Widowed for five years, Mary McDowell has found herself in dire financial straits -- even though she has been sitting on more than 300 acres of prime real estate in Prince William County.

Her late husband, retired Marine Col. Dean N. McDowell, was a well-known conservationist who had turned Merrimac Farm near Quantico Marine Corps Base into a popular hunting preserve where sportsmen could shoot quail and pheasant. The preserve closed after his death. He also had his land classified as protected open space, limiting its use to farming until 2011. The open-space designation also allowed him to defer property taxes.

As much as Mary McDowell wanted to honor her husband's memory, the elderly widow needed money, her representatives told county officials. So this fall, McDowell -- with the help of a prominent environmentalist who also is a Prince William planning commissioner -- asked the county to lift the zoning restrictions early and open the land to development. They were successful, and the value of McDowell's property rose from $184,300 to $2.6 million.

The environmentalist, Kim Hosen, executive director of the Prince William Conservation Alliance, then asked a state agency for $2 million to exempt the property from development.

But now, the elaborate plan has unraveled, and Sean T. Connaughton, the Prince William Board of County Supervisors chairman, is calling it a scheme to inflate the farm's value and use taxpayers' money to buy and preserve it as open space.

"There appears to have been a concerted effort to open the property up to development in order to create a crisis and cause the expenditure of millions of dollars in public money," said Connaughton (R). "You can't get away from the basic fact that this property had five years left of preservation."

Connaughton's objections, which he has shared with a state agency and the Marine Corps, have thrown the fate of Merrimac Farm into uncertainty.

They have also split the board of supervisors and the community in the fast-growing county, where every open acre appears to be the target of development. The land could now be the site for as many as 30 homes.

Hosen said she had planned to have her organization buy the property with a $2 million grant from the Virginia Land Conservation Foundation. The Marine Corps would pay $1.75 million to preserve a buffer of undeveloped land near the base.

Yesterday, the board governing the Virginia conservation foundation rejected Hosen's proposal, citing the last-minute changes in the property's status and value among their reasons for denying the grant, spokesman Gary Waugh said.

"We didn't know until very late in the ballgame about it being appraised for its development value. We weren't aware until the last minute that it was taken out of the [agricultural] district," he said.

The foundation had 50 other applicants to consider and less than $10 million to spend, Waugh said. Twenty-two projects were approved yesterday.

Hosen said she was simply trying to save the property from development while still ensuring that Mary McDowell would be fairly compensated. McDowell, who lives in North Carolina, needed to sell the land, Hosen said. Her health and age made it impossible to wait five years for the restrictions to be removed, Hosen added.

On Sept. 20, Hosen, acting as the conservation alliance's executive director, applied for the $2 million state grant. In her proposal, she stated that the land's sale was imminent and points to a vote of the county Planning Commission scheduled for the next day.

There is no indication on the application that Hosen is on the Prince William Planning Commission or that she is a family friend.

In an interview yesterday, Hosen said she had been in a hurry to complete the application and was tired. Her most important goal, she said, was "to convey a quantitative sense of urgency" because of the upcoming planning commission vote, in which she did not participate.

"It came to a perception of a conflict of interest enough that I recused myself," she said. "I very strongly believe in conflict-of-interest laws. I don't understand how I could have possibly made it more public."

The application requested $250,000 in administrative costs, which she said would have been matched by other donors and would have included payments to herself to manage the land. "My normal pittance. I'm a salaried employee of the conservation alliance," she said, adding that she is paid $50,000 annually.

As she walked along serene Cedar Run on the property yesterday, Hosen said she hopes to find another way to work with the family to preserve the land.

McDowell's daughter Anne Schafer said the family was disappointed with Connaughton's interference. "He's trying to kill the deal," Schafer said.

Connaughton also drew the ire of some of his peers, who worry that he stirred up trouble. Supervisor Maureen S. Caddigan (R-Dumfries) said she is sponsoring a resolution to show the county's support for Hosen.

There was no wrongdoing in the transaction if there is a "change in circumstance," such as Dean McDowell's death, and the zoning could have been changed, said Supervisor W.S. Covington (R-Brentsville).

Under Hosen's scenario, the McDowells would have received a good price for their property and it could have been preserved, Covington said. Now, he said, development is sure to come to the property.

"We all looked bad at the end of the day," he said.

Conservationist Kim Hosen gives a tour of Merrimac Farm in Prince William County.

Hosen walks through Merrimac Farm, a property she tried to preserve. She was unable to secure a $2 million state grant.