The Salton Sink 



2 3 



This fertile soil has attracted large 

 irrigation projects over the Imperial Val- 

 ley, south of the Sink, where 15,000 to 

 20,000 people are now engaged in putting 

 400 square miles of country under irriga- 

 tion by means of canals from the Colo- 

 rado River. It was while this canal 

 system was being constructed, with in- 

 adequate headgates at the river, in the 

 soluble soil, that in 1905 the headings 

 opened by wearing in the banks and let 

 the entire waters of the river flow down 

 the steep gradients to the north. The 

 Imperial Canal, the Alamo and the New 

 rivers became raging torrents and cut 

 away immense masses of country, which 

 was transported into the Salton Sink. 

 At Brawley the Alamo River was cut 

 down from a shallow channel to a gorge 

 60 feet deep, and it spread out many 

 hundred feet near the sea ; also the New 

 River, which at Brawley is 6 miles west 

 of the Alamo River, now has a bed 800 

 feet wide and 80 feet deep, whereas it 

 was lately only a shallow stream. The 

 entire system of canals constructed by 

 the California Development Company be- 

 came disorganized, many towns were in- 

 jured, and it is estimated that $400,000,- 

 000 of property was in jeopardy. 



To meet this emergency the Southern 

 Pacific Railroad Company undertook, in 

 connection with the Development Com- 

 pany and the U. S. engineers of the 

 Reclamation Service, to build suitable 

 levees to control the future course of the 

 Colorado River, and in February, 1907, 

 after several disappointing failures, this 

 was finallv accomplished. The new levees 

 withstood the floods of June with a stage 

 of about 30 feet, and there is every reason 

 to believe that the Colorado River will be 

 permanently diverted to the southern 

 slopes of its delta instead of to the north- 

 ern, as was recently its course. 



KNOWLEDGE OF THE RATE OF EVAPORATION 

 VERY NECESSARY 



The result of this temporary flow of 

 the river to the Salton Sink was to make 

 a lake of fresh water about 45 miles long, 

 10 to 15 miles wide, containing 440 



square miles of water surface, having a 

 depth of 80 feet in the middle. 



In May, 1907, the surface of the sea 

 was 205 feet below sea-level, and in Octo- 

 ber it had fallen to about 207.5 f eet - This 

 loss is due to evaporation, but the actual 

 evaporation should be made to include 

 the amount that has been added through 

 the flow of the Alamo and New rivers, 

 which has been quite considerable. Dur- 

 ing the past year, while the canals were 

 only partially repaired, more water 

 flowed to the sea than will be the case 

 after the beginning of 1908, when opera- 

 tions for irrigation will be fully resumed 

 for that season. 



It has been supposed quite generally 

 that as much as 8 feet of the Salton Sea 

 would evaporate annually, though we 

 now have reasons to think it may not be 

 more than 4 or 5 feet, as will be shown 

 from the results of the Reno work. It 

 is evident that, as the sea evaporates, in 

 the course of a few years we shall have 

 a series of lakes of different sizes, and 

 that in general this sea gives us an un- 

 usually good opportunity to study the 

 subject of evaporation on a large scale 

 and under favorable conditions. Mr G. 

 K. Gilbert, of the Geological Survey, pro- 

 posed that the government should take 

 up this subject, because the theory of 

 evaporation in application to bodies of 

 water in the open is very unsatisfactorily 

 understood, as shown by the discordant 

 results of several researches along this 

 line. 



The engineers of the irrigation projects 

 require to know how much a given area 

 of water surface will evaporate in a given 

 climate, in order that the dams may be 

 built at an economic height, and that they 

 may know how much water will be avail- 

 able for distribution to farmers. The 

 engineers of water-works systems for 

 large cities, especially in the arid West, 

 need such information in a reliable form 

 as a factor in their estimate of resources. 

 The meteorologists also require the same 

 knowledge to supplement their observa- 

 tions on precipitation. For example, in 

 the United States, east of the Mississippi 



