Technical Abstract: In the United States, many state and federally funded conservation programs are required to quantify the water quality benefits resulting from their programs. The objective of this research was to evaluate the impact of conservation practices subsidized by the Oklahoma Conservation Commission on phosphorus and sediment loads in the Lake Wister Basin. The construction of new ponds, improved pasture fertility, establishment of improved forage, additional fencing and limited grazing were evaluated. Pond construction reduced phosphorus and sediment loads by 1.8% and 2.1%, respectively, by trapping nutrients and serving as alternative water sources for cattle. Conservation practices designed to increase vegetative cover in grazed pastures were evaluated using Landsat-derived vegetative indices and the Soil and Water Assessment Tool (SWAT). Overall, these conservation practices yielded a 1.9% improvement in vegetative cover and a sediment load reduction of 3.5%. Changes in phosphorus loss ranged from a 1.0% improvement to 3.5% increase. The use of phosphorus containing fertilizers as conservation practice in low productivity pastures was predicted to increase net phosphorus losses despite any improvement in vegetative cover. The net benefit of the practices evaluated in this research was a 5.4% reduction in sediment and a 1.8% to 2.8% reduction in phosphorus to Lake Wister. This combination of vegetative cover analysis and hydrologic simulation was a useful tool for evaluating the effects of conservation practices at the basin scale, and may provide guidance for the selection of conservation measures subsidized in future conservation programs.