The currently available modeling software have challenges simulating water quantity and quality modeling in mixed agricultural/rural/urban areas. Built on the SWMM platform, the Rural Storm Water Management Model (RSWMM) was recently developed to accurately simulate hydrology, hydraulics, and water quality in agricultural and urban watersheds, and to assess the effectiveness of a suite of agricultural best management practices (BMPs). Using PCSWMM as the base software, additional water quality routines were added to improve functionality in rural areas. Improvements include: addition of MUSLE for sediment yield estimation; components of SPARROW for in stream P and N processes; ability to represent agricultural BMPs; and seasonality in parameterization. Overall, the RSWMM provides a unique tool to examine hydrology and water quality in agricultural and urban catchments of Lake Huron. Given this new modeling flexibility for rural applications, it can serve as a state-of-the-science watershed assessment and decision making tool throughout North America.