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It has been determined that Hay Gulch meets the criteria for an AVF based on the <br />following findings: (1) The valley contains unconsolidated stream-laid deposits; (2) <br />The valley contains sufficient water to support agricultural activities as evidenced by <br />(a) the historical use of flood irrigation in the area, and (b) the demonstrated capability <br />of the area to be flood irrigated, and (3) the valley has demonstrated subirrigation. <br />Hay Gulch does not contain a stream channel probably because the original channel <br />was plowed over and smoothed out to facilitate hay production and grazing. Surface <br />water flow in the gulch is diverted into the Hay Gulch Irrigation Ditch which parallels <br />La Plata County road 120. <br />The Hay Gulch Irrigation Ditch is used for flood irrigation in the vicinity ofthe King I <br />and II Mines. The naturally occurring water table of the AVF fluctuates from just <br />above the ground surface to a few feet below the surface. This ground water supply is <br />sufficient to provide subirrigation on the AVF. The land use on the AVF is primarily <br />pastureland with occasional hay production. The essential hydrologic functions that <br />supply water to the AVF are flood irrigation and subirrigation as described above. <br />Absent information to the contrary, the AVF is considered significant to individual <br />farming units in the area. <br />Degraded water from the King I and II Mines could infiltrate Hay Gulch alluvium <br />either from the mines' ponds or haul roads. The infiltrating volumes would be so <br />small compared to the volume of natural flow in the alluvium that the natural flow <br />would readily dilute and attenuate the infiltration. The Division concludes that the <br />mines have been designed to minimize impacts to the AVF. <br />Sufficient information has been supplied by the operator in regard to Pine Gulch, and <br />confirmed in the field by the Division, to make the determination that Pine Gulch does <br />not contain an alluvial valley floor (AVF) in the proposed permit area. While there are <br />limited alluvial deposits in Pine Gulch, they are not currently flood irrigated for <br />agricultural purposes and have not been cultivated historically. Due to the limited <br />surface water availability in Pine Gulch and ephemeral deposits, there would appeaz to <br />be no potential for future surface irrigation along Pine Gulch within the proposed <br />permit area. Additionally, there is not sufficient alluvia] ground water to enhance the <br />productivity of agriculturally useful vegetation along Pine Gulch within the permit <br />area. <br />The operator has indicated that the area of confluence of Pine Gulch with Hay Gulch <br />which lies several miles beyond the permit area is an alluvial valley floor where <br />agricultural practices are being conducted. This agricultural activity depends primarily <br />on irrigation water diverted to the area from the La Plata River and does not depend on <br />surface or ground water associated with Pine Gulch. While subirrigation may also be a <br />factor in the productivity of this area, it is the opinion of the Soil Conservation Service <br />that this subinigation would most likely be related to the Hay Gulch water table. <br />25 <br />