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 1

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) 2

Nushagak Kvichak Lake Iliamna 3

Potentially impacted region extends beyond PLP claims Some rivers important to subsistence had no baseline water quality data Communication PLP data in pdf table format has the caveat “do not cite or quote”, limiting the potentially to release in-depth reviews The independent study was funded by the Nature Conservancy, Alaska Office 4

Surface water sampling 31 sites sampled at least once ( ) 7 sites were co-located with PLP sample sites (2009) Sampling conducted during and after ice “break-up” May 2009June 2009June 2010 Remote site helicopter support disposable tubing and filters replaced at every site Full QA/QC 5

Kaskanak Mt North Fork Koktuli South Fork Koktuli Upper Talarik 6

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AnalyteMayJune Temperature (C) Dissolved oxygen (mg/L) na9-11 pH (5.4) (5.5) Specific conductance (uS/cm) (5) (5) 8

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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 10

AnalyteunitsDEC StandardMaximum gross alphapCi/L gross betapCi/L *3.3 Antimonyug/L Arsenicug/L Chromiumug/L Cyanideug/L 5.2< 0.01 Mercuryng/L Molybdenumug/L Nickelug/L Seleniumug/L 50.3 Uraniumug/L Zincug/L Lead, diss.ug/L Cadmium, diss. ug/L

Analyte DEC Standard (ug/L) Sites with concentrations greater than DEC standards Cadmium, total0.07 SK-12 (0.09) SK-11 (0.08) Copper, total1.8 SK-12 (5.6) SK-31 (5.3) Copper, dissolved1.77 SK-31 (3.6) SK-12 (1.9) Lead, total0.28 SK-12 (0.9) CH-11 (0.6) SK-11 (0.5) KC-01 (0.4) NW-11 (0.3) UT-02 (0.3) 12

Bluebelow std Yellowat or above std Redmore 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 No sites exceeded total or dissolved copper except 2 sites near the ore body, and CH-11 in May only. Cu Kaskanak Mt North Fork Koktuli South Fork Koktuli Upper Talarik 13

Waters are low in parameters that can moderate the toxicity of metals such as hardness and DOC. 14

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. 15