Toronto — Verbal fireworks are exploding over the world's longest undefended border.
At the center of this war of words between Canada and the United States is the environment - acid rain and pollution of the Niagara River.
Consider a recent speech in California by Allan Gotlieb, Canada's ambassador to the US. ''Acid rain has become a major issue in Canada-US relations,'' Mr. Gotlieb said. ''Acid rain has become a bilateral irritant.'' Ontario's minister of environment is more blunt. Keith Norton told visiting US journalists that President Reagan's apparent attempts to weaken air-pollution controls are ''close to an act of hostility on a friendly neighbor.''
Why is Canada so upset? It's because 50 percent of the pollutants which cause acid rain blow across the border from the United States. That means if Canada shut down all its smelters, closed its coal-fired generating stations, and parked all its cars, lakes would continue to die. In Ontario alone, acid rain threatens 48,000 lakes over the next 20 years.
According to Allan Gotlieb, the solution is to reduce emissions from old, dirty smelters and power plants. ''For their part,'' he says, ''Canadians are willing to bear this cost.'' Canada has offered to cut emissions in the eastern part of the country 50 percent by 1990, if the US will take similar action.
The two nations have signed a memorandum of intent to combat acid rain. So far, the result has been several telephone-book-size reports on the problem, but little else. According to David Hawkins of the Natural Resources Defense Council , the main reason for this is the Reagan administration.
''The administration campaigned on a promise of relaxing environmental regulations. That's what the business community wanted, and they are going to try and fulfill that promise,'' he says.
Mr. Hawkins also blames the coal lobby, the utility industry, and others for ''ganging up'' on the US Clean Air Act. One of the people involved in that ganging up is James Friedman, a key spokesman for the US Coalition for Environmental Energy Balance, a lobby group composed mainly of companies generating coal-fired electricity.
According to Mr. Friedman, acid rain is just a Canadian invention to cover up domestic problems. He has told US congressmen, ''Political and economic conflicts have encouraged the Canadian federal government to seek external issues which might unify Canada. The acid rain issue is clearly one of these.''
Whether Friedman's distorted views win points in Washington is questionable. What is disturbing is the amount of sniping between Ottawa and Washington over what should be done. According to Dr. James Regens of the US Environmental Protection Agency, governments must ''determine the extent of the effects and secondly, identify the way in which the effects are produced, because if you're going to take any type of regulatory action, you have to know what the problem is and what's causing the problem.''
Not so, says Canada's environment minister, John Roberts. ''The US is suggesting we need to know a lot more before we apply specific remedies. Our view is that that's a little like saying you're not going to clear out the swamp until you know exactly which mosquitoes are carrying the malaria.''
The truth probably lies somewhere in the middle. And history shows that much can be accomplished if the two nations settle down and work on a problem together. In 1972 Canada and the US signed the Great Lakes Water Quality Agreement. At that time, Lake Erie was reported to be dead, or at least dying. Ten years and more than $6 billion later, the international joint commission was able to announce in Cleveland last November that Lake Erie is very much alive.
But the good intent of that agreement has been foundering in recent months, at least in the Niagara River region. The 36-mile-long river serves as a border between Canada and the US as it flows from Lake Erie to Lake Ontario. Once the two countries fought over this tiny piece of geography. Today, the border is settled, but a dispute over pollution of the river is raging.
The Niagara River runs through a heavily industrialized area. Although a recent EPA report says the river is cleaner than it was 10 years ago, it notes that the two countries are discharging 1,500 pounds of toxic chemicals into the water every day. The report admits that 97 percent of the organic priority pollutants and 87 percent of the heavy metals are discharged by the US.
It is this massive imbalance, coupled with an apparent unwillingness to combat it, that has Canadians upset. Take the Niagara Falls Wastewater Treatment Plant as an example. The plant's sophisticated carbon filtration beds, designed to handle the dangerous chemicals discharged by local industry, broke down after just six weeks of operation. They haven't worked for three years.
That means certain chemicals are going straight into the river untreated. Late last year, an environment official official commented, ''The level of patience that has been shown (by Canadians) I think has been extraordinary, and at this juncture one can only consider the delay unconscionable.''
Not surprisingly, while governments squabble, ordinary citizens seem to have no trouble cooperating. Canadian and American citizens joined forces to oppose a cleanup plan proposed for the giant Hyde Park chemical dumpsite owned by Hooker Chemical and Plastics. Although that battle was lost when a US judge ratified the plan, a bond has been forged for future joint activities.
Although the rhetoric shows little sign of decreasing, there are glimpses of common sense from time to time. The EPA has promised that in the next two or three years it will tighten up industrial discharge permits, expedite the cleanup of chemical dumpsites, and complete repairs to the Niagara Falls Wastewater Treatment Plant.