A proposal by Gaithersburg to annex the 148-acre Washington National Country Club golf course has civic groups in the area up in arms.

The annexation plan contains a provision that would apply a city zoning classification to the land, allowing a developer substantially greater density than would be permitted if the property remained under Montgomery County zoning jurisdiction.

Residents of the surrounding neighborhoods have jammed hearings before Gaithersburg's City Planning Commission and the City Council, decrying the rush-hour traffic already jamming Route 28, and arguing that the increase in housing density that the proposal calls for would add even more traffic. But so far, officials haven't blocked the annexation or requested lower density.

"Things keep getting worse, not better," said Diane Aronson, vice president of Westleigh Citizens Association, an organization whose neighborhood is adjacent to the land northwest of Route 28 and Muddy Branch Road. "Nobody denies that Route 28 traffic is a disaster, but nobody's doing anything about it. . . . Every time there is a new development, the traffic gets worse."

Residents of Shady Grove Village, Brighton and other neighborhoods north of the golf course told the council that traffic already is backed up Muddy Branch Road as well. With new, dense development, it would take even longer to travel along Route 28 (Darnestown Road) to Rockville or I-270, they said.

Officials said they are keenly aware of the back-up. "It is a dismal, dismal road," said W. Edward Bohrer, a Gaithersburg City Council member.

If the council adopts the annexation as the proposal asks, the developer--Alfondre Properties Inc.--could build more than 740 units, according to city officials. Aronson said that would be incompatible with her adjacent neighborhood of 516 single-family homes on half-acre lots.

Alfondre's proposal would place similar single-family homes and park areas adjacent to existing houses around the perimeter, and position garden apartments and town houses in the inside of the development.

While other developers around the area have agreed to put $500 per unit into a Route 28 widening fund, Alfondre offered to contribute $250 per unit it builds, and have the company itself add another two lanes onto Muddy Branch where it runs along the golf course property.

"But you know who's really going to pay for it--the person who buys the unit," Bohrer said.

While the council is gathering public comment until April 20, residents are mounting their objections.

When the city planning commission first considered the proposal in February, about 50 persons came to object to Alfondre's plan. Alfondre is the contract purchaser. Eig Enterprises is the current owner. The board was split on a tie vote, which was broken at the next session when a previously absent member returned and voted in favor of annexation.

At a city council meeting early this month, more people crammed into the council chambers, and 12 speakers railed about headaches on Route 28, one of the few arteries for commuter traffic between Washington and the growing suburban enclaves in western Montgomery County.

Speakers beseeched the council to trim back the density, or hold the development until after the Maryland-National Capital Park and Planning Commission completes a study of the area--one that would include new density guidelines. That study is expected next year, officials said.

The county planning staff members who came to city hearings reserved judgment on just how dense the development should be because projections on Route 28's road capacity are unresolved, and because it would be inconsistent with the current, 1971 plan for the area.

The county's latest, but unapproved, density classification is 4.8 units per acre, but that hasn't been adopted yet, Bohrer said.

Jerry E. Levine, chairman of the Civic Action committee of Dufief Home Owners' Association, which represents a neighborhood of 306 single family homes across from the golf course land, said his group would support annexation only if the density were kept to 400 units for the site.

"We frequently show a film showing this rush-hour backup," he said. "It's taken me as long as 40 minutes to travel the 3 1/2 miles from my house to Route 270."

He said that, in the past year, 1,600 units have been approved or built in the area served by that road; another 1,900 are being considered by county and city government.

"What we're talking about is another 3,000 vehicles on Route 28 and an additional 2,000 school children," he said. "People out here are beginning to feel we're being ignored by local public officials."

Bohrer said the density would have to be increased by some amount to make the project profitable, "whether it stays in the county or comes into the city."

He said the county has implored the city--one of few in Montgomery to have its own zoning power--to "use good judgment" in planning growth for its outer limits. "But with the rampant growth farther north, that gets hard to do, Bohrer said.

"What do they say, that Germantown is going to have 200,000 residents by 1990?" he said. "Just how are they going to get to points south?"