The agriculture community is faced with new challenges to increase food production on a limited amount of suitable land to keep up with the growing population. Fertilizers and intensive cropping are needed to meet food demand, but these practices contribute to environmental degradation due to nutrients and sediment leaving fields and entering waterbodies. Non-point source (NPS) pollution from agriculture has been scrutinized for significantly contributing to eutrophication and hypoxic dead zones. To reduce the harmful impacts of NPS pollution from agriculture, producers and land users have implemented in-field and edge-of-field Best Management Practices (BMP). Water and Sediment Control Basins (WASCoBs) are an example of an in-field BMP that has helped reduce erosion and sediment loading of receiving waters. Cover crops are another in-field BMP that have been used to mitigate erosion and nutrient leaching. The impacts of WASCoBs paired with cover crops on water quality, specifically nutrient loading, is lacking in the current literature and was the focus of this research. Our study site was located in Menard County near Atterberry, IL. The farm had relatively steep topography (5-18% slopes) and suffered from severe gully erosion. In 2018, the Natural Resource Conservation Service (NRCS) partnered with the landowner and installed a series of WASCoBs to address the erosion issues. Along with the NRCS and landowner, we worked with the Illinois Farm Bureau (IFB) to investigate the impacts of WASCoBs and cover crops on nutrient and sediment runoff, hydrology, and crop yields.Four sub-watersheds were included in the study: 1) a 1.5-hectare basin treated with a WASCoB; 2) a 1.4-hectare basin treated with a WASCoB and a cover crop; 3) a 0.2-hectare gully drained watershed treated with a cover crop; and 4) a control, 3.8-hectare gully-drained watershed. ISCO automated water samplers collected runoff from storm events in a time-weighted composite sampling regime. The measured water quality parameters were total suspended solids (TSS), ammonium-nitrogen (ammonium-N), nitrate-nitrogen (nitrate-N), dissolved reactive phosphorus (DRP), and total phosphorus (TP). The WASCoB treatment reduced TSS by 98.5-99.8%, TP by 83.8-97.4%, ammonium-N by 42.3-82.9%, and nitrate-N by 32.0-59.6%, respectively. Cover crop impacts on the water quality parameters were not detected, due to poor gemination of the annual rye cover crop. The water quality improvement WASCoBs are a potential tool for farmers and land managers to reduce loading of nutrients and sediment to receiving waters.

Stream ecosystems are increasingly at risk for thermal impairment as urbanization intensifies, resulting in more heated runoff from impervious cover that is less likely to be cooled naturally. While several best management practices, including bioretention filters, have been able to reduce thermal pollution, success has been limited. The extent of thermal mitigation required to prevent ecological damage is unknown. A calibrated runoff temperature model of a case study watershed in Blacksburg, VA was developed to determine the cumulative treatment volume of bioretention filters required to reduce thermal impacts caused by runoff from development in the watershed to biologically acceptable levels. A future build out scenario of the study watershed was also analyzed. Results from this study established that runoff thermal pollution cannot be fully reduced to goal thresholds during all storms using bioretention filter retrofits. While retrofitting significantly decreased temperatures and heat exports relative to the controls, increasing treatment volumes did not really enhance mitigation. Alternate thermal mitigation methods which actively remove runoff volume should be considered where more thermal mitigation is required. / Master of Science / Stream temperature is a significant ecological, biological, and chemical property affecting the long-term health of streams. However, as development intensifies, stream ecosystems are increasingly at risk of being damaged by thermal pollution, which causes warmer and less stable temperatures that distress aquatic organisms. While several stormwater management methods that reduce runoff-related pollution, known as best management practices (BMPs), were found to also decrease thermal pollution, their success has been limited. Furthermore, the extent of thermal mitigation required to prevent ecological damage is unclear. This study aimed to determine how much treatment by a popular BMP, the bioretention filter, was necessary across a watershed in Blacksburg, VA to adequately reduce thermal pollution to protect stream health. Mitigation impacts were tested on both existing and predicted future development conditions through model simulations. Results from this study established that thermal pollution from runoff cannot be fully reduced to goal thresholds consistently using bioretention filter retrofits. While retrofitting significantly decreased thermal pollution, increasing treatment volume did not considerably enhance mitigation. Results suggested that bioretention filters are not an effective method, and alternate thermal mitigation practices which actively remove runoff volume should instead be considered where intensive reductions in thermal pollution are necessary.