TOPSAIL BEACH, N.C. -- More than 40 years ago, M.A. Boryk and some friends bought about two dozen acres of land on the southern tip of Topsail Island, a long slip of sand off the North Carolina coast. As the decades passed, nature gave them a lot more.

Waves, wind and ocean currents -- the forces that create and constantly resculpt such barrier islands -- deposited sand at the point owned by the Boryk partners, adding to their plot. The buyers and their families became wealthy by selling and building homes on beachfront property. Now they are fighting to keep their right to develop another 125 acres of land that rose out of the sea.

In the wake of Hurricane Katrina and other recent storms, an increasing number of people want to stop or slow development on barrier islands, basically long sand banks that run parallel to the mainland. Their argument: Building houses, bridges and roads on the islands wastes tax money, because the structures get rebuilt so often after big storms. In addition, some scientists worry that shifting sand and dredging channels to build and maintain homes prevents the islands from growing as high as they could, and interferes with their natural movement. Both damage the islands' ability to protect the mainland from future big storms.

Topsail, a former U.S. military missile-testing site, offers a textbook case. Even as the Atlantic Ocean was creating more beach at Topsail's southern tip, the same storms and currents were eroding the northern end of the island, about 20 miles away. That erosion was accelerated by dredging in the channel between Topsail and an adjacent island. When storms hit, bridges were buried, some houses and roads had to be rebuilt repeatedly and others were put permanently under water.

"The more we know about it, it's like living in California and building on an earthquake fault line. At what point does recent knowledge figure in?" says Maggie Chesnutt. A retired elementary-school teacher from Southern California, she lives in Topsail Beach and is leading local opposition to construction on the Boryk partners' land. This year, town planners attempted to declare the property a permanent preserve.

The heirs to Mr. Boryk think they should be able to do what they want with their land, known locally as Serenity Point. "We know that it's a fragile area, and the Lord gives and the Lord takes away," says the late Mr. Boryk's daughter, Annette Oppegaard, a 62-year-old elementary-school librarian. "But if someone gave you something, you would probably want to use it to do what's best for your children and grandchildren."

Real-estate agents estimate the value of the land at Serenity Point, which includes a mile of beachfront property, to be as much as $30 million. Mrs. Oppegaard imagines building a few dozen nice homes on it, with a boardwalk and nature park.

More than a thousand miles of the southeastern and Gulf of Mexico state coasts are lined with offshore barrier systems similar to Topsail, where a ridge of dunes and beach is separated from the mainland by wide expanses of shallow marsh. When storms slam ashore, the sand and wetlands act as natural shock absorbers. Dunes blunt the energy of tidal surges pushed by high winds. Grassy marshes and their spongy soils then soak up floodwater and slow down storm-waves before they hit mainland towns and farmland.

Many scientists believe man-made deterioration of Louisiana's coastal marshes over the past 70 years contributed to the catastrophic effects of Katrina when it made landfall south of New Orleans in August. They believe marshland that had disappeared would have absorbed much of the water that overwhelmed the region's flood defenses.

"There are a lot of lessons to be learned in what Louisiana is going through for every coastal community in the United States," says Robert Twilley, a coastal ecosystem scientist at Louisiana State University, who grew up in North Carolina. "Both Louisiana and North Carolina are going to have to deal with our concept of how we control nature."

The federal government, which used Topsail as a military missile-testing site until after World War II, concluded in 1982 that seven miles of shore along the northern end of the island were so unstable that structures should never have been built there. The federal government then refused to provide those areas with subsidies toward roads, flood protection or beach renourishment projects.

But curbing development of beachfront property, especially when land owners have explicit rights, isn't easy.

Tens of thousands of homes were built on barrier islands like Topsail from the late 1960s to the 1980s, when hurricanes hit the U.S. less frequently, and economic and population growth was exploding in such hurricane-zone states as Florida, Georgia and the Carolinas. Federal flood insurance was -- and remains -- available by law for most island homes. That still applies for most of Topsail. Hurricane disasters generally provoked sympathy for homeowners who lost homes, rather than political action against redevelopment.

Politicians saw the construction boom on the Carolina coasts as important economic development, and taxpayers subsidized it generously. Federal flood insurance has paid more than $500 million to repair hurricane damage in North Carolina since 1996. Builders have put up thousands of homes since hurricanes Fran in 1996 and Floyd in 1997, making the area one of the fastest-growing in the South.

Meteorologists now say a cycle of more frequent hurricanes began in the mid-1990s and is likely to continue for at least another decade. With the combination of mushrooming coastal construction and deteriorating natural barriers, the storms are more likely to hit areas of heavy development, scientists and environmental activists say.

