Regulators plan to continue releasing water from Lake Ontario at a tied-for-record-high rate until the lake levels drops by more than a foot.
The Lake Ontario St. Lawrence River Board, which manages outflows, has kept water flowing through a St. Lawrence River dam at about 2.75 million gallons per second since June 12. That rate is tied with the highest outflow on record, previously set during the summer of 2017 flooding, and is higher than the "maximum safe navigation limit," the board wrote in a Monday post.
The high outflows caused the St. Lawrence Seaway to impose navigation restrictions, including speed controls and prohibitions on passing other vessels in some areas of the river, as it did during the high flows of 2017.
Those navigation disruptions are costing U.S. and Canadian businesses about $2.3 to $3 million per day due to reduced trade, according to the Chamber of Marine Commerce.
But by outpacing the inflows from Lake Erie, which have mostly been at record-highs since mid-May, the high outflows are slowly bringing down Lake Ontario.
The lake has dropped about 2 inches over the past week, after plateauing at a record-high 249.05 feet for nearly all of June. Forecasts now suggest the lake may fall below 247.7 feet by mid-August, at which point regulators would slow outflows. The U.S. Army Corps of Engineers, in its weekly forecast July 5, predicted Lake Ontario will drop 10 inches by Aug. 5.
However, the board will continue to meet weekly to consider the impacts of its high outflows.
Faced with the worst Lake Ontario flooding since record-keeping began, the board considered several strategies to bring relief to beleaguered landowners along the lakeshore and upper St. Lawrence. Under one alternative, the board would have increased outflows to 3.04 million gallons per second — the maximum rate possible for river outflows.
But that approach would have resulted in "stop and go" travel restrictions on ships or possibly closing the Seaway outright. The board estimated trade disruptions would have cost the U.S. and Canadian economies $50 million per day, while the Chamber put the overall cost at $1.1 to $1.75 billion, depending on the duration of the high outflows.
The board acknowledged those higher flows would lower the lake faster in the short-term. However, because the capacity for passing water down the river is directly related to the lake level, the board concluded the lake would be about the same level by year's end under either strategy.
"As the lake declines, so does maximum river capacity," the board wrote. "Maintaining the current major deviation strategy will provide comparable benefit by the end of the calendar year, without creating $1.4 billion in economic damages."
The board also stated its goal is to lower the lake "as much as possible prior to winter," when outflows must be restricted to prevent ice from breaking apart and jamming the river.
Many lakeshore residents and politicians blame the high water, as well as the 2017 flooding, on the IJC and its water management strategy, Plan 2014. Those critics say the plan prevented the board from releasing more water last winter and fall, which could have mitigated this year's flooding.
The plan was designed to raise water levels by about two inches during wet years, to the benefit of coastal wetlands and hydropower producers.
"We actually have leadership in the IJC that has the gall to stand by and do nothing for two years," Wilson Mayor Arthur Lawson said recently. "These are normal everyday people that they are affecting."
The IJC claims it cannot safety lower water levels any further during the autumn and winter. During both this spring and in 2017, the board had to restrict outflows, even as Lake Ontario rose dramatically, in order to mitigate flooding that was already occurring in downriver areas, such as Montreal.
"While the higher outflows will accelerate the rate of lowering that would otherwise occur, it is not possible, this year or any other, to lower Lake Ontario to a predetermined 'safe' water level by the onset of winter," the board wrote.
Water levels are high throughout the Great Lakes. Erie and Superior are at record highs for July, and Michigan-Huron — classified as a single lake because their waters flows both directions through the Straits of Mackinac — is tied with the high water record for this month.
Landowners on other Great Lakes shorelines will have to wait longer for relief. Lake Erie is forecasted to drop just two inches in the next month, while Superior and Michigan-Huron are expected to rise a few inches.