Page 24


Page 24
Colorado River problem
Is Part Of,8
Full text
THE COLORADO RIVER PROBLEM 327 Imperial District and Mexican high lands participate in the All-American Canal, the cost of putting water on the East Mesa lands will be about $81 per acre and on Coachella Valley lands about $120 per acre. If the Imperial Dis-trict and Mexican high lands do not participate in the All-American Canal, these costs will be raised to $113 and $153, respectively. On the East Side Mesa, 148,000 acres of the 160,000 irrigable are public lands. In the Coachella Valley and Dos Palmas combined, of a total of 77,000 acres irrigable, 4,500 acres are public lands and 11,400 acres are Indian lands. If the East Side Mesa and Coachella Valley lands are combined so as to average the costs, the figures become $90 per acre and $118 per acre, respectively, depending on whether or not the Imperial District participates in the All-American Canal. The data available are not sufficient to determine how much cost is justifiable to bring the 270,000 acres of lands outside Imperial District under irrigation. Water Supply, Storage Required, and Irrigable Areas The following is extracted from a report recently made to the Secretary of the Interior by Herman Stabler, M. Am. Soc. C. E., Chief of the Land Classification Branch of the U. S. Geological Survey: "Water Supply of Colorado River "The run-off of Colorado River available for future development above the diversion for the Yuma Project at Laguna Dam and for all development below this point can be expressed in terms of discharge at Laguna Dam, obtained by subtracting from the run-off of the Colorado at Yuma (a) the run-off of the Gila at Yuma and (b) depletion by reason of irrigation use and diversions from the basin above, and adding to the result thus obtained the diversions for the Yuma Project. "In this study there have been used (a) records of discharge of the Colorado at Yuma since 1902; (b) rough estimates of | discharge of the Gila at Yuma since 1903; (c) records of diversions for the Yuma Project since 1910; and (d) estimates of depletion since 1899, all furnished by the Bureau of Reclamation. In addition, gauge heights of Colorado River at Yuma from 1878 to 1922 have been used to extend the record of discharge back to 1878, and the estimates of depletion have also been extended on the assumption that irrigation in the basin began about 1850. Records of run-off of Salt River since 1889 and estimates of inflow to Great Salt Lake under the assumption of present-day development estimated from the record of Salt Lake levels have been studied as comparates, but have not been used in estimates of run-off. "Two methods were used to develop a relation between discharge and stage at Yuma, effort being made in both to establish a method by which allowance for shifting channel conditions could be made from the record of gauge heights alone. Both methods give similar results in years of moderate flow. One method gives results rather high for years of low flow, while the other appears to give results slightly low for years of low flow. The average results by the two methods are presented as probably being more reliable than either, though apparently indicating discharges too great for years of low flow. For the period 1902-1922, in which comparison with discharge records is possible, the annual results obtained are less than the recorded discharge by as much as 10% in three years (1907, 1914, and 1920), the maximum being 20% for the year 1907. Considered as 5-year progressive means, the period 1906-1910 is found to be lower than the recorded discharge by 5%, while the period 1902-1907 is higher than the recorded discharge by 7.6%, these representing the maximum digres-

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