AZ vs. CA:04 California Exhibits, Vol. IV; Nos. 151-192

page 26

26 THE ALL-AMERICAN CA3TAL. natural deficiency with an ample allowance for sluicing purposes. It is believed that the desilting operation can be carried on successfully at the Laguna Dam without sacrificing more than 5 per cent of what would otherwise be the continuous flow of the canals. The following table presents in condensed form the results of the studies made at Yuma from 1909 to 1916 of the quantity of silt carried in suspension by the water of Colorado River. Tjlble 3.-Silt contents, Colorado Riier at Yuma, 1909 to 1918. [Information furnished by the United States Reclamation Service. Based on semiweekly determinations by weight.] Period. Average monthly discharge at Ynma (acre-feet). Percentage of silt by ¦weight. Volume of silt at 100 pounds per cubic foot (acre-leet). January. 1911-1918.......... February, 1911-1918......... March. 1911-1918........... April. 1910-1918............. May. 1909-1918............. June. 1909-1918............. July. 1909-1918............ August. 1909-1918.......... September. 1909-191S....... October. 1909 and 1911-1918. November, 1910-1918........ December, 1910-1918........ 717.440 753; 945 L 016! 158 1,478.195 2. 887.910 A, 41L 205 2, 881. 308 1,207.054 743.196 865. 093 548. 418 465,0S4 L70 1.39 1.10 .91 .82 . 57 .76 L12 .97 L40 .59 Total and average.. 7.620 6.560 6,860 8.380 14.800 15.800 13. 800 8.430 4.500 7,570 2.040 970 . 85 97,330 The flow at Yuma and silt contents are affected by the sluicing operations at the Laguna Dam. The influence of sluicing is probably negligible at the river's high stages, March to August. If taken into account for the remainder of the year the silt contents would probably appear slightly less than shown in this table. The mean diversion of water at the Laguna Dam throughout the year has not exceeded 1.000 second-feet. There was practically no diversion preceding 1910. THE FLOOD MENACE. The contract between the Secretary of the Interior and the Imperial Irrigation District, under which this board has been appointed, is specific and definite in its requirement that an all-American canal route be surveyed and examined. No alternative has been left open. The surveys and investigations which have been made relate, therefore, to a canal, located throughout, upon American territory. Our investigations could not be broadened out to a full consideration of the wisest and best treatment of the irrigation problem of the lower Colorado River in its broadest aspect. This is to be regretted, because the lower river presents problems of unique perplexity. The