After big natural disasters like Hurricanes Harvey and Irma, federal officials often tighten up flood protection standards. That’s what happened in California after Hurricane Katrina twelve years ago.

But many flood-prone communities are still struggling to meet those standards, including Sacramento, one of the riskiest flood zones in the country.

Some residents there nervously watched as the floodwaters rose in Houston.

“One of our friends actually had to be evacuated out of the Woodlands,” says Cynthia Hextell of Natomas, a suburb north of downtown Sacramento.

A levee breach in Natomas would potentially flood the entire area.

“That definitely was a reality check,” she says. “You’re thinking: could that happen? Because I’m sure the people in Houston didn’t think it could happen to them.”

Hextell knows how people do—and don’t—think about risk. She’s also a realtor in Natomas, where rows of tidy housing developments have been springing up since the early 2000s.

“There is such a demand up here,” she says. “In the past month, I’ve probably helped six families move up from the Bay Area.”

But flood risk generally isn’t on the minds of potential buyers.

“Never,” Hextell says. “I have never had that come up.”

But the only thing keeping Natomas homes dry is a ring of levees, 42-miles around. The homes are built in a low-lying area surrounded by rivers and canals.

“During a flood event, the flood depth would be 10- to-25 feet,” says Jim McDonald, a principal planner for the City of Sacramento.

Sacramento doesn’t have hurricanes to worry about. Instead, it’s the huge winter storms that hit the Sierra Nevada.

The city was built at the confluence of the Sacramento and American Rivers, which drain a watershed the size of West Virginia. More than a century ago, it used to become an inland sea during really wet years.

The aging levees, built with river sediment or fill, aren’t in great shape.

“We realized a lot of the city didn’t have 100-year flood protection once we took another look at our levees,” says McDonald.

After Hurricane Katrina, federal flood planners tightened up the standards for levees, making them safer. That meant Natomas was no longer up to par.

Federal rules require 100-year flood protection, which is a storm that has a 1-in-100 chance of happening every year, or a 26 percent chance cumulatively over a 30-year mortgage.

Natomas was only rated for a 33-year storm.

“So there was a de facto building moratorium since 2008,” McDonald says. No new construction was permitted.

“It’s pretty scary when you think about it,” says Rick Johnson, director of the Sacramento Area Flood Control Agency. “We have over a hundred thousand people living out there.”

Natomas, a suburb in Sacramento, sits in a low-lying area protected only by levees. (Paul Hames/California Department of Water Resources)

New Orleans used to top the list of American cities most at risk from river flooding.

“They’ve rebuilt New Orleans to the point where their level of protection is higher that ours right now,” he says. “So we’re the most at-risk community in the country.”

Protecting the whole city will cost $4.4 billion and take nearly a decade more, with $1 billion to spend in Natomas alone. But money from Congress has been slow.

“They were for a while doing authorizations for water acts every two
years,” he says. “But after 2007 they didn’t do another one until 2014.”

Johnson says even now, there’s a lot of competition for those dollars. Sacramento has to fight for a share every year.

So the city decided to start construction before any federal funds came in by using state money and by taxing local residents. An average homeowner pays about $75 a year in local taxes, depending on the home’s size and location.

“We’re trying to get the worst parts done first,” Johnson says. “I’m glad we went ahead, because if not, we’d just be getting started right now.”

The city has completed about 18 miles of levee improvements in Natomas so far. In 2015, the federal government declared that enough work had been done to lift the building moratorium.

“The federal government has become an unreliable partner,” says Jeffrey Mount, a flood expert at the Public Policy Institute of California.

He says communities are starting to tax themselves to pay for flood improvements, but that creates a bizarre incentive to keep growing their tax base.

“Do they stop growing?” he says. “Well, if they stop growing, you can’t pay for new infrastructure. So you’re caught in this cycle where you need to put people at risk in order to reduce risk, to pay for the reduction in risk. And we know how that ends. Badly.”

Mount says Sacramento is doing something right: elected leaders have stayed focused on the problem and the city is going for 250-to-300-year storm protection, higher than the federal standard.

After Katrina, California officials required urban areas to have 200-year storm protection.

“But here’s the fundamental problem: what Harvey revealed for us is that our flood defenses will eventually be overrun,” Mount says.

Hurricane Harvey was a 1,000-year storm, if not greater. With a warming climate, the risk is changing because storms could be more intense.

In all, more than a million people live and work in floodplains in California. So, a lot of communities are ultimately relying on what Mount calls the Clint Eastwood approach to flood management.

“Hope we get lucky,” he says. “You feel lucky, punk?”

California Cities Will Flood, So Why Aren’t We Ready? 14 October,2017Lauren Sommer

  • Student

    We need to build more housing. Given levees, rivers, earthquakes, fire, existing cities, the voting public, and transit corridors, where should we build it? And, what should we do to prepare our existing housing stock for earthquakes and floods?

Author

Lauren Sommer

Lauren is a radio reporter covering environment, water, and energy for KQED Science. As part of her day job, she has scaled Sierra Nevada peaks, run from charging elephant seals, and desperately tried to get her sea legs – all in pursuit of good radio. Her work has appeared on Marketplace, Living on Earth, Science Friday and NPR’s Morning Edition and All Things Considered. You can find her on Twitter at @lesommer.

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