St Louis River Estuary: The stories and the science

Knowlton Creek

Knowlton Creek is a tributary to the St. Louis River with a 2.5 square-mile forested watershed that is near the Spirit Mountain Recreation Area (SMRA). The stream channel had been degraded by human activities within the watershed. The degradation had deposited a large amount of sediment into the St. Louis River, filling in a shallow sheltered bay behind Tallas Island. Part of the deposited sediment was dredged in an earlier project during 2010. The 2012 flood caused the deteriorating railroad grade at the upstream end of the proposed restoration area on the main stem of Knowlton Creek to fail.

The proposed project consisted of the restoration of 6,500 linear feet by reshaping the existing channels; reestablishment of new channels; construction of in-stream structures; native planting and seeding.  Restoration also included in-stream structures such as log vane/rootwad combinations, toe wood/sod mat, log and rock steps, and constructed riffles as well as vegetation of the stream banks and establishment of a forested riparian corridor along the stream.

The project was completed in coordination with the SMRA’s water management structure, the Grand Avenue bridge-replacement project and the City of Duluth trails project.

The project was completed as a part of the delisting process for the St. Louis River Area of Concern in spring of 2017. It was designed through a partnership between the Clean Water Legacy fund and the U.S. Army Corps of Engineers. Funding for construction was provided by the U.S. Environmental Protection Agency (through the Great Lake Restoration Initiative), the MN Outdoor Heritage Fund and the National Fish and Wildlife Foundation.

Knowlton Creek Reach 2 of the main stem prior to restoration. Click to zoom.

Knowlton Creek Reach 2 of the main stem prior to restoration.

Knowlton Creek Reach 2 of the main stem after restoration. Click to zoom.

Knowlton Creek Reach 2 of the main stem after restoration.


Minnesota Department of Natural Resources (MDNR) Objectives:

  • Restoration of approximately 6,500 lineal feet of the creek channel
  • Replacement or removal of three culverts
  • Removal of a remnant causeway and culvert destroyed during the 2012 flood and restoration of the creek channel
  • Restoration of the riparian floodplain impaired by the 2012 flood as well as restoration of a resilient stream channel

SMRA Objectives:

  • Construction of a water control structure at the bottom of Spirit Mountain Ski Hill to direct excess flow away from the creek and directly to the river through a dual-use pipe that will also be used to pump water up the hill from the estuary for snow making.
  • Implementation of best management practices on the ski hill to reduce run-off and erosion, including construction of several settling basins.

Restoration Timeline

  • 2015 – SMRA constructed Spirit Mountain water control and water uptake structures.
  • 2015 – MNDNR completed restoration objectives in the tributaries of Knowlton Creek.
  • 2017 – MNDNR completed restoration objectives in the main stem of Knowlton Creek.

What is happening Now?

Knowlton Creek will be included in the AOC post-project monitoring efforts.  After 2025, natural resources will be monitored as part of on-going programs by the MNDNR.  This will include annual fisheries indexing within the St. Louis River estuary and periodic monitoring of fisheries resources of Knowlton Creek.