Trout Brook Phase 3
Background
The South Washington Watershed District and the Minnesota Department of Natural Resources (DNR) have been completing a study and restoration of Trout Brook (a trout stream) for the last 10 years. The most noted issue was that the sedimentation within the channel was burying channel riffles and pools, limiting habitat diversity. The District wanted to restore Trout Brook, which outlets to the St. Croix River, through areas of the Afton Alps Ski Area and Afton State Park. In 2021, the District hired Houston Engineering, Inc. (HEI) to design Phase 3 of this restoration project.
The Project
Our team began by collecting and reviewing a decade of study literature on the reach as well as conducting a survey to collect data on the existing conditions. Additionally, our team conducted a wetland survey which resulted in the identification of a wetland area and linear watercourse.
HEI enhanced an existing HEC-RAS model to determine water surface profiles for the site to remeander the main Trout Brook channel by extending existing cross sections, adding additional ones, and updating various other hydraulic parameters. Topography for the HEC-RAS model came from a combination of field-surveyed cross sections, surface data provided by our partner Great River Greening, and LiDAR, which our team obtained from the DNR.
Because riffles and pools were filled with sediment, the habitat was not functioning properly. To encourage a more diverse habitat, in-channel structures like root wads and riffles were created. Emphasis was placed on maintaining balanced sediment transport through the reaches.
As part of this project, HEI completed a culvert alternatives memorandum to evaluate options for replacing two existing corrugated metal pipe (CMP) culverts, which provided a crossing for the Afton Alps parking lot and roadway. A 16’ x 7’ precast concrete box culvert with filled bottom was chosen to replace the CMP culverts. This culvert design widened the channel at the stream crossing and created a more efficient waterway opening, enhancing the conditions for fish passage.
The project includes stakeholders from the District; Great River Greening; Vail Properties; and the DNR ecology, fisheries, parks, and trails units. HEI led stakeholder meetings at each milestone to solicit input and feedback.
- Applied the MESBOAC approach to design the best culvert for the project goal of enhancing fish passage and habitat.
- Culvert design significantly reduced the frequency of flooding in the chalet parking lot.
- Worked in coordination with the District, who partnered with Great River Greening, the DNR, and Vail Properties.
- The project was recognized as the 2023 Minnesota Watershed’s Project of the Year by Minnesota Watersheds (formerly the Minnesota Association of Watershed Districts).
Project Details
Client: South Washington Watershed District
Location: Washington County, MN
Project Highlights
- Applied the MESBOAC approach to design the best culvert for the project goal of enhancing fish passage and habitat.
- Culvert design significantly reduced the frequency of flooding in the chalet parking lot.
- Worked in coordination with the District, who partnered with Great River Greening, the DNR, and Vail Properties.
- The project was recognized as the 2023 Minnesota Watershed’s Project of the Year by Minnesota Watersheds (formerly the Minnesota Association of Watershed Districts).
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