Just as the ripples were beginning to subside, the Interior Department has kicked up another wave in its continuing feud with an environmental group over Secretary James G. Watt's group of wetland and duck lovers.

The group, called Protect Our Wetlands and Duck Resources (better known as POWDR), has been a source of irritation to the Environmental Defense Fund since Watt created it last summer. EDF contends it is an advisory committee and ought to be having open meetings. Interior disagrees, although it has agreed to open the group's next meeting in Washington Jan. 25, and the General Services Administration is supposed to be sorting all this out.

Last week Interior sent GSA a file copy of a form letter it said was sent to POWDR members after their last private meeting in Alabama. But the environmentalists got hold of a real letter, signed by Watt, that contained a phrase omitted from the file copy. "The draft legislation which is attached is a compilation of mainly my own ideas based on the conversations we had in Alabama," Watt said.

Ah ha! exclaimed the environmentalists, who immediately zipped off a letter to the GSA and a variety of other interested parties, stating that this "puts to rest the contention . . . that POWDR is not an advisory committee."

The draft legislation is already known on Capitol Hill as "the POWDR Act."

Even in a town where much ado over little is not an unusual occurence, the latest POWDR puff and huff has left some shaking their heads in wonderment.

"It could be an honest mistake," one official said of the discrepancy between the letters. "But it sure has opened a Pandora's Box. Why not just charter it as an advisory committee and get it over with?"