Lake Superior Streams Sediment Assessment: Phase I

Under the Clean Water Act, states are required to monitor their water bodies for water quality impairments. While Minnesota's North Shore has relatively little development as compared to other areas of the state, degraded stream health does still exist. At present, 12 of Minnesota's major tributaries draining to Lake Superior are impaired for turbidity, mercury and chlorides as well as low dissolved oxygen, lack of cold water assemblages and pH. Turbidity and excess sediments are the leading causes of water quality impairments throughout the United States and turbidity is identified as an impairment on 10 of the 12 streams impaired along the North Shore. These turbidity impaired streams include the Knife, Poplar, Beaver, Flute Reed, French, Lester, Talmadge and Big Sucker Rivers as well as Amity and Skunk Creeks. Excessive turbidity in these streams is largely dependent on elevated suspended sediment levels. These sediments are delivered to streams from upland sources of erosion as well as instream erosion of channel banks and bluffs.