BULLETIN 82 . 
4 
of its drainage area, contained in this water are such as are intro- 
<V*> ' 
dnced by the people living along its banks. The water of the 
Cache a la Poudre is an excellent water usually containing less 
than three grains of solids to the imperial gallon. The water fur¬ 
nished to the inhabitants of Fort Collins is taken from the Pondre 
about six miles below the point where the North Fork joins the 
Pondre, and is a mixture of Pondre and North Fork water plus a nota¬ 
ble quantity of seepage. This water varies in the amount of total 
solids contained from 2.5 grains per imperial gallon to 13.5 grains, 
which is the maximum observed. The former sample was taken when 
the river was high and the influence of the North Fork and the 
seepage water together was not perceptible. The latter was taken 
when the Pondre was low. Their influence is shown by the nota¬ 
ble increase in the amount of the total solids present. 
§ 5. The conditions given for the Pondre hold for all the 
streams north of the Arkansas, and for those of the San Uuis val¬ 
ley, so long as they are mountain streams. When their waters 
leave the mountains their courses are over rocks of younger geolog¬ 
ical formations, from which they receive waters of different quality, 
and their character is materially changed. 
§ 6. I shall give analyses of waters from other streams, but 
that of the Poudre will be the only one treated of in detail. The 
considerations which have led me to confine myself to the study of 
the Poudre river water to so great an extent as I have done are evi¬ 
dent: Phrst, the water of the Poudre irrigates at the present time, 
as much if not more land than that of anv other stream within the 
mr 
State; Second, it flows through our home valley, is easy of access, 
and we have fuller data and more intimate knowledge of it than of 
any other stream in the State; Third, irrigation has been practiced 
in this valley almost as long if not as long, as in any other portion 
of the State (a few sections where irrigation was practiced by the 
Mexicans excepted), extending over a period of forty-three years; 
Fourth, the oldest and at the same time an extensive system of 
reservoirs whose beginning dates back to 1875, ^ ias been made to 
supplement the summer flow of the river. 
§ 7. Under these conditions the flow of the return waters has 
already been established, the first exaggerated effects of irrigating 
this land have passed away, and the rate at which the return 
waters are carrying the soluble salts from the soil has presumably 
approached, if it has not already reached the point, at which it will 
remain for years to come. The same may be assumed to be true 
in regard to the character of the salts taken into solution. 
§ 8. In this section the period of drainage has begun, laud 
having become valuable enough and water in such demand that 
drainage has already been instituted for the double purpose of pre¬ 
serving the land from being water-logged or seeped, and for render- 
