Granite Lake External Load Reduction as Modelled by PTMApp 3.0

The purpose of this grant application is to implement effective practices identified in the Granite Lake watershed using PTMApp. The project area is based on the drainage area to Granite Lake. The watershed is in northwest Wright County and is encompassed by Albion Township. The goal of this application is to improve the quality of water entering Granite Lake by reducing total suspended solids and total phosphorous through construction of best management practices.
This watershed has been the target of several modelling efforts. An assessment, conducted in 2017, used PTMApp version 2.0.27, in 2021 new data became available as part of the North Fork Crow Watershed rerun with version 3.0.0271. The models were combined with SWCD staff review of locations to determine the feasibility of the practices PTMApp generated. Based on PTMApp output data and staff assessments, 10 water and sediment control basins were chosen to further investigate and prioritize for possible installation, 1 wetland restoration is being targeted in the watershed but the magnitude of the project requires collaboration of multiple landowners and funding sources. Additionally, staff set a goal of 100 acres of source reduction practices (cover crops, no till, prescribed grazing, etc.).
Using this grant we intend to continue working with agricultural producer and landowners to implement practices generated by PTMApp. It is estimated that if the 10 water and sediment control basins are built and 100 acres of source reduction are implemented it would reduce the amount of sediment for Granite lake by 192 tons/year from structural practices and 108 tons/year from source reduction and the amount total phosphorus by 33 lbs TP/year from structural practices and 18 lbs TP/year from source reduction.