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Animas River below Silverton. A72 <br />Remediation of the combined mine waste and the phase 1 edit scenario should reduce <br />levels of Cd, Cu, and Zn during average stream flow. Cd and Cu concentrations will be <br />close to chronic TVS for aquatic life but may exceed those criteria in the spring. Zn will <br />continue to be at a level that exceeds both acute and chronic TVS for aquatic life year-a- <br />round. Fe and Mn concentrations may be slightly lower, however, total recoverable Fe <br />v~~ill corninue to exceed TVS year-a round. Mn currenly is lower than the TVS. Neither <br />phase 1 nor phase 2 remediation is expected to have much effect on the current level of <br />dissolved Al. Aluminum would continue to be a limiting factor. If a sufficient amount of <br />the load of Cd, Mn, and Zn that enters the Animas River between Arrastra Gulch and <br />A68 can be "reversed," further improvements in those constituents should be seen at <br />A72_ <br />Reductions in pH <br />Current TVS for pH is 6.5 to 9.0. pH is a measurement of hydrogen ions based on a <br />logarithmic scale (base 10} so that a whole number increase, from 5.0 to 6.0 for example, <br />signifies a ninety percent reduction in the concentration of hydrogen ions. The presence <br />of iron is a major factor in determining pH. <br />In winter, pH is 6.1, 5.5, and 4.8 for segments 3a, 4a, and 9b respectively. Attempts <br />were made to model potential improvements in pH due to remediation, but they were <br />unsuccessful. Because of the low potential reductions identified for iron above A68, it is <br />uncertain whether pH will be improved. The possibility of improving pH is higher at <br />M34 and A72, because of the potential for reductions in iron loading, but the amoum of <br />improvement is probably quite small. Reaching the TVS standard is highly unlikely. <br />Remediation Summary <br />Completion of the proposed remediation projects will result in TVS being met at <br />several locations for some but not all metals. It is impractical to meet TVS at all <br />locations. This is due to the large amount of natural metal and acid production throughout <br />the Upper Animas ~vatershed. This problem was evidently realized when the Clean <br />Water Act was passed as it requires that aquatic life standards be met, as a minimum, if <br />practical to do so. The Animas Watershed Plan is designed to be a practical attempt to <br />meet the requirement. There currently is no plan to treat naturally occurring metal and <br />acid contributions. The Animas UAA, plus other information developed during WQCC <br />triennial review period, demonstrates significant improvement to water quality and <br />aquatic habitat will result in an improved fishery and associated aquatic life. While <br />Cement Creek is expected to remain devoid of life, the Animas main stem is expected to <br />sustain a brook trout fishery immediately below Silverton (Segment 4a) and four species <br />of trout below Elk Park (Segement 4b}. Many streams will witness improved bernlric <br />macroinvertebrate life. New stream standards and use classifications have been adopted <br />by the WQCC that reflect the reductions anticipated from the remediation envisioned in <br />this plan, plus the biological potentials of the receiving streams. <br />