SOIL SURVEY OF SOLOMON SVILLE AREA, ARIZONA. 



23 



As indicating the alkali content of the subsoil, the character of the 

 underground water is important. In general the well waters of the 

 Gila Valley carry large, often very large, quantities of soluble salts, 

 thus indicating the presence of an excess of alkali in the subsoil. In 

 a few cases the deeper wells, reaching to the second or third water- 

 bearing stratum, and cased to prevent the entrance of surface water, 

 supply water superior to that from the shallower wells. In many 

 other cases, however, especially in the central and lower parts of the 

 valley, the water of the deeper wells carries much more alkali than 

 those of less depth. This seems to be the case wherever the heavier 

 subsoils extend to great depths. Many of the well waters of the 

 valley are unfit for domestic use. At Pima a boring was extended to 

 the depth of over 800 feet through heavy sedimentary material in an 

 attempt to secure artesian water, resulting only in a large supply of 

 underground water (not confined under pressure) inferior to the water 

 of an adjacent surface well, which was itself unfit for domestic purposes. 



The results of chemical analyses of several well waters of the area 



follow: 



Analyses of well waters. 



[Parts per 100,000.] 



Constituent. 



Ions: 



Calcium (Ca) 



Magnesium ( Mg i 



Sodium (Xa) 



Potassium ( K) 



Sulphuric acid (S0 4 ) 



Chlorine (CI) 



Bicarbonic acid (HC0 3 ) 



Conventional combinations: 



Calcium sulphate (CaS0 4 ) 



Calcium bicarbonate (CaIIC0 :i ) 

 Magnesium sulphate (MgS0 4 ).. 

 Magnesium chloride (MgCl) ... 



Potassium chloride ( KC1 ) 



Sodium sulphate (Xa._.S0 4 ) 



Sodium bicarbonate (NaHCO 

 Sodium chloride (NaCl) 



Total solids 



No. 18, sur- 

 face well, 

 sec. 2, T. 7 

 S., R. 27 E. 



6.8 

 2.1 

 48.6 

 9.1 

 40.0 

 4::. 1 

 48.4 



23.1 



17.3 

 22.8 

 06.7 

 58.1 



No. 28, open 



well, 35 feet 



deep. 



0.6 

 2.3 

 47.7 

 3.7 

 27. 8 

 30.4 

 60.5 



22.4 

 11.4 



7.0 

 4.3 

 83.3 



59.6 



Well near 

 Safford, 43 

 feet deep. 



is. 1 

 4.4 

 19.3 

 1.3 

 13.4 

 37.9 

 48.4 



18.9 

 50.9 



17.2 

 2.5 



13.9 

 39.4 



198. 4 



188.0 



142.8 



Seepage water is abundant, but has collected to a dangerous extent 

 in only a few localities. The accumulation of such water, either in 

 pools or sloughs or filling the soil spaces of low-lying and poorly- 

 drained lands, is caused either by leakage through the sides and bot- 

 toms of canals and laterals, or by excessive irrigation of higher lying 

 lands. Water in excess of the amount required by growing crops 

 percolates downward, fills the subsoil, and finds its way through the 



