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in the Grassy Creek watershed in hydrologic communication with the Yoast Mine. Based <br /> on information presented by the applicant, discussions with the Routt County office of the <br /> Natural Resource Conservation Service, interviews with farmers and field reconnaissance, <br /> the Division agrees with the applicant's conclusion. No alluvial valley floors exist in the <br /> permit area or the adjacent Grassy Creek watershed which are in hydrologic <br /> communication with the Yoast Mine. <br /> As a result of a 1990 AVF investigations in the Sage Creek watershed, Seneca Property, <br /> LLC concluded there are no AVFs in this basin in hydrologic communication with the <br /> Yoast Mine. The Division concluded that two areas along Sage Creek downstream from <br /> the Yoast permit met the regulatory definition of alluvial valley floors. These areas are <br /> discussed below. <br /> Sage Creek Reservoir Site <br /> Two fields located just upstream from the former Sage Creek Reservoir dam (Sections 13 <br /> and 18) are identified in the Yoast application as sub irrigated native wetlands and sub <br /> irrigated grass hay fields. The native area is basically the area once covered by the <br /> reservoir, which failed in 1985. This area is currently used for grazing. The area <br /> immediately upstream from the former reservoir site is currently used as a grass hay field. <br /> These fields are located in the upper reaches of Sage Creek and therefore are not typical of <br /> alluvial valley floors in this area with agricultural potential. Both fields are currently being <br /> sub-irrigated and farmed for hay. Due to the existence of flood irrigation and the presence <br /> of sub-irrigation of the unconsolidated streamlaid deposits in the fields immediately <br /> upstream from the old Sage Creek Reservoir, these fields are determined to be alluvial <br /> valley floors. <br /> The field just above the breached Sage Creek dam is dissected by the streambed. This <br /> area is undeveloped rangeland that is currently used for grazing. The limited size of the <br /> field would make it difficult for farm equipment to operate. This field is not typical of <br /> agriculturally productive alluvial valley floors in this region. <br /> Land management information and farm productivity values for the hayfield in Section 18 <br /> were provided. The field produces one hay cutting per year at a maximum rate of 2 <br /> tons/acre for a maximum production of 20 tons/year. The maximum annual production <br /> from the total ranching operation is 150 tons. The field in Section 18 provides 13% of the <br /> total productivity. The estimated worst case loss in productivity is 2.8% as shown on <br /> Table 17-17a of the permit application. Crop reductions were based on the formula <br /> presented in the Material Damage Assessment Process Pertaining to Alluvial Valley <br /> Floors, Surface Water, Ground Water and Subsidence at Coal Mines (January, 1988). As <br /> referenced in this document, less than a 3% reduction is considered insignificant. <br /> The Division finds that activities proposed by Seneca Property, LLC will not interrupt, <br /> discontinue or preclude farming on the alluvial valley floors in the Sage Creek Reservoir <br /> Site that are irrigated or naturally sub-irrigated. The field in Section 13 is undeveloped <br /> rangeland, which is not significant to farming, and the field in Section 18 provides <br /> negligible support for the farm's agricultural production (4.24.3(1) and 2.06.8(5)(a)(1)). <br /> 18 <br />