Assessing Public Health Risks of Stormwater Use in Alberta:  Case Studies and Novel Approaches
Creators: Carson, Liam R
Publisher: name: University of Alberta Library
Year: 2023

<p>Water scarcity is a growing concern in both the local and global spheres, with increasing <br>
urbanization, climate change, and population growth all contributing to a strain on potable and <br>
non-potable water supplies. Many jurisdictions across the world (including Alberta, Canada) are <br>
currently exploring water recycling, water reuse, and alternative source water use projects as<br>
approaches to supplement these stressed supplies. However, many alternative source waters, such <br>
as stormwater, are poorly characterized for acute (i.e., microbial) hazards, and thus require <br>
comprehensive study before they can be deemed to not be a risk to public health through their use. <br>
Consequently, this thesis focused on characterizing stormwater quality in Airdrie, Alberta (which <br>
was earmarked for non-potable use) in terms of general levels of fecal pollution, individual sources <br>
of fecal pollution, as well as for common waterborne gastroenteric and opportunistic bacterial <br>
pathogens. Key observations from this study included, firstly, that stormwater quality was typically <br>
poor and frequently exceeded recreational/ambient water quality guidelines. Secondly, fecal <br>
source signatures from a large variety of animal hosts were found to impact stormwater quality, <br>
including from humans, waterfowl, dogs, and ruminants. Human fecal signatures were detected in </p>

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<p>25% of samples in 2021, and represented the most common tested pollution source. The <br>
concentration of human fecal markers suggested that human sewage approximated 0.1% of <br>
stormwater flows at times. Thirdly, tracing human fecal signatures in stormwater drains proved to <br>
be a useful tool for identifying cross-connections within the drainage networks in at least two <br>
cases. Fourthly, enteric and opportunistic respiratory pathogens were sporadically detected in <br>
stormwater, with Arcobacter butzleri found to be the most common gastroenteric pathogen, and <br>
observed in ~33% of watersamples in 2021. Legionella spp. were found in virtually all stormwater <br>
samples tested, albeit the respiratory pathogen L. pneumophila was only detected in a small <br>
number of samples and at low concentrations. Given that waterfowl (Larus spp. [gulls] and Branta <br>
canadensis [Canada geese]) were also common sources of fecal pollution in stormwater, a fecal <br>
survey was done to examine birds as a fecal source for some enteric pathogens (Campylobacter<br>
spp. and Salmonella spp.). Notably, the frequency and concentrations of Campylobacter spp. and <br>
Salmonella spp. were sparse in birds, albeit that shedding levels were high in the few birds that <br>
were infected (i.e., up to 6 log10 MPN/g in supershedders). The collective implication of these <br>
findings demonstrates that stormwater in Alberta is frequently contaminated by diverse fecal <br>
sources of pollution, including human sewage, and that bacterial pathogens can be common in <br>
stormwater. As a result, careful consideration of the risks from fecal contamination is necessary <br>
for stormwater to be used as an alternative water source, and the data presented in this thesis <br>
support the risk-based Public Health Guidelines for Water Reuse and Stormwater (2021) that were <br>
recently published by Alberta Health and Alberta Health Services.</p>
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