This 35-year old hydrologic study documents conditions in the Cu-NU region of Minnesota’s Iron Range. It is primarily a technical report, but its main value is the baseline data provided, and that it contains a water budget for the area. It’s primary message for decision-makers is that “the introduction of trace metals from future mining to the ground-water system can be reduced if tailings basins and stockpiles are located on material of low permeability, such as till, peat, or bedrock." Key segments are extracted and reproduced below. Abstract: "Data were collected on the hydrology of the Copper-Nickel study region, to identify the location and nature of ground-water resources, determine the flow characteristics and general quality of the major streams, and determine the potential effects of mining copper and nickel on the hydrologic system. Ground-water investigations indicate that water generally occurs in local flow systems within surficial deposits and in fractures in the upper few hundred feet of bedrock. Availability of ground water is highly variable. Yields commonly range from only 1 to 5 gallons per minute from wells in surficial materials and bedrock, but can be as much as 1,000 gallons per minute from wells in the sand and gravel aquifer underlying the Embarrass River valley. Except over the mineralized zone, ground water in the surficial deposits is a mixed calcium magnesium bicarbonate type. Ground water over the mineralized zone generally has both a greater percentage of sulfate, compared to bicarbonate, and concentrations of copper and nickel greater than 5 micrograms per liter. "Surface-water investigations indicate that the average annual runoff from streams is about 10 inches. Plow characteristics of streams unregulated by industry are similar, with about 60 percent of the annual runoff occurring during snowmelt in April, May, and June. Flood peaks are reduced in the Kawishiwi River and other streams that have surface storage available in onchannel lakes and wetlands. These lakes and wetlands also trap part of the suspended-sediment load. Specific conductance in streams can exceed 250 micromhos per centimeter at 25° Celsius where mine dewatering supplements natural discharge. "Between 85 and 95 percent of the surface water used is for hydroelectric power generation at Winton and thermo-electric power generation at Colby Lakes. Mine dewatering accounts for about 95 percent of the ground-water used. Estimated ground-water discharge to projected copper-nickel mines ranges from less than 25 to about 2,000 gallons per minute, depending on the location and type of mining activity. The introduction of trace metals from future mining to the ground-water system can be reduced if tailings basins and stockpiles are located on material of low permeability, such as till, peat, or bedrock."
Siegel, Donald I; Ericson, Donald W.
Hydrology and Water Quality of the Copper-Nickel Study Region, Northeastern Minnesota.
Retrieved from the University of Minnesota Digital Conservancy,
Content distributed via the University of Minnesota's Digital Conservancy may be subject to additional license and use restrictions applied by the depositor.
Showing items related by title, author, creator and subject.
This very comprehensive document was reviewed and is felt to have significant content and analysis relevant to Minnesota’s coastal area and water resources. It also contains biophysical and watershed-related content directly ...
We used paired 2‐block street sections in the Amity Creek watershed (Duluth, MN) to demonstrate the effectiveness of homeowner BMPs to reduce residential stormwater flow to storm sewers in an older neighborhood in a cold ...
Arnott, Sigrid; Birk, Douglas A; Maki, David (Archaeo-Physics, LLC, 2013)
This study assessed 31 historic mill dam sites in Minnesota. Of these, one was located in the Sea Grant coastal area. The study discusses broader impacts of dams on tribal, cultural and environmental resources generally, ...