A plan for managing growth around the boundaries of Purcellville was approved unanimously Thursday by the Town of Purcellville's Planning Commission and the Loudoun County Planning Commission in a joint meeting.

The plan -- known as "phase one" -- was envisioned in 1993 by the committee that drafted the Purcellville Urban Growth Area Management Plan as the first step toward providing for orderly growth immediately adjacent to the town's boundaries as that land is annexed.

Phasing in development around this western Loudoun hub is meant to give the town control over the pace and character of development, as well as to win concessions from developers for amenities and such infrastructure as connector roads, according to town officials.

If it is approved by the Purcellville Town Council and the county Board of Supervisors, the first phase will last 10 years and include mostly residential development: as many as 450 houses and about 50 acres of commercial development.

Not included in the first phase are 800 additional potential housing units on land in the town limits that is already zoned for multifamily use. Although there are no projects proposed, that land could be developed at any time.

The plan's critics contend that it will encourage growth and strain the area's natural resources. Critics and supporters alike fret about where the town will get the water it needs to grow.

The two commissions adopted the phase one plan in separate, unanimous votes. Two members of the Purcellville commission and four members of the Loudoun commission were absent.

The plan will go before a joint meeting of the Board of Supervisors and the Purcellville Town Council for a public hearing July 7. The council is scheduled to vote on the plan July 13. Supervisors are scheduled to vote July 21.

Alfred P. Van Huyck, who represents the Blue Ridge District on the county Planning Commission, commended the plan but, like many speakers, warned that water resources must be analyzed before the town contemplates much growth beyond the 450 houses envisioned in the first phase.

"Events have overcome you, and you now have to move ahead . . . and get some additional growth to pay for the growth you already have," Van Huyck said. "Settling the water issue is going to be of critical importance to Purcellville and the other towns."

Town officials said the plan's primary aim is to plan and control inevitable growth. "We hope to do a better job with development, get viable open spaces with trees and natural areas intact," said Jim Pammel, director of planning and zoning and assistant manager for the Town of Purcellville. "Hopefully, we'll get a superior form of development."

Adopting phase one would not necessarily mean that the town would have to adopt other, later phases, Pammel said.

The county supervisors' approval of phase one would allow the Purcellville Town Council to rezone land that is being considered for annexation for denser residential development to generate more money for water and sewer improvements.

Without a phasing plan, the town can annex such land but cannot change the zoning. Most of it is zoned to allow one house for every three acres with wells and septic systems rather than town water and sewer.

This spring, the Town Council put off action on two annexation requests -- the 92-acre Case farm and the 120-acre Jost farm -- while awaiting resolution of the votes on the phasing plan.

The council already has approved the annexation of 21 acres south of town that will connect the town's boundaries to the swath of land where a waste water treatment plant is being built.

At Thursday's session, supporters touted the phase one plan as a way to exert control over the extent and aesthetics of development.

Opponents contended that the plan will encourage more growth, which they claim isn't wanted by many of the 2,800 residents of Purcellville.

"I believe that this is a door that's just a little too wide open," said Frank DiPerna, an artist.

Some residents who spoke against the plan predicted that denser growth in and around Purcellville would clog the roads, strain the resources of police and social service agencies and wreak havoc on water resources.

Last year, lower-than-average rainfall led to a six-foot drop in water levels at the town's J.T. Hirst Reservoir and voluntary water restrictions. No restrictions are in place now.

"Purcellville is, in a way, a canary," said Newell Trask, a resident and retired ground water hydrologist with the U.S. Geological Survey. "You had your drought last year, and you had to install water restrictions. . . . You're going to have the problem of supplying water for the phase one additions plus the 800 homes in the town itself."

A water resources study that will cost $40,000 to $70,000 was approved in this year's town budget.

The town has begun charging developers $9,000 a house to tap into the town's water and sewer system. Town officials have said that the fees force developers to help cover water and waste water treatment costs and ensure that the town will be able to pay the debt on the $7.3 million bond for the new waste water treatment plant.