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-~- VII. Ground Water, Geology Description, and Hydrologic Consequences Please refer to the attached memo from Roy Cox of our staff dated December 2, 1981. VIII. Surface Coal Mining and Reclamation Operations on Areas or Adjacent to Areas, Including Alluvial Valley Floors A. Snowmass should delineate the Life of mine boundaries on the AVF Reconnaissance Map 80I, as was previously requested. B. Snowmass should redraft Map 801 to highlight the geologic contact boundaries. At present, it`is nearly impossible to distinguish between contact lines, topographic contours, jeep trails and stream channels. Color shading alluvial and colluvial deposits would be very helpful in defining alluvial extent. C. The Division determines that an Alluvial Valley Floor exists if: 1. (2.06.8(3)(c)(i)) "Unconsolidated streamlaid deposits holding streams are present; and 2. (2.06.8(3)(c)(ii)) "There is sufficient water to support agri- cultural activities as evidenced by: a) The existence of flood irrigation in the area in question or its historical use; b) The capability of an area to be flood irrigated, or c) Subirrigation of the lands in question exists. Snowmass has identified unconsolidated streamlaid deposits holding streams along North and Middle Thompson Creek. From Map D801, it appears that the alluvium is greater than 10 acres in size and 50-100 feet wide. Under Federal guidelines, this would meet the geomorphic and size criteria. Snowmass also states that these areas are subirrigated and that both streams are perennial, which indicates that there is sufficient water available for agriculture, and therefore, both streams qualify as Alluvial Valley Floors. It would be to the advantage of the applicant to submit the base maps used to delineate the extent~of the alluvium in Middle and North Thompson Creek. This would conclusively demonstrate which areas (if any) meet the size criteria of Alluvial Valley Floors. Another alternative is to study the farming practices in the region. Based on this information, the Division could then determine whether the AVF along Middle and North Thompson Creek is of sufficient size to support agricultural activity. Without additional information, the Division will make a determination that an Alluvial Valley Floor exists on both streams.