For the more than 100 Virginia State Police officers stationed in the Washington suburbs, this was the spring they had long awaited. After years of enduring taunts as the regions's poorest paid police force, they suddenly were scheduled to become the region's best-paid.

But that was before downstate troopers got wind that their Northern Virginia counterparts were in line for a pay differential that would boost their salaries to a level 22 per cent above the downstaters.

"What really happened is that troopers in the southern part of the state just went wild" and succeeded in slashing the Northern Virginia officers' pay differential in half, according to Robert Giambrone, a trooper and secretary of the Virginia State Police Association.

To the chagrined troopers in the Washington suburbs, what happened to their paychecks is another illustration of Northern Virginia's political impotence and the clout that downstate legislators have over Virginia's spending.

"It was like another Civil War with the North against the South," said Giambrone, who is stationed in Fairfax and thus was one of the troopers eligible for the 22 percent pay differential. "But they [state officials] decided to make the guys in the sourthern part of the state happy . . . and cut back the 22 percent to 12 percent."

Virginia State Police officers in the Washington suburbs, like the other 2,700 state employees in the region, long have received differentials of 4.8 to 9.6 percent to compensate for the high cost of living here and to make their salaries competitive with local jobs.

But the police officers' pay lagged far behind that of Northern Virginia police forces, with the result that few troopers voluntarily requested transfers to the region. Most troopers sent to the Washington suburbs are new recruits who ask for duty elsewhere in the state after they complete a minimum tour here.

In an effort to resolve some of those problems, Virginia officials conducted a pay survey of the region and discovered that their troopers were earning 22 percent less than the regional average. That was to translate into a pay increase of anywhere from 13 to 17.5 percent for the Northern Virginians, since they already were earning 4.8 to 9.6 percent more than the downstate troopers.

Until April, beginning Virginia troopers in Northern Virginia could expect to be paid $12,593 a year, slightly above the downstate beginners' pay of $11,472, but well below the average pay of a rookie on any Northern Virginia area force.

When the downstate troopers feared the spread between them and the Northern Virginians was to get wider, they pressured the state personnel officers to "recalculate" as one official puts it, what the difference ought to be. The resulting differential was out to 12 percent.

It wasn't until this week, however, that the state troopers in Northern Virginia saw the impact of that decision in their pay checks.

They'd been given boosts of 13 to 17.5 percent in April, but they did not share in the general 7 percent pay boost other state workers received this week. Later this year the 4.5 percent merit increase that other workers will get be only about 2 percent in the Norther Virginia troopers' pay checks.

Although state officials said they have acted with the best of intentions, the next effect has been a lot of confusion and bitterness in the process.

"Nobody's sure what our salary is. It keeps changing," says Giambrone. "They promised us a pay raise, gave us the impression we'd get the 7 percent raise other state employes were to get July 1 and then they reneged."

Despite his criticism, Giambrone praised state officials for pay increases that the Northern Virginians received earlier. "It's a hell of a lot of money and I'm definitely not griping about the raises, which were all Charley's idea."

Charley is Charles B. Walker, state scretary of administration and finance, who said that the state had planned all along to review the 22 percent differential on July 1. He said the review was not a product of pressure from downstate troopers or legislators who were upset by the pay plan.

"We took another look at the salary scales in Northern Virginia . . . trying to get a parity particularly at the bottom end of the scale," Walker said.

Maj. Charles E. Olive, who heads the State Police personnel division, insisted yesterday there never has been an "aim to make State Police salaries equal" to those locally, just to make them competitive. "And our survey shows they are," he said.