Bacterial contamination of surface waters is a significant challenge in the United States, with many sources of contamination coming from human activities and failing sanitary infrastructure. Traditional methods used to determine human sources of wastewater are time-consuming and costly. The Mobile Bay National Estuary Program (MBNEP) has developed a program using a canine to detect regulatorily relevant levels of wastewater in waterways. Operating costs for canine tracking are estimated to be at least one order of magnitude lower than lab-based microbial source tracking, with markedly faster time-to-detection.
Training aids for the purpose-bred canine were created by combining homogenized samples of raw sewage from local wastewater treatment plants (including those in Mobile, Dauphin Island, Fairhope, Daphne, and Lillian). Fecal coliforms and male-specific coliphage (MSC) indicator microbes were enumerated, and the homogenate was diluted to regulatory-relevant levels (with bacterial counts higher than ADEM and EPA guidelines for safe swimming and bodily contact) before imprinting the canine on the odor. Innovative tools - particularly devices that preserve representative odor profiles and support scalability- were adopted to assist in training the canine.
In early 2025, the canine demonstrated 99.6% accuracy across 180 nose-to-odor interactions in a controlled double-blind study (10 trials; 18 odors/trial with distractors, probes, controls, blanks, and targets). Subsequent threshold testing indicated canine sensitivity ~9 orders of magnitude beyond a standard analytical limit of detection. An August 2025 environmental assessment showed 100% accuracy at regulatory-level targets with no alerts on distractor odors. As a tangible product from this work, the MBNEP was also able to develop and implement an independent certification from a national police working dog certification organization.
Results from this study support canine detection as a rapid, cost-effective complement to conventional approaches for identifying human sources of wastewater in coastal watersheds.