SEEPAGE OR RETURN WATERS FROM IRRIGATION. 
57 
EFFECT OF IRRIGATION ON THE UPPER PORTIONS OF THE STREAM. 
§ 55. A question which arises in connection with the applica¬ 
tion of water and which has been warmly disputed, is as to the 
effect on the lower stream of irrigation on the upper portions of a 
stream. In the wa}^ in which land has been brought under culti¬ 
vation, it has happened in most cases that lands along the lower 
portions of the stream have been settled, while lands above have 
later been brought under cultivation. It follows then that these 
latter lands will often see the water go by to supply those others 
which were first improved. In some places it has been contended 
that the application of water to the upper lands is an actual benefit 
to the lower lands, and in some cases the contention has been parti¬ 
ally granted. 
It is evident that the water which returns to the stream returns 
slowly. It returns sooner when the distance is short and the gravel 
is coarse. The volume of the stream fluctuates between wide lim¬ 
its, while the effect of passing through the ground is to even the 
flow, and hold the water until later in the season. Usually the 
streams are high early in the season, and in June have more water 
than can be used ; they are low in August. If this retention by the 
upper lands is such as to diminish the height in June and increase 
the amount in August, the result is evidently a benefit. As the 
effect of the subtraction of the water from the stream is immediate, 
while the return is slow, the abstraction of water in low stages will be 
felt more than the return from the seepage. Hence, for a portion of 
the time at least, it seems that the use of water on the gravelly 
plains of the upper parts of our streams will be a benefit to the 
lower portions, irrespective of the date of their respective rights. 
Just when the effect of the direct diversion is greater than that of 
the return could be told by investigation in the particular cases, but 
would manifestly vary according to the circumstances. 
There has been a tacit acknowledgment of benefit of irrigation 
on the upper portions of the stream in some of the water districts of 
this State in the fact that the upper ditches have been permitted to 
withdraw water without interference from the Commissioners or 
from the ditches with earlier rights. This has doubtless been partly 
due to the fact that the amount used bv them is small. But some 
weight has been given to the claim that irrigation on the upper 
grounds stored water which entered the river in other parts of the 
year, when it was more useful to the lower ditches. The question 
will doubtless arise in specific cases in this State and others. The 
length of time during the season when such irrigation will not be 
injurious to the later rights, can be told by special gagings carried 
on throughout the year, on the plan followed by Vigan. 
