Representatives for Pulte Homes all but assured the Montgomery County Planning Board on Tuesday night that approval of a proposal sharply limiting the number of homes the company can build west of Interstate 270 near Clarksburg will land the county in court.

Pulte has spent several years preparing to build 1,000 single-family homes on a 538-acre site. It increased the potential size of the project by spending $12 million to purchase development rights from landowners in the county’s Agricultural Reserve. The purchase was made under a program designed to preserve land for farming while allowing for higher densities elsewhere.

But in July, county planning staff, concerned about the health of the environmentally fragile Ten Mile Creek Watershed — which feeds the region’s emergency water supply — recommended allowing about 215 homes on the Pulte site and turning much of the area into open space. The finding is part of a larger look — requested by the County Council-- at possibly amending the 1994 master plan for Clarksburg, one of the last major undeveloped sections of the county.

Pulte attorney Gus Bauman called the proposal “a mistake of enormous proportions.”

“The draft amendment before you, in its singling out and laying waste to Pulte’s use of its land, violates the Constitution’s taking, due process and equal protection clauses,” said Bauman, a former chairman of the planning board. “It reduces Pulte’s land to nothingness, it is arbitrary and it is discriminatory. It also happens to violate fundamental fairness.”

The five-member board took no action Tuesday, and will hold a series of work sessions to discuss amendment of the master plan before making a recommendation to the council sometime in October.

“If the Planning Board does not fix this, the County Council will have to,” Bauman said.

Pulte’s presentation was part of a four-hour-plus public hearing in which all parties to the Clarksburg debate made what amounted to their closing arguments before the board decides. Many players in the long-running dispute came with lawyers, paid consultants and well-rehearsed community voices contending that county staff either over-or-underestimated the potential environmental impact of the development proposals.

The central issue is whether Clarksburg can withstand heavy development around it and still realize its original vision as a walkable, transit-oriented community. Another developer, the Peterson Cos., wants to build high-end retail, dining and housing on 100 acres east of I-270 close to the site of the proposed Clarksburg Town Center. Planning staff recommended only a small reduction in the project’s footprint.

Many Clarksburg residents have long yearned for more shopping options and commercial activity. But they fear that heavy development could undermine prospects for Town Center, envisioned as the social and commercial heart of the community.

Melane Hoffmann, a member of the steering group of Liveable Clarksburg, said the Peterson proposal “would be a regional mall that would have nothing to do with the survival of Town Center.”

Diane Cameron, director of conservation for the Audubon Naturalist Society said the health of the Ten Mile Creek Watershed hinges on the county’s decision.

“The county’s responsibility is to maintain clean, safe water sources for generations to come, not to reward developers who have made speculative investments,” she said.