California Coast & Ocean

That calculation rattles Saphon Hok, a young research scientist who bought a home at Mossdale Landing two years ago. He was not pleased to learn that if FEMA puts Mossdale within the flood zone, he and other local homeowners with federally backed mortgages will be required to buy flood insurance. Flood insurance, which only provides home coverage to a maximum of $250,000, can cost $1,400 to $4,600 a year, according to FEMA. Being in the flood zone could also affect a home's value.

"My wife and I are here for the long term, so we bought a house to live in, not get a return," Hok said. "But I would be concerned if we have to pay extra money for insurance."

Hok moved to Mossdale because he and his wife could not afford to buy in Livermore, where he got a job after graduating from U.C. Davis. Having almost drowned in a flood in Cambodia when he was five years old (his sister plucked him out), he is conscious of the power of large bodies of water. Before buying, he was aware the Delta was vulnerable to flooding, but, he said with a frown, "We took the risk anyway. And let us assume there won't be any flooding in our lifetime."

Although Mossdale has not flooded seriously to date, it is across the San Joaquin River from land flooded in 1997. That giant flood exposed seepage problems in the levee protecting the Mossdale community. In 2002, the U.S. Army Corps of Engineers wrote to the Lathrop City Council expressing concern at the plan to build homes in Mossdale. The Corps asked for new drains and new engineering work to bring the levee to a higher standard. Lathrop fixed the drains. But as for the engineering work, the Council merely replied that the levee met the federal 100-year standard (albeit from 1989) and left it at that.

John Cain, of the Natural Heritage Institute, said plans for another 11,000 homes in a development called River Islands just across the San Joaquin River could leave Mossdale even more vulnerable. River Islands will be protected by "super levees" along the river. Cain said this could increase the pressure on Mossdale's aging levees on the other side if the river floods. Lathrop City Council spokesman Mike Esau commented, "Our experts say to their knowledge [the River Islands levees] do not appear to represent a threat at all."

Council spokesman Esau and Bruce Myers, a vice president with Mossdale's master developer, Pacific Union Homes, both said in telephone interviews that the levees and the project met all the required standards when the development was approved by Lathrop.

All of this debate was news to Matt Kan, who was peacefully fishing on the river, just over the levee from his Mossdale home on a sunny day in early June. Putting down his rod, Kan said a flood would "be a disaster" for him. He explained that he and his family, including two children, live with relatives during the week in San Jose, where he works as an engineering manager. They could not afford their own home in San Jose, so they bought in Mossdale and stay there each weekend. It is great for the kids, he said.

"It's a place for them to grow. Everything here is brand new. The school is new. The neighborhood is brand new. People are brand new. It's a way of looking at a fresh start for my family and myself," he said.