Project rationale
Why are the Lake Manitoba and Lake St. Martin channels needed?
- Recent flooding has highlighted the need to better regulate water levels on both lakes.
- The Assiniboine River and Lake Manitoba Basins Flood Mitigation Study (2016) recommended that the Lake Manitoba outlet channel be constructed to accommodate flows of 7,500 cfs; and the Lake St. Martin Emergency Outlet Channel be made permanent and enhanced to accommodate flows up to 11,500 cfs.
- The need for these permanent outlet channels was also identified in the recommendations from the 2011 Flood Review Task Force (ZIP, 62 MB), and Lake Manitoba and Lake St. Martin Regulation Review Committee (2013).
Due to its geographic location and topography, many areas of Manitoba are susceptible to flooding. Water moves from the Rocky Mountains, northern United States and the boreal forest through Manitoba on the way to Hudson Bay. Manitoba’s landscape was largely shaped by glacial processes and as a result, large portions of the province are relatively flat and subject to flooding during high run-off events. While much of Manitoba is vulnerable, Manitobans are generally well protected due to investments in flood protection infrastructure from previous generations.
The Fairford River Water Control Structure is used to maintain suitable levels on Lake Manitoba upstream of the dam and on the Fairford River, Lake St. Martin and Dauphin River downstream of the dam. Until 2011, the control structure was effective in managing the Lake Manitoba levels within the desirable range.
The outlet channels are being designed to provide enhanced flood protection to communities (Indigenous and non-Indigenous), agricultural producers and recreational users along Lake Manitoba, Lake St. Martin, and the Dauphin River, without appreciably affecting water levels on Lake Winnipeg.
Multiple components are intended to work together:
- The Lake Manitoba outlet channel will work in tandem with the existing Fairford River Water Control Structure to help regulate water levels and mitigate flooding on Lake Manitoba.
- The Lake St. Martin outlet channel will restore a more natural water regime to Lake St. Martin and will also provide flood protection by mitigating increased inflows from operation of the Fairford River Water Control Structure, as well as additional inflows from the planned outlet from Lake Manitoba.
- In addition to providing flood protection around Lake Manitoba and Lake St. Martin the two proposed channels will allow greater flexibility in operating the provincial water control system including the Shellmouth Dam and Reservoir, the Red River Floodway and the Portage Diversion.
The Lake Manitoba and Lake St. Martin outlet channels are proposed to be operated under the following guidelines:
