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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 imgation 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 />The reclamation procedure will also restore the essential hydrologic function of subimgation. <br />Quantity and quality of water is largely regulated by the Colorado River. Any quality changes <br />resulting from the surface operations will be of short duration due to the close proximity of the <br />Colorado River and the extensive underflow associated with this relatively lazge surface water <br />flow system. In addition, if a groundwater problem is detected by the monitoring program, <br />mitigation measures will be undertaken prior to reclamation of the site. <br />In summary, surface coal mining and reclamation operations will be conducted to preserve, <br />throughout the mining and reclamation process, the essential hydrologic functions of the alluvial <br />valley floors no[ within the permit azea, and operations will be conducted to reestablish the <br />essential hydrologic functions of alluvial valley floors within the permit azea (4.24.2(1). <br />Rapid/Cottonwood Creek Area <br />Four distinct aeeas were examined for identification of alluvial valley floors in the vicinity of Rapid <br />Creek and Cottonwood Creek. These aeeas were Cottonwood Creek, Rapid Creek, minor ephemeral <br />streams and the Colorado River adjacent to the Rapid Creek and Cottonwood Creeks watersheds. <br />None of these areas are covered by the "grandfathering" exemption. <br />The Cottonwood Creek valley does not meet the geomorphic characteristics of analluvial valley floor. <br />The valley is narrow, and any fill material does not meet the AVF size criteria. <br />Valley fill deposits located along Rapid Creek have been interpreted as a mudflow fan deposit which <br />has been modified and reworked by Rapid Creek to form three terrace levels. The upper terraces (T2 <br />and T3) are irrigated or have been irrigated with the flow from Rapid Creels The lowest terrace (T 1) <br />is narrow and has not been flood irrigated. The Tl terrace includes a narrow band of subirrigation <br />along the creek, but the species present are not agriculturally useful. Subirrigated species located on <br />the T2 terrace are deep rooted and do not indicate the genera] availability of groundwater to <br />agriculturally useful species. The T3 terrace does not have vegetation indicating subirrigation. <br />Several minor ephemeral streams also drain the permit azea. The stream valleys aze narrow, steep, and <br />contain very little alluvium. None of these valleys contain deposits meeting the AVF size criteria. <br />Areas along the Colorado River have been identified as terrace landforms with existing flood <br />imgation. The lowest terrace is marginally subirrigated, but the upper terraces aze not subirrigated. <br />Based on the above information, two aeeas of alluvial valley floors can be identified. The two upper <br />terraces (T2 and T3) have been identified as unconsolidated streamlaid deposits, and have sufficient <br />waters to support flood irrigated agricultural activities. (Except, two of the areas designated on Map 1 <br />as have been disturbed by previous unrelated mining activities and by construction of water treatment <br />51 <br />