Streams and Valley Lands

WHY RESTORE STREAMS?

Historical and current land use changes continue to have significant impacts on natural features. Streams in the Toronto region have become impaired as a result of various landscape alterations. These alterations may contribute to a variety of impacts to natural system function, which may reduce the ecological services that streams provide.

Stream restoration accomplishes benefits such as:

  • Improved hydrology and water quality
  • Stabilized stream banks
  • Improved passage/migration for fish, including species at risk such as redside dace and Atlantic salmon
  • Enhanced natural corridors that aid wildlife movement
  • Increased riparian and floodplain habitat availability
  • Improved in-stream habitat to benefit aquatic insects and fish populations
  • Provision of food and water sources for wildlife populations
  • Improved passive and active recreation

To mitigate impairments to streams and the ecological services they provide, TRCA restores streams through natural channel design, bank stabilization, planting of the riparian zone and barrier removal or mitigation throughout our watersheds.

Ultimately, the streams in TRCA’s watersheds run into Lake Ontario. Restoration in the headwaters and lower reaches can have a direct influence on the water quality and habitat along the waterfront as well.

On average, TRCA restores more than 7 km of riparian area per year, and 2 km of stream per year. The examples below describe just a few of the various stream restoration projects TRCA has completed in the jurisdiction.

 


Alfred Kuehne Natural Channel Design Stream Restoration

The Alfred Kuehne Stream Restoration Project is located in the Etobicoke Creek watershed in the City of Brampton. A straightened concrete channel was replaced with natural meanders and habitat features such as riffles, pools and runs. Riparian vegetation was planted along the creek and the floodplain was reconnected to provide flood relief to downstream areas and create wetland habitat.

Before during and after images of Alfred Kuehne stream restoration

 


Agricultural Crossing Replacement in Rouge Watershed

Agricultural crossing replacement in a headwater stream: before and after. The original culverts were not embedded in the stream, limiting fish passage, and were undersized for the flow. The larger replacement culvert improves flow and fish passage and accommodates larger farm vehicles.

Despite their small size, headwater streams comprise the majority of stream length in most watersheds. Best management practices and restoration of these areas have a significant positive impact on overall stream health.

agricultural culvert in the Rouge Watershed before restoration
Before
agricultural culvert in the Rouge Watershed after restoration
After

 


Annie Crescent Stream Bank Restoration Project

The Annie Crescent Stream Bank Restoration Project is located in the Duffins Creek watershed in the Town of Ajax. This project was implemented to restore the degraded riparian zone of the stream, minimize erosion and sedimentation, and improve creek shading. In addition, this project relocated a trail that was too close to the stream bank.

Annie Crescent stream bank before restoration
Before restoration: April 2014. Note trail location and lack of vegetation on stream bank.
Annie Crescent stream bank before restoration
During restoration: September 2015. Sediment control installed while staff construct log and boulder revetment.
Annie Crescent stream bank before restoration
After restoration: May 2016. Note that the trail has been relocated away from the bank. Vegetation has been planted along the stream bank. Tree protection fencing is still in place.
View of the Annie Crescent streambank restoration project in June 2017
After Restoration: June 2017. Note the established vegetation along the stream bank.