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surface water which supplies the AVF would not be affected by the proposed operations <br />(4.24.3(3)). <br />Discharge from the Roadside and Cameo Mines will have a minor salt loading effect on the <br />Colorado River. The affect on the water quality from this discharge will be to increase the <br />specific conductance and total dissolved solids about 0.2 percent. This, in turn, would have a <br />minor effect on the water which supplies the subirrigated portion of the AVF, since recharge <br />water from the adjacent Colorado River is the source of alluvial groundwater which subirrigates <br />the AVF. <br />During mining, the sediment control system will temporarily reduce surface flows and will <br />remove sediment loads. Sediment ponds will not remove dissolved solids. Thus, the mine <br />operation will increase salt loads. Reduction in flow will only occur during significant <br />precipitation events and possibly during spring snowmeh. During these events, flows will be <br />reduced for only a period of 24 hours. Even then, the amount of water stored in the sediment <br />ponds is minor compared to the average flow of the Colorado River (3549 cfs). <br />All effects from the mining operation will be short-termed. With reclamation and removal ofthe <br />sediment control system, these effects would be mitigated. Based on the above discussion, the <br />Division finds that the proposed operations will not materially damage the quantity and quality <br />of water in the surface and underground water systems that supply the alluvial valley floor or <br />portions of the alluvial valley floor (4.24.3(3)). <br />3. The mining operations have already disturbed much ofthe alluvial valley floor within the permit <br />area prior to August 3, 1977, with construction of the overland conveyor and loadout facility. <br />No additional disturbance of this area is planned. The essential hydrologic functions of those <br />areas which will remain undisturbed will be preserved. <br />The permittee will be required to restore the essential hydrologic functions on the entire alluvial <br />valley floor where disturbance has occurred. There are no "grandfathering" provisions for <br />restoring the essential hydrologic functions on an alluvial valley floor. <br />The permittee identified subirrigation and flood irrigation as the essential hydrologic functions of <br />the AVF. In the past, the Highline Canal, which is immediately upslope ofthe AVF, has been <br />the source of water for irrigating a portion ofthe AV F. No irrigation presently takes place in the <br />site area. Subirrigation is controlled by the water level in the adjacent Colorado River. <br />Reclamation and restoration of the essential hydrologic functions will involve removing all <br />facilities, regrading to the approximate original river terrace topography, replacing topsoil, and <br />revegetating. A flood irrigation system had apparently been abandoned at some point prior to <br />loadout site development in 1977, and aeeas designated as historically flood irrigated in and <br />adjacent to the permit area, have not been flood irrigated since that time. The approved <br />postmining land use for the loadout area is wildlife habitat, and the revegetation plan would <br />establish predominantly native vegetation, which would support wildlife habitat. However, the <br />former Flood irrigation ditch as depicted on Exhibit 33 will be reestablished and connected to the <br />Highline Canal during final reclamation. Reestablishment of the original topography and <br />replacement of the irrigation ditch will restore the capability for flood irrigation of the acreage <br />identified as "historically flood irrigated" on Exhibit 33. <br />Permit Revision No. 3 <br />July 30, 2007 <br />Permit No. C-1981-041 <br />Page 55 <br />