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both the upstream and downstream limits of the area mapped by the permittee. Within the <br />area mapped (approximately 2 miles in length) the alluvial deposits constitute an azea in <br />excess of 400 acres. The permittee has indicated that ground water is contained in the <br />alluvium along the White River at depths less than 11.5 feet below the land surface. <br />Subirrigation of deeper rooted vegetation, including alfalfa, likely occurs within this <br />depth. The permittee has indicated; however, that it is a regional practice to artificially <br />flood imgate alfalfa to maintain a productive crop. Irrigation requirements are therefore <br />not satisfied by subimgation alone; it is likely, however that subin•igation does supplement <br />the flood irrigation. <br />Based on the demonstrated suitability of the White River Valley for irrigation, the <br />perrnittee concludes that the land along the White River constitutes an alluvial valley <br />floor. <br />Alluvial Palley Floor Determination <br />On the basis of available annual water yield, the presence of unconsolidated streamlaid <br />deposits, the availability of supplemental moisture through subirrigation, and the presence <br />of established irrigated lands, the Division and OSM identify the White River and its <br />associated alluvial deposits as an alluvial valley floor. <br />The permittee has supplied sufficient information to address material damages to the <br />White River AVF. For the most part, the White River lies outside the permit azea. <br />Mining will not take place beneath the river or its alluvial deposits. The perntittee has <br />adequately demonstrated that bedrock contributions of ground water from the azea to be <br />mined aze insignificant in relation to the flows observed in the White River. Flows to the <br />White River from Red Wash and Scullion Gulch, which may be impacted by mining, are <br />also insignificant in relation to the flows observed in the White River. By minimizing <br />disturbances to Red Wash and Scullion Gulch during mining, the White River will not <br />suffer material damage via either of these drainages. <br />At the time of permit issuance, Kenney Reservoir, which presently exists within the <br />project azea, had not yet been filled. As such, the original findings document for the <br />Deserado Mine contained an assessment of the potential for material damage to occur to <br />the White River AVF as a result of the permittee's proposed pumping of water from the <br />AVF for use in the mine. The permittee had demonstrated that the volume of water <br />removed from the alluvium was insignificant to the flow volumes observed on the White <br />River even during low flow yeazs, and had concluded that the effects of drawdown on the <br />alluvial water body would not significantly impact farming due to the exclusive use of <br />artificial flood irrigation practices in the area rather than natural sub-irrigation. This was <br />felt to be a reasonable conclusion; however, it was also felt that natural sub-irrigation <br />might provide additional, supplemental moisture to flood irrigated crops. In view of this, <br />two stipulations were attached to the permit to provide for ongoing monitoring of the <br />alluvial body to verify the anticipated drawdowns caused by pumping, and to provide for <br />the development of a mitigation plan to protect farming operations in the event that <br />drawdown of the White River alluvial aquifer had a detrimental effect on established <br />4R <br />