OCR Text |
Show It shows that one-eight (12.8%) of the total quantity of salts entering the reservoir are precipitated from solution within the reservoir basin. The total loss is actually greater than the above figure by the amount of salt entering as unmeasured side inflow. The data shows that the less soluble constituents, Calcium (15.3%) and Carbonate and Bicarbonate (28.0%) comprise a gre.ater than average part of these precipitated salts but, rather surprisingly, that the more readily soluble ions, Sodium and Potassium (12.5%) and Chloride (10.8%0 are also lost from solution in substantial quantities. Calcium carbonate alone comprises only about 43% of the precipitated salts. As stated elsewhere in this report, this phenomenon has not been adequately explained, but is thought by some to result partly from temperature changes in the water and partly by the settlement of finely divided sediments which seem to carry the dissolved solids down with them. If, as Dr. Howard has determined, over 6.3% of the dissolved solids entering Lake Mead have been precipitated as calcium car-oonate, it is evident that precipitation of a substantial portion of the other dissolved constituents also occurred. It appears logical by comparison with the Elephant Butte data that at least twice that percentage of all dissolved constituents in the lake influent have been precipitated. There is good evidence that at least one-eight (and probably more) of the total dissolved solids which will enter Glen Canyon reservoir will remain permanently within the reservoir basin itself. Further, there seems to be no good reason why a substantial deposition of salts from solution should not occur in each of a series of hold-over reservoirs on the stream although the amounts of such depositions will undoubtedly vary somewhat with local conditions. Effect on Ultimate Quality of Lees Ferry Water: It can be concluded, therefore, from the Elephant Butte data, substantially verified by the record at Lake Mead, that about one-eight of the salts entering Glen Canyon reservoir will be permanently deposited from solution within the reservoir basin. Further, there is reason to believe that similar deposition will also occur in holdover reservoirs both above and below Glen Canyon. A loss of 12.5% of the Glen Canyon reservoir salts would result in an effluent under ultimate development of the Upper Basin of only about 1.00 tons per acre foot of dissolved solids. Such a water supply with a sodium content of less than 50% constitutes a good water supply as defined by salinity experts, being equal to or better than the average water supply used successfully for many years by the Elephant Butte Project, one of the most successful reclamation projects of the West. The Upper Colorado River Project and the Compact of 1922 The States of the Upper Basin, by the terms of the Colorado River Compact of 1922, have the obligation of not depleting the flow of the Colorado at Lees Ferry below an aggregate of 75,000,000 acre feet for any period of 10 consecutive years. In Article VIII of the Compact there is also an obligation on the part of all seven -43- |
Source |
Original book: [State of Arizona, complainant v. State of California, Palo Verde Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, California, City of San Diego, California, and County of San Diego, California, defendants, United States of America, State of Nevada, State of New Mexico, State of Utah, interveners] : |