Along Old Baltimore Road, less than a mile from the Olney crossroads, the air is heavy with the scent of long grasses and wild flowers. The great oaks stand tall and spread their branches wide. The sun of a clear summer day filters through the leaves, dappling the road with quivering silver.

From the road, the fields are wide and rolling. For broad stretches they appear free of man's presence. Free until a group of new houses suddenly shatters the vista with a vision of the future. Like white centurions they stand on the horizon, awaiting the order to advance.

Soon they will begin the march forward. The fields along Old Baltimore road will vanish beneath their sculpted lawns and black-topped streets. And Olney, once hardly more than a dot on the county map, will grow still larger.

Last week, the Montgomery County Council approved a new master plan for Olney and its surrounding countryside. The plan is designed to save once and for all thousands of acres of prime farmland in the county's upper reaches. It represents nearly 20 years of intense effort by planning officials to keep vast areas of open space out of developers' hands.

It is only a few years too late to make of Olney a planned community.

The leaders of the 22,000 people who live there today are bitter. Though they endorsed the new master plan, they believe county officials have sacrificed their town to save the farms. The farmland preservation plan promises to bring hundreds of additional homes into the once rural crossroads area, an area that developed before planners had the means to determine its growth.

"We are losing the town we thought we would have," says Greater Olney Civic Association President Carol Henry.

By 1996, a small city of 32,000 people is expected to stand around the juncture of Georgia Avenue and Rte. 108.

Fifteen years ago, some countains fought tenaciously against the prospect of uncoordinated development spreading across the Olney landscape. Though the residents now have accepted that growth, they have fought just as hard as their predecessors to see that it is not concentrated within the town.

Through it all, county planners have been in the middle, taking abuse first from one side, then the other. Meanwhile they have watched Olney spread wantonly and unimpeded over the years, like an unruly plant growing rapaciously northward and southward so that today Olney threatens to join the suburban sprawl that stretches in concrete abandon all the way to the capital.

The old Olney, the Olney of woodframe grocery stores and gay political parties and lazy Sunday dinners at a country inn, is gone. So, too, are the voices that prevailed in those years, concerned more with the loss of an old tree than with the lack of a neighborhood movie theater.

Landmarks have been bulldozed to make room for banks and supermarkets and fast food restaurants and wider roads. Old concerns have conceded to those of the newcomers, who ask for bowling alleys and racquetball clubs and bikeways and roads and buses downtown.

The land encompassed by the Olney master plan is a huge chunk of Montgomery County, nearly 50 square miles stretching from Norbeck Road in the south to the Howard County line in the north, from Rock Creek in the west of the Patuxent River in the east. Near the middle is the community of Olney, at the juncture of Georgia Avenue and Rte. 108 (Laytonsville-Olney Road).

Twenty years ago, when fewer than 1,000 people lived around the crossraods, the area was considered a great wedge of green to separate development along I-270 and the corridor following the Baltimore Parkway.

Blair Lee III, Maryland's former lieutenant governor, fought for the idea while a member of the county planning board. So did County Council member Neal Potter, when he was a member of the Citizens Planning Association.

But they failed to stop the sewers, and the houses that followed them into Olney, and so lost their hold on development there. By the time the County Council approved the first Olney master plan in 1966, the new town's course had already been set in concrete.

"When the plan was finished," says Lyn Coleman, the Maryland-National Parks and Planning Commision planer for Olney, "it was like dropping a red flag. The developers just took off."

From the original subdivisions near the crossroads and south and west, a host of new housing developments sprang up to fill the spaces in between. By the mid 1970s, the population of Olney had grown 10-fold in almost as many years.

Without such present-day tools as "planned development zones," and "adequate public facilities" ordinances, the kidney-shaped growth. "Ideally," says Coleman, "we would have kept it in a circle much closer to the center of town."

The newcomers followed the growth by the thousands and sustained it. With them they brought their thousands of cars.

The fate of Olney is inextricably bound to that of its two major arteries: Georgia Avenue and Rte. 108. The new residents of Olney, in their rush to alleviate the traffic jams that followed their arrival, chose to widen the roads, rather than diverting traffic around the town on a "ring road."

