We often reference a “100 year flood” or “100 year storm.” What does this mean? Toronto and Region Conservation Authority (TRCA) has a useful glossary of terms that you can access here. TRCA defines the 100 year flood as a flood, based on an analysis of precipitation, snow melt, or a combination thereof, having a return period of 100 years on average, or having a 1% chance of occurring or being exceeded in any given year.
Ontario’s flood protection standards are among the most stringent in the world. The area at risk of flooding in the Port Lands and eastern downtown is in the Regulatory Flood Plain of the Don River. This means that during a Regulatory Storm, the area would take on floodwaters from the Don River. The Province of Ontario defines a Regulatory Storm as the 1 in 100 year storm or the most severe storm to ever hit the region (whichever is the larger event). For Toronto, that is 1954’s Hurricane Hazel. A common misconception about flood risk is that because an area hasn’t flooded before it won’t flood in the future. When Hurricane Hazel hit, the most intense rainfall occurred over the Humber River, not the Don. Had it centered around the Don watershed instead, which isn’t that far away from the Humber watershed, we would have seen significant flooding in this area. While the risk of a Hurricane Hazel type storm falling over the Don watershed is small, the consequences of such an event would be severe. Therefore, it’s important that riverine flood protection is implemented here.
Once we complete construction on the Port Lands Flood Protection project in 2024, a new river valley will run through the Port Lands. This natural landscape will become home to diverse plants and wildlife. Land that was once unusable and under the threat of flooding will be ready to transform into complete communities and thriving businesses.
Any development that takes place will be guided by the Port Lands Planning Framework, approved by Toronto City Council in 2017.
Planning initiatives for the Port Lands have been underway for over a decade, and have resulted in not only the Planning Framework, but a number of other key studies and plans that will guide development. Read more about those plans here.
The approach for this project was set through the Don Mouth Naturalization and Port Lands Flood Protection Environmental Assessment (EA). That EA was approved by the Province of Ontario in 2015 – it won’t change. You can find more details here about what we’re building as part of Port Lands Flood Protection. We’ve now started construction on this project and it is scheduled to be complete in 2024.
Waterfront Toronto selected Sidewalk Labs as the wining proponent in a Request for Proposals in 2017 for the Quayside project. As the chosen Innovation and Funding Partner, they have collaborated with us on ideas for a new kind of community on Toronto’s waterfront at Quayside, 12 acres of land situated along Toronto’s waterfront at the intersection of Lake Shore Boulevard East and Parliament Street.
You can find more details about that project here.
The new river valley will create Villiers Island. However, this project doesn’t include the development of new buildings on Villiers Island, or anywhere in the Port Lands. That development can begin once Port Lands Flood Protection is complete in 2024.
The guidelines for buildings, roads and more on Villiers Island are in the Villiers Island Precinct Plan. The Villiers Island Precinct Plan was adopted by Toronto City Council in October 2017, along with the Port Lands Planning Framework, which sets the long-term vision for the Port Lands. As part of the planning process to finalize the Villiers Island Precinct Plan, we collaborated with the City of Toronto to consult the public. Find public presentations and meeting summary reports in our document library.
The design work underway does consider parks, public spaces and roads on Villiers Island to make sure what we build as part of Port Lands Flood Protection works as part of the larger, future system of parks in the Port Lands. It doesn’t deal with any new buildings. Find out more about what we are building as part of Port Lands Flood Protection here.
The naturalized areas already exist in the Port Lands are staying untouched. Spaces like Tommy Thompson Park and Cherry Beach aren’t within this project area – they’re important habitat for wildlife and natural spaces for people to explore. You can see the area of the Port Lands we’re transforming on the project map located here.
