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In addition to the azea presently used for irrigated agriculture, two areas exhibited <br />characteristics of subirrigation (Figure 5.2-2). The largest azea is adjacent to the Colorado <br />River. The source of the water for subirrigation of this area is most likely the Vulcan <br />ditch, since the azea is approximately 20 feet above the level of the Colorado River. The <br />only other azea exhibiting subirrigation is in a small ephemeral drainage. This azea is split <br />in half by the Vulcan ditch. <br />The only possible sources of water for irrigation of the azeas'identified as unconsolidated <br />sediments aze Canyon Creek, the Colorado River, and South Canyon Creek. All the area <br />below the Vulcan ditch can be irrigated with water from Canyon Creek; therefore, this <br />azea meets the water availability criteria for an AVF. Water from Canyon Creek cannot be <br />used to irrigate the unconsolidated sediments above the Vulcan ditch due to the physical <br />barrier of elevation differences. In order to irrigate the remaining azea from South Canyon <br />Creek and the Colorado River, over 9 and 14 miles of ditch, respectively, would have to <br />be constructed over extremely steep terrain. Water from the Colorado River would have <br />to be diverted in Glenwood Canyon and the ditch would have to be constructed through <br />Glenwood Springs. It is not the regional practice to divert water over extremely rough <br />terrain; therefore, the azea above the Vulcan ditch does not meet the water availability <br />criteria for an AVF. The exception to this is the subirrigated area above the Vulcan ditch. <br />Based upon the above discussion, the Division has determined that all the azea underlain <br />by unconsolidated streamlaid deposits below the Vulcan ditch plus the small subimgated <br />azea above the Vulcan ditch is an alluvial valley floor. For reference, the alluvial valley <br />floor includes all the area denoted as: (1) land presently flood irrigated; (2) land <br />historically flood irrigated; and (3) areas of probable sub-irrigation, as shown on Figure <br />5.2-4 in the permit. <br />Colorado River Findines <br />1) None of the proposed mining operation will be located within the alluvial valley <br />floor. Therefore, the Division finds that the proposed operation will not interrupt, <br />discontinue, or preclude farming on the alluvial valley floor. <br />2) Surface waters which supply the alluvial valley floor are diverted from Canyon <br />Creek on the opposite side of the Colorado River from the surface facilities. A total <br />of 115 acres of land are presently flood irrigated. CBM projects that two to four <br />acre-feet of water per yeaz is required to irrigate each acre of land. Based on historic <br />records, the average flow in the Vulcan ditch is 1,400 acre-feet. Since mining has <br />ceased, other than irrigation of reclaimed azeas, CBM is not proposing any <br />consumptive use of water from the Vulcan Ditch. <br />Irrigation of the reclaimed disturbance area is considered a mining related use. The <br />permittee must, at all times, supply adequate water for flood imgation of the <br />alluvial valley flaor below the Vulcan ditch. If at anytime during the irrigation <br />season (May, June, July, August, and September) the flow in the Vulcan ditch drops <br />below 1.6 cubic felt per second, the permittee must receive Division approval based <br />on a demonstration that the water is not necessary for irrigation of the AVF before <br />26 June 1, 2006 <br />