The effects of climate change on future water availability and water quality are not well understood, making the development of watershed management plans difficult for decision-makers. Agricultural best management practices (BMPs) are commonly implemented to mitigate non-point source (NPS) pollution, but future effectiveness is unknown due to climate change. To address these problems, the following research objectives were developed: (1) quantify the impacts of climate change on water quantity and water quality, (2) assess BMP effectiveness in current and future climate scenarios, and (3) determine the reliability of BMPs in future climates by performing a sensitivity analysis. The Soil and Water Assessment Tool (SWAT), a physically-based watershed model, was coupled with climate change data from the National Center for Atmospheric Research (NCAR) Community Climate System Model (CCSM-3) for the Tuttle Creek Lake watershed of Kansas and Nebraska. Eight agricultural BMPs were represented within the SWAT model framework: conservation tillage, contour farming, filter strips, grazing management, native grass, no-tillage, porous gully plugs, and terraces. Results indicate that water quantity and pollutant yields will likely increase in future climates. Native grass, terraces, and contour farming were determined to have the highest mean annual reduction efficiencies for all pollutants in current and future scenarios, while porous gully plugs were least efficient. Native grass, filter strips and grazing management were the least reliable under all climate scenarios due to high sensitivity.
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