Sauk River Watershed Pollutant Source Assessment and Evaluation of Resource Management Scenarios

In 2012, a hydrologic and water-quality model of the Sauk River Watershed was developed with Hydrological Simulation Program–FORTRAN (HSPF) for the Minnesota Pollution Control Agency (MPCA) [Reisinger and Love, 2012]. HSPF is a continuous simulation model that typically produces data on a daily basis by using an hourly time step. The model was calibrated by using water-quality monitoring data and meteorological records of the 15-year timespan from January 1, 1995, to December 31, 2009, and it incorporates both point- and nonpoint-source loads. The Sauk River HSPF model was used to complete a pollutant source assessment for the Sauk River Watershed District (SRWD) and evaluate potential pollutant load reductions to surface waters under multiple resource management scenarios. The scenarios were selected by the SRWD and other local government units (LGUs), including resource management changes that could have a positive impact on water quality, as well as selecting options that were believed to have a reasonable potential to be adopted by landowners and municipalities. The SRWD and LGUs wanted to analyze changes to both agricultural and urban areas and wanted to view adoption rates that varied from "achievable" to "aggressive." Lastly, they wanted to review the cumulative result of combining both the urban and agricultural changes on the achievable scale, as well as the aggressive scale.