Lake Wassermann Internal Load Management

The Wassermann Internal Load Management Project is the next phase in a multi-year strategy to restore Wassermann Lake, a waterbody impaired for nutrients. The Wassermann Lake TMDL attributes 505 lb/yr of phosphorus to internal loading, requiring an 88% reduction. An estimated 374 lb/yr of this internal load is attributable to internal sediment release. By implementing a buffered alum treatment, the Minnehaha Creek Watershed District (District) will be able to achieve an estimated 90% reduction of internal sediment release, effectively addressing the largest contributing factor to Wassermann Lake's Impairment. Over the last three years, the District has prepared to maximize the efficacy of an in-lake treatment through a multipronged strategy that includes common carp management, wetland restoration, alum treatment of a watershed source west of Lake Wassermann, and implementing stormwater regulations on all new development in the subwatershed. This strategy has effectively managed both internal release not attributable to sediment release and watershed loading to the maximum extent possible, making this treatment a final step towards restoring Lake Wassermann. The project not only directly benefits Wassermann Lake, but also will produce cumulative downstream benefits in the highly interconnected and interdependent Six Mile Creek-Halsted Bay (SMCHB) Subwatershed, including a second impaired waterbody immediately downstream, East Auburn Lake.
The project is part of a broader planning partnership targeting nutrient reductions to Halsted Bay of Lake Minnetonka by addressing impairments in upstream lakes and stream segments, restoring and protecting sensitive lands, including wetlands and priority uplands, and protecting water bodies from further degradation. Partners engaged directly in the restoration of Wassermann Lake have included the City of Victoria, the Board of Water and Soil Resources (BWSR), and Lessard Sams Outdoor Heritage Council.