A Virginia House committee approved a bill today that would prevent Fairfax County from redrawing its supervisory districts until 1991, but Fairfax board Chairman John F. Herrity quickly vowed to change the districts before the state law could take effect.

"We are not going to let them get away with it," bellowed Herrity, who said the board will "exercise our constitutional rights" at its regular meeting Monday by setting in motion a plan to redraw the boundaries for the county's eight districts.

"We'll be finished by May and their law won't take effect until July," said Herrity, a Republican elected at large.

The Republican-controlled board and the Democratic-controlled legislature accused each other of partisan politics in their respective stands on the issue, which could wind up in court.

Sen. Clive L. DuVal II (D-Fairfax) said Herrity "hasn't read the fine print." DuVal said any election would have to take place before July 1 "and he can't do that because it would cut short the terms of the existing supervisors."

DuVal, a chief backer of changing the state's election law in the name of "uniformity," acknowledged there are "political implications in whatever you do about redistricting -- whether you want it or don't want it."

But he insisted that the proposed change was done in the name of "good public policy."

DuVal said the change was recommended by a bipartisan Election Laws Study Commission and noted that Republican Del. Clinton Miller of Shenandoah, a member of the commission, voted for the bill in committee today.

"That's one of the most arrogant things they've ever tried," said Herrity in a telephone interview after the vote. He accused the legislators of "trifling with one person, one vote. I think they'll have trouble with [the] Justice [Department]. They're violating the Voting Rights Act."

"There is every reason to believe there would be gerrymandering" in any plan approved by the board, DuVal said.

Democratic members of the Fairfax board have accused Republicans of wanting to redraw boundaries to increase their 5-to-4 majority. Providence District Supervisor James M. Scott is thought to be the Democrat most vulnerable to a 1987 challenge if his district were redrawn.

Doreen Williams, a lobbyist for the board's Republicans, told the panel reapportionment is needed now because population growth in Fairfax "has been nothing short of phenomenal" in the last 20 years.

The districts have been redrawn three times -- most recently in 1981 -- since Fairfax adopted an urban county form of government in 1968. "Each of these three changes were made to accommodate population growth," Williams said. She said the greatest population disparity between districts in 1975 was 33,000, and that margin exists again.

Even so, she said, "It is entirely possible that the present board would not redistrict even if Senate Bill 146 is not enacted." However, five hours later Herrity announced his intent to redistrict immediately.

Herrity said "the only difference" between the redistricting in 1975 and the one proposed this year is that "in 1975 Democrats controlled the board 8-1; this year Republicans have it 5-4."

Del. Vincent F. Callahan Jr. (R-Fairfax), one of three Republicans on the committee who voted against what he termed "this abominable bill," said it "violates the one-man, one-vote concept."

Del. James H. Dillard II (R-Fairfax) warned that acting on "partisan considerations" could be "a two-edged sword."

The bill, approved 16 to 3 by the committee, is expected to face little opposition on the House floor. It would go next to Gov. Gerald L. Baliles, a Democrat.

DuVal noted today that "if they want, they could add a couple new districts." He called that "the most sensible" way of addressing the problem, saying it would "reduce the number of constituents and give all of them a shot at better representation. But that's apparently not what they want."

"We have no intention of creating more districts," Herrity responded, adding that "good government advocates" favor reducing, rather than increasing, the number of districts.

"We're not caving in to that gang of Democrats," Herrity said.