The Environmental Protection Agency has decided not to make a decision for now on a petition asking it to determine that U.S. pollution forms acid rain hurting Canada, the agency said Friday.

The petition was filed in April by the six New England states, New York, New Jersey, Minnesota and four environmental groups. In addition, the Canadian province of Ontario filed a separate petition.Don Clay, EPA's acting assistant administrator for air pollution, wrote the states and environmental groups saying, "It would be premature to rule on your petition at this time," the agency announced.

A similar letter was sent to Ontario.

In the last days of the Carter administration in 1981, EPA Administrator Douglas Costle wrote Secretary of State Ed Muskie that sulfur dioxide emissions originating in the United States were "endangering" Canada.

These emissions help form acid rain, which environmentalists say is killing aquatic life in lakes in sensitive watersheds of the Northeast, the Upper Midwest and in eastern Canada.

The Reagan administration did nothing about the letter, though the states, environmental groups and Canada argued that it triggered an obligation under the Clean Air Act for EPA to force states to rewrite their air pollution control plans to reduce the emissions harming Canada.

A federal appeals court ruled against the states, holding that Costle's letter was not a formal enough finding of harm to Canada to trigger a requirement forcing states to act. Such a finding must be arrived at through regulations requiring notice to all parties involved and a chance to comment, and the states could request such a proceeding, the court said.

Some of the states in July lost a separate but related suit claiming that sulfur dioxide originating in power plant and industrial smokestacks of the Midwest made it impossible for them to meet federal clean air standards in their own territories.

"I do not believe that EPA presently has sufficient information to undertake the regulatory program required (if the petition were granted), including the endangerment finding requested in your petition," Clay wrote.

Clay said his letter "does not necessarily reflect the position of the administrator," but "I cannot recommend that the administrator take the discretionary action of making the findings."