The Drowning Coast This three-part special report about the ecological crisis facing Louisiana’s vanishing coast, and the people who live there, is the product of a partnership between The New York Times and NOLA.com | The Times-Picayune of New Orleans.

JEAN LAFITTE, La. — From a Cessna flying 4,000 feet above Louisiana’s coast, what strikes you first is how much is already lost. Northward from the Gulf, slivers of barrier island give way to the open water of Barataria Bay as it billows toward an inevitable merger with Little Lake, its name now a lie. Ever-widening bayous course through what were once dense wetlands, and a cross-stitch of oil field canals stamp the marsh like Chinese characters.

Saltwater intrusion, the result of subsidence, sea-level rise and erosion, has killed off the live oaks and bald cypress. Stands of roseau cane and native grasses have been reduced to brown pulp by feral hogs, orange-fanged nutria and a voracious aphid-like invader from Asia. A relentless succession of hurricanes and tropical storms — three last season alone — has accelerated the decay. In all, more than 2,000 square miles, an expanse larger than the state of Delaware, have disappeared since 1932.

Out toward the horizon, a fishing village appears on a fingerling of land, tenuously gripping the banks of a bending bayou. It sits defenseless, all but surrounded by encroaching basins of water. Just two miles north is the jagged tip of a fortresslike levee, a primary line of defense for greater New Orleans, whose skyline looms in the distance. Everything south of that 14-foot wall of demarcation, including the gritty little town of Jean Lafitte, has effectively been left to the tides.

The Drowning Coast This three-part special report about the ecological crisis facing Louisiana’s vanishing coast, and the people who live there, is the product of a partnership between The New York Times and NOLA.com | The Times-Picayune of New Orleans.

Jean Lafitte may be just a pinprick on the map, but it is also a harbinger of an uncertain future. As climate change contributes to rising sea levels, threatening to submerge land from Miami to Bangladesh, the question for Lafitte, as for many coastal areas across the globe, is less whether it will succumb than when — and to what degree scarce public resources should be invested in artificially extending its life.

One sweltering evening last July, almost everyone from around Lafitte gathered near dusk at the bayou’s edge to celebrate the expenditure of nearly $4 million of those scarce public resources. There were shrimpers and crabbers, tug captains and roughnecks, teachers and cops. All had come for the ribbon cutting for a grand new seafood pavilion, the latest gambit by the longtime mayor, Timothy P. Kerner, to save the town from drowning.

Free beer sloshed in plastic cups as folks ambled about the cavernous, open-sided shed, sampling shrimp rémoulade and alligator-stuffed mushrooms. Once the politicians had finished flattering one another from the podium, a Cajun band, fronted by a fiddler in a shimmery blue dress, cranked up a rollicking fais-dodo.

Amid the celebration, a fireplug of a man in crisp jeans and a starched white shirt cheek-kissed and bro-hugged his way through the crowd. This was Timmy Kerner’s party. In his third decade as mayor, Mr. Kerner had managed to persuade the parish, state and federal governments to pay for his signature showcase at the entry to town.

It might seem counterintuitive to keep building on land that is submerging. But Mr. Kerner did not see it as his job to take a 10,000-foot view. In the years since Hurricane Katrina, he had grown weary of being rebuffed in his quixotic campaign to encircle Lafitte with a tall and impregnable levee. He could rhapsodize all he wanted about preserving his community’s authentic way of life. The cost-benefit calculus — more than $1 billion to protect fewer than 7,000 people — always weighed against him.

So he had set out to change it. His strategy was to secure so much public investment for Jean Lafitte that it would eventually become too valuable to abandon. In a decade, he had built a 1,300-seat auditorium, a library, a wetlands museum, a civic center and a baseball park. Jean Lafitte did not have a stop light, but it had a senior center, a medical clinic, an art gallery, a boxing club, a nature trail and a visitor center where animatronic puppets acted out the story of its privateer namesake.

Some of the facilities had been used sparingly, and many at the grand opening questioned whether the seafood pavilion would be much different. To the mayor that was largely beside the point. What mattered was that the structure existed, that its poured concrete and steel beams made Lafitte that much more permanent.

“Do we lose that investment, or do we protect it?” Mr. Kerner asked, barely audible above the din. “I hope people will see that, hey, not only are we fighting hard to exist, but, you know, maybe this place is worth saving.”

The sky began to dim over the bayou. “It’s such a beautiful place, and it’s getting prettier by the day,” he said, ticking off his improvement projects. “This is just another step at building the community. It sends a message that we’re not going anywhere.

“No matter what, we’re not leaving.”

‘WE ARE LITERALLY IN A RACE AGAINST TIME’

Louisiana’s “working coast” is dotted with communities that, like Lafitte, may not outlast the people who currently live there: Cocodrie, Delacroix, Dulac, Grand Isle, Isle de Jean Charles, Kraemer, Leeville, Paradis, Pointe-aux-Chenes, Venice.

