Toronto under 'shoreline hazard warning' as Lake Ontario water levels rise

Toronto is under a "shoreline hazard warning" as water levels in Lake Ontario approach those last seen in 2017, when floodwaters inundated the Toronto Islands for months.

Toronto and Region Conservation Authority issued the advisory late Tuesday afternoon, saying the current level is nearly 75.5 metres.

"For reference, the observed water level for the month of April at Toronto in 2017 reached 75.58 [metres]," TRCA said in a release.

The highest Lake Ontario became during the 2017 flood was 75.93 metres, it added.

"Properties along the shoreline and the Toronto Islands which experienced flooding during the 2017 event could begin to experience flood impacts as the water level in Lake Ontario continues to rise," TRCA cautioned.

Residents can also expect to see increased erosion and noticeable changes to beaches in the area.

Flood mitigation measures in place

RehanaRajabali, a senior manager of flood risk management at TRCA, saysthe city is better equipped to deal with flood conditions today thanit was two years ago. A number of mitigation measures have been put into place, including strategically placed berms and sump pumps, and more detailed maps of flood-prone areas were developed.

"We have a much better idea of impact areas,"Rajabalitold CBC Toronto. "At the end of the day, we're still fighting the forces of Mother Nature, but we're much more prepared to do so."

Water levels in Lake Ontario are controlled by three factors. First, there is the water coming into Lake Ontario from Lake Erie via the Niagara River. Lake Erie is also very high for this time of year,Rajabalisaid.

Then there is runoff from watersheds surrounding Lake Ontario. Wet weather throughout springhas swampedriver systerms that flow into the lake, she added.

Lastly, there is outflow from the lake, which is controlled by theInternational Lake Ontario St. Lawrence River Board.

Theshoreline hazard warning will remain in place until May 8, according to TRCA, at which point officials will reassess the situation.Rajabali said that Lake Ontario water levels generally continue to rise until late May or early June.