Status

The Upper Riley Creek Ecological Enhancement Project is currently in the design phase with final design complete. The project will move into the bidding phase to select a contractor to build the project in 2025. Construction is tentatively planned to begin in 2025.

About the Project

The project area includes Upper Riley Creek in Chanhassen from Highway 5 (Arboretum Boulevard) to Lake Susan. The project will improve ecological functions along this reach of the creek and downstream Lake Susan by reducing stream bank erosion, reconnecting the creek to its floodplain, restoring habitat, and promoting diverse vegetation. Reducing the sediment and phosphorus load to Upper Riley Creek will also help restore and protect all downstream waterbodies, including Lake Susan, Rice Marsh Lake, Lake Riley and ultimately the Minnesota River. Project improvements will be planned and implemented in coordination with opportunities to preserve and enhance maintenance access to public infrastructure features such as stormwater outlets.

The total reduction in pollutant loading as a result of stabilizing this reach of Upper Riley Creek is estimated as 470,000 pounds per year of total suspended solids (TSS) and 250 pounds per year of total phosphorus (TP). These values are representative of an erosion rate of approximately 0.10 to 0.25 feet per year for the stream banks. The reduction in TSS and TP loading is a critical component for improving the ecological health of the aquatic ecosystems (both Upper Riley Creek and Lake Susan) and essential to potentially removing Lake Susan from the MPCA’s impaired waters list.

The project design focuses on improving the ecosystem by stabilizing the creek while also improving degraded habitat conditions along the creek. This section of creek has a primarily sandy/silty streambed with limited variability in depth. The project would provide greater stream depth variability through the addition of pools and riffles, more channel bed substructure types, and varied channel velocities (water flow speed). These improvements will enhance in-stream habitat features to benefit macroinvertebrates and fish. Improvements will also provide better floodplain connectivity for Upper Riley Creek resulting in enhanced habitat near the stream.

Reports and Related Information