8 
SEEPAGE OR RETURN WATERS FROM IRRIGATION. 
As we pass out of the first bottoms, we reach successively two 
or three terraces, or mesas, which are generally sandier and 
stretch back for varying distances. On the north side of the stream 
the watershed extends many miles, and the streams here indicated 
as Dry creek, Box Elder creek, Lone Tree creek, and several 
smaller channels, are simply ravines or depressions which at times 
after storms are filled with water and may become at such periods 
raging torrents. Ordinarily their beds are sharply marked and 
have a clear tributary country ; they are entirely dry, giving almost 
no indication whatever of water. After their channels cross the 
lines of the canals and enter the irrigated country, these streams 
begin to carry running water. 
The lines of the canals, which follow approximately contour 
lines, indicate by their bends the general character of the country 
and the slope. On the north side of the river the land, as a whole, 
is more uniform than on the south side. Nearly all the irrigation 
is, therefore, confined to the north side of the river; the exception 
being in the region near Fort Collins, and a little space near 
Greeley. Between the two there is a rougher and more broken 
country on the south side of the stream, not easily reached by 
canals from the Poudre. 
On the south side, the divide which separates the Poudre from 
the Big Thompson is but a few miles from the main river, and as 
we reach range sixty-eight, the location of the divide is indicated 
closely by the ditch which takes from the stream to the south. 
Some of the waste of this canal passes into the Poudre river. To 
the west, the drainage on the south side, even the mountain drain¬ 
age, does not flow into the Poudre to any great extent, the lateral 
valleys being nearly all tributary to the stream to the south. 
The foothills are near the western portion of range sixty-nine, 
following a line a little east of south. The first ranges, generally 
known as hogbacks, are formed of gray sandstone, and very shortly 
afterward the granite is met with, forming the foothills of the main 
Rockies. The sandstone appears in ridges, and even on the plains 
for miles the same general appearance may be seen in the buried 
ridges which traverse the country from north to south, and made 
evident on the map by the intermediate valleys, in which flow 
streams like Dry creek, Box Elder creek, etc., approximately par¬ 
allel tor a long distance and separated by pronounced ridges. 
These ridges sometimes form natural basins, which have been 
largely used for storage purposes. As the amount of water there 
stored affects, to some extent, the amount of return waters, the prin¬ 
cipal reservoirs in use are indicated on the map. 
§ 9. As the length of time that irrigation has been practiced, 
together with the distance of the land from the river, is an import¬ 
ant element in the amount of seepage, a fuller description of the 
