1902. 



FORESTRY AND IRRIGATION. 



209 



fircenr' 



DIAGRAM SHOWING AMOUNT OF WATER REQUIRED FOR THE IRRIGATION OF THE AVERAGE 

 FARM IN COI^ORADO AT DIFFERENT SEASONS OF THE YEAR. 



ency is to retard the melting of snows 

 in the spring and to hold back the 

 moisture in the ground. For this rea- 

 son the run-off is more gradual rather 

 than so violent, as is the case where the 

 hillsides have been entirely denuded 

 of their timber, either by forest fires 

 or by clearing. The absolute tendency 

 to thus retard the flow of the waters in 

 the streams is so self-evident and has 

 been so thoroughly demonstrated that 

 I do not care to go into this matter, but 

 introduce the subject for the purpose of 

 showing the necessity for long-contin- 

 ued measurements upon our streams, 

 which shall prove beyond question the 

 value of these forest reserves to the irri- 

 gation interests. The forests of Colo- 

 rado should be entirely under the super- 

 vision of the Bureau of Forestry. I 

 hope that eventually such will be the 

 <:ase, and that then the sphere of the 

 Bureau will be limited, not to two or 

 three forest reserves, but to the pres- 

 ervation and proper use of the forests of 

 the entire state. 



I cannot refrain from saying a few 



words to call attention more forcibly 

 to the importance of this relation to 

 the irrigation interests. In the accom- 

 panying diagram I have endeavored 

 to show approximately the amount of 

 water required for the irrigation of the 

 average farm in Colorado at different 

 seasons of the year. This diagram is 

 based upon observations and experi- 

 ments made at a number of experiment 

 stations, principally bj^ithe Department of 

 Agriculture, and, while any generaliza- 

 tion of this kind must be merel}' ap- 

 proximate, it is safe to assume that it is 

 nearly correct. The diagram made up 

 from the data obtainable shows that the 

 principal use of water is in June and 

 Jul}', probably the maximum in Colo- 

 rado being about the ist of Jul}-, thus 

 occurring about a month or so later 

 than the maximum of the discharge in 

 our streams. It is not my intention to go 

 deeply into the statistics showing this 

 fact at this time, but will refer you to 

 the reports of the irrigation division of 

 the Department of Agriculture, under 

 Mr. Elwood Mead, and to the reports of 



