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-9- VII. Alluvial Valley Floors - Rules 2.06.8 and 4.24 The Division has reviewed the alluvial valley floor study prepared by Leonard Rice Consulting Water Engineers and included in Appendix I of the application. Two areas were identified within or adjacent to the mine that met the geomorphic criteria of alluvial valley floors. Deposits of unconsolidated alluvial materials were identified along P1ann Draw and at the confluence of Mann Draw and the Canadian River (see Map, Figure I-3 and Plate 1-B) of the permit application. In Mann Draw, there is insufficient water to support agricultural activities. The stream channel of the draw is small and discontinuous in many sections. There is no existing or historic flood irrigation in the draw. A regional flood irrigation study was conducted in North Park to assess whether flood irrigation was feasible. Both the Canadian and Michigan Rivers and their tributaries were considered in the study (Plate 22 of the permit application). The results of the study show that irrigated watersheds in the region generally flow toward the southwest and have maximum basin elevations from 10,880 to 12,560 feet. Mann Draw is oriented northeast and has a maximum elevation of 8,34D feet. The higher elevated watersheds receive greater than 25 inches of annual precipitation, while Mann Draw receives approximately 10 inches of precipitation annually. Little evidence of subirrigation in Mann Draw was found in the study. Areas where the vegetation suggests subirrigation are discontinuous and limited to narrow bands along the channel ways. Based on evidence supplied by the applicant, the Division finds that Mann Draw is not an alluvial valley floor. The only area identified as an alluvial valley floor is the Canadian River, which is both flood irrigated and subirrigated. This river is located 1.7 miles downstream from the mine site. Alluvial Valley Floors -Canadian River - Findings 1. The proposed surface coal mining operations would not interrupt, discontinue, or preclude farming on an alluvial valley floor. The permit area is located 1.7 miles from the alluvial valley floor and would not physically affect farming activities. 2. The proposed surface coal mining operations would not materially damage the quantity and quality of water in surface and underground water systems that supply those alluvial valley floors or portions of alluvial valley floors. The Canadian River receives most of its flow from snowmelt in the Medicine Bow Range east of the mine site. Mann Draw, which flows a few weeks per year, contributes an insignificant amount of surface water and groundwater to the Canadian River alluvial valley floor.