A fourth of the state’s wetlands are already gone, with heavy losses tallied from 2005 to 2008, when the coast was battered in succession by Hurricanes Katrina, Rita, Gustav and Ike. In 2011, the federal government retired 35 place names for islands and bays and passes and ponds that had simply ceased to exist.

State planners believe another 2,000 square miles, or even double that, could be overtaken in 50 years as the land sinks, canals widen and sea levels rise because of climate change. Recent studies show that glacial melting is accelerating in Antarctica and Greenland, driving sea level rise on the Gulf Coast.

Although the recession of Louisiana's coast has slowed somewhat this decade, a football field’s worth of wetlands still vanishes every 100 minutes, according to the United States Geological Survey. That is one of the highest rates on the planet, accounting for 90 percent of such losses in the continental United States.

The Gulf Restoration Network, a nonprofit conservation group, calculates that there are currently 358,000 people and 116,000 houses in Louisiana census tracts that would be swamped in the surge of a catastrophic hurricane by 2062. The Geological Survey predicts that in 200 years the state's wetlands could be gone altogether.

“It is the largest ecological catastrophe in North America since the Dust Bowl,” declared Oliver A. Houck, a professor of environmental law at Tulane University in New Orleans who has written extensively about land loss in the state.

In addition to the effects of climate change, human engineering has contributed broadly to the losses. Since the early 18th century, the construction of levees on the Mississippi and the closing of its distributaries have altered natural hydrology and stifled land-building silt deposits from spring floods. Property owners and government regulators have allowed the degradation of swamp and marshland, first for farming and cypress-logging and then, more insatiably, for oil and natural gas exploration.

Since prospectors first discovered oil in Louisiana 117 years ago, 57,465 wells have been drilled in 10 coastal parishes, according to the state’s Department of Natural Resources. Thousands of miles of canals have been dredged through marshes for access. They broaden each year from erosion caused by boat traffic and storm currents, even as their spoil banks block natural water flow. A 50,000-mile thicket of pipelines connects rigs to refineries and tank farms across the state.

After years of laissez-faire regulation, some consequential finger-pointing has begun in the courts, where parish governments and private landowners are for the first time suing energy companies to rebuild their land. To date that burden has fallen mostly on taxpayers, even when the property being repaired is owned by oil and gas interests, an examination of state records shows.

The impact extends far beyond Louisiana’s shoreline.

The slender coastal zone, stretching west from Breton Sound across the mouth of the Mississippi to Sabine Pass, contains 37 percent of the estuarine marsh and the largest commercial fishery in the contiguous 48 states. Its ports support 24 percent of the nation’s waterborne commerce and a fifth of its oil supply. The coast provides winter habitat for five million migratory waterfowl. Along with man-made levees and flood walls, it is the buffer that keeps the Gulf of Mexico from draining into New Orleans, much of which sits below sea level.

Last year, Louisiana officials acknowledged for the first time that even with a vast restoration program, even with tens of billions of dollars they do not have, they no longer believed they could build land fast enough to offset the losses. Plotted on a map, their projections show 40-mile swaths, encompassing Jean Lafitte and everything below it, splashed in red to denote that, without action, they will disappear within decades. The crisis has become existential, with policymakers confronting choices about which communities they can afford to rescue.

In the starkest illustration, a $48 million federal grant is being used to relocate the nearly 100 residents of Isle de Jean Charles, a narrow spit in lower Terrebonne Parish that has lost 98 percent of its land over 60 years. In a national experiment, the money will be used to buy land and build homes for those willing to move to higher ground on a sugar farm near Houma, about 40 miles north.

To dramatize the state’s plight, Gov. John Bel Edwards last year declared the entire coast in “a state of crisis” and successfully lobbied the White House to expedite permits for restoration projects. “The sense of urgency has only magnified,” Mr. Edwards said in an interview. “We are literally in a race against time.”

Mr. Edwards, a Democrat, insists that his state is “not in full retreat mode,” that “the science shows there is a window of opportunity” to sustain portions of the coast. But in a state not known for fiscal oversight, concerns linger about whether good money will be thrown after bad.

“People argue that if you make the investments appropriately it will be fine, and it could be,” said Mitch Landrieu, the outgoing mayor of New Orleans. “But nobody really ever has the appetite to have a conversation about cutting off your arms so you can still walk.”

‘IF WE END UP LIVING ON RAFTS, THERE WILL BE PEOPLE LIVING HERE’

The sputter and thrum of boat motors announces the morning along Bayou Barataria well before sunup. Burly men in rubber boots load ice and bait into trawlers moored behind their houses and prepare to push off in the dark.

On a clear day out on the Pen, a four-mile lake that was farmland a century ago, the silhouettes of New Orleans office towers and the Phillips 66 Alliance Refinery are visible to the north and east. Lines of crab traps stretch across the flat water, buoyed with floats painted in their owners’ signature colors, like jockeys’ silks. Alligator snouts skim the surface of nearby canals, and a boat’s approach sends a blue heron flapping into labored flight.

