Assessing Public Health Risks of Stormwater Use in Alberta: Case Studies and Novel Approaches

• Author / Creator

  Carson, Liam R

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

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

• Subjects / Keywords

  • Stormwater
  • Microbial Source Tracking
  • Enteric Pathogens
  • Arcobacter butzleri

• Graduation date

  Fall 2023

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-m8sz-9z04

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.