AN IRRIGATION RESERVOIR Ig5 



perature of the water. That of springs is generally too low in sum- 

 mer for immediate use, and its value is greatly enhanced by being 

 raised to an equal or greater temperature than that of the air. This 

 is quickly done by exposure in a shallow pond. A reservoir can be 

 constructed entirely in the ground where the slope will admit of it, 

 and by lining the bottom and sides with clay well puddled, will 

 answer for most purposes. Some are built of adobe, backed with 

 earth and plastered on the inner side with hydraulic cement. Con- 

 crete of lime, sand, and broken stone is, however, the best material, 

 where lime can be readily obtained, and any person with ordinary 

 mechanical skill can construct them. The following hints on a dirt 

 reservoir may be suggestive : 



A reservoir should be built on the highest part of the tract sought to be 

 irrigated by scraping the earth from the outside and from such a large area 

 as not to affect the utility of the land from which it is taken. With a levee 

 all around 5 feet high, 5 feet of water could be carried safely. The slopes 

 ought to be two to one on the inside. A reservoir 20 feet square and 4 feet 

 deep would hold 12,000 gallons. With the slopes as above the reservoir 

 should be measured two feet from the bottom, or half way up the 4 feet of 

 water; consequently, to lay put a reservoir to hold 12,000 gallons, put the 

 stakes 12 feet square and build. For any other size one take 8 feet off the 

 same as this: A reservoir 25 feet square will hold 18,750 gallons and would 

 be 17 feet square at the bottom; one 30 feet square would hold 27,000 

 gallons and would be 22 feet at the bottom; one 35 feet square 27 at the 

 bottom will hold 36,000 gallons; one 40 feet square 32 on the bottom will 

 hold 48,000 gallons. This spread upon the surface of an acre would be a 

 little more than 1^ inches of rainfall. 



Almost any loam or soil will hold water with a little puddling. The 

 cheapest way to puddle is to build a pen the size of the entended reservoir, 

 including at least a portion of that to be under the embankment, wet it very 

 wet, put some hogs in the pen and keep feeding them barley, a little at a 

 time, so as to make them not only walk around, but root for the barley. A 

 half-sack of barley fed to eight or ten hungry hogs in half a day will make 

 a good puddle. If it did not work satisfactorily, the water could be taken 

 off and the bottom covered about an inch deep with coarse sand mixed one 

 part to five with Portland cement, put in dry, and let it be covered slowly. 

 A barrel of cement may be counted at about 4 cubic feet and with the mix- 

 ture above would cover the first-named reservoir about 1^4 inches. This 

 would make it tight. The supply pipe should come up from the bottom, so 

 that the lift would never be more than the height of the surface. 



Loss of Water by Seepage. The great loss of water by seepage 

 during a long run has led to the cementing of ditches, and to the use 

 of miles of large wooden, concrete and iron pipe by the irrigation 

 companies of Southern California; also, where the slope is rapid, 

 paving ditches with rock has been resorted to. Similar efforts 

 naturally suggest themselves to the user of a small supply to save 

 his flow from loss. The lining of ditches to prevent seepage were 

 tested by the California Experiment Station at Berkeley, and publi- 

 cation of results were made.* Where lumber is cheap the use of a 

 board flume is an available means of saving water, when the soilis 

 coarse and leachy. 



*Bulletin 188 and Circular 144, University of California Experiment Station. Berkeley. 



