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

page 24

24 THE ALL-AMERICAN CANAL. Table 2.-Some of the important reservoir sites in the drainage basin cf Colorado River which are under investigation by the United States Reclamation Service. Designation. River. Depth of storage at dam (feet). Capacity (acre-feet). 200 1, 550,000 200 2,520,000 225 3,500,000 170 10,000,000 230 2,200,000 21^ 2,270, 000 270 8, 600,000 210 800,000 110 440,000 f 206 [ 264 1,350,000 2, 600,000 130 2,219,000 170 400,000 Juniper....... Browns Park... Flaming Gorge. Ouray......... Kremmling___ Dewey......... Junction....... Bedrock....... Animas______ Bluff.......... Sentinel....... Rangely........ Yampa.. Green.. .....do.. .....do. Grand, .do. .! Green-Grand .! Dolores_____ . I Animas__.__ .' San Juan____ Gila... White. THE SILT PROBLEM. Od the subject of silt carried by Colorado River much information has already been collected. The silt studies which have been made by the United States Reclamation Service at Yuma since 1909 and earlier studies by Prof. R. H. Forbes, of the Agricultural Experiment Station of Arizona, have led to the following general conclusions on this subject: The water of Colorado River ordinarily carries the least percentage (by weight) of silt in suspension during the months, June to November. The water of Colorado River ordinarily carries the highest per-. centage of silt in suspension from January to March, and this percentage is about three to four times as great as when the river is at its highest summer stage and as in the fall when the river is at a low stage. The percentage of material in suspension in the water of Colorado River is ordinarily at a maximum when the river has a flow of about 30,000 to 40,000 cubic feet per second and is at a minimum at the low and at the high stages of the river. The percentage of material in suspension increases with depth below the water surface; in other words, there is more material in suspension near the bottom of the river than near the water surface. The annual average load carried in suspension is about 0.85 per cent by weight, and the range throughout the year is from about 0.20 per cent at low water and 0.30 per cent at high water to an ordinary maximum of about 1.45 per cent and to an occasional maximum at certain intermediate stages of about 4 per cent. There are numerous wide departures from these general conditions. It is estimated from these figures and the mean annual flow of Colorado River at Yuma that the river's annual load of silt carried