For meteorologists, this spring's high water levels on Lake Ontario and the St. Lawrence River have a straightforward explanation. Rain, and plenty of it, has soaked the entire region for weeks just as water from melting snow in the vast Ottawa River watershed has been flooding into the St. Lawrence from the north.
But two U.S. congressmen, Representatives Chris Collins and John Katko, whose districts border Lake Ontario's southern shore, have sought action from U.S. President Donald Trump by taking aim at a different culprit: a recently implemented Canada-U.S. protocol for regulating the height of Lake Ontario.
The two representatives, who are both Republicans, have called on Mr. Trump to withdraw from the bilateral agreement, known as Plan 2014, which came into effect in January under the International Joint Commission, the body that oversees transboundary waters. Among other goals, the plan is intended to improve wetlands by allowing for higher variability in water levels – a point that the congressmen have portrayed as a questionable benefit, linked to Mr. Trump's White House predecessor.
"This controversial and ill-conceived plan was passed at the end of the previous administration and is already wreaking havoc on communities in Central and Western New York," they wrote in an open letter Mr. Trump.
The same sentiments have been echoed on social media related to Plan 2014. "Thanks Obama," one Youngstown, N.Y., resident tweeted sarcastically.
All of this may come as a surprise to those dealing with high water levels on the Canadian side of the lake, where most people have never heard of Plan 2014 and where local news reports on the situation do not reflect the fractious political tone seen in U.S.-based coverage.
"The reality is that this situation has absolutely nothing to do with Plan 2014," says Robert Campany, a U.S. member of the International Lake Ontario-St. Lawrence River Board based in Clayton, N.Y. The board, which operates under the auspices of the Joint Commission, can adjust water levels by changing the outflow from the Moses-Saunders hydroelectric dam near Cornwall, Ont.
While Plan 2014 will increase variability in lake level over the long term, he said, the way it is being applied this spring is identical to what would have occurred a year ago when the former plan was still in effect. The reason is that Lake St.-Louis, where the Ottawa and St. Lawrence rivers meet near Montreal, is already swollen with rainwater and spring runoff. Lowering Lake Ontario, with its large surface area, by just one centimetre would translate into a 10-centimetre rise in Lake St.-Louis.
"It's a balancing act," Mr. Campany said. "Unfortunately there's no easy answer to make everyone happy."
That logic did not stop New York's Democratic governor, Andrew Cuomo, from appealing to the Joint Commission last week to release additional water through the dam (without mentioning the downstream effect on Montreal).
Asked if the plan favours the environment over property owners, Douglas Wilcox, a professor of wetland science at the State University of New York at Brockport, dismissed the notion.
"Models of Plan 2014 performance suggest that it could allow lake levels to be six centimetres higher for a few days once every century during high-water supply periods," he said. "During low-water supply periods it would let lake levels go lower, which the old regulation plan never allowed."
Since wetland species of plants and animals can only thrive in the zone between high and low water, the increased range, which is closer to what the lake experienced before the dam was built in 1958, will help keep wetlands from shrinking.
Whatever happens to Plan 2014, a key question is what to expect as climate change increasingly affects the various factors that influence lake level.
Those factors include precipitation and evaporation, both of which are projected to increase as average temperatures warm.
Frank Seglenieks, a water-resources engineer with Environment and Climate Change Canada in Burlington, Ont., said that over the coming century evaporation was expected to win out between the two effects, which should lead to a gradual decline in the average level of Lake Ontario. However, with climate change comes increased variability, which means that years like this one, when water levels are far above average, could still occur more often.
"We're actually forecasting more extreme highs and more extreme lows," he said.