lERIGATIOX IN NORTHERN" COLORADO. 85 



rather than as a matter of necessity making irrigation practice con- 

 form to the flow of the stream and future as well as current needs. 

 Were the Cache la Poudre Valley alone concerned this could be ac- 

 complished by a general pooling of interests as in the case of the 

 exchange, but no doubt appropriators on the South Platte below 

 would object strenuously to such a radical departure from custom 

 unless they could be shown that no invasion of their rights would 

 result. 



Tlie system of independent ownership of reservoirs and the re- 

 sulting scale and rental of rights which may be used at any point 

 affords a better distribution and a certain elasticity of supply which 

 is on the whole very beneficial. 



The amount of irrigation after September 15 in the Cache la 

 Poudre Valley is negligible, and considering this valley alone, 

 storage of the supply in the river should begin at that time. 



Under the system of diversified crops common in the valley a 

 relatively small amount of stored water is required. For prac- 

 tically the entire acreage under irrigation in 1916 and 1917 less than 

 25 per cent of the supply used was stored water. 



The many farm reservoirs holding a few acre-feet play an impor- 

 tant part in promoting a good use of water and their construction 

 is recommended to secure a maximum benefit from a small flow, 

 either constant or intermittent. 



Absorption losses are relatively highest in small shallow reser- 

 voirs and the proportion decreases markedly with the increase in 

 the volume of water stored. 



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