Carrie A. Epperson and her young son plan to move out of their Reston apartment in February. The 21-year-old single mother says that with the $12,066 a year she earns as a custodial worker at Dogwood Elementary School, she cannot afford the $65-a-month rent increase that will occur when her lease expires.

Epperson said that even with her current monthly rent of $465, she is struggling to make ends meets. She became so frustrated over the shortage of rental housing she could afford that she turned to the Fairfax County Redevelopment and Housing Authority for help. "That was about two years ago, shortly before my little boy was born," said Epperson.

She is still on the waiting list, and housing officials say she is far from alone.

The number of people waiting for help in finding low-income housing in Fairfax has grown by 50 percent in a few years, and the average waiting time has increased from about one year to more than two years.

There is a waiting list of about 3,000 families in the wealthy, conservative county, according to housing officials.

More troubling to officials, the waiting time is even longer than two years for the poorest families, some of whom may never get help. The reason, say housing experts and county officials, is that the poorest families are the victims of both deep cuts in the federal housing programs designed to help low-income families and a surge in community opposition to public housing for such families.

"We can no longer effectively serve the really poor," said Walter Webdale, director of the Fairfax County Redevelopment and Housing Authority.

Actually, Fairfax owns and operates relatively few public-housing projects, and, instead, has tended to rely on using federal programs to subsidize builders of apartments for low- and moderate-income families or to buy units in large apartment complexes and make them available to poorer families. Those programs, too, have encountered strong opposition.

In the last decade, the agency's aggressive push for housing in Fairfax has sparked numerous protests from residents, who voiced concerns about crime, lower property values and racial tension.

Blacks and other minorities make up less than 12 percent of the county's population, but more than half of Fairfax's public housing population.

"Our emphasis and priorities are going to have to be looked at very carefully in the next few months to plot for the future of housing in this county," said Verdia L. Haywood, deputy Fairfax County executive for human services.

On Jan. 14, the Fairfax County Board of Supervisors is scheduled to vote on a measure that would severely restrict the housing authority and allow the Board of Supervisors to veto any housing project, a step that some say will reduce the authority to the status of an advisory committee.

The authority has operated with substantial independence since 1973, when it was established in its present form.

Unlike other troubled housing agencies, like the scandal-ridden Indianapolis housing authority or the bankrupt Boston public housing authority, the Fairfax agency has been basically scandal free and in good financial condition.

The county's housing program is signficantly smaller, relative to population, than those in Montgomery and Prince George's counties and the District of Columbia.

Nevertheless, it sparked a volatile controversy that some Fairfax politicans say reached a peak in 1983 and may have played a role that year in the Republican primary defeat of Springfield Supervisor Marie B. Travesky, who was accused of supporting a public housing project in her district.

After the elections, several board members decided that something had to be done about the housing issue and to control the agency.

With the board's more politically sensitive approach, subsidized housing in Fairfax is expected to take a more conservative turn.

County officials say that housing money will go to help the elderly and to help those on the upper end of the spectrum of families considered poor in Fairfax, i.e. families with incomes ranging from about $25,000 to $50,000, depending on size.

"We have to look at the demographics of the population of Fairfax County," said County Board Chairman John F. Herrity, a Republican and an outspoken critic of public housing. "The housing authority tried to be all things to all people.

"We need to reorient public housing," said Herrity, who argues that the county should focus more on the needs of the elderly.

Republican Supervisor Thomas M. Davis said the county's hand is partly being forced by changes in federal aid. Congress and the Reagan administration have ended most building programs that provided funds for about 1,000 units for the very poor in Fairfax.

"What the Reagan administration has done for public housing has not been all bad," said Davis.

Tax-exempt bonds, construction grants and rental assistance that are available from the federal government will encourage private developers to provide housing for moderate-income families, he said.

The county government, which has a $1 billion budget, provides $2.8 million for housing in its current budget, and supervisors say there is virtually no support for increasing the county's contribution to the housing authority.

In a county with a vacancy rate of only 2.1 percent, even families with moderate incomes often have problems finding affordable rental housing, Fairfax officials say.

"We can help a lot of people," said Davis. "It's true that it doesn't take care of the really poor, and without assistance those families will have to continue to double up or move out."

As in most areas of the country, assisted housing in Fairfax is a mix of projects run by the housing authority, by nonprofit groups and by for-profit private developers in exchange for tax-exempt financing.

There are 7,551 housing units in Fairfax County that receive some form of government assistance, and about 44 percent of those come within the jurisdiction of the housing authority. The projects run by the authority are small, in good physical condition and well managed, according to a study done for the Fairfax supervisors by the firm of Arthur D. Little Inc.

Those run by private developers are more varied, according to county officials.

Although there are about 3,000 families on the county's waiting lists, private groups keep their own lists and housing officials estimate that the total need is much higher. The Fairfax County Housing Needs Study of 1983 said that 26,000 households need housing assistance, based on family income.

The heyday for assisted housing in Fairfax, as in most areas of the country, was from 1976 to 1982, when Fairfax annually received federal funds for support of between 500 and 600 housing units for low- and moderate-income families. Most were given monies under the so-called Section 8 program or the federal public housing program, both of which provided hefty subsidies for the very poor.

Congress and the Reagan administration have ended the new construction and substantial rehabilitation part of the Section 8 program. Congress did provide funds for a small number of public housing units, but "everybody is vying for them," said Webdale.

The drastic drop in federal assistance first hit Fairfax in 1982. Since then, the county has averaged only 50 to 75 new federally assisted units each year.

In 1983, Fairfax responded by turning to industrial development bonds, which local officials expect to be the county's biggest source of revenue for assisted housing in the next decade.

Fairfax has given the tax-exempt financing to private developers who agree to set aside 20 percent of their apartments for poor and moderate-income families.

For instance, a family of four with an income of $25,620 could live in one of those apartments and pay $534 a month, or 25 percent of their income.

"The object is to privatize subsidized housing, to get the housing authority out of this and return it to the private sector," said Herrity.

The county has already provided about $114 million in tax-exempt financing, including $31.5 million in financing for Chantilly Apartments, a 640-apartment development in western Fairfax, and $7 million in tax-exempt bonds for the 284-unit Seven Corners Apartments.

Fairfax County has also started buying units in buildings that are being converted to condominiums and renting them out to moderate-income families, and has a program designed to help moderate-income families buy homes.

"It doesn't give you a lot of additional units that can be directed to the very, very low-income person," said Haywood. "But I don't foresee the day in which we go back to a situation where the federal government will finance units like they did during the period from 1976 to 1982."

"I'm pessimistic in terms of helping the really poor. But, on the other hand, in terms of a few specific groups at the other end of this income spectrum of the families considered 'poor' , I'm optimistic," said Webdale.

"I think we'll be able to help more of those families into home ownership and we can help the elderly. But I can't predict where we'll go with the other side of the coin."