The District government -- faced with the prospect of finding more than 300 new homes for the homeless, mentally ill and mentally retarded people under its care -- has begun an aggressive effort to establish more facilities for them in affluent Washington neighborhoods.

Until now, most group homes have been clustered in a few sections of the District. But the city's purchase last week of a mansion in Georgetown for $2.9 million -- the most ever paid for a D.C. home in a residential area -- stands as a watershed in a new policy to distribute those facilities more equally throughout the District.

The pioneering effort met quickly with intense Georgetown community opposition that led to a lawsuit, but Robert A. Washington, the city's acting mental health services commissioner, vowed yesterday to press on with the introduction of group homes in affluent areas.

City Administrator Thomas M. Downs went further, warning that if neighborhood opposition in the city gets tougher in the future, the District will use its ultimate weapon: the power of eminent domain.

"We can, if necessary, condemn a property and use it," he said, noting that the city must expand the number of group homes from 586 to about 900 in four years. "There is no neighborhood veto over the placement of these residents. I can expect that we will be paying more and more for facilties as we push into neighborhoods, like the upper end of Ward 3, Georgetown, Spring Valley and the upper end of Ward 4, that don't have facilities because of the high prices."

A major factor in the growing need for group homes is the transfer of St. Elizabeths, a public mental hospital, to District government control on Oct. 1. In addition, the city is under court order to close two other major institutions, one for the mentally retarded and the other for youth offenders, and faces constant pressure to reduce prison crowding by placing offenders in halfway houses.

But as the city seeks to make affluent neighborhoods the new frontier for the group homes, officials most likely will continue to face the kind of opposition that arose last week during a Georgetown civic association meeting.

Georgetown homeowners criticized the city's decision to use the former Hurt Home for the Blind at 3050 R St. NW without first consulting the community and for paying what amounts to more than $120,000 for each of the 24 emotionally disturbed youths who will live and receive treatment at the facility.

When one resident, complaining that he could "see the third floor of the home without lifting my head from my pillow," raised his hand and pledged $100 to help hire a lawyer, people throughout the room pulled out checkbooks and started a collection.

Hours after the city completed its purchase of the Georgetown mansion, the Citizens Association of Georgetown filed a lawsuit in federal court accusing the city of creating a hospital without obtaining a certificate of need. The lawsuit alleges that the facility "poses a substantial threat to the health, safety and quiet enjoyment of the current residents and their children" and will interfere with the "safe and quiet enjoyment" of Montrose Park, which is across the street from the facility.

"We are committed to fighting it because we believe what the city did was illegal," said Kathleen Graff, president of the civic association. "Serving 24 emotionally disturbed youths is quite different from a group home where four mentally retarded people live together."

Washington said yesterday that of about 15 community gatherings he has attended to discuss group homes, the meeting with the Georgetown civic association was the most difficult and the only one where city officials were treated rudely by some members of the audience.

"I do believe that the major obstacle -- and believe me we have a number of difficult problems to deal with -- to the mental health reorganization plan will be the opposition of community residents," Washington said. "I consider it a ministry."

The city's goal is to achieve an equal distribution of residential facilities, which now range from 158 in the mostly middle-class lower end of Ward 4 to 23 in the largely affluent Ward 3.

The city and private facility operators historically have placed group homes in areas where property costs are low and where large houses and some measure of community acceptance were present. In the 1970s, equal distribution was not a factor because city zoning laws did not limit the number of homes that could be placed in one area.

Downs, citing the $2.9 million paid for the Georgetown mansion, said the city intends to remove cost as a barrier to establishing group homes in wealthy neighborhoods.

"In a case like this, price is secondary to the program needs and the children's needs," Downs said of the Georgetown facility. "It is near families, it has a feeling of homeyness -- good porches and a park across the street -- and it has got good neighbors. If the cost had been $4.5 million, and it was a reasonable price, we would have paid it."

The District's expansion centers on a philosophy that residents who require supervision or special treatment have a right to be integrated into neighborhoods, and that the city has a duty to avoid creating health care ghettos that limit those residents to a few areas of the city. Until now, the city has been forced to send emotionally disturbed youngsters -- such as the ones to be placed in the Georgetown home -- to facilities as far away as Florida and Texas.

