RICHMOND, AUG. 7 -- The tax base for Northern Virginia localities grew faster on average during the late 1980s than for any other area of the state, but the average tax burden imposed by local governments there dropped a bit, according to a new study.

A report released today by the state's Commission on Local Government showed that Northern Virginia's "revenue capacity" -- the potential for raising money from the available tax base -- was $1,190 per person during 1987 and 1988, a figure 76 percent greater than the statewide average.

But most Northern Virginia localities didn't take full advantage of that tax base, the report said. The area's "revenue effort," a statistic designed to show how fully governments are exploiting their tax base, fell a shade between 1984 and 1988.

For example, Fairfax County, the state's largest and wealthiest locality by far, once had the fifth-highest revenue effort in the state. Two years later, it had dropped to 19th.

Other counties in Northern Virginia recorded similar drops: Prince William County went from 19th to 26th, and Arlington went from 27th to 37th.

While this suggests that the area's tax burden is leveling off, Northern Virginia still exploits its tax base, on average, by as much as any region in the state, the report said.

Northern Virginia's local governments are also on average the fiscally healthiest in the state, the study said.

The commission's study of "fiscal stress," a composite of factors that are used to attempt to gauge the fiscal health of a locality and its ability to meet citizen demands for services, showed that every Northern Virginia locality except the city of Manassas Park was healthier than the statewide average.

The most troubled parts of the state were the rural coal-mining counties of far Southwest Virginia, the study showed.

Sixteen of Virginia's 41 cities were placed in the highest category of fiscal distress, while a much smaller percentage of counties had similarly high burdens. This is evidence of "significant and pervasive contrast" between cities and counties, according to the report.

M.H. Wilkinson, executive director of the local government commission, said he was somewhat surprised to see Northern Virginia's revenue effort go down slightly. He said he was surprised because the figures for most localities in the rest of the state were heading in the opposite direction.

But Audrey Moore, chairman of the Fairfax County Board of Supervisors, said such figures as the ones released today aren't likely to have much impact on the prevailing political sentiment against tax increases.

"These things go up, down, sideways," Moore said of the latest statistics. "Our perspective is the same. We want to keep taxes as low as possible."