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In the 1983 Findings for the Foidel Creek Mine, the Division concluded that lower Foidel Creek, lower Middle Creek and lower Trout Creek were alluvial valley floors because of a presumed capability to support Flood irrigated and subirtigated agricultural activities. The Trout Creek AVF was addressed previously in this section. Subirtiga[ed alluvium on Middle Creek downstream of Routt County Road No. 27 crossing does not meet AVF criteria due to limited farmable acreage, as was also discussed previously. The alluvial body at the confluence of Foidel Creek and Middle Creek extending from the County Road No. 33 crossing of Middle Creek upstream on Middle to the first Trout Creek irrigation diversion as depicted on Map No. I ~, Water Rights and Alluvial Valley Floors, does meet alluvial valley Floor criteria based upon existing Flood irtigation and a presumed capability to support subirtigated vegetation. These findings do not address areas further upstream on lvfiddle Creek, as they are not hydrologically connected to the proposed mining operation. The required findings for the identified alluvial valley floor at the confluence of Foidel Creek and Middle Creek are set forth below. The proposed mining operations would not interrupt, discontinue or preclude farming on the alluvial valley floor. The mine plan for the Eastem 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 Eastern 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 damage 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 stream alluvial systems due to undermining would be precluded by the low vertical permeabilities between the Wadge seam and the alluvia. Stream flow loss to su~cial 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 azea in excess of 600 feet. Also, any stream flow loss will be more than compensated by the projected and existing mine discharge to Foidel Creek averaging over 600 gpm. And lastly, the entire 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. 1 ~). 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 irtigated AVF to be more robust than adjacent areas upstream on Foidel Creek above the Trout Creek irtigation diversion (assumed to be subirtigated). The flood irrigated pasture was dominated by pasture grasses while weedy species were visually dominant on the non-irtigated reach (see vegetation data in supplemental Report of 9/2J86). From comparison of the adjacent flood irrigated and non-Flood irrigated areas, it appears that sub- irtiga[ion has little impact on the agricultural productivity of the confluence AVF, and that flood irrigation is the critical function. C:U HB\C82056\RN03\RN03FI N D.doc 35