulnerable populations, according to Jane Dolan, president of the Central Valley Flood Protection Board, a state agency that oversees flood management. But Dolan says the disparity also exists because leaders along the San Joaquin River have long tended to focus more on securing water for agricultural irrigation than on managing the rivers, which has made it hard to secure momentum for big flood improvements.


“They don’t have that consensus about managing floodwaters and allowing space for the river,” she told Grist. “Politicians from city councils to Congress are all focused on water supply.”


Not only does the San Joaquin have the shoddiest flood protection infrastructure, but it also faces the greatest degree of risk from climate-fueled storms. Both the UCLA study and a separate study by Dolan’s organization found that warmer climates will increase runoff in the San Joaquin watershed by more than they will in the Sacramento watershed — in large part because higher temperatures will cause what used to be snow to fall as rain instead. Furthermore, Stockton faces flood risk from all sides: Not only does the San Joaquin River flood during rain events, but the Calaveras River on the city’s north side does as well.


Water from the Pacific Ocean could even flood the city from the west during high tides as it pushes across a long flat expanse known as the Delta.


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