DEER LAKEMERCURY

CONTAMINATION

A Brief History and Overview of the Amended Consent Judgment

Steve Casey

DNRE

Upper Peninsula District

OVERVIEW

Central Upper Peninsula ImpoundmentHg from Mining, much via Ishpeming WWTPComplex Environmental IssueSome sources >100 yrs old“Yooper” municipal storm water system is part of the problem

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

Deer Lake ImpoundmentLake Area = 1038 acDepth = 34 ftEutrophic anoxic hypolimnia, with excellent walleye fisheryFormerly: hypereutrophicexcellent pike/perch fishery

Ishpeming Wastewater Raw sewage until 1963Primary treatment until 1987

“Known” Mercury Releases in Deer Lake Watershed

• Ropes Gold & Silver Co – 1882-1897216,894 tons of ore processed 1883-1896 Hg released – 5,000 lbs Hg release to tailings – 900 lbs

• CCIC – 1929-19811929-63 Hg discharged with NO sewage treatment1963-81 Hg discharged via primary treatment plantTotal discharge of Hg = 2,306 lbs

•Lake sediments contain about 8000 lbs of mercury today

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

Northern Pike in 1984

Deer Lake Northern Pike 1984 vs. Western Upper Peninsula Lakes

00.5

11.5

22.5

33.5

44.5

5

0 50 100 150

Length (cm)

Hg

Co

nc

en

tra

tio

n (

pp

m)

Northern Pike WesternUpper Peninsula 1984-2004

Deer Lake NorthernPike 1984

Mercury Concentrations in Pike before and after stopping CCI Discharge and Draining Lake

Deer Lake Northern Pike 1984 vs. Western Upper Peninsula Lakes

00.5

11.5

22.5

33.5

44.5

5

0 50 100 150

Length (cm)

Hg C

once

ntra

tion

(ppm

)

Northern Pike WesternUpper Peninsula 1984-2004

Deer Lake NorthernPike 1984

Deer Lake Northern Pike 1987 vs. Western Upper Peninsula Northern Pike 1984-2004

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 50 100 150

Length (cm)

Hg C

once

ntra

tion (

ppm)

Northern Pike WesternUpper Peninsula 1984-2004Northern Pike DeerLake 1987 (PostDrawdown of Reservoir)

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:

• 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

– 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

• 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

Deer Lake Perch 1984 vs. Deer Lake Perch 2001

0

0.5

1

1.5

2

2.5

0 10 20 30 40

Lenght (cm)

Hg

Con

cent

ratio

n (p

pm)

Deer Lake Perch 1984

Deer Lake Perch 2001

Deer Lake Walleye 2001-2003 vs. Western Upper Peninsula Walleye

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 20 40 60 80

Length (cm)

Hg

Con

cent

ratio

n (p

pm)

Western Upper PeninsulaWalleye 2001-2003

Deer Lake Walleye 2001-2003

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]

QUESTIONS?