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.: i~ 'h AQ -8 7/83 ~~~ 66-Tefton loam, (1 to 3 percent slopes). This deep, somewhat poorly drained soil is on gently sloping floodplains and alluvial valley floors. (Fig. 12) It is formed in mixed alluvium. The Tefton soil is cut by oxbows and old channels in many places. Elevation is 6,000 to 7,500 fee[. The average annual precipitation is 16 Co 19 inches. The average annual air temperature is 45 to 53 degrees F., and the average frost-free season is 105 to 130 days. Typically, the surface layer is light brownish gray loam about 5 inches thick. The lower part of the surface layer is pale brown loam and fine sandy loam about 12 inches thick. The underlying material is a pinkish gray loam stratified with very fine sandy loam and fine sandy loam about 39 inches thick. This overlies sand and gravel that extends to 60 inches or ,,- more. Sand and gravel may occur at any depth below 40 inches. In some ~ places the surface layer is fine sandy loam. Included with Chis soil in mapping are about 20 percent Pescar fine sandy loam, about 10 percent Alamosa loam, and small areas of soils that are similar to Tefton with better drainage. Permeability is moderate to moderately slow. Effective rooting depth is from 24 to 36 inches due to high watertable. Available water capacity is high. Surface runoff is slow and the hazard of water erosion is moderate. This soil has a fluctuating watertable in most places that rises between 2 to 3 feet of [he surface during the Spring and Summer. This soil is subject to flooding except where protected by upstream dams or channeled streams. Frequency of flooding is occasional. This soil is used mainly for irrigated crops, irrigated pasture and /-'~ rangeland. Alfalfa, barley, and oats are grown on irrigated areas. A /\ 1 mixture of alfalfa and introduced grasses are grown for irrigated pastures.