WHAT GOES UP, must come downs.

That much, almost everyone in the acid-rain game agrees upon. But that's about all.

There is no doubt that coal-burning power plants account for about 70 percent of the 24 tons of sulfur dioxide dumped into the air of the Midwest and Northeast each year. There is no doubt that this sulfur dioxide is carried hundreds of miles away, with a final resting place somewhere in northeastern North America. And there is no doubt that acid rain has engendered an international--and international--debate marked by some appropriately acerbic rhetoric.

For aside from the fact that sulfur dioxide goes up, and acid rain comes down, the coal producers, utilities, environmentalists, and politicians involved agree on virtually nothing.

After nearly a decade of research, the effects of acid rain on the lakes and forests of the Northeast are still not clear. The Canadian Government and environmentalists in this country insist that acid rain is killing millions of fish and trees. American electric utilities and coal producers dispute this conclusion. And for two years, the Reagan Administration equivocated, claiming that not enough research had been done to take a position. Last June, though, two reports on acid rain from two prestigious sources changed the whole complexion of the conflict.

The first report--released on June 24--was prepared by a blue-ribbon panel appointed by Presidential Science Advisor George Keyworth II Concluded the committee. "If we take the conservative point of view that we must wait until scientific knowledge is definite, the accumulated deposition [of acid rain] and damaged environment may reach the point of 'irreversibility." The recommendation: "Steps should be taken now which will result in meaningful reductions in the emissions of sulfur compounds into the atmosphere, beginning with those steps which are most cost-effective in reducing total [acid rain] deposition."

The committee expressed special concern for the yet unknown effects of acid rain on the microorganisms in soil that break down natural wastes into carbon and nitrogen. Committee Chairman William A. Neirenberg--director of the Scripps Institution of Oceanography--called this "a worrisome thing...that you're not going to sit around and wait 20 years" to confirm.

It was a bad week for the Reagan Administration. On June 29, a study from the National Research Council--an arm of the National Academy of Sciences--concluded that reducing emissions of sulfur dioxide from coal-burning power plants and factories will significantly reduce acid rain, which has probably contributed to the death of lakes and forests in the Northeast and Canada. Further, the NRC said that 90 to 95 percent of acid rain in North America comes from man-made sources, notably smokestacks and car exhausts. Finally, acid rain varies in direct proportion to the amount of sulfur dioxide in the air; reduce sulfur dioxide emissions by X, and acid rain will be reduced by X also.

The reports--both prepared by distinguished scientists--leave no doubt about the seriousness of the acid-rain threat. Whether to act is no longer the issue--how to act is.

Environmental Protection Agency Administrator William Ruckelshaus promised action by August 1. August passed without an announcement. So did September. Finally, at a conference in mid-October, Ruckelshsus said there was to hope for quick action on acid rain. He told the group that the Cabinet Council on Natural Resources--a White House task force--had twice vetoed his proposals, and that he found "we were dealing with a very big, very controversial action."

In a week effort to appease the Canadians, Reagan, in his State of the Union message this January, dared to be cautious: he requested $50 million for an experimental program designed to neutralize dangerously acidic lakes. To date, then, Reagan's record on acid rain has been marked by inaction and political expediency.

ABOUT TWO DOZEN bills concerning acid rain are now pending in both houses of Congress, and virtually all call for reductions in sulfur dioxide emissions. Although officially united in opposition to any new legislation, two major lobbying groups--the National Coal Association and the Edison Electric Institute--are privately divided over possible reduction plans.

The internecine conflict with NCA pits high-sulfur coal producers in the East versus low-sulfur coal producers in the West. A partial solution to the acid rain problem is to increase use of low-sulfur coal, which creates less sulfur dioxide emission. But high-sulfur coal producers argue that such a move will cost them more than 40,000 mining jobs, and nearly four times that number in related fields.

Officially, then, the high-sulfur group is against any new legislation which would mandate reduction in sulfur dioxide emissions. In private, however, the lobby hints that, if push comes to shove, it would opt for legislation requiring the installation of costly scrubbers in coal-burning power plants--thereby obviating the need for low-sulfur coal.

Very much aware of their compatriots' intentions, the low-sulfur producers have formed another lobbying group: Alliance for Clean Energy, which advocates the use of low-sulfur coal.