Fairfax County, which is running out of undeveloped land that is attractive to corporations and other businesses seeking to relocate from cities, is considering carving an industrial corridor through some of its most prized countryside.

The corridor would be built on the farmland and stream valleys now crossed only by the limited-access Dulles Airport Access Road and would be Fairfax's answer to Montgomery County's prestigious swath of industry along Interstate Rte. 270.

Such a plan would have been politically unthinkable only a few years ago because the area contains some of the most envitonmentally sensitive land still remaining in rapidly developing Fairfax. The search for new industry, seen as a way of relieving the mounting tax burden on homeownes, has emboldened county officials to consider unorthodox policies.

The current master plan decrees light residential development for the area, which in some sections, is so pristine that brook trout thrive in the waters of Difficult Run. The trout, because they are extremely sensitive to water pollution, are a prime indicator of environmental quality.

It is just such quality that is attractive to businesses that want to relocate from the concrete and congestion of big cities like New York and Washington, according to county officials.

"Such a corridor would be ideal for industry looking for frontage to display its name," said county planning director Theodore J. Wessel. "All the traffic would be very impressive for industry."

The traffic - in fact, the development of the corridor - would depend on construction of parallel lanes along the Dulles highway. The feasibility of a toll road with several entries open to commuter traffic from northwestern Fairfax and Loudoun County is being studied by the Virginia Department of Highways and Transportation

Creation of an industrial corridor also would require drastic rezoning a move that probably would arouse heavy opposition by nearby residents, who pack public hearings to oppose even the residential development permitted by the master plan.

The master plan for the area along the access road, written in 1975, generally limits development to two houses per acre - in some cases less. It also proposes that the most sensitive sections be set aside as "environment-quality corridors."

Some county officials think that well-designed industrial parks might be less environmentally destructive than less environmentally development.

"When I look at the roofs of Shouse Village, that's not my idea of esthetics," said Fairfax Supervisor Martha V. Pennino (D-Centreville), who provided the initial push for the county al quality corridors."

Shouse Village was one of the first major developments to be built in the area.Its big, expensive houses - linked by the board ribbons of asphalt roads required by the county - dot the treeless meadows north of Wolf Trap Farm Park.

James R. Hardcastle, chairman of the county government's Enivornmental Quality Council - a group that has, at times, tried to put a brake on development into sensitive areas - said he has an open mind about the proposal for an industrial corridor.

"I would be very tempted toward foavoring it, if it is very carefully done," he said. "With industry, where a lot of the land is set aside as open space, you probably would have more control over eroslon and storm water runoff. I think I would find it nicer than houses."

County officials said they are leaning toward a Tysons Corner-to-Dulles corridor because other potential areas either have the wrong image - ware-house-oriented 1.05 south of the Capital Bektway - or do not lead to an ur ban center, such as 1.66 west of the Beltway.

While Tysons Corner itself, where four major highways and the Dulles road cross, is considered a prestige location, "it is getting a bit congested for firms that want open space," according to David A. Edwards, director of the Fairfax Econimic Development Authority.