JERSEY CITY -- A 240-acre section of Liberty State Park that has been closed to the public for decades because of contamination would be transformed into a "mosaic" of freshwater wetlands, salt marshes, forests and grasslands under a plan announced today by Gov. Chris Christie's administration.

The state Department of Environmental Protection, under fire by park advocates for its plan to add a 45-acre marina to the southern end of the 1,200-acre park, intends to spend $40 million on the project, using money obtained from polluters, the DEP said today.

"Today, we are beginning the long-overdue restoration of an area that lies at the heart of this great park but has long been off-limits to the public," DEP Commissioner Bob Martin said in a statement. "The work we are beginning will transform this area into a mosaic of ecosystems that will be enjoyed by the millions of visitors who come to Liberty State Park each year, and will attract wildlife in one of the most urbanized parts of New Jersey."

Park advocates are overjoyed about the project, if a little miffed that it took Christie's administration until the final days of his tenure to give it the green light. A similar plan was announced in 2008 but shelved after Christie took office in 2010. Gov-elect Phil Murphy succeeds Christie on Tuesday.

"This is a spectacular plan," said Sam Pesin, president of Friends of Liberty State Park. "It will become an international model for urban nature restoration."

"This is huge," said Greg Remaud, deputy director of environmental group NY/NJ Baykeeper. "It's going to be one of the greatest natural restorations in the United States."

An early conceptual drawing of a state plan to create a wildlife oasis inside Liberty State Park.

The fenced-off section of the park is located in its interior, between Liberty Science Center and Freedom Way, and represents 40 percent of the park's land (600 acres of the park are underwater).

In the 1990s, the area was slated for a golf course, a plan that was shelved after park advocates objected. Former Mayor Bret Schundler once backed a water park for the spot, another idea park advocates helped kill.

The state's plan will initially focus on one 23-acre section of the interior. The state will create trails to connect this area to the park's existing trail system and to Liberty Science Center.

Subsequent phases will restore another 217 acres by creating new salt marsh, capping contaminated soil and planting trees and grass to create forested and grassland areas, Martin said. Hawks, bats, oysters and more will benefit, according to the DEP.

The salt marsh would be fed by the Hudson River by a new channel connecting the river with the park's interior.

Remaud said once the project is completed, the inland will be green like the rest of the park, but wilder and less manicured. It will create an extraordinary opportunity for environmental education, he said.

"If you're a kid in Jersey City, instead of having to go out three counties away, you can come in here and see all these habitats right in the backyard of Liberty State Park," Remaud said.

The area is contaminated with low levels of metals and hydrocarbons because of dirt used as fill in the past. Remaud said in some "hot spots" the contamination needs to be entirely removed, but in most areas it can be capped.

Pesin said his group thanks Remaud, former DEP official Frank Gallagher and John Sacco, who works for the DEP's Office of Natural Resources, for their work on the interior restoration plan.

The U.S. Army Corps of Engineers will put the project out to bid and manage construction, with the DEP overseeing the project. There is no timeline yet.

The funds come from natural resource damages settlements, which aim to reimburse the public for damage done to public lands and resources.

The marina plan is stalled until at least Tuesday, when a Hudson County judge has scheduled a hearing as part of a lawsuit Jersey City filed aiming to halt the plan altogether.

Terrence T. McDonald may be reached at tmcdonald@jjournal.com. Follow him on Twitter @terrencemcd. Find The Jersey Journal on Facebook.