2021-01-28_GENERAL DOCUMENTS - C1982057

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not interrupt, discontinue, or preclude farming on the irrigated or naturally subirrigated alluvial valley floors except for small areas that may provide negligible support for agricultural production (4.24.3(1)) and 2.06.8(5)(a)(1)). The tie across haul road constitutes the only mining related activity impacting farming on an alluvial valley floor. The Division previously determined that the 2.3 acres of hayland on the Dry Creek AVF taken out of production represented only 0.2% of the farm unit and was therefore of negligible impact. 2. With regard to Hubberson Gulch, Sage Creek and Dry Creek,mining activities will not materially damage the quantity or quality of water in the surface or ground water system (4.24.3(3) and 2.06.8(5)(a)(11)), and the proposed activities comply with the requirements of the Act and the Regulations with respect to alluvial valley floors (2.06.8(5)(a)(111). a. Hubberson Gulch drains through the 26 acres AVF located approximately a quarter mile southeast of the confluence of Hubberson Gulch and Water Trough Gulch (Section 16 and 21, T5N, R88W). The fields are flood irrigated with Hubberson Gulch water. Mining in the Seneca IIW South Extension Area is projected to increase the salinity levels in Hubberson Gulch. b. In Tab 17, SPL presents an estimate of potential crop reductions based on the increased salinity level of irrigation water in Hubberson Gulch. SPL projects an estimated annual yield reduction of approximately 4.5 tons from the subject AVF fields,which corresponds to 0.6% of the total annual hay production for the ranching operation. This is considered to be a negligible impact pursuant to the Division's 1998 material damage guidance document. C. Due to the extremely limited acreage of proposed disturbance within the Sage Creek watershed, and that regional ground water flows to the west,the potential for material damage to the quality or quantity of water supplied to the AVF is negligible. No measurable impacts to the quantity or quality of water supplying the Sage Creek AVF are projected. d. Background salinity levels in the lower segment of Dry Creek from the Yampa River upstream to Section 28, Township 6 North, Range 88 West are high enough that no degradation of water quality is anticipated due to mining. Agricultural areas potentially impacted by increased salinity levels are flood irrigated grass and alfalfa haylands in Section 28, T6N,R88W. Regarding flood irrigated fields in Section 28, the application includes detailed mapping and aerial photographs indicating that the subject fields are irrigated by water from J.C. Temple Reservoir #1, not from Dry Creek. Thus, water supplying the irrigated fields would not be affected by the mining operation. There is no projected diminution of water quantity supplied to the Dry Creek AVF. 3. Surface coal mining and reclamation operations have been and will be conducted to preserve the essential hydrologic functions of alluvial valley floors outside the permit area and to reestablish the essential hydrologic functions of alluvial valley floors within the affected area throughout the mining and reclamation process (4.24.2). Page 35 of 37