During Congressional hearings last month in Washington, D.C., scientists, taxpayer groups and lawmakers questioned whether federal flood insurance should be used to rebuild hurricane-prone barrier islands. They cited Dauphin Island, Ala., which has been wrecked by storms four times in the past decade. Katrina cut a mile-wide breach in the island's western tip and destroyed more than 200 vacation homes. Some had just been rebuilt after last year's storms.

Much of the sinking northern tip of Topsail is habitable today only because state and local governments spent millions of tax dollars to reconstruct roads and infrastructure there after hurricanes Fran and Floyd. Fishermen avoid the area because formerly waterfront houses now are submerged in the New River Inlet. Their roofs and porches snag fishing lines and nets.

When Hurricane Ophelia grazed the eastern seaboard of the U.S. in September, it cut deep rivulets in the north end of Topsail and left condemned buildings perched over the surf. The storm scoured sand from eight miles of dunes and caused millions of dollars in damage.

At Serenity Point, waves rolled harmlessly over the verdant tableau, depositing a fresh coating of sand on low-lying land but never reaching homes and streets.

Geologists say Topsail's movement has been exacerbated by quarterly dredging by the U.S. Army Corps of Engineers in New River Inlet, which separates the island from Camp Lejeune, the U.S. Marine military base to the north. Deepening the channel speeds the flow of currents through the inlet, which in turn hastens erosion and amplifies the ocean's pressure on the rear of the island. Canals built by developers and families also have accelerated erosion, geologists say.

Without humans continually replacing sand eroded by storms and dredging channels where sand has accumulated, Topsail would migrate freely to where it could accumulate the most sand from currents and big storms, according to Stanley R. Riggs, a coastal geologist at East Carolina University. It would grow into a higher, stronger barrier to storm surges, he says. Continual grading for roads, bridges, and buildings also restricts the island's height.

"The sole function of a barrier island is not for you to lay on the beach," Mr. Riggs says. "It is there because of the storm. It's built by storms and maintained by storms. It needs storms."

Mrs. Oppegaard came to Topsail as a girl, when most of the island looked like Serenity Point, and farmers like her father took skiffs to the island to fish on weekends. Her father was the son of Ukrainian immigrants who were deeded 10 acres of farm property on the mainland by a wealthy landowner. The family grew vegetables, expanded the farm and used profits to buy property on Topsail, after the military abandoned its old missile-testing site. Mr. Boryk and two friends came to the island by boat to buy parcels at auction, including the block of about 25 acres at the island's southern tip, which they purchased collectively. They sketched out a division by hand and decided who got what by drawing slips of paper out of Mr. Boryk's leather cap. The purchase price has been forgotten. Records of the sale were lost in Hurricane Fran.

The Boryk family took great risk and has earned its reward, Mrs. Oppegaard says. "My daddy only had a fourth-grade education," she says, "but he made his millions before he died."

This summer, worried about Serenity Point's long-term stability, the planning board of Topsail Beach tweaked the property's land-use designation to what Mayor Edward S. "Butch" Parrish calls "strictly" conservation from "primarily" conservation. The owners hired a lawyer who specializes in coastal development to fight the rezoning. They also hired surveyors, who determined that the 20 acres of property that remained undeveloped after the last round of construction in the late 1980s had grown to 125 acres, almost half of which were habitable.

Word of the survey traveled quickly through the 500 year-round residents of Topsail Beach. Mrs. Chesnutt, who lives in the last parcel of land sold by the original owners, has an unobstructed view from her deck of Serenity Point. She saw the surveyors tramping over the land and called a neighborhood meeting.

Mrs. Chesnutt passes out "Conserve the Point" buttons festooned with blue ribbons and brings detailed flip-charts and petitions to government meetings. She chides her neighbor, Mrs. Oppegaard, for seeking more money when the partners and their families already have made fortunes thanks to luck and the largess of a government bridge and roads that made developing the island possible. "We hug," Mrs. Chesnutt says. "But we don't mean it." Mrs. Oppegaard disagrees, though she says their relationship has become strained.

Conservationists say the best way to avoid costly and constant cycles of cleanup and repair would be to buy and set aside land like Topsail's Serenity Point. Mayor Parrish says Topsail Beach would like to buy the land to block development, in part because he doesn't want more roads and utilities to repair after storms. But with a total annual budget of $1.7 million, the town can't afford it.

After attorneys for Mrs. Oppegaard and the other owners challenged the designation of Serenity Point as a preserve, the town consulted with its lawyers. They warned that the proposed restrictions probably wouldn't stand in court unless the city reimbursed the families for the value of the land. The town backed down.

Now the town has asked the North Carolina Coastal Land Trust to apply for grant money to buy the land and negotiate with the owners on its behalf, allowing until mid-March next year for preliminary talks.

Mrs. Oppegaard, as she adjusts the white bow in her silver hair, says she is willing to wait, for a while anyway. She says the owners would be happy to sell the land for conservation at a fair price. "But it boils down to: It is our property," she says. "We hope that we can do something with it."