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It has been determined that Hay Gulch does meet the criteria for an AVF based on <br />the following findings: (1) The valley contains unconsolidated stream -laid deposits; <br />(2) The valley contains sufficient water to support agricultural activities as evidenced <br />by (a) the historical use of flood irrigation in the area, and (b) the demonstrated <br />capability of the area to be flood irrigated, and (3) the valley has demonstrated <br />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 upstream of the permit area into the Hay Gulch <br />Irrigation Ditch, which parallels La Plata County road 120. <br />The Hay Gulch Irrigation Ditch is used for flood irrigation in the vicinity of the King <br />I 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 <br />is sufficient to provide sub - irrigation on the AVE The land use on the AVF is <br />primarily pastureland with occasional hay production. The essential hydrologic <br />functions that supply water to the AVF are flood irrigation and subirrigation as <br />described above. Absent information to the contrary, the AVF is considered <br />significant to individual 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 AVE <br />The Pine Gulch drainage crosses through the southern end of the King I area of the <br />permit. Sufficient information has been supplied by the operator in regard to Pine <br />Gulch, and confirmed in the field by the Division, to make the determination that <br />Pine Gulch does not contain an alluvial valley floor (AVF) within the permit area. <br />While there are limited alluvial deposits in Pine Gulch, they are not currently flood <br />irrigated for agricultural purposes and have not been cultivated historically. Due to <br />the limited surface water availability in Pine Gulch and ephemeral deposits, there <br />would appear to be no potential for future surface irrigation along Pine Gulch within <br />the permit area. Additionally, there is not sufficient alluvial ground water to enhance <br />the productivity of agriculturally useful vegetation along Pine Gulch within the <br />permit area. The operator has indicated that the area of confluence of Pine Gulch <br />with Hay Gulch, which lies several miles beyond the permit area, is an alluvial <br />valley floor where agricultural practices are being conducted. This agricultural <br />activity depends primarily on irrigation water diverted to the area from the La Plata <br />River and does not depend on surface or ground water associated with Pine Gulch. <br />While sub - irrigation may also be a factor in the productivity of this area, it is the <br />opinion of the Soil Conservation Service that this sub - irrigation would most likely be <br />related to the Hay Gulch water table. <br />26 <br />