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Minrec, Incorporated Water Quality Assessment CO- 0048233 the most recent policy entitled Implementing Narrative Standards in Discharge Permits for the Protection of Irrigated Crops (hereafter the Narrative Standards policy). Based on available information, the water in North Thompson Creek is not used for irrigation water. However, the water in Thompson Creek, 5 miles downstream of the discharge and just prior to the confluence with the Crystal River is used for irrigation water. According to the local water commissioner, three active diversions at the mouth of Thompson Creek drain essentially all water from the creek. Thus, flow data from these diversions reflect flows in this area of Thompson Creek. To determine current flow conditions, recent flow data from each diversion structure was used in the analysis. Daily flow data for Pioneer Ditch and Northside Thompson Ditch was available for 2008, while daily flow data from 2006 was available for Thompson Ditch. The diversions and associated flows are shown in table A -8. Table A -8 WDID Structure Name Source Average Flow (CFS) 3800909 NORTHSIDE THOMPSON D THOMPSON CREEK 2 3800939 PIONEER DITCH THOMPSON CREEK 8.7 3801131 THOMPSON DITCH THOMPSON CREEK 3.9 The ratio of the flow of Thompson Creek to the Minrec design flow is 162:1. The available dilution ratio of flow to discharge is > 100:1, therefore in accordance with the Division's Protection of Irrigated Crops Policy, no limitations are required. Thus, details of this policy are not applicable to this discharge and will not be considered at this time. VII. Antidegradation Evaluation As set out in The Basic Standards and Methodologies for Surface Water, Section 31.8(2)(b), an antidegradation analysis is required except in cases where the receiving water is designated as "Use Protected." Note that "Use Protected" waters are waters "that the Commission has determined do not warrant the special protection provided by the outstanding waters designation or the antidegradation review process" as set out in Section 31.8(2)(b). The antidegradation section of the regulation became effective in December 2000, and therefore antidegradation considerations are applicable to this WQA analysis. According to the Classifications and Numeric Standards for Upper Colorado River Basin, stream segment COUCRF 10 is Reviewable. Thus, an antidegradation review is required for this segment if new or increased impacts are found to occur. Appendix A (WQA v 7.0) Page 15 of 25 Last Revised Sept 14, 2009 /ES