IMPACT OF HUMAN ACTIVITIES ON WATER QUALITY IN THE MANTLED KARST OF THE SOUTHERN OZARKS, NORTHWEST ARKANSAS

With the sixth fastest regional population growth rate in the United States, municipalities and urban areas across northwestern Arkansas are experiencing environmental change due to expanding animal production and suburbanization. At the 15,000 ha study area near Tontitown, rural land on mantled karst is being developed into confined animal feeding operations (primarily poultry production), housing developments, and light industrial areas. These applications have the potential to significantly impact existing water quality. This study provides a framework for assessment of human impact on water resources through development of accurate databases of water resources for comparison with prior and future datasets, verification of temporal water-quality variations, and documentation of spatial variations in groundwater quality. Historically, water-quality impacts to the area were primarily nonpoint-source nutrients associated with animal production. However, point-souce impacts to water quality have occurred, or are likely to occur, as urbanization expands. A preliminary review of existing data suggests groundwater is impacted by a suite of organic and inorganic constituents related to urbanization. A recent study suggests more than 500 potential sources for groundwater contamination within the study area. Over half of the sources are poultry operations, which add poultry litter to fields as fertilizer. High in inorganic and organic compounds, the litter breaks down into water-soluble chemicals that are potentially hazardous to human health. Other sources of contamination are a regional municipal landfill, urban stormwater runoff, neighborhoods, cemeteries, automotive repair shops, gas stations, and other small businesses, which may add volatile organic compounds, lawn fertilizers, septic system runoff, and much more to the groundwater. In order to provide easy access to the spatially distributed data, all existing data for the water resources, including a karst inventory, a well inventory, groundwater-monitoring data, and coordinates for potential point and non-point sources were compiled into ArcGIS, along with relevant geologic and remotely sensed satellite data to reflect evolving land use. These data are being evaluated to assess water-quality changes, so future studies may address identification of groundwater contamination sources.