Water levels on Lake Ontario have reached the highest point in recorded history, putting the Toronto Islands at risk of significant flooding.

Current levels have reached 76.03 metres above sea level, topping the previous record of 75.93 metres which was set in 2017 when the islands were inundated with water.

Ferry service to Hanlan's Point has been suspended and the area around Gibraltar Point has been closed off as a result. Worse, strong winds are expected on Thursday afternoon, something that could lead to "significant wave action," local Coun. Joe Cressy warned.

"This is a difficult time for local residents, who are also working tirelessly to protect the Islands. We are all grateful for volunteer assistance from visitors and the public," Cressy said in a tweet.

We are committed to doing everything possible to ensure the Islands remain safe & open. We continue to work closely with senior city & TRCA staff, & the Island community. However, as I have said before, as the climate crisis accelerates, annual sandbagging cannot be the solution. —@joe_cressy

City officials say the winds and rising lake levels could lead to further breaches of the Islands' shoreline, which has been heavily sandbagged in anticipation of flooding.

Cressy said city workers pumped between 20 and 30 centimetres of water from Algonquin Island after lake water breached the area on Wednesday.

Crews are now working "around the clock" to protect the Islands, he added.

The operation includes 30 pumps, 24,000 sandbags and 30 large meter bags in especially vulnerable areas.

The city has been spending $100,000 per week since April in a bid to mitigate flooding, which devastated the Islands in 2017.