Montgomery County residents and elected officials beat up on Northern Virginia developers last night for wanting to build what the Marylanders called a development highway through the rural western part of the county.

Virginia and Maryland transportation officials are considering a proposal to build $1.7 billion bypasses east and west of Washington outside the Capital Beltway.

Montgomery doesn't mind the eastern route, which doesn't go through the county, but the western route proposal has touched off a bitter border war.

At a hearing in Germantown last night, almost every one of 48 speakers opposed the western bypass, most casting the highway as an effort by Northern Virginia developers to extend sprawling growth to Montgomery, which has been more restricted by land use regulations.

"In Virginia, developers make all the decisions," said R. Thomas Hoffman, of Gaithersburg. "In Maryland, citizens and voters still have something to say . . . . If we in Maryland wanted to experience the joys of traffic jams and unregulated growth, we would move to Fairfax County."

Referring to Northern Virginia developer John T. "Til" Hazel, Laury Miller, of Barnesville, said, "At some point the public is going to catch on to the fact that they are subsidizing the Til Hazels of this world and destroying their environment."

Montgomery's elected officials, some of whom attended the hearing, are united against the western plan, and Maryland's highway chief and transportation secretary also have characterized the western route as a development tool for Virginia.

They believe the eastern bypass would better achieve the goal of diverting through traffic from the Capital Beltway.

The hearing illustrated the prickly political dilemma facing both states: Neither state can build the bypasses without the other's approval. Yet there is opposition in both states to each of the routes.

The western route, designed to provide through traffic with another route from the South to the Midwest, would begin as far south as Interstate 95 in Stafford County, Va., and continue on a northwest route through Prince William County, past Dulles International Airport, across the Potomac River and into Montgomery, ending at Interstate 70. It would be up to 82 miles long, and cost as much as $1.7 billion.

The eastern bypass, which Maryland wants for through traffic headed from the South to the Northeast, generally would start as far south as I-95 in Caroline County, Va., continue northeast across the Potomac into Charles County, up the Route 301 corridor through Prince George's County, and end at 301 and Route 50 near Bowie. It would be up to 93 miles and also cost as much as $1.7 billion in today's dollars.

What particularly worries Montgomery and Howard county residents is the threat of development that a western bypass would pose to open space and farmland that both counties have sought to protect.

Ten years ago, Montgomery created an agricultural preserve of 89,000 acres of farmland and open space, allowing only one house for each 25 acres -- the lowest density in the Washington area.

Howard officials set up a similar program aimed at preserving 20,000 acres of farmland over the next 30 years.

Two of the three proposed western routes would slice through Montgomery's preserve.

Though the routes would not traverse Howard, officials there said they are concerned that the presence of the road nearby and additional traffic on Interstate 70 could destroy the agricultural preserve.

"A bypass . . . would tear the fabric of our agricultural reserve to shreds," said Timothy W. Warman, a Montgomery County agricultural planner. "What would surely follow any major highway through the reserve is wholesale suburban sprawl."

Several residents of the reserve gave emotional speeches about the impact the western bypass would have on their way of life.

James Watkins, of Poolesville, who said one of the proposed routes would go through the dining room of his 13-acre estate, spoke of the beauty of seeing wildlife and stars, and warned, "I don't want any of you guys from Virginia driving through it."

Another complaint from the speakers last night was that the western bypass would not reduce congestion on the Beltway, as its supporters have said.

For example, said John Snitzer, of Dickerson, the environmental impact study conducted by Maryland and Virginia said that traffic on the American Legion Bridge would swell from the current average of 170,000 vehicles a day to as many as 224,000 a day in 2010 even if the western bypass is built.

Carl Balser, Howard County's chief transportation planner, said the additional traffic from the western bypass on I-70 would cause the traffic problems of the Washington area to spread to the western part of the Baltimore region.

Three more bypass hearings of 11 remain.

Maryland Gov. William Donald Schaefer and Virginia Gov. L. Douglas Wilder are expected to make a decision late this year or early in 1991.