Intensive copper mining and reclamation took place in the Keweenaw Peninsula from 1845 through 1968. Extraction of copper metal from mined rock and reclamation materials during that time continues to affect the Torch Lake area decades later.
For example, the Torch Lake area experienced the following:
- Between 1868 and 1968, six large-volume stamping mills crushed rock to separate the copper ore, creating stamp sands as a waste product.
- Vast amounts of stamp sands were discharged into Torch Lake by the stamping mills along the western shore of the lake; as a result, 50 percent of the lake volume was filled with stamp sands at one point.
- Process wastes from refining metal in smelters were quenched with lake waters and left in the lake or on land.
- Between 1915 and 1967, stamp sands containing residual copper were dredged from the bottom of the lake and reprocessed chemically by three mills on the western shore of the lake.
In the 1970s, fish caught in Torch Lake were found to have tumors. This finding led to fish consumption advisories and the recognition that the lake bottom had been damaged (degraded benthos). Ultimately, Torch Lake was deemed so polluted it was both designated as a Superfund site (on the National Priority List) in 1984. In 1985 it was included on the original list of Areas of Concern (AOCs), under the U.S.-Canada Great Lakes Water Quality Agreement (GLWQA, 1985).
What is an Integrated Assessment?
Rather than collecting new data or running additional experiments, an integrated assessment (IA) summarizes what is known and offers an assessment of how the science could be interpreted and used. The research team focuses on a complex environmental issue and then conducts a comprehensive analysis of natural and social scientific data and information.
The IA process is different from traditional research because researchers work closely with stakeholders to examine an issue from many perspectives, identify challenges, and evaluate feasible solutions. The aim is to create results that are current, trusted, accessible, and useful.
In 2012, Michigan Sea Grant funded a Michigan Technological University research team to conduct an integrated assessment of the Torch Lake AOC, a site which includes Torch Lake and its watershed.
This is a challenging site to investigate because of conflicting information on the success of remediation efforts and the remaining problems on site. For instance, from 2002-2006, the EPA conducted remediation by capping sediments and removed portions of the site from the Superfund site list. The Public Advisory Council petitioned the State of Michigan to delist the site as an AOC. However, the State of Michigan Department of Environmental Quality reported that sampling of the site showed contamination above acceptable levels and that two of the environmental issues (called beneficial use impairments or BUIs) that caused the AOC designation still exist as of October 2016.
Further, the caps of polluted soils are proving to be vulnerable to erosion at Torch Lake, which could potentially introduce dangerous substances into the lake, where they may prolong the impairment of the lake bottom. The EPA reported that there was not enough information available to accomplish rapid remediation of the site, where rapid means before natural attenuation will cover the lake bottom with sediments through sedimentation (a process expected to require hundreds of years).
This integrated assessment project included the following activities:
- Gathered available data about past and current contamination using existing reports, archives, and oral interviews of former mine workers.
- Evaluated, refined, and in fifteen meetings, presented information to stakeholders.
- Worked with local, state, and federal stakeholders to identify approaches for reinvigorating the restoration process.
- Developed information to guide future work, including maps illustrating sites with high PCBs and copper, as well as models indicating likely sources of ongoing contamination.