IRRIGATION WATERS AND THEIR EFFECTS. 5 
have issued from the mountains is the same in the quantity and char¬ 
acter of the salts that it holds in solution as before, we err and are 
confronted by a series of facts that prove us to be in error. 
There may be occasions when the pure waters of the mountains 
are carried further down their course before thev suffer changes 
than under normal conditions, but that they subsequently fall a 
prey to the general lot is beyond question. 
If flood conditions prevail and the level of the water in the 
stream is higher than that of the water in the country through 
which it flows, in which case the velocity of the flow will also be 
increased, the purer, though turbid flood waters, may flow for 
miles further down the stream without being perceptibly changed 
than is the case when the flow of the stream is normal. This 
question might be of importance and certainly would be an inter¬ 
esting one to study, but the writer has never had occasion to go 
into this detail of the study of flood waters. 
If we think of the water of a stream as a body of water flow¬ 
ing through a channel whose sides and bottom have no influence 
upon the water, just as though the water were flowing onward 
through a flume, we misconceive the facts. The sides and bot¬ 
tom, or bed of the stream are not only not tight but they are in 
places full of water that they discharge into the river. At others 
they present conditions permitting water to flow from the river 
into the bed and so disappear. The stream may lose water by 
evaporation from its surface and by leakage. The latter loss is 
often very considerable. These facts which are common subjects 
of discussion in our state suggest sufficient causes for the changes 
in the waters of our streams upon their issuing from the mount¬ 
ains into the plains. Our climate is comparatively dry but our 
soils are not devoid of water. The fourteen and one-half inches 
of rainfall may largely run off, and some of it be lost by evapora¬ 
tion from the surface. There is, however, a sufficient supply 
stored in the soils, valleys, and the marginal territory of streams 
to supply enough water differing wholly in character from that of 
the mountain streams, to modify the composition of the latter 
and to perceptibly change its character very soon after, if not im¬ 
mediately upon its leaving the mountains. 
The mountain masses represent very old rocks which have 
been changed into schists and granites. Lapping upon the flanks 
of these are younger and different rocks, some of the latter being 
made up of fragments of the former. The water gathered within 
the mountains carries some mineral matter that dissolves out of 
the rocks, but this amount is not great and its character is very 
uniform throughout this section. The amount and character of 
the mineral matter is rather a benefit than a detriment to the 
water, it not being sufficient to change its character as soft water. 
