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I 1 I I I I I I I I I I I I I I I I I Grande Basin that establishes the designated use classifications (Aquatic Life, Recreation, Water Supply, and Agriculture) for the 12 stream segments in the Alamosa River Watershed (31). See Attachment 7 for the surface water standards specific to the Alamosa River. Figure 8 provides the location of the stream segments within the watershed. Each use classification has its own set of water quality standards as identified in the Basic Standards and Methodologies for Surface Water (32). These water quality standards are numeric standards that have a concentration limit (e.g. 10 ~gll-copper) associated with them based upon human and or environmental risk It is WQCC policy to review stream water quality standards and designated uses every three years. This tri-annual review allows the WQCC to evaluate the appropriateness of designed uses, improvements in water quality conditions and the likelihood that water quality standards will be achieved in impacted watersheds. The last revision to the water quality standards for the Alamosa River was June 1998. The Alamosa River was sampled routinely in 1998 and 1999 as part of the Summitville Mine Superfund Project (Figure 9). Water samples were collected and tested for aluminum, iron, pH, manganese, zinc, lead, copper, and cadmium. Acute and chronic water quality standards were exceeded at the following sampling locations: AR 45.5 (Segment 3a) Confluence with Wightman Fork AR 43.6 (Segment 3b) at Jasper AR 41.2 (Segment 3c) Downstream of Fern Creek AR 34,5 (Segment 3c) Upstream of Terrace Reservoir T1A (Segment 8) Upper portion of Terrace Reservoir AR 31.0 (Segment 9) Downstream of Terrace Reservoir AR 21.6 (Segment 9) Gunbarrel Road Bridge For most of the water quality parameters tested, no specific time of the year was noted that water quality standards were exceeded. It is clear that copper, pH and zinc were the parameters that caused most of the water quality problems (18). 4.6 Use Attainability Analysis The Colorado Division of Minerals and Geology and Division of Wildlife (CDOW) in 1997 performed a Use Attainability Analysis (UAA) on the Alamosa River Watershed. The ability of certain stream segments in the watershed to maintain aquatic life based upon natural conditions or irreversible water quality conditions was assessed. Based upon this UAA, several changes to water quality designations were proposed (33): 1. Resegmentation of Alamosa River Segment 3b into an upstream reach (3b) with downgraded Class 2 Aquatic Life Classification. Segment 3c would be the downstream portion of the segment with a Class 1 Aquatic Life Classification. 2. Resegmentation of Iron Creek into an upstream segment with a new Class 1 Aquatic Life Classification and a dovmstream segment with the current no aquRfc life classification. 4-6