THAT WAS A GOOD balance the Environmental Protection Agency struck in its rules for new power plants, though you wouldn't know it from the uproar. The rules, culminating six months of heated debate, are crucial to the expanded use of coal in this country through the rest of the century. Coal smoke is highly toxic and, in the absence of strict regulation, wider reliance on coal would represent a reckless threat to public health. A number of environmental organizations have attacked the EPA's decision as a sell-out to narrow industrial interests.

That's an adversary's view of the choice.The most dangerous of the pollutants in coal is sulfur, and two-thirds of the sulfur in the atmostphere comes from the utilities' huge coal-fired generators. The ideal way to reduce these sulfur emissions is to do it directly, setting a limit at the smokestack and leaving it up to the utilities to get down under that limit. But that, Congress feared, would shift the utilities onto low-sulfur Western coal and create unemployment in the Eastern mines where sulfur content runs much higher. To protect jobs, Congress decreed that all new plants must have sulfur-removal devices called scrubbers. It left to the EPA the next question - whether to require utilities to remove a uniform 90 percent of sulfur regardless of any other circumstances or, alternatively, to build some flexibility into the system. Environmental organization argued for a flat 90 percent requirement.

Instead, EPA administrator Douglas Costle wisely chosen sliding scale. If a plant can get its emissions down below a certain level by any other means, it will be required to scrub only 70 percent of the sulfur out of the smoke.

Mr. Costle's decision gives utilities an incentive to use clean coal. As for the Eastern miners, they don't have to fear for their jobs; the soaring costs of transporting coal will protect them from Western competition. Even more important, the decision encourages utilities to introduce new technologies that, with time and further development, may prove more effective than the present scrubbing equipment. And then there is the matter of obsolescence. These rules apply only to plants built in the future. If they were to make new plants unnecessarily expensive, utilities would have reason to delay them and to keep patching up and nursing along the older plants to which only a looser and cheaper pollution standard applies.

The principle of government regulation is not currently fashionable. But EPA's new power-plant rules are an example of intelligent policy in a field where regulation is essential to protect the public health.