Flood Protection
On October 15-16th 1954, Hurricane Hazel dumped 210 millimetres of rain in the Toronto region within 12 hours. Flooding was inevitable: steep slopes along rivers and soil saturated by previous rainfall funneled 90 per cent of the rain directly into rivers and streams. Flows in the Humber River were four times greater than previously recorded.
Hurricane Hazel caused the most severe flood in the Toronto area in recorded history. Eighty-one people died and thousands of people were left homeless. Most of the bridges on the west side of Toronto were destroyed or badly damaged, as were many on the Don River. Many roads, parks, public utilities - even an entire street of houses - were washed out. The damages were astronomical, reaching an estimated $25 million in 1954 ($169.5 million in 2000 dollars).
Three Stages of Flood Control
Hurricane Hazel jump-started the TRCA's flood control program. In 1959, the Plan for Flood Control and Water Conservation was finalized. The plan identified a need for 15 large control dams, as well as 4 major flood control channels, and initiated an erosion control program. In addition, 7,200 acres were identified for acquisition at a cost of $11.6 million. In 1960, the Lands Acquisition Program was implemented as the first stage in the flood control plan. The intent of this program was to transfer the liability of floodplain land from private hands to the Authorities and to acquire lands necessary for the construction of flood protection works.
The second stage was the flood control works. This program was designed to construct as many structures as necessary to control flooding. The works consisted of dams, reservoirs, channel improvements, and other infrastructure. These works, which cost an estimated $22.5 million in the 1959 plan, were designed to control damage in flood-prone areas.
In addition to the TRCA initiatives, an 11-year process to develop and implement a floodplain planning policy was initiated provincially. Within this process, the province began developing floodplain regulations and updating the Conservation Authorities Act to allow for fill regulations. In essence, flood plain regulations were implemented to restrict future development and land use in flood hazard areas, thereby reducing potential flood damage. The implementation of new regulations was the third stage in the flood control plan.
Other Flood Control Programs
Two other major programs were implemented to enhance the flood control plan. These included the flood forecasting and warning program and the stormwater management program. The flood warning and forecasting program was designed to monitor watershed conditions including snow, precipitation and flows, as well as to issue flood messages to municipalities when conditions warranted. The program also dictated the operation of flood control facilities. Gauging stations became operational and a rainfall observer network organized. These were designed to forecast and warn against potential flooding in the area. Operational practices were designed to deal with immediate conditions. With forecasting, warning and operational facilities steps could then be taken to minimize potential flood damage.
The stormwater management program was initiated in 1980, in recognition of the impact urbanization has on flooding and erosion. The program has since evolved to include water quality and temperature impacts, source control, and retrofitting facilities that do not meet current design standards.
What We've Accomplished
Three of the original 15 dams identified in the Plan for Flood Control and Water Conservation were constructed, including Clairville dam in 1964, Milne dam and G. Ross Lord dam in 1973, plus two not previously identified, at Stouffville and in Black Creek at Sheppard. In addition, 12 major flood control channels and two major flood dykes have been implemented. In total, more than 280 erosion control works have been completed.
The TRCA has purchased 32,000 acres through the land acquisition program for flood control purposes. Much of this land in Toronto has been turned over to the parks department and provides an integrated parks system. The greenspace along each watercourse not only provides recreation opportunities, but also an area for wildlife to flourish. The lands have become a wildlife corridor for both permanent and migratory species. What began as a flood control project has helped turned Toronto into a green and beautiful city.
Minimizing the Risks of Flooding
The Humber River courses through Raymore Drive following Hazel.
Raymore Drive as it looks today;
the majority of the area has been converted to parkland, now known as Raymore Park.
Tragic events like the recent and far reaching Asian Tsunami or Toronto's Hurricane Hazel of 1954 can no doubt drive our level of preparedness for natural vulnerabilities. The lessons learned are important to take into consideration when framing future policies. For example, rainfall data from Hazel combined with current land use patterns have been continuously used to define flood risk in the Toronto region.
The recent references made to Hurricane Hazel reiterate the province's commitment to defining and minimizing the risks of future flooding. However, the reduction or elimination of flood risk has been a core objective for conservation authorities, acting in cooperation with our municipalities and the province, prior to and following Hurricane Hazel. The construction of the Brampton Flood Control channel in 1952 is a prime example of dealing with existing flood risks. However, the focus shifted from specific flood responses such as the Brampton flood works to a more holistic approach for dealing with these risks in Ontario following Hazel.
The new holistic approach involved both structural and non-structural considerations. Structural approaches included the development of dams, channels, dykes, and any other forms of protection to control or reduce peak flood flows. Non-structural approaches included activities such as acquisition of flood prone lands, the development of natural hazard policies, the introduction of flood forecasting and warning systems, and the development of networks of flow monitoring sites.
All of these tools have been, and continue to be, utilized by the province, conservation authorities and municipalities to reduce or eliminate existing flood risks and to prevent new vulnerabilities from emerging through development within floodplains. Ontario's natural hazards policies are integrated into municipal planning and zoning and continue to be among the most effective methods of ensuring that new development takes place with as little risk as possible.
In order to address the impacts of a changing hydrologic response from our watersheds as a result of land use changes, conservation authorities such as Toronto and Region Conservation (TRCA) strive to manage our floodplains using the most current information available. New hydrologic models and mapping are developed as the need arises to address these issues with the support of our municipal partners. Research on integrating the effects of climate change into these activities is also underway.
In terms of structural works, the Lower Don River West flood protection activities reflect some of our current initiatives with our partners to try and deal with existing flood risks. With support and funding provided by the three levels of government through the Toronto Waterfront Revitalization Corporation, we are now fast approaching completion of the Class Environmental Assessment for the Lower Don River West Remedial Flood Protection Project. Once the Class EA is fully implemented, we will realize the long identified need to remove the risk of flooding to an area of downtown Toronto that extends westward from the Don River to Toronto Metro Hall, and from King Street in the north to Toronto's central waterfront.
TRCA has just initiated a second environmental assessment that is also supported by the Waterfront Corporation. The EA will identify the best means available to naturalize the area surrounding the Keating Channel at the mouth of the Don River, removing the risk of flooding to the east and south of the Don River in the Port Lands area, while also improving habitat for water fowl, spawning fish and other natural wildlife. This project will also provide significant enhancements for recreation and cultural pursuits along Toronto's Central Waterfront. We continue to include the reduction or elimination of flood risk as a core objective in every activity we undertake. Whether managed through the permit review and planning commenting process, the watershed planning process, or daily flood forecasting and warnings, TRCA will continue to proactively manage our natural vulnerabilities.
