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Although the SAR is projected to increase significantly, the level is still below that considered hazazdous to crop development. The increased SAR would impact alluvial water in contact with the coal seams, specifically water available through subirrigation. The essential hydrologic function of this AVF is flood irrigation, as supplied by the surface water of the Williams Fork River. As the Williams Fork stream water is noY projected to be significantly impacted by the mining operation, the essential function of flood irrigation will not be impaired. This essential hydrologic function, flood irrigation, will be reestablished upon completion of reclamation activities. The surface facilities will be removed, topsoil replaced, and the site seeded with the rangeland or the pastureland mixture, where applicable. The pasturelands will then be flood irrigated. The rangeland and marshy azeas will not be irrigated. Yampa River Alluvial Valley Floors The Eagle No. 9 Mine has undermined portions of the Big Bottom alluvial valley floor (AVF). The Eagle No. 5 Mine has mined in azeas beneath or hydrologically adjacent to two alluvial valley floors (AVF's) along the Yampa River; the Big Bottom and the Round Bottom alluvial valley floors. Each of these alluvial valley floors are discussed sepazately, along with the potential impacts of mining, Yampa River Big Bottom Alluvial Valley Floor The approximate boundary of the Big Bottom AVF is shown on Map 25 of the permit application. Hayfields and pastureland are located in the Big Bottom (AVF) azea and are flood irrigated. The Big Bottom AVF will not be undermined during this permit term by the Eagle No. 5 or 6 Mine. Portions of the Big Bottom AVF were previously undermined by the Eagle No. 5 Mine. Monitoring has shown no impacts to the alluvial valley floor due to previous undermining by the No. 5 Mine. The life-of--mine projection shows undermining by ]ongwall methods of a small portion of the Big Bottom by both the No. 5 and No. 6 Mines. The application contains no information on possible impacts to the Big Bottom AVF or on mining methods to be utilized to mitigate such impacts for future extraction under the Big Bottom AVF. For this reason, the permit approval is for the five-year mine plan only of the Eagle No. 5 and 6 Mines. The Eagle Mine Complex operation ceased coal extraction in December 1995 and entered into temporary cessation. No additional underground development or coal extraction has occurred since that time. The now abandoned Eagle No. 9 Mine has development entries under the Big Bottom AVF; however, full extraction mining was not conducted. An AVF exemption for this past mining was requested and approved by the Division and OSM. A copy of the AVF exemption request is presented in Exhibit 4, and the extent of the No. 9 Mine workings is shown on the mine plan map, Map 23. No mining is approved for the No. 9 Mine 36