THE COUNCIL OF GOVERNMENTS is trying to draft new regional growth policies to discourage suburban sprawl and foster more compact, less costly patterns of development. The effort is timely and important. The big question is whether it will have any more effect than, for instance, trying to stop a bulldozer with a paper chain.

COG's studies predict serious strains on regional resources - financial and environmental - if growth continues along current paths for another two decades. Though the pace of growth has slowed, the region's population is still likely to exceed 4.2 million by 1995.According to COG's projections, most jobs and commerce then will be located in downtown centers such as Tyson's Corner and Silver Spring, along major highways and Metro lines, and around the Beltway. New homes, however, are likely to be spread all over, especially in the stretches of Prince George's, Fairfax and Prince William counties where development has just begun.

The dispersion of housing, COG's reports warn, will be expensive in terms of wasted land, squandered energy and strains on water resources. With so many people living some distance from jobs, at low densities - which make mass transit uneconomic - suburban traffic snarls are bound to increase. All this adds up to public-service demands and costs that, as COG's summary puts it, "probably cannot be met."

Exhibit A is Fairfax County, which is booming now - and seems to be committed to the very kind of low density home-building that produces sprawl. The county is already feeling the strains on its water supplies and even more on its roads. Unless public-transit service is greatly enlarged, most Fairfax residents will have to get around by car. Cross-county routes are already inadequate, and the tangles at commercial centers, especially Tyson's Corner, are already great.The county's long-range road-improvement plans add up to more than $900 million - but no one knows where such sums might be found.

The policies proposed by COG would commit local governments to reduce such problems by designating growth centers and concentrating new housing closer to jobs, stores and mass-transit routes. Such sensible concepts are hardly new; they were at the heart of the 1964 "Year 2000" plan and the much maligned "wedges and corridors" strategy. So far, however, only Montgomery County has made any real commitment to channeling residential growth, primarily along I-270.

One might think the region would be more receptive now. There is certainly more public sensitivity to environmental problems, energy issues and - above all else - the soaring costs of public services. But the appeal of detached homes on separate lots remains as strong as ever. And the perennial agruments about growth usually turn into debates over densities - with self-styled environmentalists often advocating the low-density development that brings not only higher home prices but also much larger public costs.

All in all, it seems that much of the region still hasn't gotten the message in the COG reports. Until those warnings do penetrate, any new set of growth-directing policies is likely to have a little real effect. Thus, while we support the thrust of COG's proposal, we would urge area governments to endorse it only if they are prepared to follow through. Otherwise, they would do better to acknowledge that they have chosen a differnet way to grow - and start figuring out how, and whether, they can bear the costs.