THE INTERIOR Department's plan for offshore oil exploration is not necessarily a bad one, despite Secretary James G. Watt's excessive enthusiasm for it. Mr. Watt keeps lathering it up in rhetoric that he borrows from the oil industry, and that alone is enough to make most other people suspicious. But there's good reason to accelerate offshore drilling. As for the impact on the environment, the protective laws are sharp and strong. As Mr. Watt has already discovered, if he does not uphold them, the courts will do it for him--vigorously.

In the past, the government has accepted oil companies' proposals for drilling sites only in designated areas. Mr. Watt is now inviting the companies to propose sites almost anywhere in the coastal waters. In those cases where the department chooses to go ahead with the proposal, it will then begin the usual process of preparing an environmental impact statement and notifying state governments. All of those safeguards remain in force. The idea of entertaining proposals anywhere has incensed some of the coastal states. But it serves the useful purpose of establishing a reliable inventory of the sites where the industry's technical work points to promising prospects. 2 Offshore oil is one of those splendid issues that invites everyone to work up a fine fit of righteous wrath, and Secretary Watt's choice of words always encourages that reaction. But it's important to remember that the future of offshore production is a good deal less than the assured bonanza, merely waiting to be tapped, that the secretary's exhortations might lead an incautious listener to suppose.

Currently, about one-eighth of this country's domestic oil comes from the offshore wells, nearly all of them in the Gulf of Mexico. For the past several years, that flow has been slowly falling. The eastern Gulf, which oil geologists once rated as extremely hopeful, has produced almost nothing. There's been a good deal of drilling along the length of the Atlantic coastline, with little to show for it. There has been one important find in the Pacific, at Santa Barbara. But the Gulf of Alaska, advertised several years ago as endlessly rich in prospects, has been an enormously expensive disappointment so far. It is precisely this diminished hope for large discoveries offshore than makes the case now for widening the search.