Notes on Recent Ground-Water Developments in Arizona

Document: "notes on Recent Ground-Water Developments in Arizona," prepared by George H. Davis, U.S. Geological Survey, 1962, page 4Current Developments Viewing the Arizona water scene in 1962, the observer is aware of many new significant developments in the water problem in the diverse fields of international relations, law, economics, sociology, and hydrology. One legal development of great importance was the ruling of the Secretary of the Interior last fall withdrawing from entry desert lands in the public domain. This will limit development in areas where much of the land is in the public domain, and thus preserve valuable ground-water resources for more efficient use in the future. A problem that has received serious attention only recently, but may be the single most serious long-range water problem facing Arizona is the effect of use on the quality of water. Nearly all economic uses of water result in deterioration in the physical or chemical quality of the return flow. Irrigation invariably results in concentration of dissolved mineral matter in the return water because the plants consume a large part of the water applied but only a small part of the dissolved mineral matter. Also mineral fertilizers and soil minerals are carried off in solution in the return water. A permanent irrigated agriculture absolutely requires that the excess mineral matter be removed from the area irrigated. Most municipal and industrial uses result in a concentration of mineral matter, although to a lesser degree than in irrigation. In these uses additions of dissolved matter is a more serious problem than simple concentration. 4Epson Perfection 4870 Photo, 400 dpi, 8 bit, 2,470,042 byte