206 IRRIGATION IN THE SOUTHWEST. 



$8,000,000, while the development ef the waters of Kings and Kaweah 

 rivers has created values many times greater than these figures. 



IRRIGATION IN SOUTHERN CALIFORNIA. 



In Southern California irrigation has reached a greater degree of 

 refinement than elsewhere in America, because of the scarcity of water, 

 the high value of the products grown, and the frequent combination 

 of irrigation and domestic supply in one system. The waste of water 

 in open canals by seepage and evaporation has led to the general 

 employment of cement lined ditches for the larger volumes carried, 

 or cement, vitrified clay or iron pipes for smaller quantities. The 

 prevention of waste by these expensive methods has thus permitted 

 an enormous increase in the duty of the flowing streams, and ex- 

 tended their sphere of usefulness. The building of small farm reser- 

 voirs has gone steadily forward with the growth of the industry, until 

 the farm or orchard which is not thus supplied is the exception rather 

 Ihan the rule. This has increased the general cost of water to con- 

 sumers, but has at the same time increased the productive area by 

 adding to the economic measures for waste prevention. These indi- 

 vidual reservoirs, however, are in no sense a substitute for the larger 

 and more expensive impounding dams needed to regulate the streams 

 and control floods. 



The first of these of any importance to be constructed was the 

 Bear Valley dam, built in 1883. At that time the site was well nigh 

 inaccessible by wagon, and the cost of cement at the dam was so great 

 as to induce the projector to cut down the dimensions of the dam to 

 what is unquestionably the slenderest structure in the universe of 

 equal height. It has special interest to the engineering profession in 

 that it is capable of withstanding the pressure against it, and yet it 

 has continued to defy preconceived theories for thirteen years. It is 

 64 feet high, and barely 3 feet thick at top, and but 8 feet thick at a 

 point 48 feet below the crest. It relies solely upon its arched form 

 for its support, and upon the fact that it is of a superior quality of 

 masonry. It is reported to have cost $75,000, although it contains but 

 3,400 cubic yards of masonry. 



The capacity of the reservoir is about 40,000 acre-feet, and the 

 watershed area about 56 square miles, from which the run-off reaches 

 an estimated maximum of 100,000 acre-feet. The maximum run-off of 

 the dry season of 1898-99 was less than 1,000 acre-feet. 



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