44 



The National Geographic Magazine 



The engineers in charge had detected 

 cutting in front of and below the gates, 

 and in anticipation of their failure had 

 built a trestle across the river above the 

 gates, with the intention of dumping in 

 enough rock to partially close the gates 

 and relieve the situation there. At 3.15 

 on Thursday, October 11, a large part of 

 this gate, known as the Rockwood gate, 

 went out. The river rapidly scoured a 

 deep channel, lowering the surface of 

 the water above the dam until there was 

 only a difference in elevation of about 

 three feet. Work was immediately be- 

 gun on repairing the trestle below the 

 gates, which had been injured both by 

 the increased flow and by the timber 

 carried away from the gate. From all 

 the available quarries within a radius of 

 from three to four hundred miles, rock 

 was hurried to this point and dumped 

 rapidly from the lower trestle. At the 

 same time the trestle which had been 

 started above the gates was strength- 

 ened, and as soon as it was in shape cars 

 were run out on that and rock dumped 

 in. In the meantime part of the material 

 that had been dumped between the two 

 abutments in the river and over which 

 the overflow had taken place was re- 

 moved and gradually the channel through 

 the Rockwood gate was filled up. 



When this was entirely filled, so as to 

 throw the entire flow of the river over 

 the central portion of the dam, the fill- 

 ing of this portion was again resumed. 

 Large blocks of granite weighing sev- 

 eral tons, as well as smaller material, was 

 hauled out as rapidly as trains could 

 bring it and gradually the gap was 

 closed. 



The river during all this time did not 

 go below about 9,000 second-feet, adding 

 materially to the difficulties expected. 



On November i there was an eleven- 

 foot difference in the elevation between 

 the water below and above the dam and 

 about one-half the water in the Colorado 

 was going down its old channel. By 

 noon of November 4 the dam was high 

 enough so that practically the entire flow 

 of the Colorado River was returned to 



its old channel, and since this time the 

 work has steadily gone on raising the 

 dam and riprapping its upstream and 

 down stream slope. 



Great credit is due to Mr Epes Ran- 

 dolph, general manager, and Mr H. T. 

 Corey, engineer in charge, for the energy 

 and skill with which this work was han- 

 dled. 



HOW SOON WILL THB LAKU DRY UP? 



The area of the present Salton Sea is 

 over 400 square miles, and its depth 

 about 90 feet. If the river discharges no 

 water into the sea, it will probably dry 

 up in about 10 or 12 years. 



Levees must be built along the entire 

 western bank of the Colorado River 

 from Pilot Knob to high ground far into 

 Mexico, probably 15 to 20 miles, be- 

 cause if high water ever overflows this 

 river again and reaches the deep channel 

 which now exists there, it will rapidly 

 erode the channel back to the river and 

 the disaster of 1905 will be repeated. 



In order to prevent the Imperial Valley 

 being deprived of water for irrigation, it 

 is necessary to build a new canal from 

 the headgates at Pilot Knob to the chan- 

 nel of the Alamo River. This can doubt- 

 less be completed in a few months, and 

 some water is already flowing through 

 the old Imperial Canal, which is approxi- 

 mately along the same line, so there is 

 no danger to the people of the Imperial 

 Valley. 



Some persons have suggested that the 

 existence of the Salton Sea during the 

 past year has had a tremendous effect 

 upon the climate in that vicinity in 

 Arizona, and even as far east as Texas 

 and New Mexico. Much publicity has 

 been given to this idea, it having been 

 caught up by newspapers as something 

 worthy of a story. 



The absurdity of any such idea may be 

 inferred when we notice that only a 

 short distance to the southward of the 

 Salton Sea occurs the great inland Gulf 

 of California, which is hundreds of times 

 larger than the Salton Sea, and yet there 

 is no very marked influence upon the 



