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~!~ I 2.06.8 Alluvial Valley Floors I IIIIIIIIIIIIIIIIIII Do~Daet 1211112001 • An alluvial valley floor is the unconsolidated stream-laid deposits holding streams with water availability sufficient for subirrigation or flood irrigation agricultural activities. Upland areas which are generally overlain by a thin veneer of colluvial deposits composed chiefly of debris from sheet erosion, deposits formed by unconcentrated runoff or slope wash, together with talus, other mass movement accumulations, and windblown deposits are not considered alluvial valley floors. The primary consideration in the AVF investigation is the identification of alluvial deposits. These deposits should be located within the valley floor and should not include isolated high terraces, alluvial fans, or landslide deposits. Once allu- vial valley floors are identified, then the capability to support flood irrigated or subirrigated agricultural activities must be assessed. Identification of locations where unconsolidated stream-laid deposits may occur was performed through field investigation and discussions with personnel knowledgeable of the area. No areas on the mesas, where mining is to take place, are potential allu- vial valley floors because their is not adequate water to support flood irrigated or subirrigated agricultural activities. This lack of a dependable water supply also precludes the ephemeral drainages which surround the permit area from being classified as alluvial valley floors. The only potential location for alluvi- • al valley floors is adjacent to Naturita Creek or the San Miguel River. Two locations were identified that are considered alluvial valley floors as follows: 1. Township 46 North, Range 15 West, N.M.P.M. Section 29: N/2NW/4 Section 20: S/2SW/4 An alfalfa field located on the San Miguel River at the mouth of Bramiers Draw. This field is about 15 to 20 acres in size. Both Naturita Creek and Bramiers Draw bisect this field in a westerly direction. Bramiers Draw is a sand wash in the field about six feet deep. Naturita Creek is also considered a sand wash in the field and it is about 10 to 12 feet deep. 2. Township 46 North, Range 15 West, N.M.P.M. Section 21: SE/4SE/4 A cultivated field located on the north side of Naturita Creek at the mouth of Broad Canyon. This field is about 4 acres in size. Broad Canyon flows into the south side of Naturita Creek at about the midpoint of this four acre field. • 2.06-1 May 1991