Hydrologic, land cover and seasonal patterns of waterborne pathogens in great lakes tributaries

Authors: LENAKER, PETER - Us Geological Survey (USGS); CORSI, STEVE - Us Geological Survey (USGS); Borchardt, Mark; Spencer, Susan; BALDWIN, AUSTIN - Us Geological Survey (USGS); LUTZ, MICHELLE - Us Geological Survey (USGS)

Submitted to: Water Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2017
Publication Date: 3/1/2017
Publication URL: http://handle.nal.usda.gov/10113/5624141
Citation: Lenaker, P.L., Corsi, S.R., Borchardt, M.A., Spencer, S.K., Baldwin, A.K., Lutz, M.A. 2017. Hydrologic, land cover and seasonal patterns of waterborne pathogens in great lakes tributaries. Water Research. 113:11-21.

Interpretive Summary: Rivers are major conduits for contaminants such as human and livestock pathogens to reach the Great Lakes. We measured loading rates of various pathogens in eight rivers in the Great Lakes basin and related these to land use, season, and flow conditions in the rivers. Pathogens from both human and bovine sources were present in the rivers and corresponded with the dominant land uses in the rivers’ watersheds, i.e., human viruses were more common in urban land use areas and bovine viruses were more common when land use was dominated by pasture or cattle. Both pathogen groups generally had similar transport behavior, with occurrence highest in the winter and spring seasons and loading rates greatest during runoff events compared to base-flow conditions. However, there was wide variability in these relationships among the rivers, suggesting that management practices must be designed for each specific watershed to effectively reduce pathogen inputs.

Technical Abstract: Great Lakes tributaries deliver waterborne pathogens from a host of sources. To examine the hydrologic, land cover, and seasonal variability of waterborne pathogens, protozoa (2), pathogenic bacteria (4) and human (8) and bovine (8) viruses from eight rivers were monitored in the Great Lakes watershed over 29 months from February 2011 – June 2013. Sampling locations consisted of a wide variety of land cover classes from urban to agriculture to forest. A custom automated pathogen sampler was deployed at eight sampling locations which provided unattended, flow-weighted, large-volume (120 – 1630 L) sampling. Human and bovine viruses and pathogenic bacteria were detected by real-time qPCR in 17%, 18% and 1.4% of samples collected while protozoa were not detected (n=290). Five of the eight human viruses and four of the eight bovine viruses analyzed were detected at least once with human adenovirus C, D, F (9.0%) and bovine polyomavirus (11%) being present most often. Human and bovine viruses were present in 16.9% and 14.8% of runoff-event samples resulting from precipitation and snowmelt, and 13.9% and 12.9% of low-flow samples, respectively. Mean human and bovine flux from all eight sampling locations was greater during runoff-event periods than low-flow periods, but this varied by watershed. Human and bovine viruses occurred more frequently in spring and winter seasons than during the fall and summer. As urban land cover and population density increased, the potential for human virus contamination in surface water increased. Similarly, as agriculture land cover, specifically pasture, and cattle density increased, the potential for bovine virus contamination in surface water increased. Consideration of concentration, occurrence and flux in the context of hydrologic condition, seasonality, and land use must be considered for each watershed individually to develop effective watershed management strategies for pathogen reduction.