Luther Marsh's history is that it was a poorly drained portion of Ontario with soils conducive to the formation of wetlands, so very high-organic soils. In the 1950s, they recognized that it would be important to have a large water storage feature at that site, partially for flood control but mostly water supply. The water from our reservoirs is used to dilute the effluent from the sewage treatment plants for roughly a million people, so storage of water is very important to us. This wetland, essentially, was a wet area and now it's a standing marsh, and it actually is almost self-sustaining. It's a relatively easy site to restore. Put water there, and if the underlying soils are correct a wetland will emerge.
On April 30th, 2013. See this statement in context.