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Quantifying loads and establishing allocations for nonpoint source nutrient loads has become a significant part of the development of TMDLs. As a result, modeling tools used for TMDL development are rapidly evolving from steady-state simulations of instream processes to dynamic representations of a waterbodys response to activities within its watershed. These dynamic models are often applied for extended time periods, encompassing a multitude of weather conditions within the watershed. Although significant efforts have been invested in collecting nutrient data throughout the Yazoo River Basin in Mississippi, water quality data collected during wet-weather conditions were generally not available. In order to collect this type of data, the Mississippi Department of Environmental Quality conducted a wet-weather monitoring project in the Yazoo River Basin, Mississippi. Seven monitoring stations were established throughout the basin in watersheds of mixed landuse types. Each station was equipped with YSI data sondes for semi-continuous monitoring of in situ parameters and ISCO refrigerated samplers with modem capabilities for water sample collection. Water samples were collected during both wet-weather and baseflow conditions for analysis of several nutrient species and other parameters beginning in October 1999 and ending in February 2001. Initial analysis of the wet-weather monitoring data suggests that this type of monitoring program will be essential for model calibration and development of TMDLs for nutrients and other nonpoint source pollutants in the Yazoo River Basin.