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DEER LAKE MERCURY CONTAMINATION

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DEER LAKE MERCURY CONTAMINATION. A Brief History and Overview of the Amended Consent Judgment Steve Casey DNRE Upper Peninsula District. OVERVIEW Central Upper Peninsula Impoundment Hg from Mining, much via Ishpeming WWTP Complex Environmental Issue Some sources >100 yrs old

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Presentation Transcript
slide1

DEER LAKE

MERCURY

CONTAMINATION

A Brief History and Overview of the Amended Consent Judgment

Steve Casey

DNRE

Upper Peninsula District

slide2

OVERVIEW

  • Central Upper Peninsula Impoundment
  • Hg from Mining, much via Ishpeming WWTP
  • Complex Environmental Issue
  • Some sources >100 yrs old
  • “Yooper” municipal storm water system is part of the problem
mercury an unusual element
MERCURY: AN UNUSUAL ELEMENT
  • Metal that’s liquid at room temperature
  • Direct Toxicity of Ionic Mercury
    • Drinking water: 2,000 ppt
    • Aquatic Life: 770 ppt
  • Indirect Toxicity
    • Protect Wildlife (Fish Consumption): 1.3 ppt
  • Mining Uses
    • Explosive in blasting caps
    • Amalgam with gold and silver for processing
    • Laboratory Assay of Iron Ore
slide7

Deer Lake Impoundment

    • Lake Area = 1038 ac
    • Depth = 34 ft
    • Eutrophic anoxic hypolimnia, with excellent walleye fishery
    • Formerly: hypereutrophic
    • excellent pike/perch fishery
  • Ishpeming Wastewater
    • Raw sewage until 1963
    • Primary treatment until 1987
slide8

“Known” Mercury Releases in Deer Lake Watershed

    • Ropes Gold & Silver Co – 1882-1897
  • 216,894 tons of ore processed 1883-1896
  • Hg released – 5,000 lbs
  • Hg release to tailings – 900 lbs
    • CCIC – 1929-1981
  • 1929-63 Hg discharged with NO sewage treatment
  • 1963-81 Hg discharged via primary treatment plant
  • Total discharge of Hg = 2,306 lbs
    • Lake sediments contain about 8000 lbs of mercury today
timeline
TIMELINE
  • Ropes Environmental Assessment in 1980’s
  • One of 14 IJC “Areas of Concern” in Michigan
  • Consent Judgment with CCI in 1984
  • Reservoir Drained in mid 1980’s
  • Expectation for mercury levels decline not met
  • Late 1990’s, CCI and DNRE conduct studies
  • Parties Decide to Settle Issue in 2002
  • Amended Consent Judgment Entered in 2006
late 1990 s cci uw and dnre conduct parallel studies
Late 1990’s, CCI, UW and DNRE Conduct Parallel Studies
  • Cliffs Focused on:
    • External Loadings of Methyl and Total Mercury,
    • In Lake Production of Methyl Mercury
    • Reference Lakes
    • Recommended Alternatives to Reduce Water Column Methylation and Increase Fish Growth Rates
    • Implemented Hypolimnetic Release
dnre focused on mercury in sediments
DNRE Focused on Mercury in Sediments:
  • How Much
  • Distribution
  • Concentrations in Newly Deposited Sediment
  • Cost to Remove or Cover Sediments ($50-$100M)
dnre also looked at external sources of mercury to deer lake
DNRE Also Looked at External Sources of Mercury to Deer Lake
  • Total Loading to DLI = ¾ Pounds per Year (was ~40 lbs/yr)
  • About 22% from Cliffs Shaft Mine
  • About 2% from Ishpeming Area WWTP
parties decide to settle issue in 2002
Parties Decide to Settle Issue in 2002
  • Technical Issues will not Likely Be Resolved
    • Sediments a problem?
    • Drawdown may impact fish 20 to 30+ yrs.
    • Effectiveness of Dredging is Questionable
    • Natural Sedimentation Should Cover Contaminated Sediments in ~25 Years
key issues
Key Issues
  • Maintain Dam to Keep Sediments in Place and Provide Recreational Value [$750,000 Financial Assurance]
  • Provide the State Mitigation for Damages and Compensation for Taking Responsibility for Liabilities Associated with Mercury in Deer Lake [Cliffs transfers 1500 acres of land with 7 miles of lake frontage, 3 miles of river frontage, 7 lake and 6 river access points to state or local governments]
  • Funding for Improvements as Necessary [$500,000]
  • Control Mercury From Cliffs Shaft Mine [City of Ishpeming is seeking stimulus funding for new storm sewers]
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