The neighborhood grid of overgrown avenues still appears on Google Maps.

But most of the houses were bought and demolished decades ago by the chemical giant Rohm & Haas, whose Bristol Township plant sat nearby.

Only four houses remain on this secluded speck of land known as Maple Beach, along the Delaware River and the shadow of the Burlington-Bristol Bridge. All occupied, they are now imperiled, too.

Dow Chemical, which bought Rohm & Haas in 2008, has stopped maintaining to federal standards an 80-year-old levee it owns on the river as it has scaled back operations. The earthen berm protects the four houses and a few hundred undeveloped acres behind them.

Dow's decision will likely force property owners there with mortgages - now or in the future - to buy expensive flood insurance, a predicament that often erodes property values. It also threatens the financially struggling township's hopes to develop its last swath of open space and generate much-needed tax revenue.

"This is just Dow Chemical being a very bad corporate citizen," Bristol Township Solicitor Randy Flager said. "This is the way you behave if you don't care about the community."

Dow says the levee can still prevent flooding, although it has lost federal accreditation. And the company has not written off the possibility of seeking federal approval or of developing the land.

Meanwhile, homeowners such as John Delancey worry about property values falling.

"Dow is like that large homeowner in the neighborhood who has to maintain his property," said Delancey, whose Maple Beach house has been in his family for more than 70 years. "They're responsible because they're our neighbor."

Variations of this dispute have played out across the country as the federal government redraws flood maps and checks the quality of the nation's levees. And it is not just corporations that have let accreditation slip away.

In 2011, the Congressional Research Service reported many of the nation's levee owners, private and public, had struggled with the cost of following federal guidelines, which require them to prove periodically the levees can withstand a major flood.

Carver City, Minn., along the Minnesota River, decided in the fall the $12 million in repairs its levees needed to maintain federal approval was too much, at least in the short term. Many homeowners in the center of the historic town will be forced to buy high-risk flood insurance for the first time.

Such insurance, depending on a variety of factors, most often costs hundreds to thousands of dollars per year.

A levee along the Allegheny River in Coudersport, Pa., in Potter County was in danger of losing federal certification, too, potentially affecting more than 100 houses. But it was rescued with a $450,000 state grant last year.

Just like heaven

It is unclear what defects, if any, plague Dow's levee in Bristol Township or what the cost of maintaining accreditation would be. Dow has declined to comment.

The company said in an e-mail federal regulations required certification of the levee decades ago to protect tanks storing hazardous materials. But the tanks were removed in 2004, eliminating the need to maintain the berm to federal standards. The Federal Emergency Management Agency said the company simply chose not to seek federal approval.

Rohm & Haas's history on Maple Beach dates to 1917. The company built the levee in 1931, improving it over the years while buying up and demolishing almost all the houses on the neighborhood's nine roads, leaving only the four that remain.

Brad Nickerson, who owns one, called the area "heaven," a place where he can drink a beer and watch ships on the Delaware and deer play in the wooded wetlands behind his house.

Because he has a mortgage, he is concerned about having to buy flood insurance. He said he also pays a lot in property taxes to Bristol Township and would like to see the land around him developed. The municipality is struggling with a mostly residential tax base that is burdened by nearly $100 million in unfunded pension and medical liabilities for employees.

Dow has tried to sell some of the land, and almost signed a deal last year with a private equity firm to create wetlands on about 400 acres. But the township blocked the plan because it would have generated little tax revenue. Dow said it was working with the Heritage Conservancy to preserve about 80 acres and said it remains open to economic development.

But the township says development requires a federally accredited levee.

"If Dow is going to make the land worthless, maybe it should just give it to Bristol Township," Flager said.