The International Lake Ontario-St. Lawrence River Board has increased outflows through the Moses-Saunders Dam following the recent decrease of water levels from Lake Ontario over the long weekend.
Lake Ontario outflows have been increased this Saturday by 200 m3/s, or 7,100 cf/s, above the amount set by the Plan 2014, and will continue for about eight weeks into mid-December to return water levels in Lake Ontario to the level they would have been if outflow deviations were not required this year, stated the Board.
"In accordance with the directive, the board must obtain IJC approval for strategies to return to plan flows through what is known as equivalent offsetting deviations, or payback," said David Harper, Canadian co-chair of the International Lake Ontario-St. Lawrence River Board, in a prepared statement.
The board received approval from the International Joint Commission (IJC) for the offsetting deviation strategy on Oct. 12.
According to the Board, drought-like conditions this past spring caused water levels on Lake Ontario to decrease below the so-called Criterion H14 major deviation threshold.
As required by the IJC directive, the regulation plan has to be followed unless water levels reach any of the defined triggers specified by that directive. So the International Lake Ontario-St. Lawrence River Board decreased outflows from May 29 through July 16 of this year, until the water levels on Lake Ontario increased above the major deviation threshold.
The board had previously decreased outflows on Lake St. Lawrence recently to assist with boat haul-out during the Thanksgiving weekend, which was under the minor deviation authority defined by the IJC's directive. During the summer it maintained an extra 4 cm of water on Lake Ontario relative to Plan 2014, board officials stated.
According to the board, the fall and summer deviations resulted in a combined total deviation of 4.8 cm, but the increased outflows for mid-October through mid-December will remove the 4.8 cm of water that was maintained on Lake Ontario.
"Lake Ontario remains a natural system and is not a reservoir," said Steve Durrett, co-chairman of the Board.
The board continues to maintain a record of all deviations and the amount of water that is temporarily maintained or removed from Lake Ontario.
That record allows the board to return to the water levels that would have occurred under Plan 2014 after outflows have been influenced as required by the LJC directive.
Jessica Munro is a Local Journalism Initiative reporter who works out of the Brockville Recorder and Times. The Local Journalism Initiative is funded by the Government of Canada.
Jessica Munro, Local Journalism Initiative Reporter, Brockville Recorder and Times