14 
Colorado Experiment Station 
which year we unfortunately have no gaugings so we do not know 
whether the flow would have shown a gain or loss between the U. S. 
Gauging Station and the State Bridge. 
THE GROUND-WATER AND ALKALIS SOUTH AND WEST OF THE 
RIVER 
The statement has been made that no return waters could be find' 
iitg their way into the river, and the reason assigned was that, owing 
to the character of the soil and the prevalence of alkali, such waters 
would change the composition of the river water. We have, in fact, 
no return waters by whose composition we can definitely demonstrate 
that this is the case—the best that we can do is to present some 
ground- and drain-waters. 
The use of these, unfortunately, needs an explanation as to why 
they are of limited and not of general application to the whole valley. 
Any samples taken to the south and west of the river would be appli¬ 
cable to this portion of the valley but samples taken north of the river 
and in the eastern part of the valley, about Hooper for instance, would 
not apply to that portion of the valley south and west of the river, 
though both sections abound in alkalis. 
There are two classes of artesian wells in the valley which are 
commonly designated as white and brown waters. The former waters 
are colorless and of excellent quality, the latter are of various shades 
of brown. Analyses of these waters will be given subsequently, but it 
may be stated here that these brown waters differ in composition from 
the white waters in carrying considerable quantities of sodic carbon¬ 
ate which forms, in the deeper strata, a solution of humus, imparting 
the brown color to the waters. These brown waters are confined to 
the northern and eastern part of the valley. I may anticipate a little 
by stating that the color of the water is determined by the humus ob¬ 
tained from the strata underlying this section of the valley and in this 
case may be taken as definite proof of the presence of sodic carbonate, 
but the converse of this, that a colorless water is free from sodic car¬ 
bonate, is not necessarily true. N 
Our statement is practically this, that no ground or return waters 
are finding their way into the Rio Grande during its flow through the 
valley, because the composition of its waters retains the characteris¬ 
tics which it possesses on entering the valley, those of a mountain 
water, i. e., such as contain carbonates as the essential salts in solu¬ 
tion with subordinate quantities of sulfates and chlorids with an ex¬ 
cess of silicic acid. The character of the ground and drainage waters 
will undoubtedly vary somewhat from place to place, but their general 
character will persist just as the character of mountain waters per- 
