Restoration projects have been implemented to address streambank headcuts and erosion on the tributaries to Brown’s Creek. The desired outcomes of restoration were to:
- Prevent further degradation of upstream wetland by likely headcut migration upstream.
- Reduce accelerated sediment and nutrient delivery associated with instability.
- Improve overall creek/corridor health and aquatic habitat.
2018 Long Lake Tributary Headcut Stabilization
Background
Surveys completed in 2013 and 2014 found streambank erosion and undercutting in the Long Lake tributary to Brown’s Creek, about 500 feet downstream of Boutwell Road North in Stillwater. It was estimated that 22 cubic yards of soil eroded and washed away in the 17 months between the two surveys. Monitoring and a cost-benefit analysis indicated that BCWD should address the instability. The primary concerns were:
- Stream health (excess sediment and nutrients)
- Wetland dewatering
- Streambank erosion and property loss.
These issues were compounded by increased connectivity, changes in precipitation, changes in vegetation, and soils.
Project Details
The BCWD worked with private landowners and the city of Stillwater through a series of meetings and property access to address the instability. In the fall of 2018, a series of rock grade control structures were installed. The project was estimated to reduce 24 pounds of phosphorus annually to the diversion structure, which directs water to McKusick Lake or Brown’s Creek, and on to the St. Croix River.
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2021 Diversion Tributary Restoration
Background
In the spring of 2019, a drone flight and ground survey were conducted for the three tributaries upstream of the McKusick Diversion Structure. Channel incision, headcuts, and subsequent floodplain abandonment were observed along the Long Lake Tributary, South Central Tributary, and the Zephyr Tributary. Additional data collected at the Diversion Structure and the formation of a sediment plume at the McKusick Lake inlet suggested a significant sediment load over the prior 10 years, which was largely attributed to the channel incision and bank erosion of the upstream tributaries. If not addressed, the headcuts would continue to threaten stream health and fish habitat as well as erode the streambank and contribute more sediment upstream.
Project Details
The BCWD worked with private landowners and the City of Stillwater for land access to complete the repairs. The restoration work was completed by Minnesota Native Landscaped (MNL), who fixed the headcuts and restored the tributaries and adjacent wetlands starting in September 2021, with follow up management through 2024. Work included:
- Removal of Invasive trees and shrubs
- Installation of rock grade checks
- Restoration of native riparian vegetation
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