NEW BEDFORD, Mass. -- A hurricane barrier stretches 3 1/2 miles here, for years breaking storm-driven waves at a yawning river mouth as seas surge toward the smelly scallop fleet and old houses on the hill.

Now the snaking structure also threatens to break the bank. The city says it can't afford to inspect its part of the system, a move that could push the federal government to decertify the entire barrier.

Without the probing checkup, officials won't know if the guts of the fortification -- like swinging steel street gates and the earthen interior of the ocean-cutting levees -- would stand up to rising sea levels and future hurricanes, which many scientists believe are strengthening. More flooding could occur.

A severe storm hasn't spun onto the southern coast of Massachusetts in decades, softening the memories of sunken trawlers and drowned streets. Other forms of protection are urgently needed now in this hardscrabble city of 94,000 people.

"I'm fighting to keep police, firefighters, teachers serving our community," New Bedford Mayor Scott Lang said in his office. "I think everyone understands this is something we don't have the money to do."

New Bedford boasts the most lucrative seafood port in the United States, but the former whaling center still seems to be struggling to stay off the rocks. Overfishing sent the industry into decline late in the last century, and the city's marine habitat suffers from industrial pollution. Signs along the barrier warn people not to eat the fish because of contamination by polychlorinated biphenyls, or PCBs.

Hiring engineers to study the hurricane barrier could cost the city $1 million, or much more if weaknesses are found and improvements needed, said Lang, who believes the federal government should pay the city's share.

That choice is striking to some. A consultant for the Federal Emergency Management Agency (FEMA), which requires the inspection, told a group of floodplain managers in Florida this summer that the cost amounts to "nothing."

"It doesn't seem that large nowadays," said Brian Caufield, who works for the consultancy CDM.

'Homes will flood'

It's less than half of 1 percent of the city's annual budget of $282 million. On the other hand, if the structure is decertified, hundreds of residents in New Bedford and Fairhaven, a town of 16,000 on the opposite shore of the Acushnet River, could have to buy federal flood insurance.

The communities would suddenly be plunged into a new floodplain.

"You assume the structures aren't there [and] the homes will flood," Caufield said of the barrier being decertified. He told the crowd that about 2,500 homes in the two communities would be affected.

The barrier is a rare piece of infrastructure, completed 43 years ago by the Army Corps of Engineers after repeated hurricanes crushed one of the nation's leading fishing ports. Hundreds died in the storm of 1938, and tidal surges inundated the area in 1944 and 1954.

The system's backbone is a sprawling dike nearly 2 miles long that bisects the harbor. It's the domain of the Army Corps. A 150-foot opening is sealed during storms by two 440-ton doors that trundle shut on wheels 39 feet underwater. The gate, which takes some 20 minutes to close, is not held open for late-coming boat captains, who often air blasphemous radio protests to the control house.

"I don't make a lot of friends," Steven Fluegel, who runs the gate, admitted in his cement lookout, furnished with a folded cot.

Please, not a northern Katrina

Other appendages of the barrier are just as crucial. New Bedford is responsible for a dike stretching more than a mile toward land's end on a jutting peninsula. Short dikes spike perpendicularly from the main wall to prevent roiling surges from flanking the main abutment. Three armored gates, or "street-closers," swing shut to rebut the ocean.

"The gates have to shut. We don't want to see a Katrina up here," said Thomas Kennedy, 50, whose backyard is filled with one of the massive stone spurs. "It's better to spend a little money to fix something than have destruction and a travesty."

Across the harbor, Fairhaven maintains a connecting dike, extending more than a half-mile, and a sluice gate that prevents storm surges from racing up Boys Creek. The town is ready to pay for its share of the inspection, which it expects will cost about $250,000. But officials are uneasy about the findings.

"What happens if we get the study back and it says the barrier won't withstand a category 3 hurricane?" worried Brian Bowcock, chairman of the Fairhaven selectboard.

Water will find a way in

This is a team effort. If one of the three owners of the system -- New Bedford, Fairhaven and the Army Corps -- fails to conduct its inspection, the entire barrier could be decertified. The deadline is next year.

"The system is only as good as the weakest link," said Scott Michalak, who runs the corps's levee safety program in New England. "If New Bedford doesn't close its street-closer, then the possibility is that the ocean is going to come in through the open area."

That could make the barrier a hazard. If portions of the system stop operating, angry seas could pour through an open gate and be trapped behind the structure. Flooding could be worse than if the communities had no protection.

"You don't want to think about that," said Fluegel, who operates the harbor gate.

The inspection coincides with an aggressive effort by FEMA to check the strength of levees around the country, following the failure of New Orleans' flood control walls during Hurricane Katrina. About 120 structures are known to be deficient, according to a list placed in the Congressional Record by Sen. Chris Dodd (D-Conn.) in 2007.

Overall, the certification process is used to establish flood insurance premiums. The floodplain could be smaller or larger, depending on the amount of water a structure can hold back. That affects the number of homes that have to buy insurance, and its price.

There is a push in Congress to expand the use of flood insurance behind levees, which can give people a false sense of security. That means more people could be financially protected from damaging floods, but it also highlights controversial aspects of the federal insurance program.

Forget inspections; the true test is a storm

Critics say the program encourages development in vulnerable areas, even as seas rise and scientists predict that storms will become more muscular as atmospheric greenhouse gas levels increase. This can be especially true in areas behind barriers like the one in New Bedford.

If the structure there is not recertified, hundreds of homes would be placed in the federal insurance program, even though they're positioned along a risky coastline predisposed to flooding. Many of them would receive subsidized insurance, despite not meeting modern building standards that could minimize flood damage.

Homes in areas that are known to flood often are considered "repetitive loss" properties. Here's the cyclic scenario: Damage occurs, federal insurance pays to rebuild, and damage and claims occur again. By 2005, there were 111,000 of these properties in the program, accounting for 38 percent of its claims, according to David Conrad, a senior water resources specialist with the National Wildlife Federation.

Moreover, FEMA may be underestimating the frequency with which areas will be flooded, he says.

"As climate is changing, Mother Nature feels no obligation to stay within our engineers' calculations," Conrad added. "That is especially problematic when flood control systems have been based upon the minimum standard, which many today believe is too low."

Behind the hurricane barrier in Massachusetts, folks are more concerned about the strength of their stone and steel defenses. Talk of flood policies and maps is for Washington.

So is the aging structure able to withstand a pummeling storm?

"You're never gonna know until you have that hurricane," said Jeffrey Osuch, Fairhaven's executive secretary.