Prince William Supervisor Edgar S. Wilbourn III eked out an apparent 11-vote victory yesterday in a hotly contested Republican primary in the rapidly developing Gainesville District, beating back challenges from two slow-growth candidates who had characterized the race as a referendum on development policies.

Yet to the west in Fauquier County, two candidates advocating slower residential development easily won GOP primaries for supervisor seats there.

The only clear message yesterday was that growth issues are destined to dominate numerous local election races this year, as slow-growth activists attempt to thwart policies that encourage development of homes, roads and offices in jurisdictions struggling to keep up.

"The one thing to take away from this is that people are unhappy," said defeated Gainesville candidate Kevin P. Childers, who together with another Wilbourn challenger won almost 60 percent of the vote. "I think it's the growth issue."

Yesterday was primary day for several supervisor races in Prince William and Fauquier counties. It was also the last day that independent candidates and others nominated without primaries could file to be on the ballot next November.

In Fairfax, Supervisor T. Dana Kauffman (D-Lee) acquired an opponent, Republican Robert M. Jones, a home builder. A disgruntled landowner filed to run as an independent against Supervisor Robert B. Dix Jr. (R-Hunter Mill), who is already under siege on the other side of the growth issue from a Democratic nominee. And independent Stephen Lee Lawrence filed yesterday to run against Democratic incumbent Penelope A. Gross and Republican Christine R. Trapnell.

In Loudoun, Dale Polen Myers, the chairman of the Board of Supervisors who was trounced by a slow-growth supervisor in a special Republican primary last month, filed yesterday to run again, as an independent. Several others have also joined that race and others in Loudoun in recent days.

The Myers defeat had buoyed the hopes of slow-growth activists in Prince William's Gainesville District, where two GOP contenders tried to woo voters by hammering on Wilbourn for opposing many development limits.

The result was a nail-biter, with Wilbourn and Martha W. Hendley each finishing with just over 41 percent of the vote each. Hendley said last night that she may ask for a recount and criticized Childers for refusing to drop out of the race in order to consolidate opposition to Wilbourn.

"I think there's a lot that's going to fall on his shoulders and deservedly so," Hendley said. "If his motivation was to do something good for the people of Gainesville, he should have done the right thing and gotten out."

Childers, who received less than 20 percent of the vote, said he had never intended to be a spoiler.

Wilbourn, who voted against a popular slow-growth plan that was approved by county supervisors last year, said the race was tight only because Hendley mischaracterized his views on development policies.

"I have such a strong base of supporters that are depending on me for balance inside and outside I-66," he said, "that I feel a real obligation to stay and fight."

In November, Wilbourn will face Democrat Gary Friedman, a slow-growth advocate, whom Hendley said she may actively support.

In Loudoun, Myers (R-At Large), who lost her May primary to Supervisor Scott K. York (R-Sterling), followed through on her promise to get back into the race as an independent in November.

"The records have been totally distorted -- this idea that I was responsible or at the helms of this growth that's happened in the county," Myers said. "I believe that the person that ran against me is just as much responsible for the houses that have come here as I am."

York has said that Myers, by deciding to run this fall, has failed to listen to the will of the voters.

Another candidate, novice James G. Kelly, has also entered the chairman's race as an independent, saying York would not do enough to curb growth.

Kelly has also filed to run for district supervisor in Dulles.

Planning Commissioner Alfred P. Van Huyck, who also filed as a candidate in the chairman's race, said yesterday that he planned to withdraw from the race unless Myers changes her mind in the next few weeks. Van Huyck said he did not want to risk splitting the slow-growth vote with York, possibly giving Myers a victory.

Several independents filed to run in other Loudoun supervisor races, leaving only Eugene A. Delgaudio, of the Sterling District, unopposed in November.

In Prince William, independent Robert K. McBride of Woodbridge will challenge board Chairman Kathleen K. Seefeldt (D), and Republican Lester Gabriel will face Woodbridge Supervisor Hilda M. Barg (D).

In Fairfax, which held no supervisor primaries yesterday, Dix will be challenged in November by Democrat Cathy Hudgins, a former aide to board Chairman Katherine K. Hanley (D), and independent John Thoburn, who filed yesterday.

Thoburn says Dix and the other board members have unfairly prevented him from developing land he owns along the Dulles Toll Road near Wolf Trap. Dix has said that Thoburn's land is fairly zoned for its largely residential location.

Growth was not the only issue on the electoral agenda, of course. In Fauquier County, which had three GOP primaries yesterday, several voters said other issues drove them to the polls.

"I buy hay from her brother," said Warrenton retiree Paul Blackmer, 56, explaining why he voted for Sharon Grove McCamy in the Lee District primary.

McCamy, known for slow-growth views, won her primary, as did Raymond E. Graham in Cedar Run.

Staff writers Libby Copeland, Peter Pae, Michael D. Shear and Graeme Zielinski contributed to this report.