California is on the forefront of a new wave of flood risk management that centers on natural engineering over structural
The Tuolumne and San Joaquin rivers meet on the edge of the Dos Rios Ranch Preserve in Modesto, Calif., Wednesday, Feb. 16, 2022. The 2,100-acre preserve is California's largest floodplain restoration project, designed to give the rivers room to breath and restore traditional riparian habitats. MODESTO, Calif.
The state wants to fund and prioritize similar projects that lower risks to homes and property while providing other benefits, like boosting habitats, improving water quality and potentially recharging depleted groundwater supplies. By notching or removing levees, swelling rivers can flow onto land that no longer needs to be kept dry.
A flood in the 1860s demonstrates the potential for disaster; up to 6,000 square miles of the valley were submerged. As the state's population rapidly expanded and farming boomed through the 20th century, the government engineered vast systems to move water around to supply people and farms, and erected levees to protect cities and crops.
California officials began centralizing valley flood planning a decade ago. Though some of the worst and most notable floods in recent decades have occurred in places like Houston and New Orleans, parts of California are at serious risk that's only expected to increase due to climate change. In 1997, major storms caused levees to break throughout the valley, including on the Tuolumne River, causing nearly $2 billion in damage and destroying more than 20,000 homes. Nine people died.
“Dos Rios is an amazing example, but we need like 30 more of those,” said Jane Dolan, chair of the Central Valley Flood Protection Board.