Legislation to preserve Plum Island and prevent its development is currently making its way through both chambers of Congress. Rep. Nick LaLota introduced a bill last year to designate the island a national monument, while Sen. Chuck Schumer has championed a similar bill in the Senate that would preserve the island as it is in perpetuity.

Plum Island’s 822 acres are home to 111 species of conservation concern. More than 229 bird species nest there, which is a quarter of all the species known in North America north of Mexico. Because elements of its ecosystem have remained undisturbed since the mid-1950s, much of the natural systems have recovered. This provides habitat for diverse species, including rare plants and breeding birds, including endangered breeding birds such as the piping plover. Plum Island also has the largest seal haul-out in New York State. Hundreds have been seen hauling out in the winter along its south shore.

“For years, I have been fighting tooth and nail to protect and preserve the national treasure that is Plum Island,” Mr. Schumer said in an emailed statement. “Long Islanders should have input over this natural environment, not some outside ‘high bidder.’ This legislation would take a huge step forward in ensuring this natural wonder is permanently preserved for generations to come, a true win for Long Island, the environment, its rich history and the communities and advocates who have fought so hard to preserve Plum Island.”

Former local congressmen Tim Bishop and Lee Zeldin both contributed to the effort to preserve Plum Island. More recently, the East End’s supervisors and mayors all endorsed Mr. LaLota’s bill, showing local, bipartisan support.

“The very first bill I introduced was the Plum Island National Monument Act. As you know, it would protect Plum Island’s natural resources and ensure that future generations can appreciate and learn from this natural wonder,” Mr. LaLota said. “It would bring economic benefits to the East End. Eco tourism is a growing industry, as you know, on the East End especially, and protecting Plum Island as a national monument would attract visitors and generate revenue from the local economy. The scientific research conducted on the island has potential to bring jobs and investments into Suffolk County.”

While preserving the island would certainly be a triumph for conservation and research, the level of public access has yet to be determined. Scientists and others will need to go there in order to prescribe a level of access that does not harm the ecosystem. At the same time, public access is crucial in order to engage people with their environment and make the case that it is worth preserving. “We believe that when people see Plum Island, they’re transformed, and they love the place, and they want to bring stewardship to Plum Island,” said Louise Harrison, Long Island natural areas manager for Save the Sound.“It’s time to return Plum Island to the people, but we want the level of access to be suitable, and we don’t want to trample the North Fork of getting there.”

Beyond its natural wonders, there is a historical contribution in the form of the island’s many uses to the federal government. There is a lighthouse, a former military fort, and the research facility. “It’s not just amazing because it’s outside of New York City and has such incredible biodiversity. It has two national register historic sites, the Plum Island Light Station and Fort Terry. It has the famous Plum Island Animal Disease Laboratory, where discoveries have been made and vaccines have been developed, helping to preserve our own nation’s food supply and food supplies around the world, with top scientists and veterinarians,” said Ms. Harrison. “It’s an employer of many people who live on the North Fork, Shelter Island and Connecticut. It’s a phenomenal place.”