In his first major speech to environmentalists since taking office in May, Environmental Protection Agency Administrator William D. Ruckelshaus suggested yesterday that their groups were using scare tactics to achieve their goals.

"I realize that fear is a great goad to action, and provoking action is one way that some organizations justify their existence," Ruckelshaus told an Izaak Walton League convention in Harrisburg.

"I further believe that a policy of fear is ultimately detrimental to environmental goals . . . . Reviling every change suggested in an environmental law as a 'rollback' or 'gutting' of the statute will, ironically, lead to an environment less protected than it could be . . . ," he said.

But Ruckelshaus also told the league, one of the nation's oldest and largest conservation organizations, that a controversial proposal to relax water-quality standards has been rewritten to be in "better accord" with the federal clean-water laws "and the desires of the Izaak Walton League."

The proposal, promoted by Ruckelshaus' predecessor, Anne M. Burford, had been attacked by the league as a gutting of the Clean Water Act.

In a speech that was half olive branch and half willow switch, Ruckelshaus told the league that he welcomed the help and support of environmentalists, who have been among the administration's sharpest and most effective critics.

But he made clear that he did not appreciate the checklists or "report cards" that have become popular among environmental groups as a way to gauge his administration of the EPA.

"In the cooperative spirit in which you provided one for me, let me offer mine for you," he said. "The first mark would be for cooperation. Are you on the shore throwing rocks or are you willing to be part of the crew, bending to the oars and the tiller?" --Cass Peterson