Regulators reduced outflows from Lake Ontario by 3 percent at midnight Wednesday, after keeping outflows at record highs for 69 days.
The International Lake Ontario-St. Lawrence River Board set outflows from a dam in Massena at 2.75 million gallons per second June 13 to relieve shoreline flooding amid the highest water levels on record. The board indicated it would continue those high outflows, which has caused travel restrictions on the trade-crucial St. Lawrence Seaway, until water levels dropped below 247.7 feet.
The board reported Aug. 20 water levels had fallen just below 247.7 feet for the first time since May 3, and responded by lowering outflows to about 2.67 million gallons per second. The board also forecasts water levels falling to 245.4 feet by Dec. 31, 2019, nearly mirroring the levels reported at the end of 2017 and 2018. However, wetter conditions could keep the level as high as 247 feet; drier conditions could cause a drop to about 244.4 feet.
A board spokesperson said as the water level drops, currents in the St. Lawrence River speed up, because there is less space for the released water to move in.
"Imagine the channel as a trough and as the water level lowers, the depth of water in the trough decreases. For the same flow to go through that trough, the water has to move faster," the board wrote in a statement.
The faster currents are causing unsafe cross-currents, high erosion, and impacting boating, swimming and navigation, according to the board.
The U.S. Chamber of Marine Commerce said previously the high outflows were costing U.S. and Canadian businesses $2.3 to $3 million per day in reduced trade. However, other strategies the board considered to lower the lake could have cost the two economies as much as $1.75 billion.
Meanwhile, the board forecasts the lake is likely to drop by about a foot over the next month.