North of Sacramento, Calif., there are vast tracts of housing developments on agricultural land, surrounded by rivers and protected by levees. Many of the homeowners who bought there in recent years are finding out that their homes may not be as safe as they thought.
A few decades ago the neighborhood of Natomas was all rice fields surrounded by massive rivers. Now it's urban, with 80,000 residents, chain restaurants and subdivisions for miles. And the Federal Emergency Management Agency is now in the process of reclassifying the neighborhood as a Special Flood Hazard Area.
Standing on a levee overlooking a sea of rooftops, John Hess of the Army Corps of Engineers said new studies have found the levees here are more vulnerable than originally thought.
"It's a deep basin, meaning flood waters — should they get into the Natomas area — could be up to 25 feet deep on the southern end," Hess said. "If there were the breach of a levee there's going to be a lot of water going into this area."
Alex Dewey and his family live in Natomas, in a house with a giant American flag out front.
"Right now I don't trust the city of Sacramento," Dewey said. "I don't trust them at all."
Dewey said he can't understand why the city would allow so many homes to be built in an area at risk of flooding. And he said he didn't learn about the risk until six months ago, when news spread that the Army Corps was pulling its certification of the levees.
Dewey described how he got the news and how he reacted:
"'Oh, by the way guys, you're in the flood zone, welcome,'" he said. "I'm like, 'Wow. Wait a minute.' I went back to my escrow papers and it said, 'You're not in the flood zone,' but in small print it said 'FEMA can change the zoning.'"
Dewey just recently bought flood insurance. But before Hurricane Katrina put the spotlight on flood risk, just 10 percent of homes in his neighborhood were covered by flood insurance. Now it's 25 percent.
Ron Stork, an advocate with Friends of the River, said a whole lot of people are making a mistake.
"They actually are in God's flood plane, if not the FEMA flood plane," Stork said.
Stork said many of the worst floods in California and in the country have happened in areas shown on FEMA maps to be outside of the flood plain.
"We define a flood plain as whether or not you're in a FEMA flood plane or not — not whether or not you're in a real flood plane," he said. "Until we begin to map flood-prone areas more realistically, people will always be able to say 'I'm not in a flood plane, don't bother me.'"
FEMA officials say the reclassification of Natomas makes it likely every resident with a federally backed mortgage will have to get flood insurance at a cost of $300 a year or more.
Developers are now passing out a slick promotional DVD to make sure no future residents can say they didn't know what they were getting into. "This desirable lifestyle could be at risk if the force of nature overcomes our manmade protections," the DVD warns.
Levee improvements were made in the 1990s that cost $100 million. But the bar has moved, Sacramento City Councilman Ray Trethaway said, and the reinforcements now needed will cost four times that much.
"We're at risk, but by every measurement, the levees are stronger than they've ever been since 1911 when they were built," Trethaway said. "On the other hand, we need to make them stronger over the next three to five years."
The local flood control agency will soon ask property owners to help fund the levee improvements. For residents, it's another expensive consequence of moving to Natomas.
Tamara Keith is a reporter for member station KQED in San Francisco.