Riley Purgatory Bluff Creek Watershed District (RPBCWD), together with St Hubert Catholic School, and Carver County Soil and Water Conservation District (CCSWCD) has identified a campus retrofit that will improve water quality, reduce runoff volumes, improve ecological diversity and provide many educational opportunities near Rice Marsh Lake in Chanhassen. Rice Marsh Lake is impaired.
In early 2016, the district completed an analysis of the Rice Marsh Lake’s watershed to assess its overall health. Rice Marsh Lake does not meet MPCA shallow lake water quality standards due to phosphorus loading. Additionally, high impervious cover in the area has increased stormwater runoff volume and rate, and reduced habitat availability and biological diversity. The District has been looking for “opportunity projects” within this watershed where measurable water quality improvements are achievable.
RPBCWD and St. Hubert School have been working together since 2013 to grow environmental awareness in the school community. Leadership from the school approached RPBCWD in 2018 with interest in taking action on that awareness. Many potential projects were considered, weighing benefits of water quality, runoff volume and rate reduction, ecological biodiversity, educational opportunities and aesthetics of the property, with considerations of safety, cost, and maintenance. Ultimately, four stormwater treatment projects were identified: A parking lot median retrofit to a tree trench that would collect water from the adjacent parking lot, Underground storage of stormwater runoff from the school roof and impervious playground surface, addition of a rain garden, removal of impervious surface, flooding and gully repair, and native vegetation on the south side of the parking lot, and restoration of a turf grass parcel into a native prairie with impervious disconnection from the parking lot to catch/treat stormwater. The project is expected to treat 3.6 acres runoff, remove 455 lbs of TSS and 1.8 lbs of P per year, reduce volume by 0.33 acre-ft per year, and add 0.7 acres of prairie restoration.
Status: Substantially Complete
Start: August 2020
End: August 2021
Partners: St. Hubert Catholic School, Metropolitan Council, Carver County Soil & Water Conservation District