Jean Lafitte, the pirate and smuggler, patrolled nearby waters before helping to defend New Orleans in the War of 1812, earning a pardon in exchange. Many here trace their lineage back to his day or to the 18th century Acadian settlers whose cuisine and dialect still prevail (although the Frenchman might be confused to hear locals call their home Gene Lafitte).

The people of Lafitte have lived off the water for generations — trapping and skinning muskrats and other marsh dwellers, fishing, crabbing, oystering, building and repairing boats, ferrying workers and supplies to offshore rigs. Many accept the irony that the water may eventually destroy the economy it built.

As it is, cheap imports and domestic farming of shrimp and fish have depressed prices and made it all but impossible to turn a profit. The global oil glut has reduced drilling activity on the coast by almost two-thirds since 2014. Recent graduates of Fisher High are as likely to seek careers in a casino or pharmacy as on a Lafitte skiff, the iconic fan-tailed fishing boats designed here.

Jean Lafitte is laid out for six linear miles along a two-lane road that curves around the east bank of the bayou. Newer houses on land subdivided from a 19th-century sugar cane plantation were built atop six-foot mounds to keep the water at bay. Many older structures have been elevated hydraulically and placed on pillars 10 feet or higher, a process that can cost nearly as much as the house is worth. While government programs pick up some of the expense, there is not enough funding, and some homeowners cannot afford their share, which often exceeds $100,000.

Yet many cannot imagine living anywhere else. They complain that the bloodless cost-benefit formulas determining which communities get protection give little weight to the qualities that make Lafitte desirable (the name Lafitte is used to refer to the town and its adjacent unincorporated areas). Children, they point out, still spend barefoot summers tubing and fishing and training bird dogs to leap off docks. And when they graduate from high school, three-fourths will have been together since prekindergarten.

The policymakers “don’t place value on anything but the money, not the longevity of these communities, not the culture,” said Tracy Kuhns, 64, a longtime resident of the Barataria community across the bayou from Jean Lafitte. “One of the problems in this country is that people don’t have any connection to where they live. People really want that. Why would you take it away from people who already have it?”

Ms. Kuhns, the president of Louisiana Bayoukeeper, an advocacy group for water quality and clean fisheries, pointed out that she did not lock her door (which flies open all day as her 17 grandchildren come and go). There have been but two murders in Jean Lafitte in the past 20 years, compared with 3,829 in New Orleans.

At the center of town sits St. Anthony Catholic Church, which sponsors the Blessing of the Fleet Festival when brown shrimp season opens each spring. The first catch fills the freezers of cousins and neighbors before anything left is sold to Nunez Seafood and other dockside wholesalers.

After a long day on the water, some may wet their whistle with $2.75 Budweisers at Mitch Martin’s Welcome Inn, where a swamp-pop band plays on Wednesday nights and gray-haired ladies line dance.

The tavern is run by Timothy and Thomas Wiseman, brothers better known as White Boy and Zabo. Almost everybody in Lafitte has a nickname, some more self-explanatory than others: Skinny Boy, Sandbags, Lunch Meat, Pink Cow. When Tom Wiseman, 52, was a child, someone decided he looked like another guy nicknamed Zabo. “Forty years it has followed me now,” he said.

The Wisemans find that the absence of levee protection reinforces the sense of Lafitte as a place apart, for better and worse. “We’re outside the line, and they don’t care about us,” Tim Wiseman, 54, said. “It’s always been like that.”

“Now we just expect water and damage every five years,” his brother said. “It’s a way of life.”

“And you know what? It still does not make us want to leave,” Tim said. “Are we economically feasible? Hell no. But this place will survive. If we end up living on rafts, there will be people living here.”

‘WORST FEELING I’VE EVER HAD. NOTHING YOU CAN DO ABOUT IT’

Although only two feet above sea level, Lafitte rarely experienced significant damage from hurricanes until 2005. That year, Katrina’s 120-mile-per-hour winds stripped roofs off houses; a month later, Rita sent enough water coursing through lower Jefferson Parish to dislodge whitewashed tombs from graveyards. Homeowners in Lafitte found skulls and an artificial hip among the debris. Together, the storms forced the demolition of more than 150 houses.

There would be more of the same with Hurricanes Gustav and Ike in 2008, Tropical Storm Lee in 2011 and Hurricane Isaac in 2012. With only 2,000 residents, the Town of Jean Lafitte racked up $9.3 million in federal flood insurance payments in the eight years after Katrina, according to an analysis by Rui Hui, a researcher at the University of California, Davis. (Statewide, the program has paid out $19.5 billion in claims since 1978, or 30 percent of the national total, including $1 billion for properties that have flooded repeatedly, according to the Federal Emergency Management Agency.)

“The first time, I sat on the sofa and just watched it come in,” remembered Chris Dufrene, 73, whose house flooded three times before he had it elevated eight feet three years ago. “Worst feeling I’ve ever had. Nothing you can do about it.”

Shrimpers and guides had been noticing astonishing changes out on the water for years. Shambles of fishing cabins sat stranded on pilings, more distant from shore each season. Duck blinds had dissolved into muck. Land bridges no longer bridged.

