IRRIGATION IN NORTHERN COLORADO. 
RAINFALL— INCHES 
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or from May 5 to September 26, while at Greeley the period is 9 days 
longer, from May 1 to October 1. 
In spite of low relative humidity and moderately high wind move- 
ment, the average annual evaporation from a water surface is com- 
paratively low at Fort Collins. The average for the year is reduced 
by the small amount for the winter months. During the summer 
months, when water is held in reservoirs for future irrigation, the 
evaporation is heavy. 
Weather conditions dur- 
ing the period of investiga- 
tion varied from the aver- 
age only to a small extent. 
Figure 1 is given to show 
the rainfall, temperature, 
and evaporation at Fort 
Collins during 1916 and 
1917 as compared with the 
average for a period of 31 
years. 
SOILS. 3 
A soil survey including 
the Cache la Poudre Valley 
was made in 1904 by the 
Bureau of Soils, United 
States Department of 
Agriculture, and 10 soil 
types were found and 
mapped. Those occurring 
most extensively in the 
valley were designated as 
Colorado fine sandy loam, 
Laurel sandy loam, and 
Fort Collins loam. 
The Colorado fine sandy 
loam covers a large area 
north of the river between Fort Collins and Greeley. It is a residual 
soil, light to dark brown in color, extends to an average depth of about 
3 feet, and is underlain by a loam or a heavy fine sand} 7 loam to a 
depth of 6 feet or more. The silt and clay content increases with the 
depth. The loose texture of this soil affords good drainage and. except 
in draws or depressions where seepage comes to the surface, there is 
II 
1 
MEA1-4 I8a7-iei7 
EVAPORATION - 
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Fig. 1. — Meteorological conditions at Fort Collins 
during the period of the investigation compared 
to the average for 31 years. 
3 Soil Survey of the Greeley Area, Colorado, by J. Garnett Holmes and N. P. Neill, 
Field Operations of the Bureau of Soils, 1904. 
