bulletin 82. 
5 8 
sewage of the town of Greeley. The water returning within the 
next six miles came from land irrigated with this water and carried, 
in round numbers, 80 tons of salts. Our method shows the . net 
results effected, but the work done by the irrigation waters is 
actually much greater than the figures indicate. 
§ 109. The salts removed stand as follows in the order of 
their relative quantities; calcic sulfate, magnesic sulfate, sodic car¬ 
bonate and sodic sulfate. In the case of the Arkansas river water, 
the sodic sulfate stands next to the calcic sulfate. The samples 
of ground water from the Arkansas valley which I have examined, 
have been very rich in total solids with much sodic sulfate. In 
one there was over 57 per cent of this salt and in another almost 
30 per cent. 
§ 110. It is true, the area in the Poudre valley under irrigation, 
the seepage water from which finds its way into the Poudre, is 
large. In 1894 it was 176,848 acres. It is now much greater, 
but the amount of salts carried out of the valley under the con¬ 
ditions of 1902 is also large. Assuming the flow of 29.1 feet of 
water, as found by us, to continue for 270 days—the results will 
be too low, for the flow is at least six second-feet below the aver¬ 
age—we will have removed from the valley 21,532.5 tons of salts, 
over one-third of which is calcic sulfate, one-fourth magnesic sul¬ 
fate and a little less than one-eighth sodic carbonate. 
§ 111. I am not certain that the Arkansas water is compar¬ 
able as a return water to these samples of Poudre water. If it is, the 
ratio would be materially changed and we would have 2-5 for the 
calcic sulfate, 1-5 for the sodic sulfate, almost 1-5 for the magnesic 
sulfate and very much less sodic carbonate. The analysis of this 
water shows a very considerable excess of bases. I have already 
called attention to the fact that this sometimes occurs and that I 
am unable to satisfactorily account for it. The alkalies and some 
other determinations were repeated in this analysis with excel¬ 
lently agreeing results. We therefore leave the excess unexplained. 
§ 112. The analysis of the Platte river water gives results 
in agreement with those of the Poudre water and there is nothing 
to be gained by further discussion of this. The flow of the Platte 
at this point is very much larger than that of the Poudre and the 
amount of salts carried will be almost exactly proportional to their 
respective flows. All that has been said concerning the Poudre 
could be repeated concerning the Platte. Its water is made to re¬ 
peatedly serve the purposes of irrigation. Their waters receive 
the sewage of several towns, the Platte proportionately more than 
the Poudre. The general character of the land irrigated is similar 
and so are the general features of the results produced. 
§ 113. Too much emphasis should not be laid upon the 
similarities between the composition of the drain waters analyzed 
