Lake Ontario flooding risk diminishes

Niagara Gazette, Niagara Falls, N.Y.
·2 min read

Mar. 2—The risk of flooding on Lake Ontario and the upper St. Lawrence River is currently considered low, dropping from a moderate risk, as reported in December.

The risk analysis, provided by the International Lake Ontario-St.Lawrence River Board, indicated a 28% chance of water levels exceeding a threshold at which damages occur in many shoreline communities in December. The risk is now down to 8%. There is a comparable risk of flooding on Lake St. Louis in the lower St. Lawrence River.

This risk reduction is largely the result of dry conditions throughout the Great Lakes Basin in January and February. Lake Ontario water levels declined 3 inches in January and 2.7 inches in February. Lake Ontario's level is currently 4.3 inches below the long-term average level for this time of year. The lake level is almost 2 feet lower than at this time a year ago and the lowest it has been at this time of year since 2015.

Board officials say they will continue to closely monitor the persistently high levels and flows from Lake Erie, which flows directly into Lake Ontario. In response, Plan 2014 continues to call for very high outflows from Lake Ontario. However, it is also noted that the Lake Erie level has also declined and is now more than a foot lower than it was at this time last year, which means inflows from Lake Erie have begun to moderate.

Given these factors, the board has decided to cease deviating from Plan 2014 effective and revert to the high outflows prescribed by Plan 2014.

Due to the uncertainty of seasonal conditions and the potential for conditions to rapidly change, officials intend to meet regularly through the spring. The board retains authority granted by the IJC to deviate from the plan flows through the seasonal crest of Lake Ontario this year.

The risk of high water on Lake Ontario in 2021 remains a low possibility and is much lower than the risk was at this time last year. However, board officials continue to emphasize that, if basin weather conditions should become extremely wet, similar to those observed in 2017 and 2019, no deviation strategy will prevent water levels that can cause flooding and damage to shoreline properties. Eliminating such damages is beyond the reach of outflow regulation and are more reliably addressed through coastal resilience and planning.

Further information is available at www.ijc.org/en/loslrb.