The Loudoun County Board of Supervisors, paying heed to an angry crowd of 200 opponents of private landfills, deferred action yesterday on the politically explosive question of how to dispose of the huge volumes of debris created by the county's development boom.

The crowd of residents filling the county board room in Leesburg cheered and leaders of the landfill foes declared a temporary victory when board members, in a surprise move, agreed unanimously to delay votes on the debris landfill issue until after a public hearing in September.

The board's willingness to delay the long-debated question of whether the county government or the private sector should bury Loudoun's construction trash seemed to underscore the deep extent of resident opposition to privately owned dumps.

"If you have an affinity for political suicide, then vote for private landfills," resident Bert Hoffberger told the supervisors during public comments before the deferral. "If you sow the wind, you're going to reap the whirlwind."

Supervisor Thomas S. Dodson (D-Mercer), a leading opponent of privately owned landfills, said the parade of midday speakers, most of whom left work to attend the meeting and all of whom were against private dumps, caused proponents on the board to proceed cautiously.

"We were so afraid it would be voted on today," Dodson said. "Now we've got more time for the public to state its beliefs."

However, Supervisor Andrew R. Bird III (R-Sterling), while agreeing to the new public hearing, said afterwards the supervisors will win little by the delay.

"Quite honestly, we're going to be fighting this same issue over again" in September, Bird said. The fight so far has been among the most acrimonious Loudoun has seen in recent years, several supervisors said. Many residents charged yesterday that by allowing the private landfills, Loudoun would clear the way for debris to be buried there from Fairfax County and other neighboring localities.

"I don't understand for the life of me why the citizens of Loudoun County should have to pick up the tab for trash from other jurisdictions," said county resident Stanwyn Shetler.

Other speakers agreed.

"Between the pressure of developers on one hand and potential landfill operators on the others we may soon see the beginning of the end of the Loudoun County landscape as we know it," said Albert F. Marra, representing Countryside, a large subdivision in the eastern part of the county.

Private sector proposals to operate debris landfills have thrust the issue onto county government agendas in both Loudoun and Prince William County in recent weeks.