GATE STRUCTURES FOR IRRIGATION CANALS. 23 



The gates in the main canal are placed at right angles thereto and 

 the gate leading into the reservoir inlet canal is set at an angle of 

 4:5° with the main canal and at right angles to the inlet canal. 



The use of a wooden slide gate for openings of this width, 12 

 feet, is rather unusual, and the writer would suggest the use of wood 

 or steel radial gates in adapting these same general plans if the regu- 

 lation to a great degree of accuracy is not required, and there is to 

 be very much changing of the gates. Many bifurcations of this 

 sort — supplying a reservoir — do not require to be changed more than 

 once or twice in the course of the year, all the water being turned to 

 the reservoir during the winter and early spring and then the inlet 

 to the reservoir closed for the balance of the season and the main 

 canal gates left open. In such cases economy in gate shutters at the 

 expense of time and labor for one or two operations a season may 

 be recommended. 



This structure was constructed by contract at a time when com- 

 mon labor cost $2 and teams $4 per day. Water was close at hand ; 

 sand and gravel were hauled 1^ miles and cement and lumber 3 

 miles. The district furnished at the site all steel, hardware, and 

 lumber except forms that went into the structure. Cement was fur- 

 nished, mixed, and placed by the contractor. The successful bid 

 was as follows: 



For concrete in place, including the setting of all anchor bolts and placing 

 steel reinforcements, $8.65 per cubic yard. 



For labor, framing, and completing gates (shutters), bridges, etc., $12.75 

 per thousand. 



For all excavation required for concrete, not included in inlet ditch, $0.34 

 per cubic yard. (The above quoted from contract.) 



The total cost was $2,685.48. 



DIVISION GATES. 



Bifurcation works on a small scale are usually called division 

 gates or division boxes. As a rule, they divide water between two 

 small laterals, between one consumer and all others below him on a 

 lateral, or very small ones are used by a single consumer to dis- 

 tribute the water in his head ditch to various parts of his land, the 

 various shutters beii^g used alternately as check and delivery gates, 

 depending on where the water is to be sent. 



DIVISION BOX, SHELL CANAL, WYOMING. 



Plate VII, figure 1, shows the type of construction used to divide 

 the water of a lateral 8 or 10 feet wide between two smaller laterals. 

 The water in the foreground is turned to one or the other or both 

 of the small laterals leading to the right and left of the picture. 

 Simple flashboards are inserted in the slots as shown. Where the 



