Faced with mounting public needs and dwindling tax dollars, Fairfax County voters will go to the polls in three weeks to decide whether the county should sell bonds and go into debt to finance transportaton, education, housing and other projects.

Seven bond referendums totaling almost $300 million will be on the Nov. 6 ballot. County residents also will cast votes in U.S. Senate, House and county sheriff races, select directors for the Soil and Water Conservation District and vote on four proposed amendments to the state Constitution.

Polls open at 6 a.m. and close at 7 p.m.

Some local officials wonder whether Fairfax County's impressive winning streak on bond referendums could be drawing to a close. In the 1980s, when new development fueled a strong demand for public facilities but also poured a steady stream of cash into county coffers, voters approved 29 of 30 bond issues, rejecting only a jail bond in a 1980 referendum.

As a new decade opens, county tax and spending policies are under increasing criticism from residents angry at ever-higher property taxes and the growth in expensive government programs. Concern about these issues is dovetailing with a general downturn in the local and national economy, leading some political observers to conclude that there are no shoo-ins among this year's bond referendums. They include:

$169.2 million for school facilities, including construction of two new elementary schools (about $22 million), renovations at 13 elementary, two intermediate and two high schools ($103.7 million), and air conditioning at 10 elementary, two intermediate and one high school ($17.5 million).

$80 million for transportation projects, including $36 million needed to match a possible $36 million federal grant for parking lots and an express bus program in the Dulles Toll Road corridor and $25 million to resolve environmental problems at the future Franconia-Springfield Transportation Center site.

$21.7 million for housing projects, including construction of 164 units of afforable rental housing for families, a senior citizens center and 62 units for low- and moderate-income elderly people.

$9.5 million for human services, including $6.2 million for child care centers at public schools and $3.3 million for a home to provide long-term care for mentally retarded adults.

$8 million to finish 28 trail and sidewalk projects and upgrade older trails to conform with current design standards.

$6.7 million to complete 18 previously approved but unfinished storm drainage projects.

$4.6 million for public safety and maintenance, including $3 million to add four new courtrooms, two hearing rooms, judges' chambers and other improvements at the Fairfax County Circuit Courthouse and $750,000 for land acquisition, design and engineering for a new animal shelter.

Bonds are a form of long-term borrowing that enable the county to stretch out the cost of major capital projects and public facilities over several decades.

With bond financing, the county makes smaller annual payments on principal and interest, which forces future users of facilities to help pay for them, rather than paying the full cost of a project out of current tax revenue.

The key downside on debt financing is the cost of borrowing. Spread over 20 years, the county would pay $220.5 million in interest to borrow $300 million at a 7 percent interest rate.

The county has a self-imposed limit on bond sales of $150 million a year, and must carefully schedule bond sales according to market conditions and the urgency of projects. If voters approve all the referendums in November, the county would have about $956 million in authorized but unsold bonds, meaning that some projects could be delayed until 1997.

"While we are asking the public to okay these projects, the actual spending will depend on what the circumstances are and a conservative approach to managing our debt," said Board Chairman Audrey Moore. "We have the highest credit rating in the country and we are not going to put that at risk in any way."

Fairfax is one of only 13 counties nationwide that has AAA ratings from both Moody's Investors Services Inc. and Standard and Poor's Corp., which allows the county to save millions of dollars by borrowing money at lower interest rates.

Supervisors, however, are divided on the bonds.

"If we vote for all of these, it will delay implementation of bonds already passed, and the next board, which I'm expecting to be on, will lose flexibility in dealing with emergency matters," Supervisor Thomas M. Davis III (R-Mason) said.

Davis and the board's other Republican supervisor, Elaine McConnell (R-Springfield), both said they would vote only for the proposed $169.3 million school bond and $80 million transportation bond. The reason, they said, is twofold:

First, given the county's economic slump, the other proposed bonds are not a high enough priority, Davis and McConnell said. Second, they said, a proposal to pay for the Fairfax County Parkway (formerly the Springfield Bypass) with $330 million in revenue bonds has been appealed to the state Supreme Court, and if the court rules against the plan, the county may need most of its remaining borrowing authority to finish building the road.

"If the courts rule against us, we have a real problem," McConnell said. "We're borrowed to the hilt."