The proposed sale of Plum Island and a support facility on Orient Point, N.Y., would have no major environmental impacts, a federal report has concluded.

The Environmental Impact Statement on the proposed sale of the 840-acre island and 9.5-acre support property, home of the federal Animal Disease Center, was released Tuesday by the General Services Administration, the federal agency in charge of the sale.

While their review of the 512-page report has just begun, environmental groups and others advocating conservation of the island said their initial look at the document leaves them very disappointed.

"Steps that should be taken to conserve the natural resources of the island have not been given consideration," said Charles Rothenberger, attorney for the Connecticut Fund for the Environment-Save the Sound. "There's no recommendation to condition the sale on conservation easements to protect critical habitats."

Sen. Richard Blumenthal, D-Conn., called the report "deficient and flawed" and said he would support challenges to the Environmental Impact Statement. He advocated that the GSA work with the town of Southold, N.Y., where the island is located, "to ensure that environmentally sensitive areas of the island remain permanently off limits to future development."

The research center occupies about 25 acres of the island, with undeveloped beaches, dunes, meadows and wetlands occupying most of the remainder.

The Preserve Plum Island Coalition, comprised of more than three dozen environmental and local groups, supports conservation of 80 percent of the island and reuse of the remaining 20 percent for a research lab, said Chantal Collier, director of The Nature Conservancy's Long Island Sound Program. The conservancy is a member of the coalition.

The coalition also supports a proposed town zoning plan for the island which would establish the developed area as a research district and designate the majority of the property for wildlife habitat conservation.

A law passed by Congress in 2008 directed the GSA to sell the property if the lab were moved elsewhere, and the next year, the Department of Homeland Security decided to build a new facility in Manhattan, Kansas, at an estimated cost of $1.4 billion. Depending on when the funding becomes available, the new facility is expected to be completed by 2019, and the transition of the research and lab functions of Plum Island to Kansas would take place over the next two years.

About 360 scientists and support staff work on the island, traveling to the island by ferries that leave from Old Saybrook and Orient Point. It is located in Long Island Sound off the tip of Long Island's North Fork, about 10 miles from the Connecticut coast. The lab has been located there for 59 years.

The report, which is required by the federal Environmental Policy Act to assess the impacts of proposed government actions, analyzed the possible impacts of sale of the property and three possible reuse options: the 50 buildings that comprise the center would be adapted for a similar research or scientific facility; the property would be developed for low- to high-density housing; or the island would be purchased for natural resource conservation.

All of the possible uses would be subject to local zoning requirements of Southold and New York state regulations. The report also analyzed the impact of taking no action and mothballing the property.

Patrick Sclafani, spokesman for the GSA, said the 512-page report does not advocate either of the three reuse options. He said that by law, the only action the GSA can pursue is sale of the island.

The report's assessment on the three reuse options on 12 areas, from cultural resources to air and water quality to traffic, is that most would have "no impact" or "negligible impact." A few areas would have "minor" or "moderate" impacts, but none would cause "major" impacts, the report states. Reuse for residential development is deemed to have the greatest potential impacts, mainly on land and visual resources, water, biological and cultural resources, traffic and transportation.

Sclafani said the sale would not take place until the lab project is well under way.

"It's safe to say it would be years away," he said.

Rothenberger said his group and others are considering possible action to prevent the sale.

"The GSA is taking far too narrow a view of the authorizing legislation directing them to sell the property," he said. He believes a case can be made that preservation of open space and endangered species habitat are in the public interest, so that a sale or transfer to another government agency such as the Fish & Wildlife Service would be possible.

The report is available for public review for 30 days. After that, it will become final. It can be found at www.plumislandny.com and at the Acton Public Library in Old Saybrook.

j.benson@theday.com