Hydrologic Analysis of the Major Tributaries Within the Lower Dan River Watershed Between Milton, NC and Paces, VA

According to the Clean Water Act of 1972, Virginia is required to develop Total Maximum Daily Loads (TMDLs) for its impaired waters. A TMDL is the maximum amount of particular contaminants that a body of water can accept, without violating federal and state water quality standards. Approximately 130 waters have been targeted for TMDL development, with fecal coliform contamination cited as one of the top five violations. The purpose of this study was to examine a ten-mile segment of the Dan River that has been designated as impaired, along with seven tributaries that contribute to that segment. The segment is found along the VA and NC border in Pittsylvania and Halifax Counties. From February to September 2000, hydrologic and chemical data were gathered on six sampling events at ten sites: three on the Dan River and seven tributary locations. All of the waterways were tested for temperature, pH, conductivity, nitrates, nitrites, phosphates, and fecal coliform. Additionally, discharge was calculated for each tributary from field measurements. Averages and standard deviations were calculated for each of the chemical parameters for each site. The analysis of variance for the chemical parameters shows no significant change from the upstream Dan River site to the downstream Dan River site. Hydrographs were constructed for each of the tributaries, as were stage-discharge diagrams. For most of the streams, the correlation between stream depth and discharge, based on a linear regression, was very low; therefore, the diagrams should not be used for discharge prediction. Overall, the tributaries are not contributing a significant pollutant load to the river system based on chemical and hydrologic data