Microbial Source Tracking

One measurable type of potential human-related water pollution is fecal bacteria. These bacteria may derive from humans, various domesticated animals, i.e. dogs, cats, cows, etc. or from wild animals. Bacteria within the genus Enterococcus has been widely adopted to indicate the presence of fecal matter from warm-blooded animals in 305(b) monitoring efforts. Delaware has risk-based numeric criteria for Primary Contact Recreation (PCR) and Secondary Contact Recreation (SCR) in freshwater and saltwater “determined by the Department (DNREC) to be of non-wildlife origin based on best scientific judgment using available information”. Important among the limitations of the Enterococcus test is that it does not differentiate as to what type of animal the detected bacteria are from. It could be any mix of warm-blooded animal types that might be in the watershed – i.e. mammals and birds, domestic and wildlife.

While these Enterococcus criteria are generally recognized to be protective of human health and the continuation of routine monitoring of waters is necessary to track status and trends, this test does not help in locating sources of bacterial contamination, which may be abatable. A supplemental, complimentary addition to the existing monitoring format is needed to facilitate where to apply pollution control practices and maximize the frugal utilization of the increasingly scarce resources available to bring about the environmental improvements intended under the CWA, such that waters meet standards criteria and attain designated uses, for example, PCR, SCR, fish, aquatic life and wildlife and harvestable shellfish waters.

Ecosystem services of coastal waters are important for community health, tourism and aquaculture. However, our coastal waters are under constant threats from pollution, land use change and increasing severe hydrologic events including coastal and areal flooding. Inherent in a coastal healthy ecosystem is a lack of pollution from anthropogenic influences, a tolerance for flooding without additional pollution and a resilient natural biota. A main threat to coastal ecosystem health is the introduction of fecal material from humans, pets and livestock. As waste material these concerns are primary for human health, but also of concern is that infectious materials can be spread between species. As such, the continual monitoring of waterways for fecal material is inherent to statewide monitoring efforts. If bacterial loads are raised in waterways, tourism can be shut down and aquaculture can be impacted. As such the spread of bacteria in the environment is of great concern for the continued maintenance of a healthy coastal ecosystem.

In the state of Delaware, the Department of Natural Resources and Environmental Control (DNREC) Department of Water, located in the Office of Environmental Protection, produces data for the monitoring of waterway health. The DNREC Department of Watershed Stewardship, located in the Office of Natural Resources, is responsible for enacting policies and actual management of watersheds. While the data produced regarding microbial impairment of waterway health can be acted on by stakeholders for conservation and ecosystem service health priorities, the watershed-level impacts of waterway impairment are often not able to be acted upon, as the data collected by standard required measurements are not explicit enough to enact policy level enforcement by the Department of Watershed Stewardship. Our project seeks to gain detailed data on the microbial impairment of coastal waters in Delaware, tracking the sources of microbial input from watershed areas, in powerful enough form to compel the offices within DNREC, and potentially as large as the EPA, to reconsider the practices of waterway monitoring and policy enforcement regarding potential microbial pollution.