THE STRUGGLE between Interior Secretary

James Watt and members of Congress over whether to encourage energy development in wilderness areas has advanced a step with a decision by U.S. District Court Judge W. J. Jameson. The case stemmed from the House interior committee's declaration of a state of emergency in the Bob Marshall Wilderness in Montana, in order to stop Mr. Watt from issuing oil and gas leases there.

The judge did not dispute the validity of the law's emergency provision, but he ruled that it is the secretary of the interior who has the right to determine the scope and duration of any such ban on leasing of public lands. However, the decision also specifically took note of an agreement that had been reached between the interior committee and Mr. Watt for a six-month moratorium on leasing in the wilderness, so the decision should have no immediate effect on further wilderness leases either way.

Congress therefore has until next July to take a more careful look at the broader questions of wilderness leasing. It needs to find reliable answers to two questions. First, approximately how much of the country's oil, gas, oil shale and coal reserves lie in wilderness areas? Second, how great is the need to develop those resources now?

Although it might seem that the answers must already exist, the extent of wilderness energy resources and of those available for development outside the wilderness has not been systematically addressed. For example, The Wilderness Society, a group with an obvious special interest, recently released a study concluding that only about 2 percent of oil and gas reserves lie in the wilderness. The study used oil and gas estimates made by the U.S. Geological Survey. The Department of the Interior strongly disputes the results but has offered no specific criticisms. The differences need to be thrashed out and a consensus reached.

The Senate energy committee has been debating whether to expand leasing rights for oil shale development, on grounds that shortages of land are holding back the growth of this new industry. Yet the available evidence indicates that it is not land restrictions but a matter of cost, technology and environmental impacts that is delaying oil shale development.

Like the oil industry, coal companies regularly decry the "lock-up" of energy and other mineral reserves on public lands. A study issued last week by the congressional Office of Technology Assessment found that in the next decade the "extent of increased market demand, not the availability of additional Federal leases, is expected to determine the amount of coal that will be produced." The study identifies billions of tons of coal reserves that have been leased but not yet mined.

The fragmentary evidence now available hardly seems to justify disturbing the wilderness areas when apparently large reserves are available for development elsewhere. But the evidence needs to be much better than fragmentary, and the debate needs a more objective forum than the conflicting and often inflated claims of energy developers, environmentalists and Mr. Watt. Congress would perform a real service by finding the answers.