“I’ve been out here since 1981, and the beaches are eroding, the salt water’s intruding and all the islands in Barataria estuary that were protecting the land are washing away,” said Troy Schultz, 54, who trawls and crabs with his son, Troy Jr., 28. “Big Island is gone. Cat Island is gone. St. Mary’s Island is gone. They were miles long. Now it’s so open that every time you get squalls and storms it pulls up the marsh grass.”

These days, the main road through Jean Lafitte floods almost any time a gusty storm blows in from the south. A mere sideswipe from Tropical Storm Cindy last June pushed several feet of water into streets and yards. The merciless hurricane season of 2017, with Harvey followed by Irma, Maria and Nate, made clear that the town’s days may be numbered.

After Katrina left 1,833 dead in 2005, local, state and federal governments spent more than $20 billion to redesign failed and inadequate levees and pumps for metropolitan New Orleans. Even those improvements may not be sufficient to spare the area’s more than 1.3 million residents from another monster storm.

But in Lafitte, only 25 miles south, the hurricane defense system consists mainly of Mr. Kerner and whichever men he can employ to sling tens of thousands of 25-pound sandbags, often for days on end.

The mayor feels the threat viscerally, like many with deep roots here. His family settled in Lafitte in the early 1800s. He married a local girl at 18 (Darla Kerner was 16), and worked as a commercial fisherman, barkeep and tax collector before assuming his place as heir to one of the country’s most enduring political dynasties.

Mr. Kerner has been mayor for 26 of his 58 years. With a gap of only eight years in the 1950s, a Kerner has held Lafitte’s top office since 1888, when his great-grandfather became justice of the peace. His father, Leo E. Kerner Jr., spearheaded the effort to incorporate Jean Lafitte in 1974 and became its first mayor, serving 17 years.

Leo Kerner had been a welterweight champ in the Navy, and taught his boys how to spar, in politics as in the ring. The current mayor is known in Jefferson Parish, Baton Rouge and Washington as a single-minded scrapper who fights best from a defensive crouch. He can be quick to lose his temper when he feels Lafitte is being disrespected, but is also fast to apologize and hug it out.

“He’s like a big teddy bear,” said Susan H. Maclay, president of the Southeast Louisiana Flood Protection Authority — West, which maintains levees on the west bank of the Mississippi. “It’s hard to tell him no when he needs help.”

Mr. Kerner, a self-described Kennedy Democrat, has made a career of going hat in hand to Republican administrations. He has little choice, as Jean Lafitte’s operating budget hovers around $2 million. Legislative audits show that virtually all of the $27 million amassed by Mr. Kerner for construction since Katrina came from federal, state and parish grants. He has lobbied for scores of millions more for bridge and road improvements.

Paradoxically, perhaps, some of the funding — including about a third of the cost of the seafood pavilion — has come from federal recovery grants that flow south each time the town is bludgeoned by a storm.

As the water creeps closer, Mr. Kerner has increased the value of Jean Lafitte’s physical plant sevenfold in a decade. And yet, on his central mission to ensure his town’s future, he considers himself a failure.

“When I ran for this office,” Mr. Kerner said, “I ran to provide a levee. That was my dream. I guess I haven’t done a very good job so far, because we don’t have one.”

‘WHAT DO YOU SUGGEST WE DO?’

If Lafitte has a chip on its shoulder, it is not without cause.

When the Army Corps of Engineers first mapped out Louisiana’s hurricane protection system in the 1970s and 1980s, it drew the footprint just north of Lafitte. The priority was to protect New Orleans, its booming West Bank suburbs and Louisiana’s ports (the state has five of the country’s 12 largest). Feasibility studies repeatedly concluded that extending the levee to defend Lafitte was “not economically justifiable.”

That left Mr. Kerner to devise his own plan, and find a way to pay for it. His concept was to phase in the construction of a chain of 10 linked ring levees, 65 miles in all, that would enclose each populated sector of Lafitte. Cost dictated that the walls of dirt, steel and concrete would be seven-and-a-half feet high at the outset, enough for protection from modest storms but not from a major hurricane. A levee of at least twice that height is typically needed to meet the standard of “100-year protection,” meaning it should withstand flooding from a hurricane with a 1 percent chance of occurring in a given year.

For a while, the corps encouraged the mayor to pursue small federal grants to build segments of the system. In 2003, with about $10 million, construction began on the first link, which will eventually contain the town’s schools and municipal buildings.

Then came Katrina, producing storm surge that overwhelmed portions of the New Orleans-area levee and flood wall system. In addressing the damage, Congress raised standards for the height and strength of the levees that the Corps of Engineers would build, effectively disqualifying the Lafitte project.

Mr. Kerner also found little support locally, where the regional levee authority with jurisdiction over Lafitte was focused on protecting areas closer to New Orleans. In 2007, David J. Bindewald Sr., then the president of the Southeast Louisiana Flood Protection Authority — West, told Mr. Kerner explicitly that there would be no money for his levees.

Instead, he sent Mr. Kerner a letter offering “several thousand un-filled sand bags and sand sufficient to fill the bags” along with “a quantity of shovels.”

