Increasingly surrounded by mega-subdivisions, tiny Haymarket, a half-square-mile of more than 300 homes and about 900 residents, is trying to enforce a provision in its 55-year-old charter that allows the town to approve or reject subdivisions within a mile of its boundaries.

The Haymarket Town Council passed a resolution in September to enforce the regulation and sent it to Prince William County last month. Acting County Attorney Ross G. Horton responded in a letter, saying that landowners within a mile of Haymarket must comply with the charter but that the county, in deciding on subdivisions, does not need the town's approval first.

With its open space and proximity to Interstate 66, the western end of the county -- where Haymarket is located -- has been the center of Prince William's development boom. Although the Board of County Supervisors has protected open space by creating the Rural Crescent, which limits the number of houses in the western end, it has also approved several planned communities in the area with hundreds of units.

Haymarket's charter says that the council can "make and adopt a comprehensive plan" for the town and any plats that are subdivided and that the power extends "within one mile," which includes several developments approved by Prince William.

The General Assembly approved the charter in 1950. The provision requiring approval for projects was waived in some instances, and the county never submitted plans to Haymarket for more recent subdivisions, Town Council member Bob Weir said.

"Take Dominion Valley, Piedmont, Somerset," he said, naming some surrounding planned communities. "It's having a dramatic effect on the residents of the town."

Haymarket is feeling the toll of development, including increased traffic on Routes 15 and 55, which intersect at the town, and low water pressure. There is also more demand on fire and police, Weir said.

In his letter to Haymarket Mayor Pamela E. Stutz, Horton said: "The obligation to comply with the Town's Charter provision rests with the owner of the property within one mile. . . . The County may neither delay nor condition its approval of the subdivision plat on the Applicant's receipt of additional approval from the Town Council."

Weir said he thinks Haymarket's push to enforce its charter has already had an effect.

In the resolution, the Town Council listed three proposed projects that prompted its action. The Board of County Supervisors voted unanimously to reject one of the proposals, Carolina Manor, a subdivision of 117 houses.

"You could have knocked me over with a feather, because the county approves any development on the western end," Weir said. "How much of it is Haymarket being the squeaky wheel? How much of it is politics? I don't know."

Board Chairman Sean T. Connaughton (R) said Haymarket's resolution did not influence the vote. Instead, he said, his vote was influenced by a lack of road improvements, including an interchange to handle the increased traffic in the area.