Pre-restoration Assessment of Biological Condition for Radio Tower Bay in the St. Louis River Estuary

Abstract

The St. Louis River originates in northeast Minnesota and the lower 20 miles forms a 4856 ha freshwater estuary along the border with northwest Wisconsin. At the confluence with Lake Superior, the harbor is home to one of the busiest shipping ports on the Great Lakes. Despite more than 100 years of industrial use and urban development in the region, the St. Louis River estuary remains a significant source of biological productivity for western Lake Superior. Land use alterations through years of residential expansion and active industrial operations have created conditions in the estuary ranging from heavily impacted to those that remain relatively pristine. The estuary provides numerous sand and gravel beaches, islands, upland forests, sheltered bays, wetlands complexes, and other aquatic habitat types deemed essential for maintaining viable fish and wildlife communities. The lower St. Louis River and surrounding watershed was designated an “area of concern” (AOC) under the Great Lakes Water Quality Agreement in 1989 due to chemical contaminants, poor water quality, reduced fish and wildlife populations, and habitat loss. Nine beneficial use impairments have been identified in the AOC, including loss of fish and wildlife habitat, degraded fish and wildlife populations, degradation of benthos, and fish tumors and deformities. The St. Louis River Alliance is a community-sponsored organization that facilitates collaborative efforts associated with the St. Louis River AOC. Following the recommendations of the St. Louis River AOC Stage II Remedial Action Plan, the St. Louis River Alliance completed the Lower St. Louis River Habitat Plan (Habitat Plan) in 2002 as “an estuary-wide guide for resource management and conservation that would lead to adequate representation, function, and protection of ecological systems in the St. Louis River, so as to sustain biological productivity, native biodiversity, and ecological integrity” (SLRA 2002). The St. Louis River Alliance also facilitated development of “delisting targets” for each beneficial use impairment (BUI) in the St. Louis River AOC in December 2008. Radio Tower Bay is a small (18 ha) bay located in the upper reaches of the estuary near Gary, MN. Radio Tower Bay contains shallow open water, emergent and submergent aquatic vegetation, and is influenced hydrologically by both river currents and seiche activity. Historically, a sawmill operation in the early 1900s left the bay with significant amounts of wood waste and support pilings. The Minnesota DNR (MNDNR) and Minnesota Land Trust (MLT) secured funding from NOAA’s Marine Debris Removal Program to begin the restoration process by removing wood waste, pilings, and abandoned radio tower footings from the site. An adjacent reference location (North Bay) was included in the habitat assessment in order to provide an opportunity to establish comparisons both temporally and spatially regarding a target condition as restoration progresses in Radio Tower Bay. The Natural Resources Research Institute (NRRI), in cooperation with MLT and MN DNR, sampled Radio Tower Bay and North Bay to establish baseline information benthic macroinvertebrates, adult, juvenile, and larval fish assemblages and accompanying sediment and vegetation types. The project has been informed by previous collaborative efforts among NRRI, MLT, USFWS, MPCA, and MNDNR through the 40th Avenue West and 21st Avenue West remediation-to-restoration efforts.