Figure 20.--Streambed gravel sampling tool. 
In 1955, large fruit juice cans, filled with washed gravel and small 
rocks which had been run through a half-inch separator screen, were 
buried in the stream bottom with the top of the can slightly below 
the stream-bottom surface. This method avoids many of the difficulties 
encountered in the other methods. The cans will be removed in 1956 or 
1957 and a separation made to determine the quantity of silt which has 
been deposited during the period. 
A combination of these sampling methods should provide realistic in- 
formation regarding the content of fine material in the upper few 
inches of the stream bottom. New techniques of gravel sampling will 
be investigated. An intensified program of sediment sampling is 
planned for 1956. 
iy ae 
