Date of Award

2018

Document Type

Open Access Dissertation

Department

Environmental Health Sciences

First Advisor

Geoffrey Scott

Second Advisor

Dwayne Porter

Abstract

Zoning and land-use practices have a direct influence on hydrologic systems and can impact water resources. Linkages between change in land uses and degradation of water quality in stream and watershed environments have been well established. Shem Creek, located in Mount Pleasant, SC, has a history of fecal indicator bacteria levels that exceed the Environmental Protection Agency’s recreational water quality standards. With recent coastal population and development trends, proper management and the sustainability of beach and estuary environments are a rising public health concern. The objective of this study is to determine what climatic and water quality parameters are associated with Enterococcus density levels and to characterize the changes in zoning between 2010 and 2017 in the Shem Creek watershed. Public health implications of development and impaired waters are also addressed. Geographic Information Systems allowed for analysis of changes in zoning in the Shem Creek watershed between 2010 and 2017. Multivariate partial least squares regression was used to determine statistically significant correlations between Enterococcus density levels and the following predictor variables: water quality monitoring station location; month; water temperature, height, and specific conductance; precipitation collected at two locations for 1, 2, and 3 days leading up to Enterococcus sampling; and number of septic tanks located within a 0.5 and 1 mile radius of each water quality monitoring station. Because the amount of impervious surface is directly related to water quality degradation, a change from zoning categories associated with permeable surface to zoning categories associated with impervious v surface was calculated. This equated to 3.2% of the total land area in the Shem Creek watershed that changed from agricultural, recreational, vacant, or undevelopable to commercial or residential. Results indicate that Enterococcus density levels have increased over time and that precipitation and water height are positively correlated with bacteria levels in Shem Creek. In addition, stations located further inland, where the creek was surrounded by extensive marsh, had higher concentrations of Enterococcus compared with stations located near the outflow of the creek into the harbor surrounded by seawalls. Understanding what parameters are associated with increasing Enterococcus density levels in Shem Creek will allow for future mitigation procedures to be implemented, protecting ecosystem services and the public’s health

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