Old Saybrook — Declaring that preservation advocates are “closer than ever to protecting Plum Island for generations to come,” three members of Connecticut’s congressional delegation announced Friday that significant progress has been achieved to prevent the federal government from selling the island to the highest bidder.

“We now have the law on our side in a way that we didn’t have before,” Sen. Richard Blumenthal said to representatives of a coalition of conservation groups and other attendees during a news conference at the Saybrook Point Inn. “We now have a critical mass of support, and the fiscal reason for selling the island is no longer present.”

The 840-acre island in eastern Long Island Sound, part of the town of Southold, N.Y., is home to the Plum Island Animal Disease Center, which is slated to be closed when the National Bio and Agro-Defense Facility in Manhattan, Kan., opens to replace it in 2022.

The existing high-security lab, there since 1954, only takes up a small portion of the island, with much of the remainder left as open space that provides critical habitat for endangered birds, plants and other wildlife.

Both labs are part of the federal Department of Homeland Security.

Congress enacted laws in 2008 and 2012 that required the island to be sold by the General Services Administration, with proceeds going to fund construction of the new facility.

The 2016 appropriations bill that passed Congress late last year, however, provided about $55 million toward the construction from the federal government’s general fund, Blumenthal said, meaning that “Congress has said, in effect, that there is no reason for the sale.”

“The sale of Plum Island wasn’t going to fund the total amount (of the construction) anyway,” he said.

Now that funding of the new lab has been “unhinged” from the sale of Plum Island, the state’s congressional delegation is working with its New York colleagues to pass measures that would “strike the law requiring the sale of Plum Island” for good, said U.S. Rep. Joe Courtney, D-2nd District.

Bills are pending both in the House of Representatives and the Senate that are expected to be taken up in April.

Rep. Rosa DeLauro, D-3rd District, told supporters of making Plum Island a wildlife refuge or national park to start contacting lawmakers to urge actions be taken to prevent the sale of the island.

"The way Congress moves is with external pressure," she said. "You have to keep up the pressure."

In addition to designating other funds for the construction of the Kansas lab, the Congressional Appropriations Subcommittee on Homeland Security has directed the agency to study conservation options for the island.

The report, to be completed in June, is to consider the environmental and historic resources on the island, including the ruins of Fort Terry, as well as the costs and actions needed to protect those resources and clean up contamination from the lab, Blumenthal said.

The report is being created in collaboration with the Environmental Protection Agency, the Department of the Interior and the General Services Administration, he added.

About 50 people representing the Plum Island Coalition, a collection of 66 groups from both states supporting protection for the island, gathered at the news conference Friday.

Leah Lopez Schmaltz, program director for the Connecticut Fund for the Environment/Save the Sound, said her group will be sending the homeland security department 1,000 comments from advocates of protecting Plum Island.

The purpose, she said, is to make the department aware of the level of public support for preservation of the island as it prepares the report.

Her group, one of the members of the Plum Island Coalition, is advocating that the 20 percent of the island where the lab is located be reused as an education facility for universities and an office to manage the wildlife and historic resources on the island.

The report also should detail how permanent conservation of the island can best be achieved, she said.

“We’d like to see the actions be recommended to make sure that the future we all see for Plum Island becomes a reality,” she said.

Stewart Hudson, executive director of Audubon Connecticut, another member of the Plum Island Coalition, said the chance to preserve such a large and important area for wildlife in the heavily populated Northeast will not come again.

“This is a once-in-a-lifetime opportunity,” he said. “They’re not making any more islands in Long Island Sound.”

j.benson@theday.com