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-Z9- <br />Pursuant .to Rule 2.06.8 (5)(a)(i)(A)(III), the Division finds that surface <br />coal mining and reclamation operations ~,auld be conducted to preserve, <br />throughout the mining and reclamation process, the essential hydrologic <br />functions of the alluvial valley floor. <br />The alluvial valley floor would: not be physically disrupted by mining. <br />No material damage to the quantity of water in Good Spring Creek is <br />anticipated as a result of mining. The "Probable Hydrologic Consequences - <br />Surface Water" portion of Section VIII - Probable Hydrologic Consequences <br />and Cumulative Ltnpact Assessment of the document notes that the application <br />predicts a slight decrease in runoff from reclaimed areas as a result of <br />temporarily increased infiltration rates. This effect would be short <br />term and any reduction of flow in Good Spring Creek would be insignificant. <br />With respect to quantity of water supplied to the Good Spring Creek alluvial <br />valley floor, the essential hydrologic functions will be preserved. <br />Runoff from disturbed areas at the mine will be controlled by diversions <br />and sedimentation ponds. Discharges will meet NPDES standards. As discussed <br />in the Section VI - Hydrologic Balance - Ground Water, the only impact <br />which could potentially occur would be the degrading of the Good Spring <br />Creek alluvial waters due to the leaching of salts from the reclaimed spoils <br />of the Streeter Canyon Fi11. The potential impact is not considered <br />substantial enough to warrant changes in the mining and reclamation plan, <br />This conclusion will be substantiated by the monitoring plan, which is <br />designed to ensure that the essential hydrologic functions are maintained. <br />The monitoring plan originally provides by the applicant was not adequate <br />to meet the objectives of Rule 4.24.5 of the rules and regulations. <br />Colowyo has subsequently committed to the establishement of a surface water <br />monitoring site on Good Spring Creek below the Streeter Fi1I but above <br />the irrigation diversion to monitor the predicted effects-of mining on <br />Good Spring Creek. An additional ground water well will be located in <br />the Good Spring Creek alluvium upstream of the base of the Streeter FiI1. <br />The surface and ground water monitoring will be accomplished quarterly and <br />data will be submitted to the Division in an annual report. Monitoring will <br />include aII of the parameters listed in Section VI -Hydrologic Balance - <br />Ground Water, with the addition of total suspended solids. The monitoring <br />requirements may be refined after the colleciton of 1 year's data. <br />WILSON CREEK <br />The aZluvia2 deposits along Wilson Creek constitute an AVF because there <br />are enough unconsolidated stream-laid deposits and sufficient water <br />yield to be beneficial for crop irrigation. Wilson Creek is a perennial <br />stream. There is both historical and current flood irrigation occurring <br />on the AVF. Map 10 of the permit application delineates the boundaries <br />of the AVF and shows existing flood irrigated crop Lands. Information <br />presented by the applicant in the letter of October 8, 1981 shows that <br />areas in the upper reaches of the Wilson Creek AVF were historically flood <br />irrigated. Historically irrigated lands are not within the Colowyo permit <br />area. <br />