The St. Louis River Estuary is the confluence of the St. Louis River with Lake Superior; to the west is Duluth, and to the east is its twin port city, Superior, Wisconsin. At 12,000 acres, the St. Louis River Estuary is the largest freshwater estuary in North America and is the headwaters of the Great Lakes.
In estuaries, water flow and the natural movement of sediments combine to provide unique shallow water habitats. Over the past 100 years, a legacy of historic commercial uses of the estuary disrupted and altered these natural habitats as shorelines and near shore areas were dredged and developed, and chemical contamination impacted the waters.
People recognized that legacy sediment contaminants needed to be remediated and that legacy habitat restorations needed to be restored. The St. Louis River Estuary was designated an international "Area of Concern" and a partnership of federal, state and tribal agencies is working together to restore the estuary.
Minnesota DNR is leading habitat restoration projects in the estuary intended to address degradations to fish and wildlife populations and to restore fish and wildlife habitat. DNR and its partners have identified ecological targets to guide selection, design, construction and monitoring of projects. These targets set goals for softening shoreline, increasing riparian connectivity, increasing diversity and area of wetlands, restoring aquatic vegetation, improving benthic macroinvertebrate communities and reducing sediments.
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The Chambers' Grove Park, a long established park of the Duluth park system, contains an artificial shoreline that has deteriorated over time. The current project replaces the park's deteriorating metal retaining wall and rock-filled gabion baskets with a more natural shoreline. This project removes the artificial structures, creates a natural shoreline, with improved conditions for migratory fish including sturgeon and provides access to the river for everyone. Project construction is scheduled August to November 2015.
Radio Tower Bay is a great example of the sheltered bays that distinguish an estuary. This one is choked with wood waste from historic sawmill operations, much of it deposited more than 100 years ago. The project is removing more than 100,000 cubic yards (CY) of logging-era wood waste and sediment within a 29 acre area. The material is removed from the bay, processed in a grinder on the barge, and then piped with slurry to a holding pond, where it dries. Once dried, the material will be used as mulch on the former U.S. Steel industrial site. The material removed from the water has been tested and is clean. The project was completed in summer 2015.
Knowlton Creek flows to the St. Louis River, adjacent to the ski slopes of Spirit Mountain. The creek's banks were washed out in several locations as a result of the June 2012 floods. The creek's banks will be restored and enhanced, which will provide habitat for trout and associated cold-water organisms, as well as reduce sediment loading to the St. Louis River. The project begins in fall 2015 and ends in December 2016.
Formed in 1934 when the St. Louis River navigation channel was dredged, Interstate Island rests on the border and is co-owned and managed by the states of Minnesota and Wisconsin. The island is federally listed as critical habitat for piping plover, and is one of only two nesting sites in the Lake Superior watershed used by the common tern which is listed as endangered in Wisconsin and threatened in Minnesota. The project restores the height of the island with high quality sandy material and anchoring stone and coble to restore the sandy, wind-swept habitat needed by both birds. Fencing and string grids already located on a small portion of the island will be repositioned so they can continue to provide protection from gulls and other avian predators. The project will be complete by December 2015.