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~~ The essential hydrologic functions of the floor have been identified as the capacit flood irrigated agricultural activities. n u Trout Creek alluvial valley y to support subirrigated and The proposed plan would not result in any surface disturbance or undermining of the AVF. Also, as discussed previously, no material damage would result from changes in the quality of surface and ground water that supply the alluvial valley Floor. Thus, the essential hydrologic functions of the alluvial valley floor would not be affected by the proposed operation. Fish Creek The boundaries of the Fish Creek alluvial valley floor are as delineated on Map No. 15 of the Foidel Creek Life of Mine application and include all alluvial deposits within and downstream from the proposed permit area as delineated on supplemental Map No. 1. Recently submitted information discussed below has reaffirmed the Division's original determination that alluvial deposits on Fish Creek meet alluvial valley floor criteria based on existing flood irrigation, potential for flood irrigation and subirrigation. The existence of a currently flood irrigated field on lower Fish Creek and the presence of diversion structures and irrigation ditches on various stream segments as delineated on Map 15 document the potential for flood irrigation. Information provided in application Exhibit 16 (Soil Mapping Unit Descriptions) and backhoe pit data provided on Page 206 - 9F show that a number of alluvial soil types exhibit late growing season ground water elevations within 6 feet of the surface. Hay crop species commonly grown in the Yampa Basin would be expected to derive benefit from ground water when present at such depths. The major vegetation type on the Fish Creek AVF within the proposed permit area is a sagebrush meadow community dominated by silver sagebrush with a number of sedge and rush species contributing significantly to the community. All of these species are hydrophytes typically associated with subirrigated conditions. Information has not been provided concerning the significance of the alluvial valley floor to farming. Consequently, the Division must assume that the Fish Creek alluvial valley floor is significant to farming and make the three required alluvial valley floor findings. The proposed mining operations would not interrupt, discontinue or preclude farming on the alluvial valley floor. TR-14 approved the undermining and subsidence of a small portion of Fish Creek due to longwall extraction in panels 5, 6 and 7. No farming activities are currently undertaken along Fish Creek in this area. Subsidence would not preclude the farming of this area. The proposed mining operations would not cause material damage to the quantity and quality of surface and ground water that supply the alluvial valley floor. The potential for subsidence cracking at the surface and subsequent interception and reduction of flow in Fish Creek is minimal. Depths of subsidence cracks produced by tensile stress are generally less than 50 feet. However, due to the presence of thick, fine-grained sediments in this area, significant surface cracking ie not anticipated. Any cracks which due develop in the stream channel will 22