Thirty-nine square miles of land tucked away in southeastern Montgomery County, dormant for a decade under a state-imposed sewer moratorium and lying in the shadow of the more ostentatious growth in the county's west, is due for some changes.

Now, single-family houses do the area and large tracts of undeveloped land, supporting some farming, give the eastern part of the county a rural flavor. In the 1970s this section of the county was closed to developers because there were not enough sewer lines or treatment capacity. With relief lines in place and expanded treatment plants, the moratorium has been lifted, and construction trailers are appearing on the edge of many vacant lots.

To the relief of those who live in the Fairland, Cloverly and White Oak areas, the master plan for eastern Montgomery County, now in the final stages of preparation, will not permit the main thoroughfares of Route 29 and New Hampshire Avenue to become Rockville Pikes of Strip-zoned commerical development. Residents' groups began forming action coalitions even before the first public forum on the plan in 1978, to make sure the planning board preserved the region's residential character.

What they will see in the next few years will be more townhouse sections, expanded shopping centers and mammoth parking lots.

"A few years ago we saw that the sewer moratorium was going to end and that there was a lot of undeveloped land. Now, you can bury your head in the sand and say you hope it will stay that way. But developers will ask for a get density. So we need a plan for guidance," said Barbara Foresti, a former kindergarden teacher and member of the White Oak Area Civic Coalition who has spent much of her time following the development of the master plan.

The planned area, stretching from the Beltway to the Howard County line and to the Prince George's County line on the east, is largely open. It did not fulfill planners' expections in the 1960s -- that it would parallel the I-270 corridor as an economic base for the county. Trees cover 30 percent of the area, and suburban homesites 40 percent. Route 29 and New Hampshire Avenue carry commuters south into Silver Spring or north to Howard County and Baltimore.

"A lot of people moved out there because it's rural -- suburbia in a rural atmosphere. And it's nice, but it's changing," said Planner Lael Adams. "It's not going to change as fast as Gaithersburg, but there will be change."

The plan proposes that commercial development be continued at intersections along Rte. 29 and that housing density be increased around the commercial centers. With the addition of parking lots there, the plan envisions that residents will use buses more and automobiles less.

Brown trout in the upper Paint Branch watershed are protected by zoning that requires at least two acres per homesite in areas to the stream.

Still, some residents are unhappy with the plan; particularly with its naming of 827 acres in six different locations as the first "receiving areas" in the county's Agricultural Preservation Plan.

To save 114,000 acres of farmland in the prohibited from developing their land but are granted "development rights" they may sell to builders to use in specific areas named by the planning board. A developer who buys the "rights" from a farmer will be granted a higher density zoning than the land previously carried.

"People have the perception that the eastern part of the county is being asked to absorb things that other parts of the county don't have to," said Donald Spivack, head of the eastern planning division. All new master plans will include receiving areas, he said and Gaithersburg is next.

"This plan is the first one since the mandate. Therefore, there's a certain amount of suspicion that there won't be a second one," he added.

"It's a bad idea," said Robert Price, a member of the Columbia Road Citizens Association who testified last month before the planning board. "The farmers upcounty are going to sell their TDRs (transferable development rights). The developers will buy them; we'll get higher-density development and then the County Council can just change the law. There's nothing permanent about undeveloped land. Nothing's changed about that land that can't be undone by the council."

The planning board hopes that TDRs and another kind of zoning called planned development (PD) zones will encourage the building of moderately priced housing by offering density bonuses. In the PD zones, increased density is allowed in return for a builder's agreement to vary the types of housing, such as townhouses and single-family homes. In addition, the plans must be submitted for public review and planning board scrutiny.

The control the planning board has been able to exercise over the county's growth is not, however, universally appreciated.

"There are all kinds of fancy zones for specific purposes in specific areas. In the old days there were certain kinds of commercial, residential and industrial zones. Now it's so complicated that the average person can't understand it. The zoning process has broken down to the point where sooner or later they're going to have to redo the whole thing," said Price.

Indeed, today there are 47 types of zones in the county. In 1958 there were 14.

Price says he became a local activist 18 years ago when a flyer in his mailbox caught his attention. "Whose house is going to be bulldozed next for the new highway?" read.

Today he and his neighbors have the same concern. The eastern Montgomery County plan includes the right-of-way for the long-studied, much-disputed Intercounty Connector. Planners contend there is no choice but to retain the option to build the east-west route until state highway studies are completed in 1983. t

The staff of the Maryland-National Capital Park and Planning Commission is writing a final draft of the plan, which is to be submitted to the County Council in late February or early March. Once the council gives its approval -- usually after public hearings and making some changes of its own -- the park and planning commission formally adopts the plan and it becomes the guide for the area's zoning and construction.