California can do more to prepare for future floods, says think tank

As Golden State farmers brace for another rainy winter, a new report is urging state officials to aggressively prepare for wet years as much as it prepares for dry ones. Climate change is expected to fuel both more extreme droughts and more winter storms. And while California has made progress in managing drought conditions, it has a long way to go in managing floods.

“This is a challenge Californians can and must rise to meet,” wrote Letitia Grenier, director of the Public Policy Institute of California’s Water Policy Center, in the report’s introduction. “Collaboration and cooperation [between stakeholders] are no longer icing on the cake: they are essential to help us respond to rapidly evolving conditions.”

The report, “Priorities for California’s Water: Stewarding the Wet Years,” analyzes state officials’ response to the chaotic series of droughts, storms, floods, and heat waves that swept through the state this year. At the beginning of 2023, most of California was still in the throes of a severe multiyear drought, and the state’s Department of Water Resources was struggling to fill its perilously low reservoirs. The drought wreaked havoc on the state’s agricultural sector, which uses about 80 percent of the water in California that’s allocated for human use.

The dry spell ended with a bang in January, when the state was inundated by nine atmospheric river storms in three weeks. “That was a wake-up call,” said Tessa Beach, the chief of planning and environmental services for the U.S. Army Corps of Engineers’ San Francisco District, who was interviewed for the report. The storms swamped communities and farmland throughout the state, fueling what the report characterizes as an “epic” snowpack in the Sierra Nevada mountains. When that snowpack melted, it fueled more historic flooding, refilling the ancestral Tulare Lake Basin for the first time in 25 years. For the state’s agricultural industry, the storms were both a godsend and a disaster. Some farmers managed to funnel the floodwater into their depleted aquifers, recharging their groundwater supplies; other stretches of farmland may remain underwater for years to come.

The report praised state officials for acting quickly to contain the floodwaters — and taking advantage of the unusually wet year. Through a series of groundwater recharge projects, the Department of Water Resources was able to capture and store about 3.8 million acre-feet of water by the middle of the summer. According to the report, most of that recharge occurred in the San Joaquin Valley, where farmers have critically overdrawn the aquifer through overpumping. The report also applauded Gov. Gavin Newsom for signing several executive orders that allowed water managers to divert water for recharge without a permit if there was an imminent threat of flooding.

Still, said the report, California has a lot of room for improvement. In many cases, water managers who considered the rainfall a reprieve from years of drought were unable to take full advantage of it. Some regions were simply unprepared to funnel the floodwater into groundwater recharge or other storage basins, and agencies did not set aside sufficient water for habitat protection. Water managers also struggled to prevent flooding, which the report attributed, in many cases, to aging or dysfunctional infrastructure and poor regional flood planning and response. Low-income communities were often swamped as flood infrastructure collapsed. Those failures bode poorly for future disasters. As the report notes, 2023 was not a particularly bad flood year by California standards.

“Everyone wants to call this event ‘unprecedented,’ but it’s not,” said Lois Henry, a longtime water journalist in the Central Valley who was interviewed for the report. “We should learn from this.”

The report urges the state to launch a “multi-decade infrastructure investment program” that focuses on funneling water to groundwater recharge sites, as well as improving flood defenses and improving regulation and permitting. It also argues that vulnerable low-income communities — as well as the state’s fragile ecosystems — should remain top priorities in wet years.