308 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



giving the results of the work on the flow of water in open chan- 

 nels has been published during the year ; the results of similar work 

 on the flow in wood pipes have been compiled, and observations on 

 concrete pipes have been begun. These experiments have proven to 

 be of great value to hydraulic engineers by giving them more accu- 

 rate data for the desiring of new conduits. 



Pumping investigations for the year have consisted in mechanical 

 tests in the laboratory of the New Mexico experiment station, me- 

 chanical tests in the field in Idaho, Kansas, and Nebraska, and 

 the collection of data on the cost of operation and maintenance of 

 Work on a general bulletin on pumping for irrigation has continued. 



Studies of the operation of irrigation districts have continued. 

 These studies have for their primary object the improvement in 

 district legislation in such a way as to make district bonds more 

 salable. The investigations of the operation of mutual and co- 

 operative irrigation enterprises were continued, and reports of these 

 investigations are in preparation. 



The irrigation investigations remained in direct charge of Dr. 

 Samuel Fortier. 



GENERAL REVIEW OF IRRIGATION INVESTIGATIONS, 1898-1915. 



By order of the Secretary, on April 1, 1915, this work was placed 

 under the general supervision of the Director of the Office of Public 

 Eoads, in anticipation of its transfer to the new Office of Public 

 Eoads and Rural Engineering on July 1. By this transfer the irri- 

 gation work of the office came to an end. This work was first pro- 

 vided for in 1898, and has been carried on continuously since that 

 time. While many phases of irrigation have been studied during 

 these 17 years, two problems have been foremost. When the work 

 started the greatest need of the arid region seemed to be a reform in 

 the legislation relating to irrigation in the several States contain- 

 ing arid land. Consequently much eifort was devoted to studying 

 the needs of the arid region in this regard and urging better laws. 

 Largely through the efforts of the office most of the arid States have 

 adopted codes of laws relating to irrigation conforming to the gen- 

 eral principles urged in the earlier publications of the office. Next 

 to the need for improved legislation seemed to be the need for a 

 more economical use of water. The water supply of the arid region 

 is sufficient for only a small part of the land which is arable except 

 for the lack of water, while large areas are being ruined by excess 

 water from irrigation. Therefore studies to determine first how 

 much water was being used, then how much should be used, and 

 methods of preventing waste and encouraging economical use have 

 been a leading line of investigation. 



These studies have involved many others, both engineering and 

 economic. An intelligent use of water in irrigation requires that the 

 water be measured, and any general adoption of the practice of 

 measuring water requires inexpensive and simple measuring de- 

 vices. Since satisfactory methods of measuring water for irrigation 

 had not been developed, considerable attention was given to this 

 subject. A hydraulic laboratory used exclusively for this purpose 

 has been established in cooperation with the Colorado agricultural 

 college, at Fort Collins, where existing measuring devices have been 

 calibrated and new devices developed. 



