Access to safe, high quality water for consumption, agriculture, industry, and recreation is critically important. Continuous agricultural and mining activities have impaired the waters of the Grand Lake watershed in the central Great Plains region of the United States. The Grand Lake watershed encompasses portions of southeast Kansas, southwest Missouri, northwest Arkansas, and northeast Oklahoma, and drains into Grand Lake in northeast Oklahoma. The Cherry Creek watershed drains approximately 882.2 km 2 (218,000 ac) of land in southeast Kansas and is a contributor of water to the Grand Lake watershed. This paper presents a water quality assessment in the Cherry Creek watershed, with an end toward mitigation of nonpoint source pollutants that are a major contributor to sediment and nutrient contaminants in Grand Lake. A hydrological model was developed using the Hydrological Simulation Program Fortran code and was updated, calibrated, and verified with measured data reported by US Geological Survey (USGS) and the Kansas Department of Health and Environment (KDHE). The model was extended to simulate water quality within the study area. Nitrate (NO 3