Bioswales are linear channels designed to concentrate and convey stormwater runoff while re-moving debris and pollution.

Bioswales improve water quality by infiltrating the first flush of storm water runoff and filtering the large storm flows they convey. The majority of annual precipitation comes from frequent, small rain events: much of the value of bioswales comes from infiltrating and filtering nearly all of this water. They are also beneficial in recharging groundwater.

The National Association of City Transportation Officials notes that “Bioswales are the most effective type of green infrastructure facility in slowing runoff velocity and cleansing water while recharging the underlying groundwater table.” Several Ontario cities are members.

In Action

Brampton, Ontario: The City of Brampton installed its first bio-filter swales along County Court Boulevard as part of planned road resurfacing in 2014. The primary role of the bio-filter swales is to collect and clean storm water run-off from County Court Boulevard before it enters the Etobicoke Creek.

New York City: In Brooklyn, bioswales around the Gowanus Canal are helping to control stormwater and reduce water pollution caused by the legacy of industrial activities in the area. It is estimated that the curb-side installations will keep eight million gallons of stormwater runoff out of the city-wide sewer system each year.