2023-07-27_GENERAL DOCUMENTS - C1981038

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portion of Stevens Gulch; and 3) Alluvial gravel(Qag). The valley fill deposits are located along the North Fork Valley side slopes. The applicant has identified alluvial/colluvial deposits in a second area that is located along Stevens Gulch in the W'/2NW'/4 of Section 13, T13S, R92W. As identified in the Phase 1 AVF Study, the area is approximately 20 acres in size and is composed of valley fill deposits (Qvf). The mine has a well in this deposit that can pump 30,000 gpd from the alluvium/colluvium. Depth to water varies from about 7 feet in May to approximately 36 feet in February. The area is high and isolated,but has been used for pasture-hay meadow. The area is not flood irrigated, has not been flood irrigated, and is too high in elevation to be flood irrigated (at this elevation, the growing season is too short for the normal flood irrigated crops). Subirrigation is limited to areas along the stream channel itself. The area is determined not to be an Alluvial Valley Floor based on its lack of flood irrigation potential and lack of significant subirrigation. An additional area along Stevens Gulch which lies within and to the south of the mine permit area contains areas of alluvium. This area includes alluvial gravel deposits in Sections 24 and 25 (T13S,R92W)and the W'/2 of Section 30(T13S,R91W). Four separate deposits have been identified within this area, as shown on Map No. 2-2 in Volume 2 of the PAP. The two larger deposits may meet the geomorphic criteria of Alluvial Valley Floors, but do not meet the water availability criteria for either flood irrigation or subirrigation. Due to the steep slopes, rocky surface, and lack of sufficient water, these areas cannot be flood irrigated. Regarding subirrigation potential, the field investigation to detect subirrigated species along Stevens Gulch did not identify any such species within these areas. Vegetation suggests subirrigation does occur along portions of Stevens Gulch, but these species are confined to the extreme channel bottom areas. Based upon this information, these two areas are found not to meet the criteria for Alluvial Valley Floors. These are older terraced deposits that have been dissected by stream channels, such that the channels have completely cut through the deposit. These areas are found not to be Alluvial Valley Floors. The larger of the two areas totals 11.5 acres, but the residential access road that passes over the area reduces the acreage to below 10 acres. A third area identified as having alluvial deposits is located along the North Fork of the Gunnison River. These consist of floodplain and low terrace alluvial deposits and are identified as (Al) on Plate No. 2 of the PAP. This area meets the geologic and hydrologic criteria of an Alluvial Valley Floor in having unconsolidated stream laid deposits, with water sufficient to sustain agriculture. Portions of the loadout facility and rail spur have been part of the mine plan before August 3, 1977; therefore, their construction is grandfathered (see Alluvial Valley Floor Findings that follow). Adjoining these deposits on both sides of the river are deposits of coarse grained outwash (pediment). Geomorphically, the deposits form lobes and undulating topography that extend down to the low alluvial terrace deposits of the identified Alluvial Valley Floor. The slope outwash deposits are flood irrigated, which meets the hydrologic criteria of an Alluvial Valley Floor, but geologically they are mixtures of Mancos shale and eroded 41