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<br /> <br /> <br /> 65 C1981-041 RN7 findings <br />removal of the sediment control system, these effects would be mitigated. Based <br />on the above discussion, the Division finds that the proposed operations will not <br />materially damage the quantity and quality of water in the surface and <br />underground water systems that supply the alluvial valley floor or portions of the <br />alluvial valley floor (4.24.3(3)). <br /> <br />The mining operations had already disturbed much of the alluvial valley floor <br />within the permit area prior to August 3, 1977, with construction of the overland <br />conveyor and loadout facility. No additional disturbance of this area is planned. <br />The essential hydrologic functions of those areas which will remain undisturbed <br />will be preserved. <br /> <br />3. The permittee identified subirrigation and flood irrigation as the essential <br />hydrologic functions of the AVF. In the past, the Highline Canal, which is <br />immediately upslope of the AVF, has been the source of water for irrigating a <br />portion of the AVF. As described below, no irrigation presently takes place in the <br />site area. <br /> <br />Subirrigation is controlled by the water level in the adjacent Colorado River and <br />is not affected by the reclamation plan. No actions are necessary to reestablish <br />subirrigation. The reclamation procedure will restore the essential hydrologic <br />function of subirrigation. Quantity and quality of water is largely regulated by <br />the Colorado River. Any quality chan ges resulting from the surface operations <br />will be of short duration due to the close proximity of the Colorado River and the <br />extensive underflow associated with this relatively large surface water flow <br />system. In addition, if a groundwater problem is detected by the monitoring <br />program, mitigation measures will be undertaken prior to reclamation of the site. <br /> <br />A flood irrigation system had apparently been abandoned at some point prior to <br />loadout site development in 1977, and areas designated as historically flood <br />irrigated in and adjacent to the permit area, have not been flood irrigated since <br />that time. The quantity of water available from the Highline canal for flood <br />irrigation is 4 A-F per acre and is limited to 14 acres. The original post mining <br />land use for the UTL area was wildlife habitat. The original reclamation plan was <br />to restore the capability of flood irrigation but not necessarily implement flood <br />irrigation. With approval of Permit Revision No. 4, the postmining land use for <br />the loadout area was changed from wildlife habitat to industrial/commercial. This <br />land use change associated with PR-4 will preclude the Operator’s from restoring <br />the capability of flood irrigation inside the UTL loop. <br /> <br />Exhibit 33 of the permit application package shows the acreage at the UTL area <br />identified as “historically flood irrigated”. With PR-4 approval SCC submitted <br />new exhibits for insertion into the permit application package. Exhibit 33-1, <br />Irrigated Fields 10-14-76 and Exhibit 33-2, Potentially Irrigated Fields 11-16-94 <br />show the irrigated fields prior to, and after loadout site development. Based on <br />aerial photos taken on October14, 1976 there were a total of 26.1 irrigated acres