Hicks on Irrigation of the Niobrara Valley. 75 
the stream is not lost because it fills interstices which must other- 
wise be supplied by rains, thus raising the water table, and 
leaving the rain water to flow off and swell the volume of water 
available for the next section of the valley. Even the water 
which sinks below the level of the river contributes to the same 
result of raising the water table and freeing the rains for surface 
flow. The loss by percolation would therefore be insignificant 
if the whole valley were irrigated. In fact, however, only a 
few fields here and there will be watered, and the dry lands 
adjacent will drink up much water which might otherwise re- 
turn to the river. 
The farmer who irrigates thus benefits his neighbors directly, 
as well as indirectly by influencing the rainfall. Those enor- 
mous loads of moisture which I have shown to be constantly 
escaping from growing crops must have an appreciable influence 
upon precipitation. This should be taken into the account in 
estimating the amount of land which may be irrigated from the 
Niobrara river. The increased rainfall resulting from irriga- 
tion may double or treble the capacity of the river. This has 
been almost uniformly the experience of irrigators in Utah. 
"In many places the service of a stream was doubled, and in a 
few it was mcreased ten fold, or even fifty fold,"' 
No direct observations have been made, so far as I know, to 
determine how much of the water of irrigation returns to the 
stream from which it was drawn. Fair consideration being 
given to all the sources of loss by percolation, by evaporation, 
and by absorption in vegetable tissues, we may state as a proba- 
ble inference that it is not more than one-tenth. Granting this 
and then recalling our division of the valley into ten-mile sec- 
tions, we have in the second section water enough for only 980 
acres instead of 9,800 acres; in the third section 98 acres only 
can be watered, and so on in a diminishing series. 
But as a matter of fact the water never is, and cannot easily 
be, completely used up in an}' section of the valley. Perhaps 
by drawing out no more than one-third of it in any section of 
the valley, much more could be made of it along its whole 
course than if it were completely exhausted at one point. 
It is certain that irrigation does use up a river; else the com- 
' Gilbert — Lands of the Arid Ret^ion, p. 57. 
