THE IKRIGATION AGE. 



205 



the canal was then run out, each plate angle of azimuth 

 and stadia distance being read by the transitman to the 

 field draughtsman, who responded by calling the cal- 

 culated course, which was checked by a glance at the 

 needle, the magnetic declination being set off on the 

 plate. The draughtsman then platted the readings and 

 sketched in the canal, the laterals and such other fea- 

 tures as were thought desirable. The field maps were 

 drawn upon a scale of 500 feet to the inch. 



After all the canals in a given territory were accu- 

 rately located and the points of departure of laterals 

 indicated, needle traverses were run along controlling 

 lines, from which radial shots to determine boundaries 

 were recorded and platted. Contour traverses were 

 sometimes necessary to cut out land above the gravity 

 lines of canals. Land was classified as "irrigated hay, 

 irrigated tilled, dry but irrigable, and non-irrigable un- 



of the co-efficient of friction (n). By these means, 

 complete data were obtained for computing Q by Kut- 

 ter's formula. The use of meters in gauging velocity 

 was impracticable, as canals were seldom or never 

 flowing at their maximum capacity. 



Measurements, sketches and descriptions were also 

 made of diversion dams, headgates, waste gates and 

 flumes in order to show the, condition of works. 



In the office, profiles of every cross-section were 

 constructed and the computations of capacity were made. 

 About 245 detail maps, showing the land in colors to 

 correspond with the canals that serve them, and an 

 index map of the whole valley on a much smaller scale, 

 was made to expedite reference to the detail sheets. 

 Progressive maps were also furnished to the United 

 States Geological Survey monthly. 



Perhaps the most remarkable feature about the 



Big Cut, on Mink Creek Canal. Oneida Irrigation District, Idaho. 



der existing systems." The boundaries of these tracts 

 were indicated on the maps by different colored pencils. 

 The draughtsman also sketched in the feed laterals to 

 show how and by what system the lands were watered. 

 Notes as to the character and porosity of the soil were 

 taken by the transitman. It was found that ordinarily 

 about two square miles could be mapped by each party 

 daily, after the canal lines had been run. 



Measurements for capacity were made at repre- 

 sentative points along each canal. In determining cross- 

 sectional areas, rod readings were taken at two-foot 

 intervals on large canals and at every foot on small 

 canals, and the mean of several measurements was 

 assumed to represent the true cross-sectional area. The 

 grade for several hundred feet was then determined, 

 and the condition of the bottom and sides of the chan- 

 nel minutely described as a basis for the evaluation 



undertaking was its comparatively low cost, no doubt 

 due principally to the size and scope of the under- 

 taking, making an economical organization possible. 



The total expense of the survey was $28,000, which, 

 divided by the number of acres involved, gives a cost 

 of approximately 3~y 2 cents per acre. The Reclamation 

 Department of the United States Geological Survey 

 assumed a portion of the cost, amounting to $9,735, in 

 order to obtain the information for its immediate use, 

 and the balance is assessed to the litigants. As the 

 maps are of public record, every landowner in the 

 Upper Snake River valley has the benefit of an excel- 

 lent map of his property at a cost to him of 2.3 cents 

 per acre. In other words, every 80-acre farm was 

 surveyed and mapped for $1.85. 



The work was under the direction of State Engineer 

 James Stephenson Jr. The writer had immediate 



