Toronto Waterfront Aquatic Habitat Restoration Strategy

Scroll to learn how the habitat along Toronto's shoreline has been restored over the last 18 years!

In 2003, the  Toronto Waterfront Aquatic Habitat Restoration Strategy (TWAHRS)  was developed to guide restoration efforts along the Toronto waterfront. TWAHRS provides agencies practical aquatic habitat restoration guidance with illustrated drawings of restoration techniques. It also sets out a strong framework for inter-agency cooperation prior to the start of a waterfront development project. Since its implementation, TWAHRS has guided 44 waterfront aquatic habitat restoration projects, and restored approximately 55 hectares of aquatic habitat!

In 2019, TWAHRS was reviewed to evaluate the impact of aquatic habitat restoration efforts on fish communities. Habitat was evaluated using pre an post restoration fish community data collected from 28 waterfront project sites. The dataset represents over 30 years of fish community information collected by Toronto and Region Conservation Authority's (TRCA) monitoring team. This StoryMap highlights some of the main TWAHRS techniques used as well as key findings from the 2019 assessment report.

Main TWAHRS Techniques Used

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Anchored Logs

Anchored logs provide structural elements that improve nearshore habitat, submergent vegetation, and provide foraging areas for aquatic species. Exposed limbs may also provide habitat for roosting birds. This treatment type is most commonly used in sheltered embayments.

Emergent Vegetation Sections

Emergent vegetation increases the primary production of an area by providing forage for terrestrial and aquatic species. It is most frequently used in sheltered embayments and coastal wetlands.

Estuary Hooks

Estuary hooks are constructed by placing stones in a hook pattern adjacent to a high bank or an estuary wall. These hooks deflect and concentrate flows, and direct bedload sediments. This results in highly productive areas like eddy pools that encourage the growth of emergent vegetation.

Surcharged Groynes

Deployed along the open coast, surcharged groynes are used to create cells along the shoreline by trapping sediment and dissipating wave energy, thus mitigating shoreline erosion and attracting cold and coolwater fish species.  

Inner Harbour Quay Treatment

Existing conditions along the inner harbour dock walls and quays are often void of structural habitat elements or aquatic vegetation. Restoration of harbour quays involves the strategic deployment of several structural habitat features including log cribs, anchored logs, floating docks and boardwalks, and rock gravel shoals and reefs. These features increase the extent of submergent vegetation and improve forage for aquatic and terrestrial species. 

Log Tangles

Log tangles are deployed to improve structural habitat and attract cool and coldwater fish species. Logs are anchored by piling rocks on top of root wads or driving logs into soft sediments. This technique is typically used in sheltered embayments and coastal wetlands,

Offshore Boulder Pavement Repair

Deployed in open coast habitats, boulder pavement repair is a technique use to fill depleted offshore areas with boulders and cobble stones. These materials are placed on the lakebed and brought to grade with the surrounding substrate. Typically, material greater than 8” in diameter will stay within the location, especially if material is placed in areas greater than 2 m in depth. The coarse material will trap and hold smaller material on site including small cobble, gravel, and sand.

Reptile and Amphibian Habitat

The addition of structural habitat elements can help attract reptiles and amphibians to sheltered embayments and coastal wetlands. Habitat elements may include basking logs and rocks, extensive emergent vegetation, south facing sandy slopes for turtle nesting and basking, and a riparian buffer. 

Aquatic Vegetation

Targets of this treatment include improving both emergent and submergent vegetation, increasing high quality riparian vegetation, and improving forage for aquatic and terrestrial species. This technique is typically used in sheltered embayments.

Carp Barrier

Carp exclusion barriers are installed at wetland access points to prevent adult spawning carp from entering the wetland and destroying vegetation.

Four Aquatic Habitat Types

Four main types of aquatic habitat exist along the Toronto waterfront: Coastal Wetlands, Sheltered Embayments, Open Coast, and Estuaries.

Each type of habitat supports different fish communities. These communities were monitored at TWAHRS sites in order to evaluate pre and post restoration activity.

Scroll through the following sections for case studies from each of the four habitat types.

Coastal Wetland: Tommy Thompson Park Cell 1

Cell 1 is one of three complex coastal wetland restoration sites at Tommy Thompson Park. From 1979 to 1985 the site was a confined disposal facility (CDF) which is an area specifically designed for the containment of contaminated dredged material. Habitat restoration efforts in Cell 1 began in 2004.

Years restored: 2004 to 2007

Project Area: 114,820 m²

TWAHRS Techniques Used: Creation of a wetland berm, carp exclusion barrier, shoreline shoal, log tangles, anchored logs, shoreline vegetation zones, lowland riparian woods, and reptile habitat.

Results:

Sheltered Embayments

Extensive embayment restoration has taken place across Toronto's waterfront. Some of these embayments are naturalized like Tommy Thompson Park's Embayment C, while others are more urban like the Spadina Slip.

Urban Embayments: Toronto Inner Harbour

Sheltered Embayments: Tommy Thompson Park Embayment C

The landform of Embayment C was completed in 1974 and both terrestrial and riparian vegetation was allowed to grow naturally. The pre-restoration shoreline was characterized by silt and sand substrate, was relatively homogeneous in formation, and was bordered by a successional forest of shrubbery and young trees. In 1996-1997, pike spawning channels as well as sand ‘footpads’ were added to increase nearshore habitat diversity. 

Years Restored: 2008 to 2011

Project Area: 15,700 m²

TWAHRS Techniques Used: Log tangles, log piles, anchored logs, shoreline shoal, wetland berms, carp exclusion barrier, shoreline vegetation zones, complex shoreline profile improvements, wetland shoreline profile, and lowland riparian woods.

Results:

Live stakes, nearshore boulder shoal, and anchored log fringe for the created wetland berm in Embayment C

Sheltered Embayments: Spadina Slip. West of Spadina Slip is a created wetland. When water levels are high, fish can pass between the Spadina Slip and the south end of the wetland. In addition to wetland creation, Waterfront Toronto installed fish habitat features such as anchored logs and stones as well as a Wavedeck for fish cover.

Years Restored: 2008

Project Area: 2245 m²

TWAHRS Techniques Used: Shoreline shoal, aquatic vegetation, anchored logs, and inner harbour quay treatments.

Results:

Spadina Wavedeck

Open Coast: Port Union Armourstone West, Phase 1

Restoration along Port Union Road addressed waterfront erosion and introduced some diversity to the nearshore environment.

Years Restored: 2001 to 2006

Project Area: 71,902 m²

TWAHRS Techniques Used: Surcharged groynes.

Results:

Estuaries: Humber River Estuary

The Humber River Estuary Restoration project involved the installation of high estuary hooks to improve the linear shoreline which was constructed of informally placed rubble intended for shoreline protection.

Years Restored: 2007 to 2008

Project Area: 978 m²

TWAHRS Techniques Used: High estuary hooks

Results:

Additional reading:

If you are interested in learning more about TWAHRS and its application please visit the following sites...

Urban Embayments: Toronto Inner Harbour

Live stakes, nearshore boulder shoal, and anchored log fringe for the created wetland berm in Embayment C

Spadina Wavedeck