486 EXPERIMENT STATION RECORD. [Vol. 37 



" In the lower g:i*ound-water horizon the water is under hydrostatic pressure, 

 so that it rises in wells when the water-bearing beds are penetrated. In the 

 San Simon flowing-well area the pressure is suflicient to cause this water to 

 rise above the surface in wells. In the Bowie area the water is also under 

 pressure and in sorae localities it rises close enough to the surface to be eco- 

 nomically pumped for irrigation. Measurements show that the head and yield 

 of wells has decreased considerably in the two-year period between 1913 and 

 1915. This increa.se is largely due to the filling of the uncased wells with sand 

 and the caving of the walls of those wells, but it may in part be due to the 

 increase in the number of wells and depletion of the artesian supply. It is 

 of the utmost importance for the future welfare of the valley that all wells be 

 properly cased to the bottom with heavy casing and be fitted with valves which 

 will be closed when the water is not needed. . . . 



" The flowing-well waters are mostly of the sodium carbonate type, but they 

 generally contain only small amounts of dissolved solids and are of good qual- 

 ity for irrigation and domestic use. In the vicinity of Apache and Moore's 

 Spur the ground-water .supply is small and uncertain, but some water for 

 stock and domestic purposes is obtained from shallow wells and springs. In 

 the vicinity of Rodeo and in the central part of the valley north of Rodeo there 

 is a considerable area in wTiich the depth to the water table is less than 100 ft. 

 In this area the supply is probably large, but on account of the lift that would 

 be required it would probably not be profitable at present to pump it for irri- 

 gation. All the waters analyzed from the Rodeo area are good irrigating and 

 domestic waters." 



A section on general agriculture In the valley, by R. H. Forbes, is also in- 

 cluded. 



Report [of the California] State water problems conference {Sacramento, 

 Cnl.: Stair, li)16, pp. 125). — This report deals; with the con.sorvation and use 

 of water, the flood problems of California, riparian rights, irrigation, under- 

 ground water, reclamation, inland wattTways, relation between navigation and 

 irrigation, storage for flood control, intristate waters, water for mining, water for 

 municipal purposes, expense and delay in water litigation and State aid in the 

 interest of conservation. 



Ditch flow found quickly and accurately with new portable weir, E. S. 

 Fuller (Engin. Ncirs-Rec, 78 {1917), No. 7, pp. S7S, 37^, fig. 1).— A portable 

 weir for use in quickly determining seepage losses along a canal is de.scribed 

 and diagranitiiatically illustrated. 



Determining daily discharge of canals affected by check control, H. W. 

 Humphrey {Rcclaw. lice. [V. S.], 8 {1917), \o. 6. pp. 28S-290, fig. i).— The use 

 of the Hall slope method in determining daily discharge of canals afTecte<l by 

 variable slopes due to check control is demonstrated (E. S. R., 32, p. 382.). 



The turbidity of water, A. A. Bado and R. A. Tkklles {An. Soc. Quiin. Ar- 

 gcntlna, Jf {1016), No. 16. pp. 283-293, figs. i). — New methods and apparatus 

 for determining turbidity in river waters, which are considered to be especially 

 applicable to South American river waters, are described. All are based on 

 the relative distances through which light or objects may be .seen through the 

 water. 



Silt observations at Yuma gauging station, <"ompile<l by L. M. Lawson 

 {Rcclam. Rcc. [U. S.], 8 {1917). No. 5, pp. 2.',0. 21,1. fig. i).— Silt determinations 

 begun in 1909 on the Colorado River are summarized. 



"The maximum percentage of silt during the rising stage is carried at a 

 discharge of approxinintoly 2G.000 second-feet, which is also the stage at 

 which the river at this point reaches its maximum velocity — 6.2 ft. per second. 



