OCR Text |
Show PART II PRESENT STATUS OF IRRIGATION to install elaborate irrigation systems. Costs for applying water are low. The added increment of crop production (above that which would have been obtained from normal precipitation) has made the large ranching oper- ations economically feasible. Ranchers in some areas obtain adequate water for most of the irrigation season by direct diversion of available streamflow. In other areas irrigation shortages occur as the runoff di- minishes and storage water is held in reserve for the more intensively cropped lands. Irrigation water is taken off the meadows early enough to allow harvesting to begin about August 1. Continuous and intermittent irrigation are both commonly used. Some seeped areas, phreatophyte growth, and salt accumulations have developed where proper management and develop- ment are absent. Where rotation pasture and improved hay are produced, permanent turn- out structures and contour ditches are maintained. Some leveling and smoothing in preparation of the seedbed are accomplished and water, in- cluding supplemental storage water, is applied intermittently and in an efficient manner. This method of irrigation, though somewhat laborious, results in increased production of improved species with less water applied. Border irrigation is an infrequent method used on flatter lands of the region. Alfalfa is produced on 20 percent of the irrigated cropland in the Upper Colorado Region with the largest share (56 percent) produced in the Colorado portion. The irrigation methods used for alfalfa consist of contour ditches, border, furrow, corrugation, sprinkler, or wild flooding, 17 |