The furious mayor figured he could do better than that on his own, and persuaded allies in the Legislature to create the Lafitte Area Independent Levee District. Funded by a small property tax, the levee authority pays Mr. Kerner $12,000 a year as its president, on top of his mayoral base salary of $79,538, according to legislative audits.

Mr. Kerner’s power play did not instantly change the essential dynamic. In 2009, after Hurricane Gustav, the corps began studying options for a new levee that would span a stretch of the lower coastal zone. Only one of several routes under consideration would have protected Lafitte. But at a levee board meeting in 2011, corps officials announced their determination that none of the proposed alignments could be justified economically.

“What do you suggest we do?” an exasperated Mr. Kerner asked Mark Wingate, the corps engineer managing the project.

Mr. Wingate said he suggested studying nonstructural options, including relocation.

“You’re reading my mind,” Mr. Kerner responded, “because when I saw that map the first thing I thought was that I wanted to relocate your jawbone.” He nodded at Mr. Wingate’s two associates. “And your jawbone and your jawbone.”

In the parking lot after the meeting, the corps officials stiffened when they saw the pugilistic mayor striding purposefully toward them. But he was only coming to apologize.

‘THEY JUST BASICALLY SLAP YOU IN THE FACE AND SAY BYE’

Bruised but not defeated, Mr. Kerner thought there might be another way.

Four months after Katrina, the State of Louisiana had created the Coastal Protection and Restoration Authority to centralize planning. The authority was tasked with devising a master plan for the coast, which it did for the first time in 2007, and with updating it every five years. Science, not politics, was to control its deliberations about the most cost-effective ways to protect people and property.

The ambitious 2012 update pledged to use “every tool in the toolbox” to improve flood protection “in every community in coastal Louisiana.” It proposed a $50 billion buffet of projects — marsh creation, barrier island restoration, oyster shell reefs, river sediment diversions — that it asserted could start to neutralize land loss over the next 23 years and outpace it by year 30. There also would be billions for house elevations and flood walls — including $870 million to build Mr. Kerner’s ring levees at full “100-year” height: 16 feet.

Over the past decade, the authority has grabbed money from a bag of sources to undertake 135 projects at a cost to the state of more than $2.4 billion (with another $2 billion budgeted for the next three years). Sixty-five square miles of land have been built or improved, along with 297 miles of levee and 60 miles of barrier islands and berms, according to the authority.

The coast these days is awash in ambitious engineering projects. Near Jean Lafitte, for instance, more than 1,000 acres of marsh have been created in and around Bayou Dupont in an $82 million state-managed project that pumped sand from the Mississippi up to 13 miles away. Where open water stood in 2009, there is now walkable land, thick with saplings and shrubs.

But before money could be appropriated for the Lafitte levees, the master plan’s authors adopted far more pessimistic forecasts of the impact of climate change. They effectively doubled their previous 50-year projections for likely sea level rise to more than two feet, the highest rate in the country, according to the National Oceanic and Atmospheric Administration.

That made the worst-case scenario in the 2012 master plan the best case for 2017 and led to a startling reversal: Louisiana could slow the submergence of the coast, but not arrest it. Even if the plan was somehow fully funded, and the state succeeded in adding or maintaining 800 square miles of wetlands over 50 years, there would still be a net loss of at least 400 square miles and possibly as many as 3,300.

That recalibration necessarily shifted the state’s approach. “Once you accept the diagnosis that much of south Louisiana is going to disappear, you still have to have a strategic retreat,” said David Muth, director of the National Wildlife Federation’s Gulf Restoration Program. “How do you plan this shrinking of the footprint, which is complicated by socioeconomics and by real questions about how fast sea level will rise and how fast you can build wetlands?”

Torbjörn E. Törnqvist, a Tulane geologist who is an authority on subsidence, warned that decisions about places like Lafitte would be “a piece of cake compared to what’s coming — because a little down the line we’re going to be talking about communities not of 2,000 people but of much bigger things.”

And then there’s the matter of where to find the master plan’s aspirational $50 billion — twice the entire state budget.

To date, the only dependable financing model has been catastrophe, namely the 2010 Deepwater Horizon oil spill. BP and its drilling partners agreed to pay $7.1 billion over 15 years to settle litigation by the state, and the money has been earmarked for coastal restoration. Mark Davis, director of Tulane’s Institute on Water Resources Law and Policy, analogizes that to “paying for a gym membership by winning pie-eating contests.”

The state and its coastal parishes have been counting on about $176 million a year from federal offshore oil leases under a revenue-sharing law passed in 2006. But steep declines in prices and drilling have lowered those projections.

All told, even under the rosiest circumstances, the $50 billion master plan, which many experts consider inadequate, lacks at least $30 billion in revenue.

“All of us believe our citizens deserve more than probably we can deliver,” said Bren Haase, the authority’s chief of planning and research.

