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<br />2. Sufficient water to support agricultural activities <br />Hydrologic data available for North Thompson Creek indicates an <br />annual runoff of 16.2 cfs or 0.6 cfs per square mile. Eighty <br />percent of this runoff occurs during the snowmelt season of April <br />through June. Low flows during late summer average less than one <br />cubic foot per second. <br />Although water is limited within the Thompson Creek drainage, the <br />Division feels that sufficient water is available to support <br />limited agricultural activity. Therefore, the Thompson Creek <br />drainage satisfies one of the criteria for alluvial valley floors. <br />The second and final alluvial valley floor criterion that needs to <br />be considered is that of unconsolidated streamlaid deposits. <br />Using current Federal Office of Surface Mining guidelines, the <br />Division identified three areas that are sufficient in size to <br />support agricultural activities. Because there is sufficient water <br />available to support at least a portion of these areas, they all <br />qualify as alluviai valley floors. <br />The first area identified as an alluvial valley floor is the <br />alluvial fan, 14 acres in size at the confluence of Yank, Sand, and <br />North Thompson Creeks (see Map D-3-7 of the permit application). <br />Its size barely qualifies it as an alluvial valley floor. In <br />addition, subirrigation is restricted to the immediate streambanks <br />and water may not be available to flood irrigate this area, as it <br />is in the upper reach of the North Thompson Creek drainage. <br />However, without more information on water availability, the <br />Division must assume this area is capable of supporting agriculture. <br />The essential hydrologic function of this area is flood irrigation <br />potential. This will not be impacted by the Snowmass Coal Company <br />operation. The site is 2.3 miles upstream from any mine facility <br />and one mile west of the maximum anticipated life-of-mine for the <br />operation. The operator has not identified any actual or potential <br />impact that might extend to this area. <br />The second alluvial valley floor body identified by the Division is <br />a 15-acre tract located in Willow Park along Middle Thompson <br />Creek. This area has the potential to be flood irrigated and is of <br />sufficient size to support agricultural activities. <br />With the exception of an existing mine vent fan, no surface <br />disturbance is planned by the operator within the Middle Thompson <br />Creek drainage. Although mine workings extended under a small <br />portion of this watershed, the alluvial valley floor was not <br />undermined. <br />Both the Willow Park and above-mentioned Sand/Yank Creek alluvial <br />valley floors are currently undeveloped rangeland which are not <br />significant for farming. The essential hydrologic functions of <br />these areas will be preserved. Surface and ground water monitoring <br />at the mine will continue to verify the applicant's predictions. <br />-?4_ <br />