Areas of Toronto Islands are vulnerable to flooding because of high winds predicted on Thursday but 15,000 sandbags and 30 sump pumps are in place as city crews try to manage rising Lake Ontario water levels, officials say.

Coun. Joe Cressy, who represents Spadina-Fort York, said residents have been working "nonstop" and crews have been doing day and night shifts to protect the Toronto Islands. The city is making an additional 9,000 sandbags available to residents.

"This is a distressing time for Island residents and Island businesses. There is no sugar coating it," Cressy told reporters on Wednesday. "But unlike 2017, where we were forced to close down the Islands, we are going to make sure that they stay open and safe."

The city says it has been spending $100,000 a week since the end of April on measures to control flooding on the Toronto Islands. The amount includes staffing and rental of pumps.

Water levels, expected to rise over the next seven to 10 days until they peak, are extremely close to 2017 levels, when historic highs were reached. Current water levels are 75.9 metres above sea level, compared to the peak of 75.93 metres reached in 2017.

A major windstorm is in the forecast for Thursday evening that could bring northerly and northwesterly winds of 25 kilometres per hour and wind gusts of 45 kilometres per hour. The winds could have a "serious impact," Cressy added.

The city says it has been spending $100,000 a week since the end of April on measures to control flooding. The amount includes staffing and rental of pumps. (Paul Smith/CBC)

James Dann, manager of waterfront parks for the city of Toronto, said the storm could be "problematic" in particular for Algonquin Island, a small island near Ward's Island. More metre bags are being put out on Wednesday, he said.

Storm to bring 'large waves and wind action'

Officials are particularly concerned about homes on Seneca Avenue on Algonquin Island. The storm could bring "large waves and wind action," he said.

Water has breached a road on Hanlan's Island and the area is closed. Dann described the situation as a "serious issue" and it has limited ferry traffic. All ferry traffic for vehicles goes through Ward's Island instead of Hanlan's Island, he said.

"Basically we have to wait for the lake to go down in one of these sections," he said.

But sandbags has been available for more than a month and they are making a difference to other areas, he added.

Coun. Joe Cressy says high winds forecast for Thursday could cause further flooding. (Paul Smith/CBC)

"The Island is open. It is a real testament to the work that we have been able to put in. Centre Island is predominantly dry, which is a real bonus for us. Centreville is open. The restaurants have been able to stay open," he said.

"Our major concern for the next 48 hours will be the residents, then we will focus back onto the roads to make sure we are able to stay open and operational for the remainder of 2019."

Dann said the area where reporters were listening to the news conference was underwater two years ago and the Toronto Islands themselves were closed. "We are standing on dry ground as we speak," he said.

He said the island itself has "weakened" and low-lying areas on the main road are vulnerable.

Rehana Rajabali, senior manager of flood risk management for the Toronto and Region Conservation Authority (TRCA), said the high winds predicted on Thursday could lead to erosion along the waterfront.

'We learned a lot from last time,' resident says

Peter Freeman, a resident, told reporters that people who live on the islands have a firsthand view of the effects of flooding. The shoreline adjacent to the main road, used by visitors to the islands as they come off the ferry, is weaker than it was two years ago.

Peter Freeman, a resident, says: 'We learned a lot last time. But we need to do a lot more now. We need take advantage of every source of information.' (CBC)

"We learned a lot from last time. But we need to do a lot more now. We need take advantage of every source of information," he said.

'We're building up our barriers,' another says

Tony Fairbrother, co-chair of the Toronto Island Community Association, said the community has come together to fend off flooding and hundreds of people have volunteered their time to help.

"We're doing fine. We're a resilient community. We're building up our barriers. We're buying our own pumps to supplement those from the city. Yes, there are frustrations, but we are all learning together how best to manage this. We definitely need a long term solution." Fairbrother said.

"We are feeling confident that we will get through this."

Cressy said the city is expecting a report in June from the TRCA on long-term mitigation measures. An estimated 675 people in about 262 homes live on Toronto Islands.