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APPENDIX A <br /> Reference Water Quality <br /> A_1 Definition of"Reference Water Quality" and the Time Periods of Concern <br /> "Reference water quality" is defined as a statistical determination of dissolved <br /> zinc (Zn) concentrations at reference point A-72 for the time period of January 5, <br /> 1989 through September 6, 1995. During this time there exist 63 measurements <br /> of dissolved zinc at the reference point which also have either simultaneous <br /> measurements of stream flow or inferred stream flows based on linear regression <br /> analysis of flow data from the Howardsville Station to Station A72. The set of 63 <br /> measurements of coupled flow and dissolved Zn data collected is termed "the <br /> baseline set" representing the available history of dissolved Zn and stream flow at <br /> the reference point. This set of data defines reference water quality against which <br /> future water quality will be compared. The reference water-quality data are listed <br /> in Attachment 1. <br /> Time following the signing of a Consent Agreement between the State of <br /> Colorado and Sunnyside Gold Company (SGC) shall be divided into two periods: <br /> ► "Project period" is defined to be the time period that begins with the <br /> initiation of mine closure and reclamation activities that are the subject of <br /> the Consent Agreement and ends when (a) A-list projects have been <br /> completed; (b) mine pool equilibrium has been reached; (c) Cement Creek <br /> treatment has ceased; and(d) lower American Tunnel hydrologic controls <br /> and portal plug are complete. <br /> ► "Post-project period" is defined to be the time period that begins <br /> immediately after the "project period" and ends when SGC has been <br /> released from water-quality permits under the terms of the Consent <br /> Agreement. <br /> A=2 Classes of Flow <br /> The high-mountain portion of a river such as the Animas is subject to seasonal <br /> fluctuations in flow due to hydrologic response of the basin to climatic factors. <br /> Flow and the concentration of dissolved constituents in any river water are <br /> generally inversely related. <br /> 325/2-/,512�96 La <br />