IRRIGATIOIsr IN NOETHERN COLORADO. 



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 Avater 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.' 



A soil survey including 

 the Cache la Pouclre Valley 

 was made in 1904 by the 

 Bureau of Soils, United 

 States Dej)artment of 

 Agriculture, and 10 soil 

 tj^pes 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 bj^ a loam or a heavy fine sandy 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 



Fig. 1. — Meteorological conditions at Fort Collins 

 during the period of the investigation compared 

 to the average for 31 years. 



^ Soil Survey of the Greeley Area, Colorado, by J. Garnett Holmes and N. P. Neill. 

 Field Operations of the Bureau of Soils, 1904. 



