THE PROSPECT of oil rigs in areas designated by Congress as protected wilderness raises large questions about this country's values. Ten days ago, in this space, we chided the Interior Department for having issued drilling leases on land contained in the Capitan Mountain Wilderness in New Mexico. Today, in an adjacent column, we publish a letter in response from Undersecretary of the Interior Don Hodel.

Replying to a further question from us, Mr. Hodel says that Interior has flatly prohibited, without qualification, any surface drilling within Capitan under these leases. The leases overlap the boundaries of the wilderness; the lease holders may, if they wish, try to drill diagonally under the wilderness from sites outside it. But, Mr. Hodel emphasizes, regardless of any success or lack of it in slant drilling, oil rigs cannot enter Capitan under these leases. This assurance from the Interior Department is important and welcome--particularly since the rules were less than clear on the point.

That settles the case of these particular Capitan leases. But on the broad and general question of drilling elsewhere in wilderness areas, there remains a wide difference of opinion between ourselves and the Interior Department. The department agrees that drilling in the protected areas is, in principle, undesirable at present. But it is rendered necessary, according to the department, by an artificial deadline in the Wilderness Act to which Mr. Hodel refers. Interior considers it important to allow some drilling there, before the deadline, to establish an "inventory" of oil and gas resources.

The concept of an inventory has, in our view, little relationship to the realities of oil exploration. You can never know that an oil reservoir exists until you've actually drilled into it and tested it. You can never know how large the reservoir is until you've done much more drilling to map it. That's a lot of drilling, and it's expensive. Oil companies will risk their money only where they have the right to produce what they find.

This country's energy requirements have not yet reached a point at which it must invade the most spectacular and remote of landscapes in a desperate attempt to scrounge up the continent's last bucketful of oil. The Interior Department is not blind to its responsibilities under the Wilderness Act, and we urge it to consider its position further. True, the act forbids leases in the protected wildernesses after 1983. That, we believe, means that the wilderness areas ought to be the last places in the country to be drilled--not the next places.