Kensington Gold Project Final Supplemental Environmental Impact ...

Table 2. Summary of Water Quality Criteria for Toxics in Discharges
to East Fork Slate Creek and Sherman Creek a
A-11
Kensington Gold Project Final SEIS
Appendix A
Pollutant Most Stringent Applicable Water Quality Criteria
Ammonia For Sherman Creek, acute and chronic criteria for the protection of aquatic life are
5.62 mg/L and 2.43 mg/L as N, respectively. These criteria are based on a maximum
water temperature of 14 °C and a maximum pH of 8.0 and the presence of early life
stages of salmonids in Sherman Creek. For East Fork Slate Creek, acute and chronic
criteria for the protection of aquatic life are 4.64 mg/L and 2.10 mg/L as N, respectively.
These criteria are based on a maximum water temperature of 14 °C and a maximum pH
of 8.1 and the presence of early life stages of salmonids in East Fork Slate Creek.
Nitrite 1 mg/L as N—primary MCL for drinking water
Nitrate 10 mg/L as N—primary MCL for drinking water
Total nitrite plus 10 mg/L as N—primary MCL for drinking water
nitrate
Aluminum 750 µg/L and 87 µg/L—acute and chronic aquatic life criteria
Arsenic 50 µg/L—primary MCL for drinking water and the standard for agricultural use
(stockwater), human health criteria
Cadmium 0.52 µg/L and 0.10 µg/L, 1.1 µg/L and 0.2 µg/L, 2.1 µg/L and 0.3 µg/L, 4.3 µg/L and
0.5 µg/L—acute and chronic aquatic life criteria with receiving water hardness of 25, 50,
100, and 200 mg/L CaCO3, respectively
Chromium III 0.58 mg/L and 0.028 mg/L, 1.0 mg/L and 0.05 mg/L, 1.8 mg/L and 0.09 mg/L, 3.2 mg/L
and 0.2 mg/L—acute and chronic aquatic life criteria with receiving water hardness of
25, 50, 100, and 200 mg/L CaCO3, respectively
Chromium VI 16 µg/L and 11 µg/L—acute and chronic aquatic life criteria
Chromium (total) 100 µg/L—the primary MCL for drinking water and the standard for agricultural use
(stockwater)
Copper 3.8 µg/L and 2.9 µg/L, 7.3 µg/L and 5.2 µg/L, 14 µg/L and 9.3 µg/L, 27 µg/L and
17 µg/L—acute and chronic aquatic life criteria with receiving water hardness of 25, 50,
100, and 200 mg/L CaCO3, respectively
Iron 1 mg/L—chronic aquatic life criterion
Lead 14 µg/L and 0.54 µg/L, 34 µg/L and 1.3 µg/L, 82 µg/L and 3.2 µg/L, 197 µg/L and
7.7 µg/L—acute and chronic aquatic life criteria with receiving water hardness of 25, 50,
100, and 200 mg/L CaCO3, respectively
Mercury 0.012 µg/L—chronic aquatic life criteria
Nickel 145 µg/L and 16 µg/L, 261 µg/L and 29 µg/L, 469 µg/L and 52 µg/L, 843 µg/L and
94 µg/L—acute and chronic aquatic life criteria with receiving water hardness of 25, 50,
100, and 200 mg/L CaCO3, respectively
Selenium 20 µg/L and 5 µg/L—acute and chronic aquatic life criteria
Silver 0.37 µg/L, 1.2 µg/L, 4.1 µg/L, and 13.4 µg/L—acute aquatic life criteria with receiving
water hardness of 25, 50, 100, and 200 mg/L CaCO3, respectively
Zinc 37 µg/L, 67 µg/L, 120 µg/L, and 216 µg/L—acute and chronic aquatic life criteria with
receiving water hardness of 25, 50, 100, and 200 mg/L CaCO3, respectively
a
From 18 AAC 70.020(b), which incorporates Tables I, II, III, and Columns A and B of Table V of the Alaska Water
Quality Criteria Manual (2003).