Loudoun County and the corporate descendant of Levitt and Sons Inc. have settled a major, nine-year-old zoning dispute with a compromise that will allow 2,500 new housing units, enough for about 8,700 new residents, in eastern Loudoun County.

Both parties in the battle described the agreement, which cuts almost by half the 4,715 units first sought by Levitts, making a new maturity for both developer and regulator in the complex field of growth.

"The county is recognizing that it has to deal with growth and can't make it go away by wishing it would," Joseph Trocino, Loundoun's zoning administrator, said of the agreement on the 1,270-acre between Rte. 7 and the Potomac River at Rte. 28.

"I think that responsible developers and landowners have recognized that it is not in anyone's best interest to take a maximum density approach," said James DeFrancia, vice president and general manager of Four Thirty Seven Land Co. Inc., the New York company that now owns the tract.

With this rezoning, the country - which had developed a "no growth" reputation through the mid-1970s - now has approved enough new housing units to accommodate about 20,000 more people over the next 10 years, Trocino said.

The agreement reached by negotiators for the two sides calls for construction of no more than 2,500 housing units with no more than eight units on any single acre. No more than 750 units could be built in a year and the project would have to take at least five years.

DeFrancia, whose company took over land holdings of Levitt after an antitrust decision forced ITT Corp. to divest itself of Levitt, said that construction could start in 18 months with the first houses ready for occupany in the spring of 1980.

The first phase of construction will be of detached, single-family dwellings, probably in the $75,000 to $95,000 price range, DeFrancia said. Construction of the full project will take seven or eight years, he said, and although there will be some townhouses," "our emphasis is on single-family, detached units."

Marc E. Bettius, lawyer for the developers, said, "I think everybody was generally interested in a solution but nobody was going to sell out their position. We adopted some of their positions and they adopted some of ours."

The result, Bettius said, was "as fine a settlement as I have ever participated in."

WIlliam C. Crossman Jr., chairman of the county Board of Supervisors during much of the Levitt dispute, said, "I feel like the county came out a winner. It's nearly what we desired down there."

The harmony of the agreement contrasts with the long and often bitter dispute, said, "I feel like the county came out a winner. It's nearly what we desired down there."

The harmony of the agreement contrasts with the long and often bitter dispute which began soon after Levitt bought the land in 1969.

The company filed for rezoning from agricultural use (allowing a house on every three acres) to permit a new town of about 12,500 persons.

The county, faced with a project that could have increased its 1970 population of 37,150 by more than a third, rejected the rezoning in 1971 in what was seen then as one of the first actions by a suburban Washington jurisdiction to check growth.

Levitt sued the county. It lost the case in the state circuit court and appealed to the Virginia Supreme Court but later withdrew the appeal.

In 1974, the county board again rejected the application and Levitt again sued. By this time, the supervisors had developed a reputation as a "no-growth" board.

Two years ago, the Four Thirty Seven Land Co. took over the Levitt land. The county lost a series of rulings on preliminary motions in the Levitt case, lost on a final decision in a similar suit and approved several other rezonings in eastern Loudoun near Dulles Airport.

"We decided we didn't have much chance in court and thought we would see if we could reach a compromise," Trocino said. He said Commonwealth's Attorney Donald Devine was authorized to negotiate for the county.

Fortunately for the county, market conditions had changed and a study by the developers indicated that the land might be successfully developed at a lower density with less impact on a county now grown to 60,000.

"We came away from our study satisfied that it was esthetically and economically feasible to do it at two units to the acre," DeFrancia said. Trocino also concluded that two units to the acre was the best the county could do and the concurrence was the basis on which other details such as school sites and roads could be worked out.

"We did perceive a shift in the mood of the county . . . to one of legitimate concern for proper land use balanced with the view that growth was inevitable and proper," DeFrancia said. "And we would admit that there is a responsibility on our side to take a look at the best use and reach a rational agreement with the public sectors, as we did in the Loudoun case.

"We didn't think the original plan was the best plan. Notwithstanding the fact that we might have been able to win in court, we didn't think it was worth winning," DeFrancia said.