For its 2017 revision, the authority split its theoretical budget between hopeful restoration efforts, like rebuilding marshes and barrier islands, and defensive risk-reduction projects like raising levees and elevating houses. It re-evaluated proposals with a refined formula that weighed each project’s cost against the flood damage it would avert.

The price tag for the Lafitte ring levees had risen to $1.2 billion, equating to more than $170,000 per resident. Despite Mr. Kerner’s efforts to rebalance the cost-benefit calculus, the annual savings amounted to less than a tenth of that, placing it near the bottom on the state’s list. When the authority published its draft in January last year, the mayor found that his ring levees, his lifeline for Lafitte, had been discarded.

The mayor and his constituents felt betrayed once again. “It just makes all your fears justified,” said Ray Griffin, the manager of Cochiara’s Marina. “When they make a decision like that they just basically slap you in the face and say bye.”

‘WE JUST CAN’T DO THAT. BUT WE HAVEN’T GIVEN UP ON THEM EITHER.’

In an ecosystem as multifaceted as the Louisiana coast, the protection of one habitat may pose a mortal threat to another, or at least be perceived that way. Flood control is a zero-sum game. The water has to go somewhere.

So there is natural suspicion in Lafitte about the most audacious engineering proposal in the state master plan, the $1.4 billion Mid-Barataria sediment diversion. The experimental project, which is under design, would carve a gap in the levee on the Mississippi’s west bank just southeast of Lafitte. When the river is high, floodgates could be opened to redirect sediment-rich water into adjoining marshland at up to 75,000 cubic feet per second.

This occasional freeing of the river may build land more gradually than the continual pumping of dredged sand. But environmental groups argue that it will do so in a self-sustaining way at comparatively low cost. The state estimates that the diversion will deposit enough sediment over 50 years to fill the Superdome more than 22 times.

“We know we need benefits now,” Mr. Haase said, “but if we’re not doing anything to fundamentally change the causes of our land loss, then we’re perhaps not investing our dollars wisely.”

In Lafitte’s fishing community, there is deep concern, with some scientific backing, that flushing fresh water into brackish marshes and bays will imbalance the salinity needed to nurture shrimp, oysters and crab. Scientists argue that salinity will change with or without the diversion, but seafood industry groups have threatened to sue if it is built.

“It will completely kill these fishing communities,” said Clinton Guidry, a Lafitte resident who once presided over the Louisiana Shrimp Association. “Is that the trade-off you want? If you lose shrimp fishermen for one generation, they’re gone forever.”

For Tim Kerner, the Mid-Barataria diversion provided a bargaining chip. After his 100-year levees were axed from the master plan, he continued to push for funds to complete the ring system at lower height. The state owed Jean Lafitte, he argued, because the diversion would make the town even more vulnerable.

Things came to a head in January last year when Mr. Kerner made his case, loudly, at a meeting with state officials. Seated nearby was his great benefactor in Baton Rouge, State Senate President John A. Alario Jr., a soft-spoken power broker whose district includes Lafitte.

“You know,” Mr. Kerner told Johnny Bradberry, the chairman of the Coastal Protection and Restoration Authority, “if I was a senator or a state rep from my area sitting at this table, I would be very upset. You have projects all along the coast, and this area, where the Senate president is from, you have nothing but a sediment diversion that nobody really wants.”

He reminded the officials of all of the money the state had been spending in Lafitte — the bridges, the civic center, the seafood pavilion. “It’s so inconsistent for C.P.R.A. to say we’re not worth saving when other government agencies are spending hundreds of millions of dollars,” he said. “It’s throwing away the investment of tax dollars you already put in this place.”

When the final master plan was presented to the Legislature in June, language had been inserted that the state and the Lafitte levee authority would be “focused on securing nearly $308 million” for the lower tidal protection levees and flood walls. The plan also called for spending $200 million in Lafitte over 30 years to elevate 1,237 houses, flood-proof nine businesses and buy out two property owners. (Coastwide, the master plan calls for spending a theoretical $6 billion over 50 years to elevate, improve or buy out 26,200 properties.)

The question now is how quickly money will materialize. Mr. Kerner believes the levees can be completed for considerably less than the $308 million estimate. Regardless, the state has budgeted only $35.5 million for them over the next four years.

“Those 2,000 folks down there would like very much for us to be committed to a $1 billion ring levee,” said Mr. Edwards, the governor. “Well, we just can’t do that. But we haven’t given up on them either.”

‘YOU DON’T BITE THE HAND THAT FEEDS YOU’

Prospects seem dim for a federal bailout to shore up Lafitte and the rest of Louisiana’s coast. Preserving the state’s wetlands is a tough political sell because many Americans do not appreciate the magnitude of their self-interest there. Increasingly, Louisiana faces competition from more populous coastal zones that also are at grave risk, like South Florida, metropolitan New York and the Texas Gulf.

The only other pockets deep enough to fill the financial gap belong to oil and gas. Even in a time of retrenchment, the energy industry remains among Louisiana’s most vital employers, revenue generators and civic and political donors. But with drilling in decline and the BP oil spill a fresh memory, Louisianans seem newly receptive to holding the industry accountable for the consequences of its activities.

