Here's a summertime day trip worth dreaming about.

One day a few years from now, you take the Long Island ferry to Orient Point. A short walk from the terminal is a museum that tells you all about mysterious Plum Island.

After taking it in, you get on another ferry, which brings you to the island, a remote place that, as of now, few people have ever seen. A guided tour takes you through a vast, unspoiled nature preserve and the restored remains of a military post with a compelling story.

If that doesn't satisfy your Plum Island fix, you can book an overnight stay at a 150-year-old lighthouse.

This is one possible future for the isolated, 840-acre place that lies just 8 miles south of the region's shoreline. Another is that the U.S. government, which owns the island, sells it to the highest bidder, and the public is shut out forever.

A long-running effort to prevent the latter possibility just reached a significant milestone. A report has been released that offers the first detailed vision for the island, one that mixes conservation, research, historic preservation and public access.

At the moment, the island, home to the Plum Island Animal Disease Center and off-limits to the public for decades, is still set to be sold off once the lab closes and moves to Kansas by 2023.

But the 72-page report, called "Envision Plum Island," lays out a road map for turning it into a prized public jewel under state and local ownership. The report is the work of the Preserve Plum Island Coalition, 110 organizations that banded together to prevent the sale.

Three years ago, the coalition was asked by Congress, "What do you see instead?" Its answer is a suite of uses that maintain the island's key features: undisturbed nature, historic buildings and an active laboratory complex.

The plan's specifics will inform the ongoing debate in Congress, where there are hopeful signs about the island's future, including a measure passed by the House on Friday.

"The tide definitely has turned, but we still have a lot of work to do," said Chris Cryder of Save the Sound, one of two groups that took the lead in creating the report.

The plan

Envision Plum Island is the result of two years of meetings involving hundreds of people to articulate a plan. It was led by Save the Sound and the Nature Conservancy in New York. The report's main points include the following:

Conservation: The bulk of the island, 640 acres, would be a preserve supported by partnerships among federal, state and local governments, nonprofits and volunteer groups.

The report notes that as many as 227 bird species, nearly a quarter of all species in the U.S. and Canada, have been sighted there. In addition, hundreds of harbor seals come ashore to rest, and the surrounding marine habitats host rare sea turtles and other creatures. Yet the waters remain mostly unexplored, the report says.

At a news conference to unveil the report on July 22, Steve Ressler, a scientific diver, noted the island's striking biodiversity.

"It has one of the most diverse and most abundant species compositions on the East Coast of the United States," he said.

Research: The laboratory complex used by the animal disease center, on a 125-acre campus at the island's western end, would be available for reuse. Suitable activities include renewable energy, biotech, health, cybersecurity and climate science, the report says.

This would support the goal of job retention pursued by the town of Southold, N.Y., of which Plum Island is a part.

In addition, archaeologists and Native Americans would investigate life on the island before European settlement.

Historic preservation: The buildings of Fort Terry, a former coastal defense fortification, would be stabilized and restored, with application made to place them on the National Register of Historic Places. One would be refurbished into a dormitory for researchers.

The report notes that Fort Terry is by far the most intact and historically important of a string of island forts established in eastern Long Island Sound in the Spanish-American War era.

The island's other significant structure is an 1869 lighthouse already listed on the National Register. No longer a functioning aid to navigation, it would be restored and possibly used as a bed-and-breakfast or a visitor center.

The more recent history of the animal disease lab also should be preserved, the report notes.

"Even though Plum Island has appeared in novels that heightened fear, films made frightening references to it, and conspiracy theorists spread rumors about activities there, great things were done there," the report says.

Public access: The Plum Island property includes a 9.5-acre ferry terminal at Orient Point that serves the lab. This could be used by both a successor lab and the public.

Visitors' first stop could be a museum at the terminal that outlines the island's story.

Louise Harrison of Save the Sound said at the news conference that limiting ticket sales for the ferry might be a way to control public access in the interest of protecting the island's natural resources.

"We want to love Plum Island but not love it to death," she said.

Preventing the sale

Before any of this can happen, Congress would have to repeal laws from 2009 and 2012 that mandate the sale of the island to the highest bidder. That has been the primary goal of the Preserve Plum Island Coalition.

Those laws bypass the standard process for disposing of surplus federal property, which normally would be offered first to other federal agencies, then to the state where it's located, and finally put on the open market.

Instead, a public sale was mandated in the hope that it would generate a significant sum to help fund the animal disease center's replacement, the National Bio and Agro-defense Facility in Manhattan, Kan., according to Greg Jacob, a policy adviser for the Nature Conservancy in New York.

But the new lab, which is nearing completion, has since been fully funded, and Plum Island's likely value on the open market has decreased. In 2014, Southold zoned the island into a large conservation district and a smaller research district, which would prevent other uses if the island falls into private hands, Jacob said. A future owner could not build condominiums or a golf course, for example.

Last year the coalition had the island appraised in light of the zoning restrictions and found it was worth $17.5 million, a third of what the government had expected to sell it for, Jacob said.

Still, the Department of Homeland Security, which oversees the lab, sees the island's sale as a revenue source for other projects, he said.

Over the years, several bills repealing the 2009 and 2012 laws have been passed by the House of Representatives with bipartisan support, but one has never passed in the Senate, Jacob said.

Two similar bills are now in committee in both houses of Congress, one sponsored by Rep. Lee Zeldin, R-N.Y., and the other by Sen. Richard Blumenthal, D-Conn.

"We need to ensure that our neighbors are able to experience what we've been able to experience and to keep (Plum Island) as protected and as beautiful as it is today," Zeldin said at the news conference.

Both bills are stand-alone efforts, which are harder to move through the legislative process, so the strategy of the coalition, working with congressional partners, has been to insert repeal language into broader measures like appropriations bills.

While that failed last year, the coalition succeeded in getting a measure passed that temporarily stopped the General Services Administration, the government agency tasked with the sale, from actively marketing the island.

This year, repeal language was included in a House appropriations bill until last Tuesday, when it was removed. But an amendment was added by Zeldin and U.S. Rep. Joe Courtney, D-2nd District, that continued the restriction on GSA marketing until September 2021. The bill was passed by the House on Friday.

"I'm optimistic that it's still in play, that we can still make this happen," Jacob said, noting that repeal is still a possibility in the Senate version of the appropriations bill, which has not yet passed. 

Some members of Congress reluctant to back repeal of the sale question whether the island would continue to cost the government money in terms of maintenance and security if there is no plan for its future, Jacob said.

"I think the report is going to be very helpful because it answers that question," he said.

j.ruddy@theday.com