There is good news and bad for politicians and the public alike regarding Virginia's crowded state prison system.

State corrections officials this month held opening ceremonies for a new 500-cell, 750-inmate prison in Brunswick County on the North Carolina border. That was good news for Virginia sheriffs, plagued with a backlog of convicted felons--now more than 1,000--confined in local jails because the state has no room for them.

The new $23.6 million, medium-security prison, and another one like it set to open in November in Buckingham County west of Richmond, will help relieve overcrowding problems, which have inmates in many localities, including some in Northern Virginia, sleeping on jail floors.

The bad news, says the state Department of Corrections, is that bed capacity then will level off while the projected inmate population continues its upward climb. The gap is expected to narrow again in 1984, when two more medium-security facilities--with $30 million price tags on each--are due to open in Nottoway and Augusta counties.

By January 1985, the corrections department foresees itself responsible for 10,814 felons and 11,483 beds to put them in, according to a department spokesman.

But the long-term outlook on prison capacity is bleak, although there are vague plans to build a fifth prison somewhere in the state's northern region. In January 1990, if state estimates prove accurate, there will be 15,364 convicts and room for only 12,473.

Virginia Secretary of Public Safety Frank White has warned that the state may be looking at the specter of building four more prisons, at a total cost of $250 million and with an operational budget of an extra $100 million, just to keep up.

Corrections officials say the figures illustrate the growing clash of two traditional social concerns in Virginia: a suspicion of government spending versus prevailing public sentiment that criminals belong in prison.

That confrontation has touched off a search--already far along in some other states--for alternatives to costly incarceration as the sole means of punishment for offenders convicted of nonviolent crimes.

"I can't say it's caught on in a big way," says state corrections spokesman Wayne Farrar. One Virginia reform measure--the Community Diversion Incentive Act, a program of state grants to localities that agree to develop jail alternatives--has affected fewer than 100 defendants in its first 18 months. "A drop in the bucket," says Farrar.

Fairfax County Sheriff M. Wayne Huggins faults the CDIA program as too restrictive in its guidelines. "The criteria are so strict, the judges can't find people who qualify," he says.

Still, the hunt for alternatives appears to be growing. It has widening support from law enforcement officers across the state, including Huggins, Attorney General Gerald Baliles and Raymond Procunier, Gov. Charles S. Robb's new director of corrections.

Fairfax County's situation illustrates why. The county's modern adult detention center, with a rated capacity of 198, last week held 440 inmates, 42 of them state prisoners, says Huggins. That is in spite of a successful lawsuit filed by Huggins last year that forced the state to remove 60 of its prisoners from Fairfax within 21 days. State prison officials took 80, and Huggins praises recent efforts by Procunier--whom he admiringly calls "a real hard nut"--to further speed the transfer of state inmates into the Virginia prison system. Still, the prisoner tide keeps rising.

To avoid drowning, Huggins is relying on a mix of new construction and alternative forms of punishment. On the drawing board in Fairfax:

* Renovation of a large basement area in the modern county jail, expected to add 82 beds by early September;

* A 300-bed addition to the jail, about three years from completion;

* A 100-bed work camp, with the Lorton area as a probable site, to open in about five years.

It is alternatives to incarceration, though, that seem to Huggins to offer additional promise of relief. The sheriff says he considered such proposals pie-in-the-sky until he took a closer look in a study last year. "Before the study, I was cynical," he says. "My eyes were opened."

The key, he maintains, is tailoring a program for a relatively large number of nonviolent offenders. "In Fairfax, we're absolutely alternatived to death. One Fairfax judge says we have alternatives sitting like old cars fading away into junk" because too few prisoners meet the criteria.

The answer, in Huggins' view, is his "weekenders" program. Those who qualify include some first offenders, certain drunk drivers and some convicted of serious misdemeanors. Defendants report to the county jail on Friday evenings for a two-hour orientation session. They return on Saturdays and Sundays for all-day work assignments. Participants have painted school rooms and other county buildings and done weeding and mulching. When Huggins' staff moved last week into the county's new courthouse, "weekenders" performed the task.

"It achieves punishment, plus there's some social benefit," says Huggins.

Attorney General Baliles agrees, in general. In his campaign for the post last fall, Baliles pushed a program of financial restitution by those convicted of property crimes. It not only aids victims, Baliles argued, but helps alleviate prison crowding and cuts down on repeat offenders. Baliles quoted a Minnesota judge who found a recidivism rate of 3 percent among those he sentenced to make restitution. The figure was 27 percent for those who went to prison.

Is alternative sentencing the good news of the future for Virginia's crowded jails and prisons?

"It's a very complicated question," says Huggins. Then he recalls a recent exchange with a Fairfax County taxpayer. If prisoners are too abundant, the woman told him, the sheriff should simply pitch tents and string a 10-foot fence around them. "If I did that, I'd be in federal court tomorrow," Huggins says with a sigh. "And the inmates would be out the next day."