In a recent poll of 565 Louisianans by NOLA.com | The Times-Picayune, 72 percent said the oil and gas industry should help pay for coastal restoration along with the government. (Mr. Kerner happens to agree.) Another 18 percent said the industry should bear the cost alone. Only half said they were willing to pay higher taxes to redeem the coast.

In 2013, with the political landscape shifting, the levee authority charged with flood control in New Orleans sued 97 oil and gas companies, presenting a novel claim.

“Everybody understood that the industry was responsible for a significant part of the damage and had placed an increased burden on those responsible for protecting the population from storm surge,” said John M. Barry, the New Orleans author who spearheaded the litigation as vice president of the Southeast Louisiana Flood Protection Authority — East. “So it seemed clear there would have to be some avenue to get them to accept their liability.”

Over the prior 20 years, plaintiffs’ lawyers had won judgments and settlements in Louisiana cases demanding the cleanup of oil field contamination. The flood protection authority hired one of them — Gladstone N. Jones III of New Orleans — and constructed arguments evocative of those used 30 years earlier against Big Tobacco: Energy companies had known for decades that they were destroying the marsh but ignored legal and contractual obligations to repair it, at great cost to taxpayers.

There is considerable documentation of advance knowledge. Scientists and conservationists have sounded alarms since the 1920s about the loss of land to oil exploration. Documents uncovered through discovery show that the industry’s own studies began making the connection nearly 50 years ago.

In 1972, a report commissioned by oil and gas transmission companies estimated that pipelines decimated up to two square miles of marsh a year and that access canals destroyed at least that much. Seventeen years later, a study of aerial photographs for the Louisiana Mid-Continent Oil and Gas Association, which represents major producers, concluded that “the direct and indirect effects of canal development tend to be the overwhelming cause of wetland losses.” In 2000, a study sponsored in part by the Gas Research Institute estimated that the industry bore responsibility for 36 percent of Louisiana’s coastal land loss between 1932 and 1990.

More recent research links the industry to subsidence — the compaction and sinking of sediment. “Rapid subsidence and associated wetland loss were largely induced by extraction of hydrocarbons,” concluded a 2005 study of the Mississippi Delta plain by the Geological Survey. It added that the collapse of Louisiana’s marsh “appears to be unprecedented and not repeated in the geological record of the past 1,000 years.”

And yet, some Louisiana lawmakers, both in Congress and the State Legislature, do not support efforts to regulate what may be the most lasting environmental legacy of fossil fuels: climate-driven sea level rise. Among them is Representative Steve Scalise, the House majority whip, whose district includes Lafitte. Mr. Scalise, a Republican, applauded Mr. Trump’s announcement in June that the United States would withdraw from the global Paris accord to regulate greenhouse gas emissions.

The state’s leadership initially viewed the levee authority lawsuit as a direct assault. The Republican governor at the time, Bobby Jindal, demanded that it be withdrawn and removed Mr. Barry and others on the authority. He orchestrated passage of a law that would have invalidated the litigation had a state judge not declared it unconstitutional.

“It’s that old saying — you don’t bite the hand that feeds you,” said Lt. Gov. Billy Nungesser, also a Republican. “I don’t say they have no effect, the canals, but I think it’s a money grab against an industry that has been very good to Louisiana.”

In 2015, a federal judge dismissed the levee authority lawsuit, primarily on grounds that the agency lacked legal standing. That ruling has been upheld on appeal. But the original lawsuit was followed quickly by scores of others, some filed by private landowners and a total of 43 by six different parish governments (the equivalent of counties).

In August, a different federal judge ruled that pipeline companies must repair erosion that had occurred since 1953 along canals on 20,000 acres of privately owned wetlands in Plaquemines Parish. The first of the lawsuits filed by the parishes is scheduled to be heard in state court in Plaquemines in 2019.

The parishes, all represented by the Baton Rouge firm of Talbot, Carmouche & Marcello, claim that oil and gas companies violated state permitting laws in the dredging of canals, as well as regulations requiring production sites to be “cleared, revegetated, detoxified and otherwise restored as near as practicable to their original condition upon termination of operations.” The suits seek actual restoration of degraded land in addition to monetary damages.

In 2016, when the governor’s office changed parties, Mr. Edwards reversed Mr. Jindal’s stance and intervened in support of the parish cases. “Oil and gas is a huge component of our economy, and we want them to be successful,” Mr. Edwards said. “But we also want them to act responsibly when they explore for and produce hydrocarbons.”

Oil and gas industry leaders acknowledge that their potential exposure is substantial. They warn they will not roll over to trial lawyers who they believe are extorting them for a global settlement.

“We’re going to fight every single last issue because we don’t believe we’ve done anything wrong,” said Gifford Briggs, vice president of the Louisiana Oil and Gas Association, which represents independent producers and service companies.

Chris John, a former Democratic congressman who presides over the Louisiana Mid-Continent Oil and Gas Association, said the lawsuits failed to recognize numerous other causes of coastal degradation and would not be settled. He said that “the energy industry has conducted its operations in accordance with government-issued permits and applicable federal, state and local regulations.”

