When Congress passed the water pollution control act in 1972, it was generally understood to be giving the Environmental Protection Agency power to limit the amount of industrial wastes that can be dumped into the nation's waterways. Last Wednesday, after years of litigation, the Supreme Court ruled that Congress, in fact, had done just that. EPA, the Court said, can issue mandatory, industrywide regulations limiting discharges from existing plants, as long as some allowance for variances is permitted, and for future plants with no allowance for wariances.

Several corporations had argued, with some success in some lower courts, that Congress had never given EPA such sweeping authority. They contended that the agency had power to issue only guidelines on an industry-wide basis and that the precise pollution limits had to be determined on a plant-by-plant basis. That view of the law not only would have placed an "impossible burden" on EPA, as Justice John Paul Stevens wrote, since more than 42,000 plans discharge pollutants of some kind, but also would have given state water control agencies, not EPA, the final say since they actually issue the discharge permits.

We - and we suspect Congress - would have been stunned if the Court had accepted the argument made by the corporations. Congress, we think, intended to create a national industrial waste control program, not one in which individual states could choose different levels of pollution. And it chose EPA, not the states, as the agency to set the standards for that program. The Court's decision squares precisely with that intent. Some sloppy drafting on Capitol Hill - which is not surprising given the complexity of the statute - created the opening for this long litigation.

Not only does this decision remove a roadblock to enforcement of standards that EPA has already set, but it also provides that agency with momentum to get on with its work. If the Court had ruled against it, EPA would been forced either to abandon the idea of a national pollution control program or to seek clarifying legislation from Congress. The length of time involved in getting such legislation passed, coupled with the long administrative proceedings that would have necessarily followed its passage, would have delayed the water cleanup efforts for years. As it is, there is still hope that some of the most seriously polluted of the nation's waterways will be clean enough to swim in again - perhaps even in our lifetimes.