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Addressee Name <br />Date <br />Page 2 <br />d. There is no flow data reported for NF -3 in 2011. OMLLC needs revise the 2011 <br />AHR to provide data for flow measurements for 2011 at NF -3. <br />2. Groundwater Quality: <br />a. Significant increases were reported in Sulfate (SO4), Fe (both total recoverable and <br />dissolved), and Zinc (Zn) at SC -1 and phosphate (PO4), nitrate /nitrite (NO3/NO2), and <br />TDS at SC -3. Under Rule 4.05.13(4)(c), OMLLC should revise the 2011 AHR to <br />interpret these values and identify whether or not this is a mining related impact. <br />b. Bicarbonate (HCO3) is markedly decreased at SC -1 and SC -3 in 2011. Under Rule <br />4.05.13(4)(c), OMLLC should revise the 2011 AHR to interpret these values and <br />identify whether or not this is a mining related impact. <br />3. Alluvium: <br />a. Significant increases in PO4, Fe (both total recoverable and dissolved), and Zn were <br />seen at all three alluvial wells (BC -1, EC -14, and EC -15). Under Rule 4.05.13(4)(c), <br />OMLLC should revise the 2011 AHR to interpret these values and identify whether <br />or not this is a mining related impact. <br />b. Wells BC -land EC -14 both show a decreasing trend in pH values. Under Rule <br />4.05.13(4)(c), OMLLC should revise the 2011 AHR to interpret these values and <br />identify whether or not this is a mining related impact. <br />c. HCO3 is markedly decreased in BC -1, EC -14, and EC -15 in 2011. Under Rule <br />4.05.13(4)(c), OMLLC should revise the 2011 AHR to interpret these values and <br />identify whether or not this is a mining related impact. <br />4. Surface water flow: Surface water flows reported were within historic ranges with the <br />exception of S -1 in April 2011. This site on upper Sanborn Creek was reported at 18.75 <br />cfs, well outside the historic range. OMLLC should revise the 2011 AHR to interpret this <br />value, offer any known explanation for it, and identify whether or not this is a mining <br />related impact. <br />5. Surface water quality: <br />a. Significant increases in TSS, Mn, chloride (Cl), phosphate (PO4), nitrate /nitrite <br />(NO3/NO2), sulfate (SO4), and Fe (both total recoverable and dissolved) were seen at <br />most of the surface water sites in April. Under Rule 4.05.13(4)(c), OMLLC should <br />revise the 2011 AHR to interpret these values and identify whether or not this is a <br />mining related impact. <br />b. HCO3 is markedly decreased at several surface water sites (H -1, E -1, E -2, C -1, NF -3, <br />and NF -1) in 2011. Under Rule 4.05.13(4)(c), OMLLC should revise the 2011 AHR <br />to interpret these values and identify whether or not this is a mining related impact. <br />6. Field pH and conductivity and laboratory analyzed pH and conductivity are fairly <br />inconsistent at some sites (S -1, C -1, NF -1, HN -1), indicating that the meters used in the <br />