Today Olney is wed to the automobile. The town is quartered by two major thoroghfares. And by 1996, traffic on Georgia Avenue is expected to be more than double what it was five years ago.

"We were young enough to be naive," says Henry of the decision to widen the roads. "We didn't really understand some of the implications of what was happening. We saw the town center as a place to meet friends, not four-lane highways you'd have to cross. If everyone could have seen into the future, the ring road would have looked a lot more attractive."

The new master plan envisions a town center of nearly 500 acres surrounding the crossroads -- about a half-mile across. Commericial development is being pushed largely into the northeastern quadrant, where a small shopping center already exists.

This area, as well as the property southwest of it, has been designated a "planned development" zone. Plans for the large tracts of land are expected to include single family houses, townhouses, apartment buildings and shops. They will be subject to public hearings.

The Greater Olney Civic Association expects to play an active role in designing Olney's town center. Already its members have succeeded in shaping the look of Olney.

The look is colonial.

Block after block, the rows of mock colonial houses stretch from one end of the town to the other. The colonial designed Giant food store sits unobtrusively off Georgia Ave. The Roy Rogers beef house is almost invisible with its dark wood siding. Gino's even eschewed its traditional red roof to suit local tastes.

Olney's glory, however, is its newest shopping center, nearly hidden off Laytonsville Road (Rte. 108). Civic leaders spent nearly three years working with developers on the plans. Their efforts bore an L-shape of brick divided into a Grand Union, hair cutting salons, camera shops, dance studios, haberdashers, liquor stores and a pet shop. The store fronts are staggered to break the monotony of the brick. Signs are designed to fit nearly beneath the roof lines. Shops are separated from the parking area by a broad, brick-paved walkway that allows for leisure strolling, or simply sitting and watching from intermittant benches.

Still, local leaders believe they have lost their grip on the future of Olney.

"When we moved here," said Henry, "we saw a future of quaint little shops. We didn't see the town center as being an area to bring all these people."

Determined to save thousands of acres of farmland surrounding Olney, county planners found themselves at odds with Olney leaders who would have been content to see development continue northward, rather than expanding downtown. They see the present low density as necessary to keeping the town's character, but were unable to sway county planners.

"We kept trying to convince them we understood there was going to be growth but that we wanted to preserve the quality of that growth," said civic leader Carolyn Neal.

"We're just not the kind of people who are going to live here two or three years and then move out and not care what happens."

To save nearly two-thirds of approximately 15,000 acres north of town, planners developed a method of keeping large areas free of homes while enabling land owners to make a profit from their holdings.

The plan is called "transferrable development rights," or TDR. More than half of the scenic farming area in the plan is designated a TDR "sending zone," while 250 acres bordering the town center on the east and south have been chosen as "receiving zones."

Approved by the County Council, the concept would allow land owners in the "sending zones" to sell their rights to develop on their land to owners in "receiving zones." Owners of property in the "receiving zones" could use the development rights to increase the housing density as they develop their land. This is expected to bring hundreds of additional families closer to town.

Meanwhile, Olney is threatened in the south with losing its encircling green space, the open land regarded as necessary if Olney is to remain a "satellite" city and not just an extension of Montgomery's suburban sprawl.

To save one area southeast of town, the master plan includes a new rural clustering zone that will keep houses in small groups with surrounding areas of open fields. But across Georgia Avenue, large tracts of land abutting the proposed path of an "inter-county connector" highway are the only remaining open areas keeping Olney from locking arms with Wheaton.

One of those pieces of land is controlled by Albert Abramson, the developer of White Flint and many other Washington area shopping malls.

Even without a new shopping center, however, life in Olney promises to change radically in the next 15 years. Already, plans for more than 2,000 new homes are on file. The planning commission forecasts the construction of 3,165 new houses by 1996 in areas surrounding the town center.

"We knew we weren't going to win all the big battles," says Carol Henry. "But we fought very, very hard for some of the little ones. It would have been nice to keep Olney the way it is now. But then, that wouldn't have been progress.