19^2. 



FORESTRY AND IRRIGATION. 



157 



the point of observation noted above, 

 the valley again opens and maintains a 

 width of two miles as far as could be ob- 

 ser^-ed to the south, but looks quite 

 low. 



The reconnaissance was continued on 

 down the river to Picacho, no points 

 offering opportunity for extensive inte- 

 rior diversions being noted until the 

 river finally leaves the last of its moun- 

 tain canyons some 10 or 15 miles below 

 the town. About 20 miles above Pi- 

 cacho the river encroaches on some 

 bold rocky bluffs on the right bank, but 

 the bottoms are about a mile wide on 

 the left side. The river here starts its 

 big bend to the east. These are the 

 first rocky banks encountered below 

 Ehrenberg. If any long tunnel diver- 

 sion from the river is to be made to- 

 wards the Salton Sea country in Cali- 

 fornia, it probably could best be done 

 here, but from the data now available 

 this is not believed to be feasible, as it 

 probabh' would require a tunnel of fully 

 20 miles in- length. One mile below 

 the above-described rocky cliffs, at a 

 place indicated as Norton, Arizona, on 

 the land-office map, the river runs be- 

 tween porphyry hills. The rocks come 

 down to the water's edge on the east 

 side of the river, but the di.stance be- 

 tween the walls is fully 1,800 feet. 

 Spillways on the side are available. 

 Diversion lines on either side of the 

 canyon would be quite expensive and 

 difficult, and the site does not seem 

 suitable for a cheap dam. 



Two and a half miles below Picacho 

 the river again passes through cliffs of 

 porphyry. The distance between the 

 walls at the water level is approximateh' 

 700 feet. Spillway opportunities exist 

 on the California side. This is the last 

 canyon on the Colorado River. It is a 

 dam site of considerable merit and prob- 

 ably the most available for extended 

 diversions of the lower river to the east 

 and west of Yuma. It is the best initial 

 point for surveys to determine irrigable 

 areas. 



It is believed that the water supply 

 of the Lower Colorado River is normall}' 

 greater than would be sufficient to cover 

 all areas irrigable therefrom. 



Twenty miles above Yuma, on the 



Arizona side, is a valley of about five 

 square miles. These small valleys con- 

 tinue intermittently until the valley of 

 the Gila is reached, a few miles above 

 Yuma, on the Arizona side, and the 

 lands of the Yuma Indian Reservation 

 are encountered on the California side. 

 A point known as the "Pot Holes," 

 about 14 miles above Yuma, which fre- 

 quently has been referred to by others 

 as a suitable diversion point, consists of 

 low granitic mountains on the right 

 bank and of some low buttes on the left. 

 The distance between these rocky walls 

 is at least 6,000 feet, and the river is 

 now well within the center of this open- 

 ing, though old channels indicate that 

 at a recent period the river was close to 

 the California side. The situation does 

 not seem well suited for diversion pur- 

 poses. Below^ the " Pot Holes" broad 

 river bottoms open out on either side 

 and contain probably 60,000 to 80,000 

 acres, above Yuma, of high-grade lands. 



The bottom lands described in this 

 report are covered with a dense growth 

 of Willows, Cottonwood, Mesquite, and 

 smaller brush down to the water's edge, 

 the same being so dense as to make it 

 difficult to find camping places. Back 

 a mile or so from the river the brush is 

 less thick, but a small shrub, known as 

 Arrowroot, there takes its place. The 

 mesas and the mountains back from the 

 bottoms are almost entirely bare either 

 of brush or grass. 



The soils in the bottoms are generally 

 good, consi.sting of fine river silts con- 

 taining a low per cent of alkali in the 

 form of lime compounds. 



The river meanders through these 

 bottoms, frequently changing its chan- 

 nels and cutting down and building up 

 the flats. Within half a mile of the 

 river they seem to be subject to over- 

 flow at the annual high stages of the 

 stream. It probably would be possible 

 to plant crops which could be harvested 

 before the high stage of the river, and 

 other crops after its recession. Prob- 

 ably these overflow conditions would 

 result in advantage rather than disad- 

 vantage to cultivated fields, as a new 

 layer of soil would be deposited with 

 each high water. The greater portion 

 of these bottom lands nearer to the foot- 



