Steve Cochran left southern Louisiana 23 years ago, but like many others in the delta diaspora, he kept one spiritual foot in the hometown mud.

Unlike many others, he kept his hand in as well. He’s among those — from urban planners to politicians to oyster harvesters — committed to putting back at least some of the marshes that would have partially shielded New Orleans from Hurricane Katrina’s violence.

Cochran moved to Washington, D.C., where he now runs the Environmental Defense Fund’s Mississippi River Delta Restoration project. A decade after Katrina, he and others are nurturing a shift away from the gloom that shrouded New Orleans in 2005.

With the state committed to coastal restoration as never before, with candidates for governor all on board, and with an infusion of cash from BP’s 2010 oil spill damages available for big projects, Cochran is optimistic that people and nature might get along after all.

“The enormity of the challenge is dramatic,” he said. “Whether it will all come together remains to be seen.”

But hope keeps popping up.

“It’s light-years from where we were,” he said.

While new levees and related works are supposed to keep floods out of neighborhoods, they’re a last resort instead of an overall answer. Visionaries are looking farther downstream and well into the future to find different kinds of solutions for problems that had seemed insoluble.

What the Louisiana coast needs, just about everyone agrees, is multiple lines of defense against storms — starting with the ones nature put in place.

Coastal wetlands help buffer big storms before they hit the mainland by absorbing some of the power of waves. Some research says storm surge, the dramatic rise in water levels pushed by hurricane winds, can be reduced by a foot for every mile of intact wetlands that greet the storm, the National Oceanic and Atmospheric Administration says.

Adding to the natural armor: oyster reefs and barrier islands.

For more than a century, however, the delta wetlands that had accumulated from Mississippi River sediment have been chopped and channelized, largely for oil and gas operations, and opened to erosion from ocean waves and vessels’ wakes.

Meanwhile, the engine that built the marshes ran low on fuel. The Mississippi River can’t deliver the amount of dirt it once did.

Dams and locks far upstream trap sediment that once oozed down into the delta. And modern farming practices in the Midwest have dramatically reduced soil erosion into the watershed — generally a good thing, but at the bottom of the system, the delta felt the deficit.

The result has been dramatic subsidence — a decrease in land levels. In essence, vast mats of floating marsh have sunk, with not enough new sediment arriving to offset the loss. Subsidence also plagues wetlands of the Texas coast.

Mississippi River delta wetlands the size of a football field disappear nearly every hour. In the past 80 years or so, about 2,000 square miles have vanished. In land area, that’s the equivalent of the city of Dallas sliding into oblivion — five times.

Louisianians even argue over whether the state map, which graphically freezes the extent of the land in a moment of time, should be changed to show former ground turned into vast, open water.

The status quo is challenging enough, but more problems are on the way via climate change. Sea-level rise compounds subsidence, boosting the gulf waters’ reach over the wetlands. Relative to the level of the land, nowhere else in the U.S. has seen the sea gain more elevation than at the delta’s southern tip.

Climate change also affects hurricanes by raising surface temperatures, among other factors. The end of the 21st century, climate models indicate, will bring more of the strongest storms, Categories 4 and 5.

Katrina landed on Aug. 29, 2005, as a Category 3.

And future hurricanes will dump more rain — about 20 percent more near their centers than they do now, according to the U.S. National Climate Assessment 2014.

The need, therefore, is urgent — but paradoxically, the solutions demand longer-term thinking than society is used to doing.

Louisiana’s Coastal Master Plan of 2012 took such a leap, laying out a 50-year strategy for reversing the wetlands loss. The plan is due for an update in 2017.

Last week, three teams in a competition presented their designs for extending that view out to 100 years — an unthinkable length of time for most plans. Imagine having tried, in 1915, to prepare for today’s politics and technology.

Civic leaders, academics, planners, engineers, environmental groups, fishers and others organized the competition, called Changing Course — a reference to how the Mississippi made its own way through the delta before levees and channelization.

One theme that runs through the plans is using the muscle that built the marshes in the first place. Rather than confining the river, some suggest, release it through more outlets, letting it deliver new life to the marshes.

Other technical fixes are proposed. Yet hard realities lie ahead.

There’s money now, but not enough — “You’ll never have enough money to do everything you think has to be done,” said Cochran — nor will it last forever without a dedicated source yet unfound. At a recent forum for candidates for governor, the federal government was the favorite option.

Funding aside, without enough sediment, a successful, sustainable delta will be far smaller than the one the oldest living oystermen recall. It’s a fact of physics.

Planners face other hurdles, too. Navigation must be maintained; the national economy can’t have New Orleans and Midwest shipping blocked by marshes.

Also remaining in the future will be oil and gas activities. They have been a particularly contentious source of wetlands loss, with roads and canals cut in past decades and seldom if ever healing.

None of the plans call for a ban on oil and gas work in the delta, though other factors already have reduced their impact. Much near-shore exploration and production has moved farther offshore. And tighter regulations and better technology have lessened new damage.

The industry supports the state’s coastal master plan and is committed to having “a smaller footprint,” said Ragan Dickens, spokesman for the Louisiana Oil & Gas Association.

The industry faces lawsuits from some coastal parties, including parish governments, seeking money damages in exchange for the marsh loss. The plaintiffs call the lawsuits a long-overdue redress of decades of grievances.

Dickens dismissed them as “large-scale money-grabs.”

Cochran, however, has detected a cooling of such recriminations in favor of work on common goals. He said he’s found big lessons that might apply anywhere big challenges involving humanity and nature appear.

Look long term, he said. Use nature’s power as much as bricks and mortar. Learn to live with water instead of against it.

“And don’t alienate yourself from your environment.”

Cochran is taking his own advice. After decades away, he’s coming home. His new house in New Orleans is nearly done.

Three weeks, he said, and counting.