OTTAWA — Prime Minister Brian Mulroney raised the stakes in the U.S.-Canadian dispute over acid rain by proposing Sunday in a meeting with President Reagan that the United States and Canada sign a treaty that would reduce the air pollution that causes it by 50% by 1994.
Mulroney's suggestion came in the first of a series of meetings of the two leaders, each of whom is facing the most pressing domestic political trials of his tenure. It was Reagan's first trip out of the United States since the Iran- contra affair came to light.
Previously, the Canadians had sought from the United States a bilateral agreement--a less formal accord than a treaty--to reduce sulfur dioxide emissions, which are the principal cause of acid rain. But Washington has resisted on grounds that greater study was needed.
Canada contends that acid rain, 50% of which comes from U.S. industry along the border, has "killed" 14,000 Canadian lakes and waterways. The government here has already adopted legislation requiring a 50% reduction in Canadian emissions by 1994.
A senior Canadian official attending the meeting said the President took note of Mulroney's new proposal but said only that it would be discussed further.
"The prime minister asked the President to consider the Administration and Congress moving together and joining the Canadian government and Parliament in a nonpartisan manner to sign a treaty," the official said.
White House spokesman Marlin Fitzwater sought to smooth over any differences on this sensitive issue, telling reporters after the meeting, "We share the Canadians' concern for the environmental effects of acid rain."
Reagan, posing for photographers at the start of the session, said when asked by a reporter whether he would agree to controls on acid rain and the Canadians' target dates: "We're going to discuss that. We both have this in common, and we both want answers."
The current Reagan-Mulroney summit (they have met twice before) is occurring at a sensitive period in the Reagan presidency.
It comes as Reagan and his senior advisers are making every effort to portray him as being actively involved and firmly in control of his Administration, particularly in the foreign policy realm, in the wake of the Iran affair and prostate surgery and criticism that he is not actively engaged in the details of governing.
But Fitzwater took issue with a suggestion that the meeting would offer a test in which Reagan could demonstrate his stature as a world leader.
"The President doesn't need any test. His stature is well-confirmed by six years of activity," the spokesman said.
For Mulroney, who has gotten along well with Reagan in previous meetings, the sessions Sunday evening and again today require a skillful walk between conflicting pressures.
The prime minister's popularity has tumbled to a point where only 17% of the Canadian public considers him the best qualified national political leader, according to a poll taken by the Toronto Globe & Mail.
Although Mulroney is under constant pressure from his political opposition for allegedly catering too much to American wishes, he made it clear to American reporters last week that his hope for political survival depends on good relations with Washington, particularly in obtaining a free-trade agreement.
"We're going to have a free-trade agreement," he said. "I'm going to run on it and I'm going to be reelected."
But while Mulroney and U.S. officials have stressed the positive nature of the bilateral relationship and a joint determination to reach a free-trade arrangement, a dark current runs under the surface.
Leonard Legault, the deputy chief of mission at the Canadian Embassy in Washington, said in a weekend speech in Cleveland that his government must have positive results from the trade talks if good relations are to be maintained.
After listing all the major American world and defense positions supported by Canada, Legault said that "it is a fact . . . that it would be idle to believe that rocky trade relations would not affect" Canada's backing of the United States.
So, while trying to assert Canadian independence from the United States, "the conclusion Mulroney wishes to be accepted is that Canada's future lies in cooperation with the United States," said Philip H. Trezise, a former assistant secretary of state who is now affiliated with the Brookings Institution in Washington.
Such meetings as those now taking place here, Trezise said, have "one important value: Once a year, Reagan has to focus on the fact that there is a Canada."
Otherwise, he said, "In the normal course, these are pretty much photo opportunities--no harm in them."
That the issue of acid rain gets greater attention north of the border is evident from the fact that the senior State Department official responsible for U.S.-Canadian relations only recently read a year-old report on the problem that was prepared by envoys of the two nations.
Conflict Played Down