Watershed monitoring and the TMDL modeling to assess bacterial loading in estuarine environments to improve management

摘要

Shellfish bed closures along the North Carolina coast have increased over the years seemingly concurrent withudincreases in population (Mallin 2000). More and faster flowing storm water has come to mean more bacteria, andudfecal indicator bacterial (FIB) standards for shellfish harvesting are often exceeded when no source of contamination is readily apparent (Kator and Rhodes, 1994). Could management reduce bacterial loads if the source of the bacteria where known? Several potentially useful methods for differentiating human versus animal pollution sources have emerged including Ribotyping and Multiple Antibiotic Resistance (MAR) (US EPA, 2005). Total Maximum Daily Load (TMDL) studies on bacterial sources have been conducted for streams in NC mountain and Piedmont areasud(U.S. EPA, 1991 and 2005) and are likely to be mandated for coastal waters. TMDL analysis estimates allowable pollutant loads and allocates them to known sources so management actions may be taken to restore water to its intended uses (U.S. EPA, 1991 and 2005). This project sought first to quantify and compare fecal contamination levels for three different types of land use on the coast, and second, to apply MAR and ribotyping techniques and assess their effectiveness for indentifying bacterial sources. Third, results from these studies would be applied to oneudwatershed to develop a case study coastal TMDL. All three watershed study areas are within Carteret County, NorthudCarolina. Jumping Run Creek and Pettiford Creek are within the White Oak River Basin management unit whereasudthe South River falls within the Neuse River Basin. Jumping Run Creek watershed encompasses approximately 320udha. Its watershed was a dense, coastal pocosin on sandy, relic dune ridges, but current land uses are primarilyudmedium density residential. Pettiford Creek is in the Croatan National Forest, is 1133 ha. and is basicallyudundeveloped. The third study area is on Open Grounds Farm in the South River watershed. Half of the 630 ha.udwatershed is under cultivation with most under active water control (flashboard risers). The remaining portion isudforested silviculture.(PDF contains 4 pages)