Flood Watch Issued for Lake Ontario & the Upper St. Lawrence River

Published on: 2020/04/14 - in Releases

RELEASE — Cataraqui Conservation has issued a Flood Watch for Lake Ontario and the upper St. Lawrence River due to the elevated water levels.

Higher than normal water levels persist, and further increases are expected. The current level on Lake Ontario is about 75.3 metres above sea level (masl), nearly 0.5 metres above average for this time of year, about 0.35 m below the record high for this time of year set in 1973, and about 0.3 m above typical summer peak. Heightened risks may start to develop as levels rise above 75.3 m, including potential shoreline flooding, beach submersion, crawl space and septic system inundation, and wave-driven erosion. The current water level on the upper St. Lawrence River, which is greatly influenced by the level of Lake Ontario, is about 75.0 m, measured at Brockville.

The International Lake Ontario – St. Lawrence River Board (ILOSLRB), which manages Lake Ontario outflows at the Moses-Saunders Dam in Cornwall and develops water level forecasts, is forecasting (as of April 9) that under seasonally normal weather and water supply conditions peak water levels of around 75.56 m on Lake Ontario would be expected in the week ending May 15. There remains considerable uncertainty, higher peak levels are possible if wet conditions occur. Publicly available water level forecasts are updated weekly by ILOSLRB (links provided further down this statement).

As water levels increase so does the possibility and likelihood of impacts, especially during periods of active weather. In 2017 and 2019 when levels rose above 75.8 m on Lake Ontario and 75.5 m on the upper St. Lawrence, significant dock submersions and some localized impacts to dwellings and roads occurred. Some of these impacts on Lake Ontario started to occur at levels between 75.55 m and 75.7 m

For reference, the lake-wide peak water levels reported in 2017 and 2019 were 75.88 m and 75.92 m, respectively. Daily average peaks measured at Kingston were 75.84 m and 75.91 m. And the upper St. Lawrence River saw daily average peaks of 75.57 m and 75.63 m, measured at Brockville.

Widespread flooding is NOT expected at this time. This Flood Watch provides advance warning to municipalities and residents in flood prone and low-lying areas to the potential for localized flooding and erosion impacts.

Residents in flood prone and low-lying areas should continue to pay attention to wind and wave forecasts for approaching storms with high winds from the southeast, south and southwest, such as the one forecasted for April 13 & 14, as these are the conditions when the probability of localized impacts (e.g. flooding & erosion) is increased.

If you witness flooding and require assistance, your first point of contact is the local municipality. Cataraqui Conservation does not provide sandbags. However, information about where to purchase sandbags is provided at crca.ca/flood. Residents are reminded that it is the property owner’s responsibility to properly dispose of sandbags and sand, which is considered hazardous waste, and any other debris that may have been deposited along the shoreline.

Any work along shorelines (e.g. placement of fill, armour stone, etc.) will require a permit from Cataraqui Conservation. Call our office or visit our website www.crca.ca for further information.

Cataraqui Conservation appreciates feedback from the public and municipal staff detailing flooding and erosion impacts. Please report observations on the online form at crca.ca/flood.

For further information on water levels, wind and wave forecasts, and Provincial flood messages visit crca.ca/flood.

For information directly from the International Lake Ontario – St. Lawrence River Board visit:

* Main website – ijc.org/en/loslrb

* 2017 and 2019 High Water Events page || Current conditions || Water level forecasts

Staff will continue to monitor International Lake Ontario St. Lawrence River Board water level forecasts, Surface Water Monitoring Centre Provincial Statements, and local water levels, and update Cataraqui Conservation messaging as needed. This Flood Watch will remain in effect until (or updated before) 11:59 PM July 30, 2020.

Release – Issued April 12: CRCA
Photo (Lake Ontario): Ad Meskens (cc)