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

Rehana Rajabali, a senior manager of flood risk management at TRCA, says the city is better equipped to deal with flood conditions today than it 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," Rajabali told 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."

Status of the Toronto Island: while the lake is at 2017 levels, a number of steps were taken after that flood to prevent a recurrence. Pumps in berms and pits suck water in, then pump it out as it crests. This is on Ward's Island to protect homes and businesses 1/2 —@bradrossTO

Ferry docks were rebuilt, as well, in 2017, allowing ferry service to continue to operate safely. The island is open and staff anticipate that won't change. High winds today mean high waves, so shorelines across the city will see erosion - please be careful if near the lake... —@bradrossTO

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, Rajabali said.

Then there is runoff from watersheds surrounding Lake Ontario. Wet weather throughout spring has swamped river systerms that flow into the lake, she added.

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

The shoreline 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.