Historical Study of Surface Water Quality in Sedgwick County, Kansas Using BASINS and GIS Technology

Surface water quality in Sedgwick County, Kansas was studied. The data used was historical with continued sampling beyond 1990 and was obtained from these four sources: Kansas Data Access and Support Center (DASC); Better Assessment Science Integrating Point and Non-point Sources (BASINS) modeling program created for the EPA; Sedgwick County & City of Wichita GIS offices; and Kansas Department of Health and Environment (KDHE). GIS (Arc/View) was used to investigate the relationship between pollutants in surface waters at 14 different locations, and, land use, soil type, hydrology, and topography of Sedgwick County. Queries of 24 pollutants against BASINS surface water quality threshold values were done in the GIS to determine degraded surface waters in Sedgwick County. Overall, numerous surface water locations of Sedgwick County were found to be degraded with herbicides, metals, TDS, nutrients, and bacteria at one time or another. For example, the Arkansas River at Derby had a historic total phosphorus maximum of 3.9 mg/L and a mean of 1.1 mg/L, and, a historic mean fecal coliform count of 80077 / 100 mL. The Little Arkansas River at Valley Center had a historic mean fecal coliform count of 5014 / 100 mL. An attempt was made to determine trends between these degraded areas, the pollutants found there, and the surrounding land use and natural features. Herbicide runoff was present in the surface waters of Sedgwick County in levels higher than the federal allowable limits. Nitrate and Phosphorous were present in 40% of the sampling points. The only sample location where there were high levels of most of the herbicides was downstream of a park and open land area.Metals were found in the surface water in Sedgwick County, more than one would expect for a predominantly agricultural area. While Lead and Chromium amounts increased as water passed through the city of Wichita, all other levels of metals decreased. Thus, making it seem that the most likely cause of metals pollution is not commercial and industrial areas, but rather the soils and/or agricultural land uses. Lake Afton was found to be impaired by eutrophication and Cheney Reservoir occasionally had a high concentration of chlorophyll. The Arkansas River was found to be impaired by Total Dissolved Solids. Fecal Coliform pollution seemed to follow normal trends of higher concentrations downstream of larger populated areas, probably from wastewater treatment facility discharges. Many surface water quality improvement activities have taken place over the last 8 years. Improvements in Sedgwick County's surface water are expected as a result of implemented BMPs.