4 
SEEPAGE OR RETURN WATERS FROM IRRIGATION. 
ready, it promises, if the deductions of the bulletin are correct, to 
be of still greater importance in the future and in the development 
of the State. Certainly it is true that the value of water will stead- 
iiy increase. 
The experience of all irrigation countries shows that their 
prosperity is largely bound up in the water question—in the cer¬ 
tainty of water, in the security of their rights, and the freedom 
from abuse. They have found themselves often bound by customs 
and laws, now become fixed, formed as the practice developed grad¬ 
ually. We are in danger of such here, mostly from lack of know¬ 
ledge of the conditions. This bulletin is a contribution toward a 
better knowledge of one condition of water supply, which has al¬ 
ready given rise to much vexatious litigation, to some harmful divis¬ 
ions, and to some unrest among those affected one way or another. 
§ 3. The increase which is found in such rivers is attributed to 
the inflow from innumerable springs fed and supplied by the water 
which has been applied in irrigation upon the higher lands. In 
irrigation, more water is applied than the crop uses. Of that 
applied, some is used by the crop and stored in its tissues; more is 
transpired in the process of growth; some is evaporated from the 
soil; a portion is usually lost by surface run-off; a certain amount 
passes down into the ground and disappears. This varies in 
amount and depends upon various conditions. Usually concurrent 
observations show that this water passes directly downwards, with 
little or no lateral movement except capillary imbibition, until 
reaching an impervious stratum, when, filling the interstices, it grad¬ 
ually rises in the subsoil, and passes laterally with a slow move¬ 
ment due to the slope of the water surface which is thus formed. 
When the passage takes place through the interstices of the soil the 
movement is very slow, much slower than is ordinarily supposed by 
those first encountering the subject. It is faster as the material is 
coarser. Where there are perceptible channels, the movement may 
be relatively rapid. 
§ 4. One of the first effects noted in irrigation where the soil 
is pervious, is in the filling of the subsoil. The first evidence is 
found in the gradual rising of the water in the wells which may 
have been sunk. Throughout the United States where irrigation is 
practiced, the evidence is ample, for as the application has been 
made within a single generation, the changes which have ensued 
from the application of water are within the memory of hosts of 
living observers. In many places in the Poudre valley, where it 
was originally forty or fifty feet to water, water now stands from ten 
to twenty feet from the surface, the subsoil having been filled to a 
depth of twenty to forty feet. 
There is sometimes a lowering during some seasons of the 
year, due to the lateral passage of the water. The lateral passage 
