Loudoun County's six Republican supervisors approved a 500-unit housing development yesterday on the family farm of former county board chairman Dale Polen Myers.

Myers served as the top campaign strategist for two of the supervisors and was a key architect behind the GOP's successful takeover of the county board in elections in November.

The 163-acre farm, which Myers said has been in the family since the 18th century, is being developed by Silver Spring-based U.S. Home Corp. The company agreed to buy the property if the board approved its development plans, Myers said. County officials assessed the value of the property at $2.9 million this year. Myers declined to comment on the sale price, or on what percentage of the property she owns.

"I am one of the heirs of the farm," Myers said. "I'm not going to get into our family contract."

Myers was a champion of swift development during her four-year term as board chairman, which began in 1996, and has remained intimately involved in the county's politics since she was defeated in 1999 by the current board chairman, Scott K. York (I), who advocates slow growth.

Myers spent years organizing opponents of the previous board's slow-growth policies, which reduced the number of homes that could eventually be built in Loudoun by 80,000. Last year she helped direct the victorious campaigns of board Vice Chairman Bruce E. Tulloch (R-Potomac) and Supervisor Stephen J. Snow (R-Dulles), who have pushed to increase development in the nation's fastest-growing county.

In comments before the board at the beginning of yesterday's meeting, Myers appealed to the supervisors to support an upcoming youth baseball tournament and did not mention the coming vote on her family's farm. When the board took up the issue, Myers sat in the lobby watching the proceedings on cable television.

The board voted 6 to 3 to rezone the property, which would allow 500 single-family homes, townhouses and condominiums to be built -- three times the 163 residences that would have been allowed with no board action.

Proponents noted that the development adheres to polices on housing densities set by the previous board for eastern Loudoun. Several Republican supervisors also said it was unfair, and disingenuous, to vote against an applicant such as U.S. Home that was simply trying to follow the county's rules.

Supervisor Mick Staton Jr. (R-Sugarland Run) said the proposal met "all the requirements" put in place by the previous board. "I guess you can be 'smart growth' or you can be 'no growth,' " Staton said. "It looks like the people supporting applications coming forward are 'smart growth,' and those who aren't are 'no growth.' "

Opponents of the application cited county figures outlining the fiscal impacts associated with the proposal.

"We're talking about millions and millions of dollars extra the rezoning will cost the taxpayers," said Supervisor James Burton (I-Blue Ridge).

Burton also noted that the current board has reduced the size of contributions the county expects from developers for infrastructure associated with the houses they build in the county.

According to figures prepared by the county staff, building capital facilities such as schools for a 500-unit development would cost the county between $5 million and $6 million more than it would cost the county to build such facilities for 163 units. That does not include yearly costs associated with serving new residents, Burton said.

The calculations are complicated by the fact that, according to Virginia law, the county gets no cash from the developer of such a project unless a property is rezoned. As part of the rezoning approved yesterday, U.S. Home agreed to provide about $6 million to cover some of the costs associated with its project.

Steve Calos, former executive director of Virginia's branch of Common Cause, said yesterday's approval presented an appearance of a conflict of interest that could give rise to accusations of cronyism.

"Anytime one does something that benefits one's supporters or political friends, it plays badly in some quarters," Calos said. But, he added: "There's nothing in the code that speaks to political conflicts. The code speaks to financial conflicts."

Tulloch said any suggestion of a conflict was "totally absurd."