CUMULATIVE IMPACTS OF LANDUSE ON WATER-QUALITY IN A SOUTHERN APPALACHIAN WATERSHED

Water quality variables were sampled over 109 weeks along Coweeta Cree k, a fifth-order stream located in the Appalachian mountains of wester n North Carolina. The purpose of this study was to observe any changes in water quality, over a range of flow conditions, with concomitant d ownstream changes in the mix of landuses. Variables sampled include pH , HCO32-, conductivity, NO3--N, NH4+-N, PO43--P, Cl-,Na+, K+, Ca2+, Mg 2+, SO42-, SiO2, turbidity, temperature, dissolved oxygen, total and f ecal coliform, and fecal streptococcus. Landcover/landuse was interpre ted from 1:20,000 aerial photographs and entered in a GIS, along with information on total and paved road length, building location and dens ity, catchment boundaries, hydrography, and slope. Linear regressions were performed to relate basin and near-stream landscape variables to water quality. Consistent, cumulative, downstream changes in water qua lity variables were observed along Coweeta Creek, concomitant with dow nstream human caused changes in landuse. Furthermore, larger downstrea m changes in water quality variables were observed during stormflow wh en compared to baseflow, suggesting cumulative impacts due to landscap e alteration under study conditions were much greater during storm eve nts. Although most water quality regulations, legislation, and samplin g are promulgated for baseflow conditions, this work indicates they sh ould also consider the cumulative impacts of physical, chemical, and b iological water quality during stormflow.