Velocity with respect to the v     of the parTicles it ao  g   , 
and as the 4th power of the velocity with respect to the o trtity 
of material of a given size it can carry. If the velocity of a 
stream, for instance, is doubled, it can oarry 32 times bigger 
rocks and 16 times more of them. 
The cutting power of water varies as the siuare of its 
velocity and, of course, also depends on the kind and amount of its 
suspended matter. If the velocity of a stream, for instance, is 
doubled, it can cut four times more bank by reason of the ii creaied 
velocity alone.* 
Hence a partial obstruction (as contrasted with a solid w 3 
by retarding velocity at a given point in a stream, reduces both its 
carrying and its cutting power at that point and forces a deposit. 
By skfliful arrangement of such partial obstructions, a stream may be 
forced to control itself without encountering the tremendous resist- 
ance's offered by solid works, 
Willows, brush, treetops, woven wire, piling, barbed wire 
entanglements, and "jackstraws" are all in the class of partial

obstructions and may be arranged in any number of combinations for 
the desired purpose. The point is to devise such a combination of 
materials in such a location that it will hold nLtil the deosit 
is obtained.- then to -so bind the deposit with vegetation that it 
will hold indefinitely. 
Stream Oontrol Plans: 
Where land along a stream is in the hands of various o;ners, 
control works must be correlated for the stream as a whole, else 
there is danger that works installed by one ovaier 'ill merely :ass 
the trouble down the stream to his neighbor, Securing such cor- 
relation is an excellent field for leadership by ?Zo 'est officers, 
If there is a Ranger Station on the strewan, the Service should of 
course set a good example by controlling its own stream frontageo 
Condition of Headjraters: 
Obviously the success of bank controls on the lower reachos 
of a stream depends primarily on the condition of itd headwaters. 
It may be cheaper to work over the headwaters and avoid the neces- 
sity for bank controls lower domv, than to.install bank controls 
and lose them because of the bad condition of te headwaters. 
Usually, however, conservation of vegetation on the headwaters, sup- 
plemented by bank controls lower dqv-a, is the most feasible scheme. 
.he hCeadwaters are usually 6cazing or timber lands where conserva- 
tion of vegetation pays on its own account, aside from watershed 
considerations, On the other hand, the lower reaches usually con- 
tain agricultural lands and ranch headquarters of a much higher per 
acre value, which accordingly can better stand the cost of bank con- 
trol.