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<br />Identification of Alluvial Valley Floors <br />The general area in which the Orchard Valley Mine is situated contains <br />several deposits of alluvium. These alluvial deposits are derived <br />from three sources: 1) Flood-plain alluvium (Qai) along the North Fork <br />of the Gunnison River; 2) Valley-fill deposits (Qvf) along a portion <br />of Steven's Gulch; and 3) Alluvial gravel (Qag) divided into three (3) <br />age categories younger (Qagy), middle (Qagm) and older (Qago). The <br />valley fill deposits are located along the North Fork Valley side <br />slopes. <br />Cyprus has identified alluvial/colluvial deposits in a second area <br />that is located along Steven's Gulch in the W 1/2 NW 1/4 .of Section <br />13, T135, R92W. As identified. in the Phase 1 AVF Study, the area is <br />approximately 20 acres in size and is composed of valley-fill deposits <br />(Qvf). The mine has a well in this deposit that can pump 30,000 GPD <br />from the alluvium/colluvium. Depth to water varies from about 7 feet <br />in May to approximately 36 feet in February. The area is high and <br />isolated, but has been used for pasture-hay meadow. The area is not <br />flood irrigated, has not been flood irrigated, and is too high in <br />elevation to be flood irrigated (at this elevation, the growing season <br />is too short for the normal flood irrigated crops). Subirrigation is <br />limited to areas along the stream channel itself. The area is <br />determined not to be an Alluvial Valley Floor based on its lack of <br />flood irrigation potential and lack of significant Subirrigation. <br />An additional area along Steven's Gulch which lies within and to the <br />south of the mine permit area, contains areas of alluvium. This area <br />includes alluvial gravel deposits in Sections 24 and 25 (T13S,.R92W) <br />and the W 1/2 of Section 30 (T135, R91W). Four separate deposits have <br />been identified within this area, as shown on Map No. 2-2. The two <br />larger deposits, labeled Qagy and Qago, may meet the geomorphic <br />criteria of Alluvial Valley Floors, but do not meet the water <br />availability criteria for either flood irrigation or Subirrigation. <br />Due to the steep slopes, rocky surface, and lack of sufficient water, <br />these areas cannot be flood irrigated. Regarding Subirrigation <br />potential, the field investigation to detect subfrrigated species <br />along Steven's Gulch did not identify any such species within these <br />areas. Vegetation suggests Subirrigation does occur along portions of <br />Steven's Gulch, but these species are confined to the extreme channel <br />bottom areas. Based upon this information, these two areas are found <br />not to meet the criteria for Alluvial Valley Floors. These are older <br />terraced deposits that have been dissected by stream channels, such <br />that the channels have completely cut through the deposit. These <br />areas are found not to be Alluvial Valley Floors. The larger of the <br />two areas totals 11.5 acres, but the residential access road that <br />passes over the area reduces the acreage to below 10 acres. <br />A third area identified as having alluvial deposits is located along <br />the North Fork of the Gunnison River. These consist of floodplain and <br />low terrace alluvial deposits and are identified as (A1) on Plate <br />No. 2. This area meets the geologic and hydrologic criteria of an <br />Alluvial Valley Floor in having unconsolidated stream-laid deposits <br />-43- <br />