Project Overview

Full Title
Assessing microbial contamination in the Newfound Creek watershed

Location
Newfound Creek is a tributary to the French Broad River northwest of Asheville.

Cooperating Agencies
Buncombe County Soil and Water Conservation District

Project Chief
Elise Giddings

Period of Project
2000-2003

Team Members

Callie Oblinger

WWW Resources

UNC Asheville VWIN Program

Department of Environmental and Natural Resources: French Broad River Basinwide Water Quality Plan

Clean Water Action Plan

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Newfound Creek Water Quality

Project Summary

Background

In October 2000 the North Carolina District of the U.S. Geological Survey (USGS) entered into an agreement with Buncombe County Soil and Water Conservation District (SWCD) to assess bacterial contamination in the Newfound Creek watershed, northwest of Asheville. Newfound Creek is a tributary to the French Broad River. Samples collected by the Volunteer Water Information Network (VWIN) and by Buncombe Soil & Water Conservation District have exceeded the North Carolina water-quality standards for fecal coliform. Because Newfound Creek has been identified as a priority watershed under the Clean Water Action Plan's Unified Watershed Assessments, these exceedences have triggered a need for more detailed sampling of the creek and its tributaries in an effort to focus clean-up efforts. Potential sources of bacterial contamination in the watershed are confined animal feeding operations, and septic systems that support suburban and rural residential development.

Objectives

The objectives of the agreement between the USGS and Buncombe County SWCD are to (1) establish and run a streamgage near the mouth of Newfound Creek, (2) sample fecal coliform and E. coli bacteria in Newfound Creek to aid in the identification of source areas, and (3) distinguish between animal and human sources of bacteria. The identification of source areas will aid Buncombe SWCD in prioritization of areas in the watershed for restoration and implementation of best-management practices.

Approach

The approach taken to assess bacterial contamination was multifaceted. Ten sites were selected in the watershed—five on the main stem of Newfound Creek, and five on major tributaries (table 1). Water column samples were collected during two time periods—a low-flow sample and a high-flow (storm runoff) sample. Water samples collected from each of these sites were analyzed for counts of E. coli bacteria. Because data collected previously in the Newfound watershed were for fecal coliform bacteria, counts of fecal coliform were assessed at five of the sites (table 1). The five sites were selected based on proximity to the locations sampled previously by other groups. The fecal coliform counts will be used to compare with data previously collected in the watershed and to compare E. coli and fecal bacterial counts from the same sample. While current State water-quality standards are for fecal coliform, the presence of E. coli, a member of the fecal coliform group, is direct evidence of fecal contamination from warm-blooded animals.

At five sites, coliphages in water samples were serotyped (table 1). Coliphages are bacteriophages (viruses) that infect and replicate in coliform bacteria. They are found in high numbers in sewage and are considered to be reliable indicators of sewage contamination. Serotyping of coliphages has been used successfully to distinguish human and animal sources of bacterial contamination. The sites selected for serotyping are located where the relative animal/human source contribution is most uncertain. In addition to bacterial analyses, selected water quality properties were measured at each site during the sampling visit. These included water temperature, specific conductance, pH, and dissolved oxygen.

During the low-flow sampling period, streambed-sediment samples were collected from the five main-stem Newfound Creek sites (table 1) and analyzed for E. coli bacteria counts. Fecal indicator bacteria can survive for relatively long periods in stream and lake sediments. Streambed sediments in Newfound Creek may provide a reservoir of fecal-indicator bacteria that are deposited from point or nonpoint sources and resuspended by physical disturbances, such as during high flows caused by stormwater runoff. Samples of the top 2 centimeters of sediment were collected from depositional areas at each of the five sites, and E. coli were enumerated in the sediments using the same method as for water samples.