Locating sources of bacterial contamination in the Toms Creek Watershed.

摘要

The Congaree National Park (CNP) is known for its unique ecosystem and many state and national champion trees. Popular visitor activities include birding, fishing, canoeing, hiking, kayaking and camping. Hence, good water quality in the Park is necessary not only for its ecological well being but also for visitors' health and safety. The Park is vulnerable to contamination from pollution coming from upstream watersheds. The Toms Creek watershed in Richland County is located upstream of Congaree National Park and a small part of the watershed falls inside the boundaries of Congaree National Park. The objectives of this study are to assess the spatial and temporal variability in fecal indicator bacteria, and to identify sources, either human or animal, in the Toms Creek watershed.;We accomplished this by sampling the Toms Creek watershed at multiple sites on a monthly basis for a period of one year to identify the reaches that contribute the most to bacterial contamination. This technique is known as targeted sampling. The three sampling sites located inside the Park showed that E. coli concentrations attenuate from upstream levels in most conditions. The Park is vulnerable in very high flow conditions particularly those resulting from summer storm events that create significant amounts of runoff and decrease the attenuation capacity of the watershed. The Park is also vulnerable in very low flow conditions that reduce dilution. We combined results from this sampling exercise with windshield observations and aerial photography to estimate the type of source/(s) responsible for few of the sites identified as impaired. We suspected malfunctioning septic systems to be the main source of pollution at Toms Creek on bluff Road (Site 13) and to test this hypothesis, we employed a chemical source tracking method that detects contamination from anthropogenic wastewater by testing for presence of optical brighteners (OBs)/ fluorescent whitening agents (FWAs) that are a component of laundry detergents.;Fluorometric analysis did not yield any positives for presence of OBs contrary to our expectation. At the time of our study, the protocol that we used for our analysis had not been used in the field and we suspected false negatives in our study. In our laboratory-based tests that were conducted as a follow-up protocol failed to detect optical brighteners in detergent solution with Toms Creek water potentially due to interference from colored dissolved organic matter and/or a low detection limit. Based on these results, we retain our presumption that septic tanks are the major source of bacterial contamination at Toms Creek on Bluff Road.;Other potential sources in Toms Creek watershed include at least one poorly managed horse (Equus caballus) farm and wildlife like feral hogs (Sus scrofa). Research is underway to select a suitable molecular source tracking method that can be used to characterize the sources of bacterial contamination in the entire waters.;In the last chapter, we examine the implications of current SC water quality regulations on resource management in light of our conclusions from the bacterial study in the Toms Creek watershed inside and outside the Park.