American Forest Congress 71 



reading its height upon the graduations. The mud 

 which is deposited has then been treated in the case 

 of numerous samples to a temperature of 212 degrees 

 Fah., and the final amount of solid matter determined 

 by weight. Observations were continued from July 

 29, 1895, to December 31, of the same year. Begin- 

 ning on January i, 1899, and continuing until July 

 31, 1899, similar observations were made at the same 

 station, the amount of mud and solid matter being 

 determined as previously. During the first period the 

 volume of water discharged at The Buttes was 360,523 

 acre feet, and it was found that this contained 37,984 

 acre feet of silt by volume wet. This reduced to 7,704 

 acre feet of solids. The average amount of light sedi- 

 ment during this first period was loj^ per cent by 

 volume wet, and the amount of solids a little over 2 per 

 cent. The total amount of water discharged during 

 the second period in 1899 was 118,981 acre feet, which 

 contained 1.6 per cent of solids, or 8 per cent of mud 

 by volume wet. Frequent observations were made, 

 showing 20 per cent of silt by volume wet during the 

 high stages of the stream, and in one instance 27 per 

 cent was observed. The average amount of silt for the 

 twelve months' observation was 10 per cent by volume 

 wet, and the amount of solids 2 . per cent. No other 

 stream in the United States is known to carry such a 

 high per cent of sediment. This is in striking contrast 

 with the clear streams of our northern forested basins. 

 The water supply used for domestic purposes from 

 Cedar Creek, Washington, does not require filtering or 

 settlement. 



The serious nature of this silt problem can readily 

 be appreciated by those who have studied the storage 

 of water for irrigation. It is probably the gravest of 

 all the engineering problems related thereto. Forestry 



