Broad stretches of marshes along the Chesapeake Bay’s shores could soon gain federal protection under a Reagan era conservation program popular among conservatives and progressives alike.

Bills in the House and Senate would add 277,000 acres to the Coastal Barrier Resources System, a nationwide network of low-lying beaches, barrier islands, wetlands and nearby uplands considered highly vulnerable to punishing tides and waves. A little more than half of the new acreage would be drawn from tracts in three Bay-region states: Delaware, Maryland and Virginia.

The little-known program, signed into law in 1982, takes an unusual approach to conservation. A chunk of the protected acreage is already public land. But properties in private ownership at the time of their inclusion remain in private hands. What’s more, the land can still be developed — the “coastal barrier” designation doesn’t stop any concrete from being poured.

But it doesn’t help it happen either. Under the program, lands within the system are prohibited under most circumstances from receiving any development subsidies from the U.S. government.

“It simply says this land is going to roll with nature, and if you’re crazy enough to build there, you can do so with your own cash,” said Skip Stiles, the former executive director of the nonprofit Wetlands Watch. “It’s not heavy-handed.”

Want to get a road built? Sorry, no infrastructure grants for you. Need federally backed flood insurance? You’re out of luck. How about disaster assistance after a storm? You’re on your own.

That’s part of its staying power, supporters say. More than 40 years after its inception, the program continues to attract fans from both sides of the political aisle, Stiles said. The Senate version of the latest bill to augment the stockpile of designated places, for example, is sponsored by Tom Carper, a Democrat from Delaware, and Lindsay Graham, a Republican from South Carolina.

“This fiscal savings appeal to the conservative types, and the habitat preservation appeals to the tree huggers,” Stiles said.

That rare example of bipartisanship is no guarantee of passage. With elections looming in 2024, attempts to get anything done through federal legislation risk turning into a slog. But the bills’ backers say they are hopeful they can overcome political divisions without making too many waves.

“It’s sort of a low-key environmental law since there’s no real regulation involved,” said Portia Mastin, a coastal policy expert with the National Audubon Society, one of the measure’s most vocal proponents. “It does its job without being too controversial.”

U.S. Rep. Jen Kiggans is a Republican who represents a southeastern Virginia district that includes most of the state’s coastal barrier lands. She is sponsoring the House bill, she said, partly because the program appeals to her identity as a fiscal conservative.

“They can still develop [their land], but we just don’t feel that would be a good steward of federal tax dollars by developing something that is a high-risk area for natural disasters and hurricanes,” she said.

Indeed, undeveloped lands tend to stay that way after receiving the Coastal Barrier designation. Such properties were developed at an 85% lower density compared with similar tracts not included in the program, according to an analysis by Resources for the Future, a nonpartisan thinktank devoted to environmental issues.

“They’re kind of like conservation lands now,” said Margaret Walls, one of the report’s authors.

On the flip side, the study showed that the Coastal Barrier program increased development by 20% on lands just outside its boundaries. Walls and her colleagues chalked that up to the flood-protection benefits and parklike amenities offered by the program lands.

Stiles, who now serves as a senior advisor to the Norfolk-based environmental group, recently testified on Capitol Hill in favor of expanding the system’s acreage. The program has a long track record of saving federal dollars by preventing good money from being thrown after bad on risky coastal properties, he said.

“It’s that zone at the end of the ocean, where the land collides with the sea, which is a dangerous place to be,” Stiles said.

A study commissioned by the National Audubon Society estimated that the program reduced federal disaster expenditures by nearly $10 billion from 1989 to 2013. Based on projected development rates and storm-damage forecasts, the researchers projected up to $108 billion in additional savings from the lands into the late 2060s.

Left undeveloped, coastal lands can act as storm barriers for populated areas to their rear, advocates say. A study financed by the insurance giant Lloyds of London in the wake of 2012’s Superstorm Sandy attempted to quantify those benefits.

The massive storm destroyed more than 600,000 homes and resulted directly in the deaths of more than 70 people across Mid-Atlantic states and New England. But it could have been worse. The study found that coastal wetlands staved off $625 million in property damage, reducing the overall damage costs by about 10%.

Congress has expanded the Coastal Barrier acreage several times over the years, most recently in 2018. The system now contains 3.5 million acres of land, an area roughly the size of Connecticut.

Advocates have Sandy to thank for inspiring the latest expansion bid.

After the storm, Congress set aside $50 billion in disaster aid. That funding included a little-noticed $5 million outlay toward modernizing the original hand-drawn maps of the Coastal Barrier resources in nine states impacted by Sandy: Connecticut, Delaware, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island and Virginia.

The U.S. Fish and Wildlife Service, which oversees the program, published the new maps last year. The agency recommended adding 277,950 acres to the system while removing about 1,300 acres. The proposed additions include 31,000 acres in Delaware, 19,000 acres in Maryland and 96,000 acres in Virginia. The new lands would be along of the Chesapeake as well as the seaside portions of the Bay states.

Many of the additions are in remote areas, far from the nearest road. But some skirt subdivision boundaries, standing as the only line of defense between homes and open waters.

Stiles said he hopes the final legislation, if passed, includes a provision in the Senate version that creates a pilot project to identify higher ground that can be added to the program later. Much of the coastal land currently under protection is at risk of going underwater permanently as climate change causes seas to accelerate their rise. Those low-lying habitats need spaces where they can reestablish themselves, he said.