Confined Disposal Facilities (CDFs) are common in major Great Lakes cities to permanently house contaminated sediment. There are three CDFs in Toronto, located at the Leslie Street Spit. While one remains active, two have been decommissioned and restored to wetland habitat, representing a gain of 16.3 hectares (40.3 acres) of coastal wetland on the central Toronto waterfront and contributing toward the delisting of the Toronto and Region Area of Concern. Sediment capping was completed to physically and biologically isolate the contaminants within the CDFs and the surface was contoured to elevations to achieve marsh conditions. Drawing upon habitat designs from the Toronto Waterfront Aquatic Habitat Restoration Strategy, structural habitat features including rocky shoals, aquatic stump fields, and fish cribs, along with native emergent aquatic plants, trees and shrubs were installed to initiate the wetland habitat. Fish and water level control structures were installed to restrict invasive Common Carp into the wetlands, and to manage the wetland water levels independently of Lake Ontario. A major challenge since establishing the wetlands has been invasive plants, particularly Phragmites australis which outcompeted the native emergent aquatic vegetation community that established after construction. Toronto and Region Conservation Authority has successfully managed phragmites in the Cell 1 and Cell 2 wetlands since 2018, using an integrated approach including chemical and mechanical treatment. Through careful timing and management, a 3.33 hectare (8 acre) phragmites monoculture has been drastically reduced, and the native emergent vegetation communities have naturally regenerated. The Cell 1 and Cell 2 wetlands support a variety of wildlife communities including marsh nesting birds, turtles, and fishes, conserving biodiversity on the waterfront.
