Assessing Stormsewer Impacts to In-Stream Water Quality along an Urbanization Gradient

Session: Poster session

Andrea Kirkwood, University of Ontario Institute of Technology, [email protected]
Kari Dunfield, University of Guelph, [email protected]
James Roy, Environment and Climate Change Canada, [email protected]

Abstract

Most urban environments have engineered sewersheds, which are designed to mitigate flooding and direct surface water flow to receiving waters. The influence of sewersheds on the in-stream water quality of urban creeks has been well studied, but understanding the variable influx of contaminants from a sewershed can be remarkably challenging. We investigated the relative influence of stormsewer outfalls, located across an urbanization gradient, on water quality in Oshawa Creek, Ontario. Our results show that stormsewers, regardless of outfall type or location, are major sources of chloride, nitrogen, phosphorus, and fecal bacteria to Oshawa Creek and tributaries. Water quality declined with increased urbanization in the sewershed, and nutrients generally increased. A sensitive marker specific for human fecal bacteria clearly showed that older storm-sewer outfalls were contaminated with human fecal bacteria. This indicates possible exfiltration or cross-connection with sanitary sewer lines in this sewershed. Interestingly, artificial sweeteners used as chemical tracers of human-sewage contamination did not correlate well with human fecal bacteria. Overall, geographic location of stormsewer outfalls, rather than land-use type (residential vs. industrial), explained most of the variation in water quality.

1. Keyword
water quality

2. Keyword
environmental contaminants

3. Keyword
microbiological studies

4. Additional Keyword
Urbanization

5. Additional Keyword
tracers

6. Additional Keyword
stormwater