Toolbox Approach of Source Tracking Human Sewage in Storm Drains

Public health departments are required by regulatory agencies to assess the concentrations of fecal indicator bacteria (FIB) such as Escherichia coli in the recreational waters as a means of determining relative risk for infection by sewage borne pathogens. However, the presence of E. coli in the environment does not discriminate between human and non human (birds and animal) feces, both of which may contain E. coli. County of Ottawa Health Department regularly monitors their watersheds for E. coli levels. Previous and recent monitoring at Dunton Park, Lake Macatawa exhibited high E. coli levels exceeding the state-allowed levels and often times beach closures. This high E. coli level remains a critical problem and puzzle in this watershed. Several storm drains and creeks open into the surroundings of Dunton Park area containing unknown discharges. Environmental Health Managers are in need of effective, easy, and low-cost methods to identify and pinpoint sources of human fecal contamination in storm drains and other sources that discharge into nearby water bodies. The microbiological quality of Dunton Park was evaluated and source tracked for human sewage using a toolbox approach, which combined 1) Canine scent tracking or human sewage-sniffing dogs, 2) Assessment of traditional FIB and 3) DNA based finger printing for human specific markers. The objective of this study was to deploy the sewage-sniffing dogs for source tracking human sewage in several storm drains, catch basin and creeks along the circumference of Dunton Park.

Water samples were collected and tested for traditional FIB and subjected to DNA fingerprinting based on positive signals obtained by sewage-sniffing dogs. The results of these three methods were correlated to provide weight of evidence data. This biological toolbox approach is helpful for providing significant information about the sewage sources in storm drains for implementing better management practices, thereby protecting environment and human health. This project is funded under Clean Michigan Initiative.