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of the terrace deposits. Regionally, these types of terraces are not irrigated, and are primarily <br />used for the production of dryland wheat. The potential for flood irrigating these upland <br />terraces using Animas River water is not feasible, given the length of the canal needed and the <br />fact that a canal would have to flow through the city of Durango, Colorado. The coarser <br />gravels at the base of these deposits ac[ as an underdrain and prevent subimgation. Since [he <br />terraces are not capable of irrigation or subirrigation, the Division finds that the upland terrace <br />deposits do not constitute an AVF. <br />The Stream Valley in Carbon Junction Canyon <br />Much of the stream valley of Carbon Junction Canyon flows over sandstone bedrock. <br />Alluvial deposits in this canyon are less than 50 feet wide and 10 acres in extent. Alluvial <br />deposits of such limited extent are no[ considered substantial enough [o support agricultural <br />activities. Therefore, the stream valley in Carbon Junction Canyon does not contain an AVF. <br />The Animas River Valley Within Two Miles of the Mining Operation <br />The Division has determined that the alluvial deposits and terraces directly adjacent to the <br />Animas River constitute an alluvial valley floor. The unconsolidated stream laid deposits have <br />[he potential for flood and subirrigation. These alluvial deposits aze flood irrigated south and <br />north of the confluence of Carbon Junction Canyon with the Animas River. The applicant has <br />given the Division little information on subirrigation of the alluvium and lower terrace <br />deposits; however, the Division has made aworst-case assumption that the deposits are <br />subirrigated and therefore constitute an AVF. <br />Alluvial Valley Floor Findings <br />Rule 2.06.8(5)(a)(i)(A)(I) <br />The Carbon Junction Mine will not mine within the Animas River alluvial valley floor or have <br />surface mining facilities located on the alluvial valley floor. Therefore, the mining operation <br />will not interrupt, discontinue, or preclude Farming on the alluvial valley floor. <br />2. Rule 2.06.8(5)(a)(i)(A)(II) <br />The mining operation will impact the quantity and quality of water tributary to the Animas <br />River alluvial valley Floor. However, the impacts to the quality and quantity of water will be <br />insignificant and not cause material damage to the surface and ground water systems <br />supplying the alluvial valley floor. <br />The mining operation will cause slight decreases in surface water flows due to spring flow <br />depletions and to evaporation of water from sediment ponds and water in the mine pit. These <br />losses will be minor in comparison to the total flow in Carbon Junction Canyon and miniscule <br />in comparison [o the flows in [he Animas River. <br />?2 <br />