The Toronto and Region Conservation Authority (TRCA) reissued a Lake Ontario shoreline hazard warning on Friday, with water levels exceeding those seen during the 2017 floods.
The warnings have been in effect for about six to eight weeks and as per the TRCA’s website, they are issued when “critical high water levels are imminent and/or occurring” which could lead to flooding and erosion along the shores.
The threshold for the warning is when the lake reaches 75.5 metres above sea level. The average static water level for Lake Ontario for just the month of June so far is 75.93 metres — matching the highest levels in 2017. Approximately a week ago, lake levels surpassed that peak by a few centimetres for a short time before returning to 2017 levels.
However, closer to Toronto’s inner harbour specifically, the levels can be higher than elsewhere along the shore.
“The inner harbour — because it has the mainland and the Toronto Islands so close — we see that the water level is very high but it’s also acting quite like a bath tub. The waves are sloshing from both sides so you could actually see a 20 centimetre difference [compared to the static water level],” says TRCA spokeswoman Nancy Gaffney.
Water levels at Queens Quay’s HTO Park are high enough for the waves to breach the artificial beach and water is taking over several feet of the urban park.
In addition, the agency warns that with the lake moving further inland, beaches have been shortened, trails and boardwalks along the lake in various parts of the city are closed, land and infrastructure erosion as well as localized ponding and flooding is currently occurring.
City of Toronto spokesman Brad Ross says the flooding seen in the city recently is the result of high water levels and heavy rainfall combined with the location of some of the city’s storm drains.
“This is a perennial problem in some areas when the lake levels are as high as they are,” says City of Toronto spokesman Brad Ross. “There are areas of the city where the drainage systems are lower than the current lake levels. Those drainage systems get plugged, so water doesn’t flow into them.”
To mitigate the flooding in such areas, the city has pumps to remove the water as quickly as possible but Ross says that overall, the city’s current storm water drainage system is adequate.
“The old storm water systems do get overwhelmed from time to time but [they] are able to manage despite the lake levels — it’s just in some of those low lying areas,” he says.
Water levels are already receding according to the International Lake Ontario – St. Lawrence River Board and will continue to slowly decline in the coming weeks, depending on rainfall.
Gaffney says it will take several weeks — at least until the end of July — for the water to reach less critical levels. It will likely take the entire summer for the flooding event to end and for the water to go back to normal seasonal levels.
Even as the water begins to recede, highs winds can cause “significant wave action and lake surge.” Waterfront properties are being encouraged to take additional protective measures as the water could breach any berms and sandbags put in place for the flooding.
The TRCA is also stressing public safety and asking people to stay away from areas that are currently flooding and obey all closure notices along trails and shorelines. Parents and caregivers are also cautioned to keep a close watch on children — with boardwalks and pathways currently under water, the areas can become treacherous when combined with wind and wave action.
The agency also has an ongoing note of caution in effect for the Scarborough Bluffs because of the potential for landslides.
The latest shoreline hazard warning will stay in effect as long as static water levels remain about 75.5 metres above sea level.