Performance Assessment of a Highway Stormwater Quality Retention Pond

MVC-RRThe stormwater facility at Highway 401 and the Rouge River was constructed in 1995 by the Ontario Ministry of Transportation to address water quality and fishery concerns originating from highway runoff.  The facility is long and narrow with a length-to-width ratio of 10:1. A submerged berm partitions the pond into a forebay and quiescent treatment/retention zone. Flow exits the facility via a reversed-slope pipe that draws water from below the surface of the pond such that floatables are trapped in the pond and effluent temperatures are cooler than they otherwise would be.

Between 1995 and 1997 a study evaluated the ability of the wet pond to reduce impacts on the receiving stream in terms of water quantity and water quality. To this end, the monitoring program included an assessment of hydrology, water chemistry, water temperature, water toxicity and changes in algae and vegetation communities in the pond. The pond was also the subject of a separate study investigating chloride pathways in stormwater ponds. A summary of data from the chloride study is provided in the final performance assessment report.

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Highway 401, Markham