96 



IRRIGATION PRACTICE 



the snow-water, rain-water and floods, chiefly among the 

 highlands, near the headwaters of the river course. Note 

 the following table : 



SUSPENDED MATTER IN RIVER WATERS 

 (Parts per million) 



The quantity of suspended matter as shown in the 

 above table is very variable and frequently very large. 

 Rivers rising in well-forested districts, or those that 

 travel only a short distance before they empty into the 

 lake or main river, are often comparatively free from sus- 

 pended matter. The Colorado and the Rio Grande Rivers 

 carry more suspended matter than any other of the great 

 rivers of the United States. As shown above, as high as 

 84,000 parts of suspended matter in 1,000,000 parts of 

 water nearly 8.5 per cent have been found in the water 

 of the Rio Grande at El Paso, Texas. The Colorado at 

 Yuma, Arizona, has carried nearly 31,000 parts, or more 

 than 3 per cent, of suspended matter in 1,000,000 parts of 

 water. When the immense volumes of water in such rivers 

 are considered, it is readily understood that quantities of 

 suspended matter almost beyond human comprehension, 

 are carried from the highlands tributary to the river, 



