ARTESIAN WELLS IN COLORADO. 539 
everywhere in the prairie region of Colorado, and to their comparatively reduced 
numbers everywhere in the foot-hills, where we find the upturned ‘‘ hog-backs” 
are formed of sandstone, limestone or slate, while we find them always beyond 
the upturned coal measures. 
The writer of this article was the witness, some eighteen years ago, of an 
effort made by the war department to obtain water near Fort Lyon for the quarter- 
master’s herd, north of the Arkansas river. A well was dug some thirty feet in 
tenacious clay, then borings were carried on some thirty or forty feet deeper. 
The clay continued the same at the farthest depth attained, but not one drop of 
water was obtained, and the effort was given up as wholly useless, although begun 
in the bed of a dry affluent of the Arkansas. 
To make an artesian well practically and fully useful, we must draw from the 
underground resources that are derived from our vast mountain ranges. The 
local rainfalls of the great plains west of 100 degrees west longitude are too scanty 
in amount to ever be of much practical benefit, the rapid slope of the plains and 
the excessive evaporation from their treeless surfaces rendering that supply pre- 
carious and the effect of but short duration. The effect of hard rain in this part 
of Colorado is to drain away rapidly into the Arkansas, Smoky Hill and Repub- 
lican rivers, by the numerous dry ravines that radiate from those rivers. Their 
waters rise very high in a few hours, the water drains rapidly away, but its reten- 
tion on the surface is very light in amount from the scanty nature of the herbage 
clothing the ever parched prairies. 
From observations taken at Fort Sedgwick, Fort Russell, Cheyenne, Denver, 
Fort Reynolds and Fort Lyon, on the Arkansas, the yearly rain fall will average 
over that region about 13.21 inches. 
The average along the Colorado foot-hills is about 17.30 inches. 
The average for Clear Creek valley in the mountains, as far as Georgetown, 
Bakerville, Black Hawk and Central, is about 18.75 inches. 
The rain fall and melted snow for the higher points above these, including 
the central range, will give yearly an approximate amount of 31.50 inches; or for 
the whole area of Clear Creek valley west of the range line, between ranges 69 
and 70 west, amounting*to about 400 square miles, we have a mean approximate 
amount yearly of rain and melted snow of 20.62 inches. 
This gives us then for the Clear Creek water shed of 400 square miles a yearly 
amount of 19,068,800,000 cubic feet of water. 
Now Clear Creek gives us from a series of measurements begun in Septem- 
ber, 1860, and extended to March, 1880, an average discharge at Golden, Colo- 
rado, of 5,850,000,000 cubic feet per year. This amount, subtracted from 19,- 
068,800,000, gives uS 13,213,300,000 cubic feet of water that is lost to us by 
evaporation, or which, settling into the ground, is practically lost, unless sought 
for by digging, or returned to us through artesian wells in the foot-hills.. 
In other words, of all the rain and snow-fall received in the Clear Creek 
water-shed sixty-eight per cent. is lost to us and thirty-two per cent. is discharged 
by Clear Creek where it enters the plains. 
