Urban Development Effects on Water Quality and Quantity in Southern Ontario Watersheds

English Abstract:

Urban development within the Greater Golden Horseshoe has impacted both water quantity and quality in southern Ontario. Although annual runoff is similar between urbanized and rural catchments in this region, catchments with more impervious cover have more frequent quickflow episodes, greater flow variability and less baseflow, and differences are most pronounced in the summer and fall when aquatic biological activity is highest. In addition, stream chloride levels are rising across the region and in every season, and even small areas of impervious cover contribute episodic chloride levels that exceed water quality thresholds. Although less is known about trends in sodium in these watersheds, atmospheric deposition of sodium is very high adjacent to roadways and sodium retention in soils in this area may be limited due to very high soil calcium levels. This talk will discuss implications of continued urban development across the region for both water quantity and quality.