Microbial Source Tracking of Bacterial Contamination in Recreational and Aquaculture Waters

Presented by Michael Pascucilla, East Shore District Health Department
Contact Information: [email protected]

ABSTRACT

Simple fecal indicator bacteria thresholds currently determine recreational beach closures. Water samples with bacteria counts exceeding thresholds initiate beach closures, but do not provide information about the sources of bacterial contamination. This approach simplifies routine administration, but does not provide information on the underlying causes needed to direct remediation efforts. We have recruited a Citizen Science team from the Short Beach neighborhood of Branford, Connecticut, to collect water samples for microbial source tracking (MST) analysis to find the causes of chronically elevated bacteria levels at local beaches. We employ a novel peristaltic pump storm drain sampling approach to collect post-precipitation event samples from outfalls flowing to the Long Island Sound near recreational beaches and shellfish beds. Contrary to the assumption that leaky sewage disposal systems were the source of the high bacterial counts, we find that non-source canine (dog) bacteria enter the waters in high abundance at these outfalls, with mixed-avian bacteria sources. These findings have initiated efforts, in collaboration with the Civic Association of Short Beach, to improve canine waste infrastructure at local beaches and improve education on proper waste disposal among residents. We describe our sampling procedure, stakeholder engagement, and the value of identifying bacterial sources using non-EPA-approved technologies like MST. As the magnitude and frequency of extreme precipitation events and corresponding waterborne bacterial contamination is expected to increase with climate change, we propose a broader use of MST will likely become an increasingly important public health tool to understand root cause sources better and protect recreational public beaches and aquaculture water quality.