Squirreled away in the initial version of legislation to impose new recreational users' fees is a change that would let the Interior Department impose a toll on most national parkways, including the George Washington Parkway.

Although department officials are sending conflicting signals on whether the change will be included when the legislation is resubmitted, it is already running into opposition on Capitol Hill.

Tolls are now banned on all national parkways. But legislation submitted last month and then temporarily withdrawn would lift that ban, except for the few parkways that are part of the national federal aid highway system. That provision would exclude the Baltimore-Washington Parkway and the Suitland Parkway.

The legislation, sent to Congress Feb. 22 by Interior Secretary James G. Watt, Agriculture Secretary John R. Block and Army Secretary John O. Marsh Jr., would have allowed the administration to set new users' fees on recreational properties managed by Interior, the Forest Service and the Army Corps of Engineers. Under administration budget proposals, revenues from the fees would grow from $41 million this fiscal year to $104 million in fiscal 1983.

But a flap quickly broke out over whether the proposal would impose new hunting and fishing fees. Watt withdrew the legislation four days later, saying it had been "badly misinterpreted."

Congressional staff members, however, noted the proposed parkway change, and the specter of a toll being imposed on one of Washington commuters' favorite roads sent congressmen into action.

Rep. Stanford E. Parris (R-Va.) spoke to Watt on Wednesday and said Watt "is not now contemplating a toll on the GW parkway." But Parris said that if the revised legislation "leaves the question open as to whether there should be a toll, I will recommend legislation closing that loophole. Can you imagine the backup behind a toll booth on the parkway during rush hour? I don't want to leave that question open."

G. Phil Million, a Watt aide, said the provision is meant to allow Interior to establish tolls on recreational parkways and increase what are really park admission fees for the Blue Ridge Parkway and the Skyline Parkway.

Douglas Baldwin, Watt's chief spokesman, said the new bill is likely to have much more restrictive language that would allow Interior only to increase fees on park roads already covered by a toll.

But several Interior officials who had a role in drawing up the bill--a revision of the 1965 Land and Water Conservation Fund Act--said no rewrite of the parkway provision was in the works.

"Right now, our official position is that the entire bill is being reviewed, all segments," Million said earlier this week. "I want to emphasize that this legislation has been withdrawn."

Several department officials said the department had no projections of the amount of revenue it expects to raise by establishing or increasing the tolls. Baldwin said that the department has the projections but that he couldn't produce them.