Lake Superior - South

Knife River, Lake Superior-South Watershed

Related: Duluth Urban Streams Watershed

The Duluth Urban Area Streams Watershed is a focused geographic area designed to recognize the complexity and challenges in an urban center with a water-rich environment. It is defined by a series of small watersheds that are portions of three major watersheds: Lake Superior - South, St. Louis River and Nemadji River.

The Lake Superior - South watershed covers 402,371 acres. Located in the Northern Lakes and Forest Ecoregion, the soils and subsurface geology are dominated by bedrock, glacial till complexes, and erodible lake-laid clay soils. Bedrock is complex in its evolution and contributes to the spectacular mountains and ridges that slope toward Lake Superior. Numerous streams flow through the bedrock cracks forming waterfalls, cascades, and rapids. Lakes are found predominantly in the northeastern-most section. Major developed areas include the city of Duluth and towns of Two Harbors, Beaver Bay, and outskirts of Silver Bay. Significant development is also located along Lake Superior’s shoreline.

Land use in the Lake Superior - South watershed is a mix of urban and commercial, resort and rural residential. Tourism and forest products are significant components of land-use activity. Some commercial/industrial uses, including marinas, shipping ports, and taconite processing support, utilize and/or depend upon water resources.

Two major state parks, Gooseberry and Split Rock Lighthouse, are within the watershed. The smaller Tettegouche State Park is located on the watershed’s far eastern boundary.

The watershed is a source of exceptional water quality in many lakes, streams and rivers. However, some streams do not meet water quality standards for beneficial uses such as aquatic recreation, drinking, and swimming due to excess levels of turbidity and bacteria (E. coli). Turbidity is associated with suspended sediment. Additional stressors such as elevated stream temperatures in recent summers and lack of persistent flow have become sources of concern for resource managers.

Major developed areas include the city of Duluth and towns of Two Harbors, Beaver Bay, and outskirts of Silver Bay. Significant development is also located along Lake Superior’s shoreline.

The watershed’s southwestern area is the most densely populated; this includes Duluth and an urbanizing fringe of smaller, adjacent communities and townships. Continued development pressures increase the potential for pollution problems in area streams. However, this area is also regulated through Municipal Stormwater Permits which contain specific requirements for stormwater discharges for the greater Duluth Metropolitan Area.

What's being done

Monitoring and assessment

Several streams were intensely studied most recently between 2001 and 2006. Data help resource managers better understand the rates of non-point (non-specific origins) source pollution. A more recent study (see link below) is an in-depth effort to understand sediment loading and its effect on stream health along the North Shore. The large number of sites being monitored is due to the level of interest among local residents, university researchers and professional resource agencies. For more information about individual streams, visit the Lake Superior Streams website.

The MPCA’s intensive watershed monitoring effort began in 2011. An assessment of all relevant data was completed in 2013; waterbodies identified as not meeting designated uses were added to the Draft 2014 Impaired Waters list. Additional study began in 2013 to identify stressors contributing to the impaired waters. A Monitoring and Assessment Report was completed in 2014. Watershed modeling, TMDL studies and a restoration and protection report suggesting implementation strategies have been completed.

Strategy development for restoration and protection

Implementation plans

The Knife River TMDL for turbidity was completed and approved in 2010 and the implementation plan was completed in 2011.