From Imperial Dam downstream, in addition to Mexico, the Colorado River supplies water to Arizona and California for predominantly agricultural use. In Arizona, the Colorado River is the major source of water supply to the various irrigation districts in the Yuma area. Due to legal constraints, the amount of Colorado River water available to the State of Arizona is limited. On the other hand, it was discovered that the amount of water applied to the soil in irrigation exceeds that amount needed for crop-growing. Two areas where the amount of water considerably exceeds the requirements, the mesa section of the Wellton-Mohawk Irrigation and Drainage District and the Yuma Mesa Irrigation and Drainage District, were studied in detail. The excess water applied on the mesa of the Wellton-Mohawk Irrigation and Drainage District flows into the Wellton-Mohawk Valley whence it is pumped into a conveyance channel and then discharged into the main channel of the Colorado River. This drain water has a very high salt content and therefore it adversely affects the quality of the river water. Since the drain water is discharged into the Colorado River above the point of diversion to Mexico and it is considered to be part of the Mexican water allotment, the quality of the Colorado River water has become a source of friction between the United States and the Republic of Mexico. The excess irrigation water from the Yuma Mesa Irrigation and Drainage District flows into the adjacent valleys as well as into uncultivated areas. In the adjacent valleys it is raising the water table and thus causing drainage problems. When it flows underground into the uncultivated lands, in large measure it constitutes a loss of water that otherwise could be put to beneficial use by Arizona. It is known that flood irrigation is not conducive to efficient application of water in the sandy soils that are predominant in these areas, and that the effects of this application of excess water are diverse and far-reaching. The change to sprinkler irrigation would be advantageous in many ways and beneficial to all concerned. The change to sprinkler irrigation on the mesa of the Wellton-Mohawk Irrigation and Drainage District would benefit both the farmers and the district financially. At the same time, it would decrease the salinity of the Colorado River water, thereby improving the quality of the water that Mexico receives and, consequently, the relations between the United States and the Republic of Mexico. In the Yuma Mesa Irrigation and Drainage District, the change in the method of irrigation would increase the amount of water available for use by the State of Arizona. Furthermore, it would alleviate the drainage problem of the adjacent valleys and would thereby decrease the amount of drain water flowing back into the channel of the Colorado River. In this district, such a change may entail a small added cost to the farmer. Alternatives for augmenting the flow of the Colorado River, such as importation of water from other basins, desalting sea water, phreatophyte eradication, and evaporation suppression, were found to be economically unfeasible at present or still in the experimental stages.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/190966 |
| Date | January 1970 |
| Creators | Gordon, Yoram,1928- |
| Contributors | Kelso, M. M., Evans, D. D., Maddock, T., Phillips, R. A., Resnick, S. D., Roefs, T. G. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Dissertation-Reproduction (electronic), text |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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