Date Awarded


Document Type


Degree Name

Master of Science (M.Sc.)


Virginia Institute of Marine Science


One of the main threats to water quality in the Chesapeake Bay is contamination by bacterial loading from point and non-point sources. While only very high levels of fecal bacteria (greater than 200 MPN/100ml) indicate the potential of a health threat to humans from contact with water, lower concentrations (14 MPN/100 ml) make the shellfish from contaminated waters unfit for human consumption. Many nearshore areas that are vulnerable to bacterial contamination also are suitable for the propagation of shellfish, including the hard clam (Mercenaria mercenaria). This is especially true on Virginia’s Eastern Shore, where shallow, sheltered waters with optimal salinity and little pollution support a hard clam aquaculture industry that had an economic impact upwards of $48 million in 2004 (Murray and Kirkley, 2005). Over the past decade, however, development pressures on the Eastern Shore have increased, and land has been converted from forests and fields to subdivisions and strip malls at a faster rate than in the past. Even in the absence of a point source of bacteria such as a wastewater treatment plant, bacterial loads from non-point sources associated with increased land development have the potential to degrade water quality to the detriment of marine life and marine resource users. One area where the conflict between aquaculture and other water qualitydependent uses, and development pressure is building is the Old Plantation Creek watershed on the Eastern Shore of the Chesapeake Bay. Using a GIS-based watershed model to simulate land use and associated fecal bacteria loads, linked to a Tidal Prism Water Quality Model to estimate the disbursement of bacteria throughout the water body, this study predicts that if development continues to the maximum buildout allowed under current regulations it would lead to the condemnation of a large portion of the shellfish growing waters in Old Plantation Creek. By coupling this linked watershed-water quality model with an economic Input/Output (I/O) model, it was possible to determine the economic impact of those condemnations to the aquaculture industry and the economy of Virginia.



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