The current need for facilities is acute because of imminent changes in the status of a number of institutions. The key factors:The Oct. 1 transfer of St. Elizabeths to D.C. control. To accommodate St. Elizabeths' patients and about 1,200 homeless people who are mentally ill, the city says it will need 47 additional group homes for 1,750 beds in the next four years. The court-ordered closing of Forest Haven. This institution for the mentally retarded will require -- when coupled with requests from mentally retarded persons now living with parents -- about 133 group homes for the mentally retarded in the next five years. The court-ordered closing of Cedar Knoll. The shutdown of this facility, which has held up to 140 juvenile delinquents, will create a need for as many as 10 new juvenile rehabilitation homes during the next four years. Prison crowding. Plans to reduce crowding in District correctional facilities call for placing at least 214 new beds in community-based halfway houses in the next two years.

When group homes first opened in District neighborhoods more than a decade ago, advocates say, residents almost always protested, viewing the mentally retarded, mentally ill or juvenile residents as an economic and physical threat to their communities. Although the opposition usually subsided once facilities were established, protests following the announcement of a home opening continue. Only the objections have changed, advocates say.

Today, some District residents readily agree that institutionalized residents have a right to return to the community, but they argue that neighborhoods have the right not to be subjected to the noise, added traffic, transients, trash and decline in property values that they say result from group homes. Residents also accuse the District of opening or allowing facilities to open without adequate notification to residents.

Before a new residential facility can be opened by the city, a nonprofit group or a private provider, according to the District's policy, the advisory neighborhood commission and the local civic association should be contacted at least 30 days in advance. Those groups are expected to notify residents, usually at public meetings.

In many cases, notification to residents is merely a courtesy, not a request for a neighborhood's permission. Zoning laws, as amended in 1981, allow some facilities with eight or fewer residents to be established "as a matter of right," which means no neighborhood approval is necessary. In some cases, the facilities must be at least 500 to 1,000 feet from another group home.

For example, Damien Ministries was allowed to open a home last month in Northwest Washington for women with AIDS without notifying residents because city zoning laws do not require neighborhood approval or special permits for five unrelated adults to live in the same house without supervision.

On the other hand, any proposal to open a rehabilitation facility for adult offenders in a residential area must be approved by the Board of Zoning Adjustment.

City officials say the typical community concerns have been addressed by the zoning amendments, which classify facilites based on whether they have a small, moderate or great impact on a neighborhood in terms of noise, traffic and general activities.

In the Georgetown case, members of the citizens association say they think that the city's decision to settle on the property last Friday instead of late in October as originally planned was designed to thwart community opposition.

"I cannot imagine that there was any other cause," said the association's leader Graff. "It shows that they {city officials} will brook no opposition from people who live there, and the people are the city."

But Washington said he is convinced that the citizens association does not speak for the majority of people in Georgetown: "When there is a battle like this nobody wins and nobody loses and everybody should be embarrassed."

Ward 2, which includes Georgetown, has 35 community-based facilities. Ward 1, a central-city area that has 91 facilities, has some of the most vocal proponents of placing group homes in neighborhoods where there are none.

"We are not against accepting our responsibility," said Shelore Williams, a member of the Northwest Washington Tubman Neighborhood Association.

"But unless you fight {a home} and say you are against it, they will put more of them in your area."

Williams said her association plans to keep track of every vacant neighborhood house and investigate every real estate "for sale" sign to find out early whether anyone is planning to establish a group home.

In the face of such opposition, residential facility operators are reaching out to improve their relationship with the community. Residents of halfway houses, for example, have helped neighbors plant flowers and clean streets.

Milton W. Roberts, regional vice president for Voca, an Ohio-based firm that operates seven District homes for 52 mentally retarded clients, said his company recently reached a number of agreements with neighbors near the site of two new Ward 7 facilities in Northeast.

"We made a commitment to the community to hire staff from the surrounding area," Roberts said. "Residents made input into the design of the building and decided on what trees we should plant. We have also agreed to contribute to an Advisory Neighborhood Commission scholarship fund. The amount will depend on what they need, but we are prepared to contribute up to $15,000."

The District government also has stepped up its community efforts through a special office that coordinates activities for community facilities -- educating residents about group homes and encouraging home operators to form neighborhood advisory groups and avoid opening facilities in saturated areas.

Beverly Russau, who heads the office, said that despite these efforts, "We cannot get residents' attention until a facility is announced. We talk about what they can expect. They want to know what they can do to stop it."

Although District officials promise to establish a sophisticated tracking system for the new St. Elizabeths outpatients who will be entering the community, residents remain skeptical.

"I think the city is unloading a problem," said Alex Eckmann, an Advisory Neighborhood Commissioner in Ward 1. "In the case of St. Elizabeths, there is no guarantee that people will get the kind of health care they need or that the quality of management will be what is needed. The city cannot monitor this closely enough with hundreds of these throughout the city."