aO THE SALTON SEA. 



almost hopeless, although the most strenuous efforts were being made by the engineers; 

 and it was not until February 1907 that the Colorado was finally returned into its former 

 channel. Here again, however, the vigorous vegetation of the Delta had played its part, 

 for the river bed had in the meantime become so choked by plant growth and the deposi- 

 tion of silt that the water since made repeated attempts to escape, first towards the 

 southeast through the Santa Clara Slough, directly towards the head of the Gulf, and 

 since — in spite of some rather hastily planned and inadequate efforts to control it in that 

 direction — into the head of Bee River and the Pescadero and so by various ways into the 

 Hardy, which is now, in its lower reaches, carrying virtually the whole volume of the 

 Colorado. This surcharging of the Hardy Channel had the further effect of allowing a 

 large quantity of water to flow over its western bank and towards the Pattie Basin, and 

 a large lake now fills the lower part of this Sink. 



During the summer of 190G, and at the time when the maximum inpour was reaching 

 the Salton Sink, the channels of the Alamo and the New River began to cut backward 

 from the lower end, and the soluble, loess-like soil along their courses was carried bodily 

 into the lake, leaving the deep, precipitous-sided valleys through which the present streams 

 flow. Much apprehension was felt at the time by the engineers lest their cutting action 

 should reach the Colorado and so preclude all possibility of repairing the breach, but the 

 closure was effected in time and the danger averted. 



Recent observations at the eastern end of the Salton Lake (October 1912), now that 

 the water is receding, show that there has been an enormous deposition of this or other 

 sedimentary material subaqueously; and with further recession it will doubtless be found 

 that this deposition has taken place far out into the lake. 



Some idea of the magnitude of this displacement and redistribution of material may 

 be obtained from a statement made by Mr. Cory,^ that the total yardage thus moved 

 is over 450,000,000 cubic yards, or almost twice that of the Panama Canal. 



A good deal of water still passes through both the Alamo and the New River, but 

 this is merely the overflow from the irrigation canals, and it is quite improbable that 

 with the interests now at stake in the Imperial Valley and the close watch kept upon the 

 river by the engineers, any further uncontrolled incursion of ^ater will be allowed to take 

 place. 



In the region of the lower Delta, however, conditions are very different; here we have 

 a large, wajTvard, and silt-laden river, thrown out of balance by a temporary diversion, 

 and always hampered at its mouth by great and violent tides, wandering at present virtu- 

 ally unchecked over a large area of friable alluvium with downward grades in several 

 directions. 



All these conditions tend, as may be readily imagined, toward a condition of instability 

 and possible geographical change; in fact, it is probable that even if the Colorado and the 

 general drainage conditions through the Alamo and its associated channels had not been 

 interfered with in any way by the operations of the irrigation engineers, another diversion 

 of the river water towards the west was about due from the natural causes outlined above, 

 and would in any case have ensued within a few years. 



It is furthermore evident that as so much of the flow of the river during the growing 

 season of the early spring is now diverted and utilized for agricultural purposes, and as 

 the bed of the river in its lower reaches is left practically dry during the period of most 

 rapid growth of the Delta vegetation, its obstruction and elevation will be more rapid 

 and the stability of the irrigation and protective works menaced more and more unless 

 adequate measures are taken for controUing and storing the flood-waters of the early summer 

 upon the upper Colorado. 



» Transactions of American Society of Civil Engineers, vol. lxxvi, pp. 1204, 1571. 



