Ceded territories mining update
By Bill Mattes, GLIFWC Great Lakes Biologist
Gay, Mich.—Help may now be on the way to mitigate negative impacts of stamp sands lining the shores of the Keweenaw Pennisula on important spawning grounds for lake trout and whitefish.
The U.S. Army Corps of Engineers–Detroit District (Corps) has completed a preliminary restoration plan to address stamp sand deposits along the east side of Keweenaw Bay near Gay, Michigan under the Great Lakes Fishery and Ecosystem Restoration program with funding by the Great Lakes Restoration Initiative. It is estimated by the U.S. Environmental Protection Agency and the Corps that the stamp sands cover 1,426 acres of shoreline and lake bottom lands. The most affected shoreline extends from the Tobacco River to the Traverse River breakwall (see photo courtesy of GoogleEarth), and can be seen as a dark shoreline compared with the lighter colored native sands located southwest of the Traverse River breakwall and northeast of the Tobacco River.
GLIFWC previously obtained funding to collect baseline data on the location of stamp sands in relation to Buffalo Reef, an important spawning ground for lake trout and whitefish, which is assessed bi-annually by GLIFWC's Great Lakes Section. This study concluded that the stamp sands were encroaching upon the reef as was first reported by tribal commercial fishermen.
Since this study, Michigan Technological University has worked with the Corps, the Keweenaw Bay Indian Community, and others to further define the migration and effects of the stamp sands. Additionally, the Corps has collected samples of stamp sands to conduct tests of methods to stabilize and reduce toxicity of the stamp sands.
What are stamp sands?
Shallow deposits of copper enabled the Keweenaw Peninsula to become one of the most productive mining regions of the country between 1864 and 1930. During this period, stamp mills were built near lakes and rivers to crush the ore and separate the copper from the rock by flotation. The waste material from these mills, referred to as stamp sands, was deposited in vast quantities in the vicinity of the stamp mills. These deposits of fine grained mine tailings (sand size particles or smaller) were deposited into nearshore environments of Lake Superior or piled along the shores of the Keweenaw Peninsula.
While copper mining activities ended at most sites many decades ago, stamp sand deposits persist and have had a marked effect on the region. After initial deposition, waves and currents rework the stamp sands leaving the coarsest materials along stream banks and lakeshores.
Of these features, the Gay Peninsula is among the most prominent. This peninsula, located immediately south of the town of Gay (and its copper smelter), is composed almost entirely of stamp sands. Weathering processes have caused this extensive stamp sand area to erode, and stamp sands have moved south along the coast and into Lake Superior away from the area of initial deposition.
Problems posed by stamp sands
Migration of stamp sands may pose significant environmental hazards. Leaching of trace metals from stamp sands has been well documented and research has shown that many areas of stamp sands are unable to support vegetation.
In addition, lakes into which stamp sands have been dumped have been found to be nearly devoid of benthic (bottom dwelling) animals and concentrations of mercury and copper in sediments are high compared to uncontaminated areas of the lake.
Of equal concern are the effects that the addition of large amounts of fine material may have on the habitat of the region. Fish species often depend on spaces and small openings in and between rocks to provide shelter for eggs and young fish. The filling of these spaces by an influx of stamp sands could drastically reduce suitable habitat.
Tribes maintain a commercial whitefish and lake trout fishery, and harvest of these fish is an important cultural and economic activity for tribal members. Tribal fish harvesters have become increasingly concerned about the effects that the stamp sand deposits may have on Buffalo Reef.
Evidence shows that the sands are moving toward the reef, which will likely impact the continued ability of the reef to support ample spawning sites for whitefish and lake trout. The impairment of this reef could lead to a decline in these important species, impairment to federally guaranteed treaty reserved-rights, and an impact on the tribal communities that depends on this resource.
For more information on ACOE GLFER projects visit www.glfc.int/glfer/projects.htm