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Great Lakes AOCs

About Deer Lake AOC - Delisted

Deer Lake is in central Marquette County near Ishpeming, Michigan.  In 1987, Deer Lake was declared an Area of Concern under the Great Lakes Water Quality Agreement of 1987.  It was the first remedial action plan document completed.  Deer Lake was delisted in 2014.   Learn more about what happens after delisting.

Sources of Pollution

AOC Boundaries

  • 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

Beneficial Use Impairments for the Great Lakes AOCs

  • Restrictions on fish and wildlife consumption - REMOVED 2014
  • Bird or animal deformities or reproductive problems - REMOVED 2011
  • Eutrophication or undesirable algae - REMOVED 2011

Mercury in Fish

Sign at Deer Lake AOC warning of fish consumption advisories
A fish consumption advisory is in effect for Deer Lake. Restrictions on fish and wildlife consumption is one of the beneficial use impairments for this AOC.

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.


Restoring Deer Lake AOC (timeline)


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The City of Ishpeming also contributed $700,000 to the restoration project.

MDEQ is responsible for executing many of the remedial actions that have occurred at Deer Lake. Additionally, they publish the remedial action plan documents.

Visit MDCH's website for the most up-to-date information regarding fish consumption and their "Eat Safe Fish" guide.