Historical Overview: Interplay of Contamination and in Coeur d’Alene Lake

Keynote Address Our Gem Symposium

Dr. Paul F. Woods Retired Limnologist U.S. Geological Survey

Selected Quantities, in millions of tons

• produced since 1885………………140

• Tailings discharged to rivers…………….62

• Tailings “stockpiled” on floodplain……58 Coeur d’Alene River’s Inflow Plume into Lake

Response of Industry

• Of course there’s a lot of metal in the bottom of Coeur d’Alene Lake………. it is downstream of a metal-rich watershed!!

• IF you took a deep core of the lakebed you would find high metal concentrations throughout its length.

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Selected Quantities, in millions of tons

• Ore produced since 1885………………140

• Tailings discharged to rivers…………….62

• Tailings “stockpiled” on floodplain……58

• Metal-contaminated sediment in Coeur d’Alene Lake………………………..83 Mass (tons) of Lead and Zinc in Contaminated and Background Sediments of CDA Lake • Contaminated Background Increase • Lead 516,000 1,870 275X • Zinc 254,000 10,600 24X

• Other with >10X increase included Antimony, Arsenic, Cadmium, and . • Background metal levels occurred prior to early 1900’s, about the time mining started. Federal Programs Related to Water-Quality Issues in the Spokane River Basin

 Superfund (CERCLA) - Bunker Hill Superfund Site is Nation’s second largest.

 Remedial Investigation/Feasibility Study (CERCLA) - Evaluation of contaminant release, fate, and . Considered a precursor to a Superfund listing.

 Natural Resources Damage Assessment (CERCLA) - Federal trust resources throughout Coeur d’Alene River Basin have been damaged. Largest NRDA action in Nation’s history. Metals in Water Column

Nutrients

Benthic Flux of Metals and Nutrients Productivity (Zn suppressed)

Hypolimnetic Dissolved oxygen

Benthic Flux of Metals in Coeur d’Alene Lake Benthic-flux chamber

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C6 C5 C4 TP above C3 TP below C1 0 50 100 150 200

C6 TPb above TPb bottom C5 C4 C3 C1 0 20 40 60 80

C6 TZn above TZn bottom C5 C4 C3 C1 0 50 100 150 200 Metals in Water Column

Nutrients

Benthic Flux of Metals and Nutrients Productivity (Zn suppressed)

Hypolimnetic Dissolved oxygen

Cyclic Interaction of Eutrophication and Metal Contamination in Coeur d’Alene Lake EUTROPHICATION

• Natural

versus

• Cultural Trophic State

• Oligotrophic—LOW biological production • Nutrients and Chlorophyll: LOW • Dissolved Oxygen Deficit: ABSENT

• Mesotrophic—MODERATE biological production • Nutrients and Chlorophyll: SLIGHT INCREASES • Dissolved Oxygen Deficit: MODERATE

• Eutrophic—HIGH biological production • Nutrients and Chlorophyll: HIGH • Dissolved Oxygen Deficit: SUBSTANTIAL Dissolved Oxygen, DO

• The limnological “Canary in the Coal Mine”

• That oxygen diffusing from the atmosphere into water or produced by phytoplankton photosynthesis.

• DO in lake mainly consumed by respiration, chemical oxidation, and biological decomposition.

• If demand exceeds supply, then a DO deficit occurs, usually in the lower water-column, or hypolimnion. Importance of Phosphorus as a Nutrient for Phytoplankton Growth • The “limiting nutrient” concept states that the ultimate yield of a crop will be limited by the essential nutrient that is most scarce relative to the specific needs of the crop.

• In the case of Coeur d’Alene Lake, that nutrient is phosphorus. • IF the lake’s sup