Lessons Learned in the Credit River: Reconnecting the Water Cycle for our Greater Lakes

Christine Zimmer
November 10, 2015
Water Matters - CVC Staff monitoring roadside green infrastructure

The Credit River watershed lies between Toronto and Hamilton and is one of the most diverse watersheds in Ontario. It features rich fisheries and one of the last-remaining baymouth bar coastal wetlands on the western end of Lake Ontario. Running for 90 km (56 miles), its headwaters are characterized by rural communities reliant on groundwater supply. As it travels toward Lake Ontario, it runs through growing and established municipalities in Canada.

CVC staff monitoring roadside green infrastructure within a residential neighborhood. Green infrastructure helps recreate the natural water cycle in an highly urban environment. Credit: CVC
CVC staff monitoring roadside green infrastructure within a residential neighborhood. Green infrastructure helps recreate the natural water cycle in an highly urban environment. Credit: CVC

Unfortunately, one of the Credit River’s claims to fame is that it is one of the largest Canadian contributors of phosphorus to Lake Ontario. Excessive phosphorus can stimulate algae growth, undermining the health and economy of our Great Lakes and water supply.

Real-time monitoring of the Credit River has found that urban stormwater is contributing two times more phosphorus to the nearshore than the two wastewater treatment plants within Credit Valley Conservation’s jurisdiction. This highlights the need to integrate water, wastewater and stormwater management decisions to optimize infrastructure investment.   By managing stormwater, we can reduce  wastewater treatment facility sewage discharges during storms.

This green infrastructure project is located on school property and treats roadside runoff.  Monitoring of this site showed a 70 percent reduction in nutrient loadings. Credit: CVC
This green infrastructure project is located on school property and treats roadside runoff. Monitoring of this site showed a 70 percent reduction in nutrient loadings. Credit: CVC.

Green infrastructure practices, such as permeable pavers and rain gardens, can be incorporated into new and existing urban areas to reduce stress on aging infrastructure, build capacity in light of extreme events, and improve water quality.

Credit Valley Conservation (CVC) roadside retrofit projects have shown that green infrastructure can reduce up to 70 percent of phosphorus loads. Even in clay soils and densely urban areas, these features are able to replicate nature by absorbing 90 percent of annual rainfall events, meaning less pollution entering our Great Lakes.

Green infrastructure outperformed design expectations by absorbing 30 percent of a July 8, 2013, storm in the Credit River watershed when more than 105 mm (5 inches) of rain fell over a four-hour period.

(See also: ‘How Green Infrastructure is ‘Saving the Rain’ in New York’)

For municipalities such as Mississauga, retrofitting roadways provides a cost-effective solution with benefits ranging from reducing stress on existing sewers to decreasing in-stream erosion and improving water quality. This led Mississauga leaders to pass a Council Resolution in 2014 that all future capital roads projects consider the use of green infrastructure.

Green infrastructure, along with integrated water, wastewater and stormwater management, has a significant role to play in shaping a healthier Great Lakes environment.

One highlight of these efforts is the Great Lakes Commission’s “Greater Lakes: Reconnecting the Great Lakes Water Cycle” project.

Credit Valley Conservation also has an online resource at bealeader.ca on the design, construction, maintenance and monitoring of green infrastructure development.

Green infrastructure can provide added safety, reducing parking lot flooding and ice during winter months. Credit: CVC
Green infrastructure can provide added safety, reducing parking lot flooding and ice during winter months. Credit: CVC

 

Christine Zimmer

Senior Manager of Water Science with the Credit Valley Conservation Authority