K. Zamzow*, A. Maest, C.A. Woody, and D. Bogan*Center for Science in Public Participation

Geologic Society of America, November 2, 2010 Denver, CO

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Proposed copper-gold-molybdenum mine

Discovered by Cominco in the 1980s

Claims bought by the Canadian exploration firm Northern Dynasty Ltd in 2002

In 2007, Anglo-American and Northern Dynasty formed the Pebble Limited Partnership (PLP)

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Nushagak

Kvichak Lake Iliamna

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Potentially impacted region extends beyond PLP claims

Some rivers important to subsistence had no baseline water quality data

CommunicationPLP data

in pdf table formathas the caveat “do not cite or quote”, limiting

the potentially to release in-depth reviews

The independent study was funded by the Nature Conservancy, Alaska Office

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Surface water sampling 31 sites sampled at least once (2009-2010)7 sites were co-located with PLP sample sites

(2009)Sampling conducted during and after ice “break-

up”May 2009 June 2009 June 2010

Remote site helicopter support disposable tubing and filters replaced at every site

Full QA/QC

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Kaskanak MtNorth

Fork K

oktuli

South Fork Koktuli

Upper Talarik

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Analyte May June

Temperature (C) 0-3 6-9

Dissolved oxygen (mg/L)

na 9-11

pH6.2-7.3

(5.4)7.1-7.7

(5.5)

Specific conductance (uS/cm)

11-32(5)

25-48(5)

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Waters in and around the proposed Pebble Mine site have very low concentrations of metals

Copper is elevated near the ore body; a few sites are elevated in aluminum and/or lead.

Metal concentrations increased briefly during ice break-up

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Analyte units DEC Standard Maximum

gross alpha pCi/L 15 1.8

gross beta pCi/L * 3.3

Antimony ug/L 6 0.08

Arsenic ug/L 10 2.5

Chromium ug/L 100 1.09

Cyanide ug/L 5.2 < 0.01

Mercury ng/L 50 5.4

Molybdenum ug/L 10 1.7

Nickel ug/L 10.5 0.94

Selenium ug/L 5 0.3

Uranium ug/L 30 0.12

Zinc ug/L 24 15.3

Lead, diss. ug/L 0.3 0.08Cadmium, diss.

ug/L 0.07 0.05 11

AnalyteDEC Standard

(ug/L)Sites with concentrations greater than

DEC standards

Cadmium, total 0.07SK-12 (0.09)SK-11 (0.08)

Copper, total 1.8SK-12 (5.6)SK-31 (5.3)

Copper, dissolved 1.77SK-31 (3.6)SK-12 (1.9)

Lead, total 0.28

SK-12 (0.9)CH-11 (0.6)SK-11 (0.5) KC-01 (0.4)NW-11 (0.3)UT-02 (0.3)

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Blue below stdYellow at or above stdRed more than 2x std

Standard 1.8 ug/L at 15 mg/L hardness

Bar to the left represents May; one bar only means sample was only taken in June 2009. No sites exceeded total or dissolved copper except 2 sites near the ore body, and CH-11 in May only.

Cu

Kaskanak MtNorth

Fork K

oktuli

South Fork Koktuli

Upper Talarik

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Waters are low in parameters that can moderate the toxicity of metals such as hardness and DOC.

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Low solutes, including low metals. Some higher concentrations near ore deposit.

Independent data is in agreement with PLP data.

The system has little ability to buffer acid or mitigate metal toxicity.

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