A Fairfax Circuit Court judge said yesterday the county government has the right to limit severely development in the rural southwestern quarter of the county.

The ruling apparently will end one of the longest and bitterest court battles in county history, in which landowners challenged county zoning limiting development to no more than one house on every five acres. Developers and landowners wanted to build up to five times that number of houses, which could have meant tens of millions in extra profits for them.

The ruling sent a ripple of delight through county offices, where defeat had long been viewed as likely. Most officials and observers who followed the four-month trial assumed the county would lose its fight to limit development in a state where the courts have traditionally been more sympathetic to the rights of individual landowners. The county had indicated it would probably appeal the decision if it lost.

Judge Johanna L. Fitzpatrick did grant development rights within the parcel to three landowners who had already begun the development process before the county sought to limit building there.

Because of the manner in which Fitzpatrick ruled -- granting county officials victory on the big issue while giving the specific landowners involved the right to develop -- both sides indicated yesterday that they probably will not appeal the case to the Virginia Supreme Court.

"What a good morning! I can't believe it. I am just overjoyed!" said Supervisor Audrey Moore (D-Annandale), one of the strongest supporters of the county's action. "We're just in shock."

The case had been watched closely by governments of other Virginia areas such as Virginia Beach, where fast growth has left the city hard-pressed to provide services for residents in newly developed areas. However, it will not set the precedent officials expected it would if it is not appealed, since the ruling is applicable only in Fairfax.

Fitzpatrick ruled that the county had the right to change the zoning to make it more restrictive in order to protect a relatively rural 66-square-mile chunk of land along the Occoquan River known as the Occoquan Basin.

County officials said they wanted the area of streams, forests and hilly meadows that drains into the Occoquan Reservoir to remain undeveloped in order to protect the drinking water supply for some 600,000 residents of Northern Virginia.

Fitzpatrick wrote in her 18-page opinion that officials' fear that development would pollute the water was reasonable and justified, and that sharply curtailing development was an appropriate response.

"This is a major victory for people and planning in Fairfax County," Moore said. "It means this will remain a relatively rural area, it means the water supply will be protected, it means lower taxes . . . . If this area had [been developed], I don't know how anybody would have gotten to work," she said, referring to the county's already massive transportation problems.

Marc Bettius, the lead attorney for developers and landowners, said the decision bodes ill for the county's ability to attract more business and for expanding the county's already tight and expensive single-family housing market. The land was to have been used largely for single-family homes.

"As a citizen of the county, it breaks my heart," Bettius said. " . . . You've got to ask, where will they house the upper middle income people? They have just cut the hell out of that housing stock."

Bettius said the board's action amounted to the creation of large estates, "and not many of us are going to be living on those estates."

Fitzpatrick also ruled that, in addition to the three landowners who had begun development others who had reached a certain stage in the building process also would be permitted to proceed, after court hearings.

The three owners granted development rights -- Aldre Properties Inc., J. Gordon Kincheloe and DiVito Morgan Corp. -- own a total of about 300 acres in the 41,000-acre area. At most, 10 percent of the area will qualify for development under the ruling, attorneys said yesterday.

"I think it's a tremendous victory for the people of Fairfax County in controlling their land-use destiny," said county Board of Supervisors Chairman John F. Herrity. "It's a victory for balanced growth."

Bettius said, "If they county officials don't appeal, I won't. Our clients have gotten everything they wanted . . . . But if the county appeals, if they open that door, we'll go through it like a bulldozer."

Land and how it will be developed has been at the center of almost every major political battle for the last 30 years in Fairfax.

The Occoquan cases took on special significance for two reasons: The land involved -- as large as the entire District of Columbia -- is the last developable area in a rapidly growing county. And the cases became a test of the authority of local governments to take action to protect their jurisdiction's natural resources.

Some 40 landowners challenged the county's action. Three of those cases were set for trial with the expectation that the outcome of the others would be clear when the broad issues were settled.

The county spent an estimated $1.5 million to defend its action in court; the landowners spent an estimated $750,000 to challenge it. The trial that resulted after 18 months of preparation was in court for 48 days during four months, taking testimony from 32 witnesses and resulting in a transcript more than 10,000 pages long.

The file for the case, which includes all the evidence, documents and motions filed with the court, fills an entire jury room.