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information on Hubberson Gulch. Most of the valley bottoms are used for grazing, if they are used at <br />all. The width of the valley bottom of the upland areas of Dry and Sage Creeks is rarely more than 300 <br />feet wide and is cut by sinuous channels that are incised up to approximately 15 feet. The walls of the <br />incised channels are near vertical and the maximum widths are less than 50 feet and often less than 20 <br />feet. Because of the narrow and sinuous nature of the channel, farm equipment would have to move <br />frequently from one side of the channel to another using a system of bridges. As erosion proceeds, the <br />stream will erode back the steep walls of the channel, decreasing the area potentially available for <br />farming and making temporary bridge abutments susceptible to failure. <br />In summary, the narrow terrace widths in combination with a sinuous, incised channel, would not <br />provide sufficient widths of land for farming of any significance in the upland areas of each drainage. <br />Flood irrigation could not be economically conducted in a majority of the upland areas because of <br />channel erosion and high maintenance concerns. Only one hay field in the upper portions of both <br />drainages was found to be flood irrigated, which substantiates the above conclusions. The lower <br />portions of each drainage are quite different from the upland valleys and significant areas with good <br />alluvial widths Itrue alluvium, not mixed deposits) were mapped. The principal factor controlling <br />farming in these reaches is water availability. This will be discussed in more detail in the following <br />sections concerning water availability. <br />Irrigation. A land use and irrigation map (Exhibit 16-3) was constructed to depict the extent of <br />subirrigation, existing land use, and extent of flood irrigation in alluvial areas along Dry and Sage Creeks <br />within the boundaries of the study area previously described. The extent of subirrigation was 40 <br />determined on the basis of the vegetation growing on the valley fill and alluvial deposits. In general, <br />the subirrigated areas were defined as those that were currently supporting wetland vegetation or <br />vegetation that was strikingly different from the surrounding uplands. Areas of existing flood <br />irrigation were evaluated using existing aerial photographs, field checking, and water rights information <br />(see Water Rights section of this Tab) provided to Peabody by Tipton and Kalmbach, Inc. Irrigation <br />potential was evaluated on the basis of the relative size of the valley floor, topographic considerations, <br />and the availability of water. The cost of implementing an irrigation program was also an important <br />consideration. Currently irrigated areas in Hubberson Gulch are shown on Exhibit 16-3A. <br />The water availability, land use, and irrigation study results will be discussed separately for each basin <br />to permit any basin specific characteristics to be clearly identified. The upper portion of the Dry Creek <br />study area included Hubberson Gulch. All of the upper portions of Hubberson Gulch are characterized <br />by native rangelands and native subirrigated wetlands. The wetlands occur in narrow bands along the <br />valley floor. The vegetation consists of sedge meadows and willow shrublands which grow in <br />association with beaver ponds. In this upper portion of the gulch, the stream channel is not deeply <br />incised, which in combination with the beaver ponds creates a wetland environment. The saturated <br />soil conditions and the nature of the narrow valley floor make these areas unsuitable for agriculture. <br />i <br />15 Revised 9/98