Mr. Briggs echoed that defense. “Yes, if you dig a canal or build a slip, is there technically a loss of marsh or land? Sure,” he said. “But that’s done through permit. That doesn’t mean there’s any additional liability or responsibility beyond fulfilling the obligations of the permit.”

As it is, taxpayers have spent at least $588 million to repair oil-and-gas-related damage in coastal Louisiana, according to an analysis of state records. That accounts for 84 percent of the money spent on more than 200 projects over three decades by the federal Coastal Wetlands, Planning, Protection and Restoration Act. Enacted in 1990, the program is funded by taxes on fishing gear, imported watercraft, boat fuel and motors.

Because petroleum interests own or lease much of the coast, those taxpayer-funded restoration efforts often benefit the very industry that shredded the marsh in the first place. In Terrebonne Parish, for instance, $39 million was spent to repair breaches in a land bridge across north Lake Mechant caused by erosion and oil access canals. Much of the property is owned by Apache Corporation and Louisiana Land and Exploration, both major oil and gas companies, parish records show, and operators have included ConocoPhillips, Texaco and Humble Oil (a precursor of Exxon Mobil).

‘WHY DON’T YOU JUST MOVE AWAY?’

Jean Lafitte has not yet reached the tipping point when bankers and insurers perceive that the lifetime of their loans and obligations could exceed the lifetime of the town. Indeed, real estate values are relatively high, if only because there is so little to be had.

But there are early signs of an exodus, particularly among younger residents. The population of the area declined by 21 percent between 2000 and 2010, although estimates suggest it has rebounded slightly this decade. Enrollment at the two public schools dropped 27 percent from the peak before Katrina and Rita, but has risen by 10 percent since.

Mr. Kerner believes the declines reflect temporary dislocations. But some, like Buttercup Mancuso, have left for good. She, her husband and three of their children evacuated their rental house in lower Lafitte before it flooded during Hurricane Isaac in 2012. They returned to find mold sprouting two feet up the walls.

The family abandoned their belongings except for their photographs. “Losing everything once was enough for me,” Ms. Mancuso, 43, said. “I just couldn’t do it again.” They moved to the north shore of Lake Pontchartrain, and eventually to North Carolina.

Travis Johnson, 70, a retired Army and commercial helicopter pilot who moved to Barataria in 2000, said that at his age he would gladly take a government buyout for his waterfront house.

“I drove out of here during Hurricane Rita with water flowing over the hood of my Jeep,” he said. “Should one delay evacuation, it is not possible to escape. I don’t want a lot of complications.”

But Lafitte’s lifers, for the most part, seem resigned to wait things out. The centuries spent fishing and trapping have built a resilient and self-reliant culture. More than 250 years since the Acadians were expelled from Nova Scotia, there remains a deep resistance to another forced exile.

“People that don’t understand it say, ‘Why don’t you just move away?’” said Ms. Kuhns, the Louisiana Bayoukeeper president, who refuses to join her daughter, Ms. Mancuso, on the other side of the levee. “The people who are connected to these communities don’t think that way. It’s a whole culture that’s connected to the earth and the water. You can’t replicate it.”

And so the men sandbag. Last hurricane season, they stacked them by the thousands in anticipation of Tropical Storm Cindy, then unstacked them when the floodwater receded. They did it again for Hurricane Harvey and once more for Nate.

The mayor supervises up and down the road from his white Ford Expedition, crossing himself as he passes the Catholic church. He pitches in long enough to let his back start aching, then carps that it’s because the young guys today don’t know how to properly swing and catch.

He remembers each storm as a fight, tallying them as wins and losses. In the old days, they would stack 200,000 sandbags. “It was like being in a war zone,” Mr. Kerner said. “We wouldn’t go to bed for two or three days at a time.”

With sections of two of the ring levees complete, the men got by with only 20,000 sandbags when Nate narrowly missed Lafitte last October. “Each time you just have to be ready and fight it as if it’s going to be the worst thing that ever happened,” Mr. Kerner said. “And then you may have to do it again a week later.”

The mayor has developed a sixth sense for the telltale signs of whether Lafitte will flood. As Cindy moved in last June, he watched the tide rising near the Goose Bayou bridge: “That water won’t quit,” he cursed. “Look at the whitecaps. That’s what I don’t want to see.” Soon the water was lapping at his tailpipe.

Four months later, on the night Nate landed near Biloxi, Miss., he divined better news from the bayou’s outward flow, indicating that the leading edge had curled in harmlessly from the north. “That’s it,” he said. “It’s over.”

As he drove home, eyelids drooping, Mr. Kerner could not help feeling annoyed that the town had expended so much effort for no reason. Then he remembered that no one had been hurt, no one had been washed out of his or her home or stranded in distress. “Such a relief,” he thought.

He eased into bed, bone-weary and sore, like an aging boxer, and lost himself in reveries of shiny new buildings and 16-foot levees — whatever might spare Jean Lafitte from the water, for now.