Congress is slowly approaching the point of legislating on acid rain. More than 150 House members of otherwise very different persuasions have signed onto a single bill to control what is thought to be the phenomenon's main cause. The sponsoring members include a majority of the health and environment subcommittee, where earlier acid rain bills failed in 1982 and 1984, and half the members of the parent Energy and Commerce Committee, though not its chairman, John Dingell. Key senators also want a bill. If not enough time is left this year, the members will nevertheless have made progress on which the next Congress can draw.

Acid rain is an issue that tests the regionalism in Congress. Mainly, it is an affliction of the Northeast, emanating from the power plants of the Midwest. In generating electricity, these plants burn coal. For obvious reasons of cost and convenience, it is mainly eastern rather than western coal, and eastern coal is mostly high-sulfur. To keep from polluting their environs, as they are forbidden to do by federal law, the older among these plants send their smoke up through very tall stacks, whence it wafts off into the atmosphere. (The newer plants are required to clean their smoke.) This dissipated smoke, blown eastward by the prevailing winds, contains large quantities of sulfur dioxide and nitrogen oxides, which acidify the eastern rain. Aquatic life, forests, exposed surfaces (as of buildings or cars) all suffer. Long-term results, if the rain continues, are still a subject of study and debate.

The bill would require states to control emission rates and thereby cut sulfur dioxide emissions from power plants by about half by 1997, nitrogen oxide emissions by perhaps a third. The midwestern states that would be most affected wuld basically face two alternatives: install scrubbers on their stacks to clean up the smoke, or shift to lower-sulfur coal. Scrubbers would drive up utility bills; they are costly. Shifting to lower-sulfur coal, meaning more coal from the West, would have a cost of a different kind. The eastern coal-mining states and mine workers' union would lose jobs. There is the added political problem that no bill can pass without some support from the South and the West. But the South and the West don't want to pay for an eastern problem -- the westerners especially, since they would be undercutting demand for their own coal.

The bill would sidestep these choices by requiring each governor to decide on the means for reducing emissions in his state. The governors would be the ones who would have to choose between higher rates and fewer jobs. But the bill would also limit residential rate increases from the cost of installing scrubbers to a maximum of 10 percent. The money beyond that would come from a small monthly fee to be collected on electricity use all across the country. The polluting states would pay up to a point; the cost after that would be borne nationally.

That seems like as fair a way as possible to discharge the federal responsibility, as light a hand as the government could lay on the problem and still hope to solve it. There remain a lot of scientific unknowns in this new realm of acid rain. No one wants to act precipitously. But enough is known to begin to act. That is what this bill judiciously does.