About Deer Lake AOC
Deer Lake is in central Marquette County near Ishpeming, Michigan. It was named an Area of Concern on the Great Lakes under the Great Lakes Water Quality Agreement of 1987.
The area was considered highly degraded because of:
- restrictions on consumption of fish and wildlife (primarily due to mercury contamination)
- eutrophicationeutrophicationA reduction in the amount of oxygen dissolved in water. The symptoms of eutrophication include blooms of algae (both toxic and non-toxic), declines in the health of fish and shellfish, loss of seagrass beds and coral reefs, and ecological changes in food webs. or undesirable algal blooms due to discharges of untreated and partially treated wastewater from the City of Ishpeming and Ishpeming Township
- reproductive problems in birds and animals, including bald eagles.
The Area of Concern includes:
- Part of Carp Creek, which flows into the south basin of Deer Lake
- Deer Lake, which measures approximately 1000 acres
- The Carp River, which flows about 20 miles from the north basin of Deer Lake to Lake Superior near Marquette
Beneficial Use Impairments
- Restrictions on fish and wildlife consumption - REMOVED 2014
- Bird or animal deformities or reproductive problems - REMOVED 2011
- Eutrophication or undesirable algae - REMOVED 2011
Deer Lake AOC was delisted in 2014.
Mercury in Fish
In 1981, due to very high concentrations of mercury in fish, the Michigan Department of Community Health put a ban on eating all fish from Deer Lake. Mercury concentrations in Deer Lake fish were also higher than the mercury levels found in fish from other, similar lakes at that time.
The main industrial source of mercury to the Deer Lake AOC was the Cleveland-Cliffs Iron Co. They discharged mercury-containing wastewater from its laboratories into the City of Ishpeming’s wastewater treatment system from 1929-1981. During that time, the city’s wastewater treatment plant discharged into Carp Creek, which then flowed into the south basin of Deer Lake.
In 1987, Deer Lake was declared an Area of Concern and the first remedial action plan document was completed.