Regulators explain Lake Ontario, St. Lawrence River water levels in web conference

Sep. 1—WATERTOWN — Water levels throughout the Great Lakes and its attached rivers are trending downward from their historic high levels observed just a few years ago, but the system's unpredictability is still causing some unique trends in local waterways.

In the Thousand Islands area, water levels are significantly lower than their average levels for this time of year, with many who use the waterways complaining of dramatically low levels and damaging conditions. During a web conference hosted by the International Joint Commission on Tuesday, Kyle McCune, alternate U.S. chair for all three regional water regulation boards under IJC jurisdiction, explained why that is.

"Current water levels on the upper portion of the St. Lawrence River between Lake Ontario and the Moses-Saunders Dam are at many locations near or at record low levels for this time of year," he said. "There are several drivers to low water levels in the upper portion of the St. Lawrence River, including below-average water levels on Lake Ontario, lower than average regional precipitation and high outflows at the Moses-Saunders Dam."

In Lake Ontario, water levels for 2022 trended above average until July of this year, when they dropped below their long-term average. The average water level for the last week of August on Lake Ontario is 245.64 feet, and the current level as of Aug. 29 is 244.95 feet, less than inch below its long-term average.

At Lake St. Lawrence, right above the Moses-Saunders Dam at Massena, water levels fluctuate more dramatically. Current levels at the forebay to the dam as of Aug. 29 are 238.52 feet, but the historic average is nearly two feet higher, at 240.39 feet.

Mr. McCune explained that the Moses-Saunders Dam outflows are set by a formula that takes into account the previous year's water levels and the current year's water levels, and last year's relatively high water levels require more water to flow through the dam this year. Additionally, only local conditions are really impacting the water levels on Lake Ontario and the river.

"While recent local supplies of precipitation have been lower than average, inflows from Lake Erie remain above average," he said.

He explained that the Lake Ontario — St. Lawrence River Board has the authority to deviate only slightly from Plan 2014, the international agreement that sets outflows at the dam and at Horseshoe Falls dam at Niagara Falls, therefore impacting Lake Ontario and river water levels.

"The minor deviations we're allowed provide only short-term flow changes that cannot alter Lake Ontario levels by more than two centimeters, or 0.8 inches, compared to plan flows," Mr. McCune said.

Mr. McCune stressed that while the lake and river board is considering options and ways to potentially modify Plan 2014 to account for more dramatic weather and water conditions, the outflow plans are not drafted with recreational boating in mind. Lower water levels than currently exist can be tolerated under Plan 2014.

"The Moses-Saunders Dam and forebay was not designed and built to provide a fixed summer water level for recreation," he said. "During the summer months, the forebay is required to maintain a minimum level of 72.6 meters. At the lower end of this range, some forms of recreation, related to access in particular, may be impacted."

He said the current situation, with very low water levels seen in late August in the upper St. Lawrence River, is not unprecedented. Low levels like this year's were seen, some even lower, in 1987, 1998 and 2018.

He said those low-level years have their own benefits, and were accounted for in Plan 2014.

"In the Thousand Islands region, low level years provide better conditions for specific types of desirable wetlands biodiversity to reestablish," Mr. McCune said. "Regulation Plan 2014 was designed to induce more of this natural variability, because it was found that wetland health suffered when water level fluctuations were compressed at times under the previous regulations."

Officials are looking into whether Plan 2014 needs adjustment, with that work being spearheaded by the Great Lakes-St. Lawrence River Adaptive Management Committee, known as GLAM. Chris Warren, U.S. co-chair of that group, said they have already developed a "decision-support tool" to provide better predictions of what outflow changes may be needed, and what their outcomes may be. Those findings and recommendations created during the drafting of that process will be put forward publicly in the spring, with public comment welcomed.

The second part of this project, planned to finish by 2024, is to draft a list of real changes that should be made to Plan 2014.

"Any changes would need to be approved by the IJC, and agreed to by the governments of Canada and the United States," Mr. Warren said.