6 4 
BULLETIN 82 . 
§ 116. In glancing at these analyses, a few things will be 
noticed. First, that the waters of onr mountain streams are of 
excellent quality and carry a small amount of salts in solution;, 
second, that the amount of salts held in solution is materially in¬ 
creased almost immediately upon their entering the plains, par¬ 
ticularly after they emerge from the foothills; third, that the 
waters of the mountain streams contain calcic sulfate—almost 
as their only sulfate—after this, carbonates and silicates; fourth, 
that the carbonates and silicates are rapidly exchanged for magne- 
sic and sodic sulfates upon entering the plains (compare tables 
LII. and LIU.) While these samples are not strictly comparable 
as samples of Arkansas river water, because of the length of time 
elapsing between the dates on which the samples were taken, they 
illustrate well the differences between the mountain and plains 
waters. A still better illustration will be found by comparing 
table III, an analysis of Poudre water, with table XI, an analysis 
of Windsor lake water, or with table XLIV, an analysis of Poudre 
river water, taken above Greeley. The influence of the plains is 
already discernible in the composition of the water drawn from 
the tap in the chemical laboratory, also in samples of the Big 
Thompson and St. Vrain, taken a few miles west of the towns of 
Loveland and Longmont respectively. 
§ 117. The sample of the Arkansas river water, taken near 
Rocky ford, probably represents seepage water, but the extremely 
large amounts of nitrates and nitrites met with in the sanitary 
analysis suggest sewage. I am satisfied, however, that such is 
not the case, no sewage entering nearer than Pueblo, which is 70 
miles above, and this is taken out by the ditches. The person 
who took this sample reported the water as very clear and the 
ditches above as taking all of the river water. We have in this 
sample, I believe, as good a one of return waters for the river at 
this point as could possibly have been obtained. It differs some¬ 
what from the Poudre return waters in containing a good percent¬ 
age of sodic sulfate. This salt is present, however, in the ground 
waters of this district in large quantities. 
§ 118. The analysis of the water of the Queen Reservoir 
represents flood water which had been stored 22 months and was 
obtained through the kindness of Mr. W. M. Wiley. The salts 
held in solution differ in amount and slightly in their relative 
quantities, but it otherwise agrees with the seepage water taken 
at the bridge near Rockyford. This may be due to the return 
waters entering the river during flood time, but this would seem to 
indipate a very great in-flow of return waters at such a period, and 
it would seem that a portion, at least, of these salts must find their 
way into the water, either in the ditch or reservoir, during the 
period of storage. The Arkansas river in the month of February,. 
