While metropolitan Washington's regional planning agency is attacking low-density, scattered growth as "undesirable from both a regional and a local viewpoint," Fairfax County is insisting on being free to follow a course that has resulted in just that kind of development.

Potential conflicts between regional and local planning crystalized this week at a meeting of the Fairfax Board of Supervisors. By unanimous vote, the supervisors supported revision of a draft statement by the Metropolitan Washington Council of Governments that urges that future development be concentrated in clusters served by Metrorail and other mass transit.

The regional implications are significant because Fairfax has become the major growth center in the area - a position that, according to COG population forecasts, it is expected to maintain into the 1980s.

Amendments proposed by Fairfax do not take issue with the thrust of the COG draft on regional growth policies, but they do insist that the county - and not COG - will ultimately decide what is consistent with those policies.

For example, the draft, now circulating among officials of local jurisdictions, says new jobs and housing should be located "to capitalize on the increases in transit accessibility that the Metrorail system will provide." Changes proposed by Fairfax's new planning director, Theordore J. Wessel, and endorsed by the supervisors Monday, would add the phrase, "consistent with the planning goals of the affected jurisdiction."

One of the main goals of Fairfax's two-year-old PLUS (Planning and Land Use System) program is growth tht emphasizes smaller scale development.

The goal was articulated as a result of widespread citizen presure of de-emphasize high-density development (apartments, condominium and big townhouse clusters) in already settled areas near the Beltway, and instead encourage construction of small subdivisions, usually single-family houses, in the sparsely settled western and southern areas of the county.

"There is rural subdivision mentality in Fairfax," Deputy County Executive Samuel A. Finz said in an interview.

The consequent far-flung development requires massive reliance on cars - even though Fairfax's main transportation arteries are already over-crowded and many important connecting roads remain unimproved rural roads designed for hay wagons.

The shift of many jobs to Fairfax has not lessened reliance on the auto for commuting because the new work places are usually a considerable distance from where people live. Between 1972 and 1990, daily commuting trips within Fairfax are expected to increase by 111 per cent (from 109,000 to 233,000), nearly double the projected rate of increase in Prince George's County.

Aggravating Fairfax's problem is that the scattered growth is occuring at a faster rate than county officials had anticipated. In Burke Centre, a new cluster of single-family dwelling subdivisions in the recently rural Pohick area south of Fairfax City, houses are sold when they are still in the blueprint stage. Throughout the county, building permits exceed the total for the Washington area - an indicator of short-term trends.

The low-density, scattered growth taking place in Fairfax was not ordained by its planners, many of whom favored more intensive development in areas closer to the Beltway - and thus to jobs and shopping. But such proposals were scaled down in the face of persistent and well-organized citizen pressure.

The pressure was actually encouraged by the PLUS planning process, whereby citizens were urged to take an active role in drawing up the county's development blueprint. Before PLUS, how the county was developed was largely an arrangement between the builders and county officials.

Time and again during the year the PLUS comprehensive plan was fashioned, densities proposed by county planners were shaved in the face of neighborhood objections.

Deputy County Executive Finz, however, insists that PLUS was a success because it resulted in an up-to-date comprehensive plan and provided a process by which the plan could be annually reviewed for possible revisions.

Finz acknowledges there is a "potential for conflict" between Fairfax's planning policies and those spelled out in the COG draft on growth. But Finz, like other county staff, must reflect policy set by the supervisors, and he treads a delicate course in commenting on the issue.

Asked whether the county will want - or be able - to concentrate development in "suburban growth centers," as proposed in the COG draft, he said, "I don't know."

COG expects to shape the draft into a formal statement by October. It is intended as a replacement for the Year 2000 Plan, which has been a not-always-followed guide to regional growth since 1964.

While COG cannot directly force Fairfax or any other local jurisdiction in the 16-member organization to follow its growth policies, it can apply power pressure indirectly. COG can do that in recommending whether important local projects - such as roads, and other public facilities - should get federal funding.

That happened recently when the COG board recommended that the federal government not use the interstate highway funds to finance an eight-lane extension of I-66 through northeastern Fairfax and Arlington.

Janes Rogers, chief of the COG growth policy program, concedes that "you don't change development patterns overnight." But, she adds, "you can make policies that will have an influence in the long run."

Unlike the Year 2000 Plan, the COG growth policy statement now in draft form is intended to be more specific about what is good and what is bad in development. In the introductory statement, there is this tough language:

". . . the growth pattern forecase . . . is sufficiently dispersed to cause futher environmental deterioration, to increase automobile dependency in to create service demands and costs which probably cannot be met."

That statement calls for "a more compact development pattern and a more focused effort to conserve resources (which) would lessen or prevent many of the negative impacts identified."

While the policy statement is more precise than the Year 2000 Plan, it too is likley to be overwhelmed by events and trends over which COG has no control.

For example, the proposal calling for intense development around Metrorail centers is difficult to carry out when there is uncertainty whether the suburban areas. In fact, the entire Fairfax portion of Metro - apart from the Huntington station south of Alexandria - is in doubt.