Mild temperatures and minimal ice cover in the St. Lawrence River made it possible to release record amounts of water from Lake Ontario during January and continuing into February, but inflows to Lake Ontario also set records last month. The continuing trend of extremely high water supplies, which has now lasted over three years, continues to hamper the International Lake Ontario – St. Lawrence River Board’s efforts to help reduce flood risks throughout the Lake Ontario – St. Lawrence River System.
The total amount of water released from Lake Ontario from January 2017 through December 2019 was the highest on record for any 36-month period, however, total inflows were also the highest on record.
The latest record outflows come as the Board continues to deviate from Plan 2014 to maximize outflows and remove as much water from Lake Ontario as conditions will allow, to reduce the risk of high water this spring. An especially mild month in January and limited ice cover in critical areas of the St. Lawrence River provided favorable conditions to allow the release of an exceptional volume of water from Lake Ontario. Overall, the average outflow in January was 325,200 cfs, 26,100 cfs above the previous January record set in 1987.
Despite these unprecedented outflows, Lake Ontario rose during January as record inflows to Lake Ontario averaged 358,100 cfs. The high inflows were largely the result of heavy rainfall that rapidly increased streamflows during and following a significant storm event on January 11 and 12. This storm also caused rapidly rising Lake Erie levels and resulted in record-inflows to Lake Ontario from the Niagara River by the end of January.
The net result is that water levels have begun to rise from their seasonal low, reached in December, and Lake Ontario’s level was 246.49 feet as of February 6 and again near record highs for this time of year. Lake Erie and the upper Great Lakes are all at record highs as well, and this continues to result in an increased risk of high water this spring.
The Board continues to closely monitor conditions and look for every window of opportunity to continue maximizing outflows to the extent possible to reduce the risk of high levels in 2020.
Information on hydrologic conditions, water levels and outflows, including graphics and photos, are available on the Board’s website, https://www.ijc.org/en/loslrb, and posted to the Board’s Facebook page at https://www.facebook.com/InternationalLakeOntarioStLawrenceRiverBoard.
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