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... Another area identified as an AVF is the Rapid Creek AVF. Rapid Creek has valley fill deposits that have been Snterpreted as a mudflow fan deposit which have been modified and reworked to fora three distinct terrace levels. The upper terraces (TZ and T3) are irrigated or have been irrigated with the floe from Rapid Creek. The lowest terrace (T1)is narrow and is not flood irrigated. The T1 terrace includes a narrow land of subirr_gation along the creek, but contains no agriculture. Su birrigated species located oa the T.Z terraces are deep rooted and do not indicate the general availability of ground water to agriculturally useful species. The T3 terrace does not have vegetation indicating subirrigation. Based on the above information, [vo areas of alluvial valley may be identified. The two upper terraces (Tp and T3) have been Identified as unconsolidated streamlaid deposits, and have sufficient waters available to support flood Irrigated agricultural activi- ties. Two of the areas designated have been previously disturbed by abandoned mining activities and by the construction of water treatment facilities and should not be identified as alluvial valley floor.) The areas designated as Colorado River Terrace, (CRT), as well as, the lover terraces and floodplain along the Colorado River, have been determined co be an alluvial valley floor. The areas identified as CRT's consist of uaconsolidaeed streamlaid deposits current_y flood irrigated. The lower Cerraces and _'loodplain are flood irrigated in several area e, and could be subirrigated in places. The area designated as AVF that lies outside of the permit area is dovnatream from the proposed operations. There would be no surface disturbing activities on this AVP, and the area will be undermined. The Rapid Creek~AVF receives the eater supply from the Rapid Creek/Cottonwood Creek stream system. Since no surface facilities or disturbances are located within this system, and no mine eater will be discharged Sato Rapid Creek or Cottonwood Creek, the proposed operations should not affect the water quali- ty. The CMLRD has estimated stream floe depletion in the absence of floe through fractures, either natural or caused by subsidence, would be less than 0.003 cfs, and such as minor loco will not be detectable. The company has proposed a limited extraction mine plan beneath the above streams, and subsi- dence effects should not be expected in these ar~.as. The required surface water and mine water monitoring should detect nay unanticipated change Sn the existing hydrologic system. The essential hydrologic functions of the Rapid Creek AVF are those geologic, hydrologic, topographic, and soil characte- ristics that glue the area the ability to support flood irrigated agricultural activities. Si ace only limited mining will occur under the AV£, tha int- egration of the geologic structure and essential hydrologic section should not be affected.. The upper terrace area at the mouth of Rapid Creek is irrigated by Rap 1d Creek. Mining should not affect either water quality or quantity is the Rapid Creek/Cottonwood Creek stream system. Agricultural activities on the lover terraces and floodplain area are flood irrigated vi [h water derived from the Colorado River. Some of the lover areas may be marginally subirri- gated by alluvial ground water. The proposed operation would not affect the quantity of flow in the Colorado River stream/alluvial aquifer system. Dis- posal of coal refuse material in an adjacent area and the discharge of mine water from underground working may affect water quality. The ::Q.RD Division has assessed the possible affects of these activities and has not identified any sigaificanc charge in vacer quality. _o_ .