ENVIRONMENT WATCH : Testing a Trade-Off

As an issue, acid rain was as dead as the forests and lakes it was killing in Canada and the northern United States until the fall of 1990. Then Congress was shown how to ease the cost of deeply reducing the sulfur dioxide that pours from electric utility smokestacks, drifts into the clouds and turns to acid rain.

The first step was imposing an overall ceiling on smokestack emissions calling for cuts of 5 million tons of sulfur dioxide by 1995 and another 5 million by the year 2000.

A company that could afford efficient pollution controls or burn cleaner coal, or both, would get credits for the difference between its reductions and its fair share of the overall cuts. A company that could not afford to cut deeply enough to obey the law could buy those credits.

This week the Tennessee Valley Authority, whose 11 coal-fired power plants make it one of the nation’s dirtiest utilities, became the first to try the system. It will buy credits from Wisconsin Power, one of the cleanest.

The smile on the faces of some environmentalists suddenly is very tight. But buying credits sounds worse than it will be, if the rules are clear and enforced--as the Environmental Protection Agency assures us they will be.

The law still requires a 10-million-ton bite out of sulfur dioxide. The only difference is that Wisconsin will take a bigger bite and TVA a smaller.

This is a sound approach, one that Southern California hopes to try soon on smog. It will tighten smiles here, too, unless the experiment works. But it is one the region and the nation are obliged to try.