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I . The proposed mining operations would not interrupt, discontinue or preclude farming on the alluvial valley floor. The mine plan for the Eastern Mining District was shortened from the originally proposed panel length for longwall panels 9R and 8R. Longwall panels in the Eastern Mining District did not undermine the Foidel Creek/Middle Creek Confluence AVF. Proposed longwall panels 6R through 2R in Eastem Mining District presented in PR-04, undermined a portion of Middle Creek; however, the affected portion of Middle Creek is not designated as an AVF. 2. The proposed mining operations would not cause material drnage to the quantity or quality of surface and ground water that supply the alluvial valley floor. As discussed in the PHC Section of this document, significant dewatering of the Foidel Creek or Middle Creek streazn/alluvial systems due to undermining would be precluded by the low vertical permeabilities between the Wadge seam and the alluvia Stream flow loss to surficial tensional cracks which may develop is expected to be minimal and the fine-grained nature of the alluvium will rapidly fill any cracks that may develop. Furthermore, surface cracking due to subsidence is typically limited to a maximum of 50 feet in depth and direct connection to the workings is not anticipated due to overburden depths in this area in excess of 600 feet. Also, any stream flow loss will be more than compensated by the projected and existing mine dischazge to Foidel Creek averaging over 600 gpm. And lastly, the enfve alluvial valley floor is flood irrigated by water diverted from the unaffected segment of Trout Creek above its confluence with Middle Creek, nullifying any temporary, minor impacts which could occur. (See TCC Life of Mine Application Map No. 15). The primary function of the confluence AVF is the support of flood irrigated hayland. As previously noted, the flood irrigation water is not diverted from affected segments of either Foidel Creek or Middle Creek, but is diverted from an unaffected segment of Trout Creek. Afield inspection conducted by the Division in late August of 1986 observed vegetation on the flood irrigated AVF to be more robust than adjacent areas upstream on Foidel Creek above the Trout Creek imgation diversion (assumed to be subirrigated). The flood irrigated pasture was dominated by pasture grasses while weedy species were visually dominant on the non-inrigated reach (see vegetation data in supplemental Report of 9/22/86). From compazison of the adjacent flood imgated and non-flood irrigated azeas, it appears that sub-irrigation has little impact on the agricultural productivity of the confluence AVF, and that flood irrigation is the critical function. Significant increases in the salinity of alluvial ground water in the confluence azea would not be anticipated since the majority of the recharge to the aquifer occurs during spring and eazly summer when Middle Creek and Foidel Creek flows aze highest and conductivity levels are lowest. Further dilution of alluvial waters would be provided by Trout Creek irrigation drainage water. Since Trout Creek irrigation water supports the critical function of the alluvia] valley floor and the Trout Creek waters would not be affected by the proposed operations, material damage to the quality of water supplying the AVF would not occur. 3. The proposed operation would preserve, throughout the mining operation, the essential hydrologic functions of the alluvial valley floor. The essential hydrologic functions ofthe confluence AVF are flood irrigation primazily and, to a lesser extent, sub-imgation, and both functions would be preserved. 33