As far back as third-generation resident Joan Lyon can remember, the secluded Mount Vernon neighborhood of Wellington Villa has always had a park on the Potomac River.

During the past 72 years, the people of Wellington Villa have used that park for picnicking, swimming, canoeing -- even bird-watching. The residents took it for granted that the park, marked as such on the original subdivision plat, was a sort of village green owned by the neighborhood.

But in a recent court decision, their claims on the park were severely limited.

The problem started a year ago, when residents discovered that the half-acre park, assessed by Fairfax County at $89,250, was bought for $5,000 by a Maryland excavator, Richard C. Morauer, who planned to build a home for himself on the land.

So Lyon, along with nine other neighbors, and the emotional and financial support of the Wellington community, sued Morauer to prevent the construction.

At the center of the legal tangle is the lack of evidence showing that the original land owners, Eugene and Harriet Frost, who both died before 1930, intended to give the park to either Wellington Villa or Fairfax County when the subdivision lots first went on sale in 1912.

Although the subdivision plat filed with Fairfax County's land records clerk in 1912 shows a waterfront park marked off along with 49 other lots, the Frosts apparently never transferred ownership of the park to the neighborhood or the county.

Residents hoped that their case would be helped by the fact that the disputed land was listed on county records as a tax-exempt park and appeared on county maps as a green area designating a park.

The case went to trial in September, and although all the issues have not been resolved, Judge Thomas J. Middleton, in a preliminary decision, agreed that the people of Wellington Villa should continue to have access to the water through the park because they have used it for such a long time.

But the judge did not prohibit Morauer from building a house on the property, saying, "the tax-exempt argument does not impress me or persuade me in any way."

He said that the county, at least during the trial, did not know why or how the land came to be designated a county park, implying that it may have been a mistake.

Middleton also said that the residents of Wellington Villa would have to find someone who was alive in 1912 who could say exactly what the Frost's intentions were regarding the park.

Wellington Villa residents take this to mean that the park could be theirs if such a person could be found.

"It never occurred to me that the judge would require us to come up with a living human being," said Lyon.

Wellington Villa hit the Washington-area real estate market in the summer of 1912 as "The handsomest suburb in this section of the country," according to newspaper ads from that time.

One of the first "trolley suburbs," it was touted as the only chance to buy property on the Potomac, convenient to a car line that connected Washington with Alexandria and Mount Vernon.

The real estate agents even inaugurated the opening of the subdivision with a public concert given by the U.S. Soldier's Home Band.

Joan Lyon, whose great aunt and uncle bought property in Wellington Villa in 1914, said she scoured an old newspaper account of the inaugural concert to find some mention of the park, but unsuccessfully. The oldest evidence that she and the other plaintiffs could produce to show the park was used by the residents were pictures dating from 1920 showing a dock attached to the park and people swimming nearby.

Middleton has urged the Wellington residents and Morauer to determine the exact boundaries of the park and adjacent properties, which are also disputed after three independent surveyors gave different readings.

The boundaries must be determined before Middleton can decide the area of the park that the rest of the residents are entitled to use. A preliminary injunction currently prevents Morauer from clearing the land until lawyers from both parties appear before the judge on Dec. 27 with the results of their negotiations.

Few residents are satisfied with the preliminary decision.

"What I'm concerned with is that we're being penalized for poor records kept in 1912," Lyon said.

Lyon recalled that several times since 1981, Morauer had approached property owners along the riverfront asking if they would sell. No one would, Lyon said.

Many of the people living in Wellington Villa object to the way Morauer obtained the park.

According to court documents, Morauer tracked down the Frost family heirs living in Westchester County, N.Y. The documents indicate that the heirs knew nothing of the park, nor the fact that they owned it. The heirs subsequently decided to sell the land.

Morauer and his lawyer declined to comment on the case.

Miriam and Robert Laughlin, the third generation to live in Wellington Villa, have property that abuts the park.

"We're very concerned about having a wild park where there are pileated woodpeckers, raccoons and possums, foxes, owls -- and that's going to be destroyed no matter what kind of house he'll put up," said Robert Laughlin.

"What really enrages me is the park is taken away from us," said Miriam Laughlin. "It's the principle of it."