44 BULLETIN 339, U. S. DEPARTMENT OF AGRICULTURE. 



meter determinations at the head of the main canal of each system 

 (PI. Ill, fig. 2) . The gages were read by men employed for the pur- 

 pose, and the discharge curves were based in each case upon 20 to 

 30 current-meter ratings which were made during the season at each 

 station by two to six hydrographers with different meters. The areas 

 irrigated under each system and the crops that were grown were 

 determined by a house-to-house canvass of each farm. 



BOISE VALLEY FARMS. 



The quantity of water delivered to a total of 428.64 acres on 16 

 farms in the Boise Valley was determined during the season of 1912. 

 The farms included were located in the heart of the valley, near 

 Meridian, and represented typical Boise Valley conditions,. and the 

 average use of water at the individual farmer's head gates in the dis- 

 trict during the season was found. to be 2.56 feet per acre, the quantity 

 wasted not having been deducted. Of the 428.64 acres included, 

 144.84 acres were devoted to alfalfa, pasture, and other hay grasses, 

 the remainder to grains, potatoes, and orchards. The soil of th*e 

 district is nearly uniform and consists of a clay loam 3 to 8 feet in 

 depth, underlain with a rather compact gravel. The water for irriga- 

 tion purposes in the above district is used with more than the average 

 care, and the use of water shown by the measurements corresponds 

 very closely with the requirements shown by the variation experi- 

 ments. 



SALMON RIVER PROJECT FARMS. 



The water applied to a total of 978.22 acres on 12 farms of the 

 Salmon River project was measured during the season of 1913, the 

 area involved having all been determined by transit surveys. The 

 soil of the district is a clay loam 2 to 6 feet in depth underlain by lava 

 rock. The total area involved consisted of 200.73 acres of hay and 

 pasture grasses, and 777.49 acres of grain, potatoes, and orchards, and 

 the use of water by the farmers varied from 0.77 to 5.30 acre-feet 

 and averaged 2.08 acre-feet for the entire area. This was the first 

 year some of this land had been irrigated, and it is believed the 2.08 

 acre-feet, with one or two exceptions, represented the average use 

 of water on the entire project at that time. The quantities wasted 

 from these tracts were not measured. 



WATER DIVERTED BY TYPICAL CANAL SYSTEMS. 



The canal systems investigated in order to determine their head- 

 gate diversions consisted of the Riverside, Farmers' Cooperative, 

 Farmers' Union, Settlers', Boise Valley, Pioneer, and Eureka, typical 

 canals of the Boise Valley; the Randall Canal, and the Clark and 

 Edwards in the Upper Snake River Valley; and the SoutH. Side 

 Twin Falls Canal, which irrigates approximately 200,000 acres on the 