Port Lands Flood Protection is about protecting against flooding from the Don River, which is separate from possible effects of high lake levels. When we began detailed design, we based our flood modelling on provincial guidelines to protect the Port Lands and surrounding area from flooding in the event of a Regulatory Storm. The Province of Ontario defines a Regulatory Storm as the 1 in 100 year storm or the most severe storm to ever hit the region (whichever is the larger event). For Toronto, that is 1954’s Hurricane Hazel. Our design creates 100 per cent resiliency during a storm even larger than Hurricane Hazel. Water levels in Lake Ontario typically fluctuate by up to one metre above and below average lake levels. Because of this, we’re designing wetlands that can survive extremes of high or low water levels. The wetlands will be built at different elevations, which means if water levels go up or down, there will always be some areas available for fish, birds and other wildlife to find food and shelter. This keeps the entire system healthy. In the event of prolonged extreme weather or lack of water due to low lake levels, a monitoring plan will be in place so that we can adapt the system. Hydraulic modelling indicates that that the forecasted increases in the 100-year high lake level will not significantly impact the design flood levels from the Don River.
So, if it doesn’t change the flood risk from the Don River, what impact does higher lake levels have? The Port Lands, in their existing condition, would be at risk from rising lake levels just like elsewhere on the waterfront – unrelated to its location in the Don River’s watershed. Our initial designs for infrastructure like dock walls and underground utilities were done to accommodate the original 100-year high lake level condition of 75.7m. However, due to the record high lake levels that were experienced in 2017 and 2019, the 100-year high lake level has been reforecasted twice since the beginning of the project. The first time the 100-year lake level was adjusted, in summer 2019, Waterfront Toronto adjusted our designs to reflect that new high lake condition. After TRCA’s most recent recommendation that these numbers again be increased to 76.2m, Waterfront Toronto is now exploring what changes to the design are necessary or possible, in consultation with our government partners. We are now reviewing any remaining recommendations and will provide updates when we have that information.
It’s important to clarify that higher lake levels would not result in catastrophic lake flooding on the future Villiers Island. As part of PLFP, those areas will be raised well above high lake levels to address the flood risk from the Don River. The main challenge within the Port Lands Flood Protection project area will be localized run-off and ponding from those future urban lands if lake levels are very high.
Construction began on the Cherry Street Lakefilling Project in December 2017. We started digging the new river valley in summer 2018. The Port Lands Flood Protection Project is scheduled for completion in 2024.
Read more about construction here.
290 hectares of land are at risk due to flooding from the Don River, under a Hurricane-Hazel-sized storm event.
This image shows the area of the eastern waterfront that is at risk of flooding:
This project will remove the flood risk to 240 hectares of land. The majority of the remaining 50 hectares of land will be intentionally designed to flood, and they are located within the Keating Channel and the new naturalized river valley system.
Read more about flood risks in Toronto here.
Waterfront Toronto received $1.25 billion in funding from the City of Toronto, Province of Ontario and Government of Canada to design and build the Port Lands Flood Protection Project.
In 2016, we completed a 15-month Due Diligence study that resulted in dozens of critical reports totaling over 10,000 pages. We did this to make sure our plan to flood protect and revitalize the Port Lands could work – and that includes the cost. The amount includes a contingency of 30 per cent and accounts for the projected cost of inflation throughout the project timeline.
Currently, about 290 hectares (715 acres) of southeastern downtown are at risk of flooding from the Don River watershed. This includes parts of the Port Lands, South Riverdale, Leslieville, south of Eastern Avenue and the East Harbour development site. Port Lands Flood Protection is a solution to flood protect these lands and enable the transformation of the underused Port Lands into a place where people can live, work and play, while still preserving some industrial uses.This project involves excavating a new river valley and a creating a naturalized mouth for the Don River in the Port Lands. The project also includes new parks, aquatic habitat and infrastructure such as roads, bridges, utilities and transit infrastructure to support future development. The project includes:
- Resilient, green infrastructure
- A new river valley that has the capacity to handle large volumes of flood water
- The Don Greenway that provides excess capacity to convey flood water through the existing Shipping Channel
- New roads and bridges
- Structures to control water flow and manage sediment and debris
Click here to find out more about what we’re building