Today, the area is important to the county's forest management plan, Gardina said. Planting trees would protect birds and other wildlife.

The county also could generate revenue by charging developers who clear forests elsewhere to plant at the peninsula site in what's known as a "forest mitigation bank," Gardina said.

And removing impervious surfaces and reforesting the area also would help the county meet some of its obligations under requirements that Maryland and other states cut pollution in the Chesapeake Bay watershed, he said.

Environmental protection was the reason the county bought the land, Gardina said.

"The airport happened to be there, and at the time, they made a decision to allow them to continue," Gardina said. "And at this point, we're trying to deal with multiple environmental issues, including the Chesapeake Bay watershed issues, as well as the fragmented forest."

The skypark group says it has taken care of the land and that the surrounding neighborhoods have embraced the site. Local kids learn to fly there. Families gather for an annual fly-in called Wings and Wheels every September. Boy Scouts camp there, and volunteer firefighters have used the site for training.

Carl Maynard, president of the Back River Neck Peninsula Community Association, said neighbors support the skypark, as long as the group takes care of the land and doesn't expand.

"The skypark itself lends that atmosphere of the old, country-type feeling down here," Maynard said.

Skypark association members believe an easement signed by the Maryland Environmental Trust and the Shapiro family in 2000 indicates that the family wanted the airport to stay. The document exempts the airport from a prohibition against commercial activities on the property.

County officials say they have no legal obligation to keep the skypark open. Don Mohler, chief of staff to County Executive Kevin Kamenetz, said the group let its lease lapse, adding that the officials believe they are giving members plenty of time to move.

"Five years by anybody's standards, I think, would be a very fair time frame to find an alternate location," Mohler said.

Katzenberger called the idea of finding another location for the skypark "ridiculous."

"If you told any community, 'We're going to put an airport in,' they would probably be up in arms," he said. "I don't think we could find land, and I don't think Baltimore County would give us the zoning."