The state has no consistent mandate. Most of the state’s more than 20,000 miles of flood banks and channels are operated by local governments, and many miles are on unregulated private land. Levees under the Federal Emergency Management Agency must protect against a 100-year flood or a 1% chance of one occurring in any given year.
Put in terms of a common homeowner’s 30-year mortgage, there’s a 1-in-4 chance a house will flood during that time with that level of protection. The storms of the future only increase that probability due to the ongoing effects of climate change, Mount said, adding that “most places don’t even have a 100-year level of protection.”
The extreme storms of the future will likely be much wetter than Californians experienced this winter. Daniel Swain, climate scientist at UCLA, said the storms that burst over California this winter were half as bad in total rain and snowfall as the megastorms predicted in the years to come.
“As disruptive as [the storms] have been, they are nowhere near close to the plausible worst-case scenario,” he said. “We’ve gotten a taste of what widespread flooding is this winter, but I do think it’s only a taste.”
On March 18, 2023, vehicles were submerged in floodwaters on Avenue 56 near the Central Valley Highway, a few miles north of Allensworth, where residents fortified the levee protecting their neighborhood. (Robert Gauthier/Los Angeles Times via Getty Images)
A perfect time for a big water rethink
As floodwaters recede, Mount and Brett Sanders, his peer at UC Irvine, said this is the perfect time to rethink and update the state’s aging infrastructure to accommodate the future climate. Fewer than 10% of levees in the greater Bay Area have a federal risk rating, according to a KQED analysis of the National Levee Database.
“The recent California storms showed us pretty clearly there’s a lot at risk and systems we think are there to protect us may not perform as we expect,” said Sanders, an engineering professor, of levees across the Central Valley and Central Coast that failed during winter storms.
But a switch to a higher level of protection must start with conversations locally with the people most affected by flooding, Sanders said.
“Those at risk should be involved in the planning process,” he said. “What we’ve tended to see in the past are projects designed by those with greater resources.”
Sanders said because no mound of dirt is designed to protect a community completely, legislation should include funding to ensure that when a levee fails or is overtopped, the people, regardless of socioeconomic status, have immediate access to resources.
“There will always be floods that are beyond the capacity of systems,” he said. “So, are we doing what we need to do to protect even those that aren’t protected?”
Increasing levee protections is a climate justice issue, say advocates
The levee that burst in March near Pajaro in Monterey County, temporarily displacing thousands of people, was built to protect the area from storms at about an eight-year frequency. A future levee there is limited in its protective scope to the 1-in-100-year storm.
“Nobody is fully grasping what is in store in terms of climate impacts,” said Nancy Faulstich, executive director of Regeneración, Pájaro Valley Climate Action. “We’re not prepared, and the expense of accommodating ever-increasing levels of damage from ever-increasing storms will be astronomical.”
A small or medium-sized storm could overwhelm the system as it is today, said Mark Strudley, executive director for the Pajaro Regional Flood Management Agency.
“The bottom line is it needs to be built very quickly,” he said.
Officials are supposed to break ground on a levee upgrade as soon as next year, a project jointly funded by local, state and federal governments that would bring the levee up to a 1-in-100-year storm protection. But it will take about a decade to build.
This aerial view shows the broken levee in Pajaro on March 13, 2023.
Strudley said that altering the more-than-$500-million project with more protections would take years and, in the meantime, keep this lower-income community in the path of floodwaters.
“It has been a real struggle to get this project developed,” he said. “Another more affluent community would have had a higher prioritization in terms of funding just by virtue of higher property values.”
In some areas the levee will be built wider and, in other parts, taller to withstand more water.
“There’s not a tremendous benefit to the community by further delaying the process by trying to get a 200-year-level protection,” he said. “What’s important to us is to protect against climate change but also to simply build this project that we have in front of us right now because it affords that protection.”
The levee project is designed for a wide range of flooding scenarios, said Stu Townsley, U.S. Army Corps of Engineers deputy district engineer for project management for the San Francisco region.
“There’s no way that you can build a levee system that will protect any community from the biggest of big storms in the future,” he said. “It’s just financially and, in many cases, physically infeasible.”
He said even the small storms of the future could cause anyone living in a floodplain “to get wet.”
But for Sonia Mohnot, director of climate equity and climate resilience for the policy and advocacy group The Greenlining Institute, not building the Pajaro levee to withstand the extreme storms of the future only increases the likelihood of the inevitable: another disastrous flood.
“It’s a climate justice issue to protect a community from storms, period, especially the larger storms,” she said. “If this is the opportunity to protect the people, then I would want it to be protected to the maximum extent possible.”
An aerial view shows homes underwater after levee fails in Manteca of San Joaquin County on March 21, 2023. (Tayfun Coskun/Anadolu Agency via Getty Images)
The Legislature has failed to bolster flood protections statewide before
The state Legislature has the power to bolster flood protections, but it will take bold moves. Mount said he is unaware of any effort by state lawmakers to raise the standard, even as a rapidly warming state has had to shell out billions of dollars in flood damages this winter.
“I would love to see a long-range look on the part of the Legislature, which acknowledges climate change and its increasing risk, basically by setting a [new] standard statewide,” he said. But he doesn’t expect it.
“It’s terrible to say, but I don’t think we had enough damage this year,” he said. “I don’t know if it was enough to get the Legislature off the dime on this to begin to act on it.”
Back in the early aughts, during the Schwarzenegger administration, legislators pushed to double the federal standard for most non-federal levees across California to protect against future climate woes.
“It was prescient. Nobody else was doing that,” said Mount. “Urban areas just hated it because it was going to be expensive.”
“The South Coast and Bay Area folks went nuts because their systems as they’re designed would have to be completely overhauled,” he said. “We’re talking many billions of dollars to do such a thing and they didn’t want to be saddled with that.”
