In a move that could mean a shift of power from agricultural to more urban interests, the Loudoun County Board of Supervisors last week directed its staff to do a population count to determine if election districts need to be redrawn.

The action followed an informal check of population figures by county officials, who are concerned that inequities among districts could result in a lawsuit against the county by residents underrepresented on the board. The politically sensitive issue would involve redrawing election district boundaries to reflect population shift and growth, and it could result in a ninth member on the board, with five supervisors coming from less rural areas.

"There is no question about it," said board Chairman Frank Raflo, long known as a rural preservationist. "Leesburg is growing; there is nothing to fight about. The staff should determine where the inequities are, and if their set of figures can be supported in court, the board should move toward redistricting."

Population figures gathered by the staff must be approved by the U.S. Justice Department before election boundaries can be redrawn. The Virginia code allows a jurisdiction to redistrict whenever it deems it necessary, according to Edward Finnegan, the county attorney.

County administrator Philip Bolen, who will oversee the board's request, said his staff hopes to have accurate figures to the supervisors in time for the 1987 elections. Although it is not certain that redistricting will result in a ninth board member, it is highly probable, Bolen said. An eighth member was added to the board in 1981 as a result of the 1980 census figures, said Bolen, who has served in his current post since 1971 when there were six supervisors.

Ordinarily, jurisdictions wait for census figures to decide whether election areas should be redrawn. Several months ago, Broad Run representative Steve Stockman asked the board to consider redistricting because some residents and business groups had told him privately that new growth in eastern Loudoun warranted it. If the board did not act, several residents told Stockman, they would consider taking the issue to court and forcing the county's hand.

The four representatives from Loudoun's eastern end were slated to meet with the Eastern Loudoun Business Association this week to discuss the issue.

The association's concern is that "agrarian interests have reigned supreme" on the board. In a letter to members, association president Raymond Hamrick said, "do we dare wait until 1990 when the die will be cast by the board elected in 1987?"

Loudoun's rural character has been the pride of the majority of its board members and was cited by Xerox Corp. as one of the factors in its decision to locate an $8 billion to $10 billion commercial and residential development on a sprawling tract of wooded land it owns off Rte. 7, 30 miles from the District. Ironically, that development, one of the largest in Northern Virginia, is one of the causes some supervisors are citing for projected growth in the county.

Workers hired by Xerox could boost the need for residential development as far as West Virginia, they say. West Virginia's Jefferson County borders Loudoun.

The balance of east-west interests on the board has tilted slightly toward the rural western end. But Leesburg, long considered part of the rural faction, is also undergoing rapid growth.

The town has a 5.4 percent annual growth rate, and town officials project population figures at 16,200 by 1995, 5,300 more people than this year.

Several departments will work on the assignment to gather population figures that will be defensible in court, Bolen said.

Ironically, the planning department, most needed for the assignment, is also one of the busiest in the administration because of the growth that has sparked the redistricting issue.

The staff will "look at a number of alternatives" in terms of information gathering, Bolen said. According to county planner Suzanne Allen, more than 5,000 people have been added to the Loudoun population since 1980, bringing the total to 66,000.

Most of that growth, she said, has been in the four eastern districts of Broad Run, Sterling, Dulles and Guilford, with Leesburg running a close fifth.

A report released by the planning department in May said that Loudoun is expected to grow by 139 percent by 2010, the largest increase in all Washington area jurisdictions.

The figures are based on a 2.98-person average household size, Allen said.

In his budget report to the board last winter, Bolen noted that the county was growing at the average of 72 people a week.

Between Jan. 1, 1984, and Jan. 1, 1985, Loudoun's population jumped by 4,555, the equivalent of the population of Countryside, a planned community in the Sterling district.

"It's better if these things [redistricting] are done by the more traditional processes rather than having it thrust upon you," said Bolen. "If we were forced to do it, the end result might not be as good. The board has recognized its responsibility and acted on it."