Upper Colorado Region Comprehensive Framework Study: Appendix X, Irrigation and Drainage

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PART II PRESENT STATUS OF IRRIGATION Irrigation water has made possible the opening of many new farms along the San Juan River in New Mexico. small parcels of land have a very meager supply. Cropped acreage fluc- tuates widely from year to year with the amount of precipitation received. The soils of presently irrigated lands in the Arizona segment are primarily alluvial, located along stream valleys where water is available. A smaller percentage is of aeolian origin. Textures vary from loamy sand to clay, depending upon the parent material and mode of deposition by wind or water. Irrigation Practices Because of the extreme variation in physical and economic conditions, and institutional arrangements in distributing the water supplies, irri- gation practices vary from primitive to highly sophisticated methods of applying water. Unavoidable losses occur in all methods of water applica- tion and therefore the desirable efficiency of 100 percent cannot be obtained. Application losses include evaporation, deep percolation, and surface runoff. The extent of losses depend on a number of factors in- cluding: water intake characteristics of soils, topography, climate,