46 



just west of the Sonoran Mesa, had become so choked with 

 vegetation and a heavy deposit of silt from the standing 

 water, that, when finally turned back from the Imperial 

 Valley, the Colorado sought new outlets towards the south- 

 west and broke into the channels of a maze of rivulets in the 

 delta, among which the Hardy River now carries by far the 

 greatest bulk of water. This stream skirts the southern end 

 of the Cocopah Mountains, and, when surcharged by the spring 

 freshets, it spills over the flood-plain on its western bank into 

 the Pattie Basin, there increasing the area of the Laguna 

 Salada, which is again reduced, after the subsidence of the 

 river, by rapid evaporation. 



It thus happens that the river water in the whole of the 

 Colorado Delta, from near the United States borderline to the 

 Gulf of California, is in a condition of unstable equilibrium, 

 and is likely to break out afresh in a time of extreme flood 

 and once more to submerge the vast acreage of arable land in 

 the lower, adjoining basins. Owing to the presence of high 

 ground along the border, the inhabitants of the Imperial 

 Valley are dependent for their irrigation upon a canal that 

 passes through Mexican territory, and there are those who 

 have recommended the purchase by the United States of 

 the southern half of the Colorado Desert in order to safe- 

 guard an American population of more than fifty thousand 

 people, and millions of acres of the richest, most easily tilled 

 soil known in the western hemisphere. In the words of one 

 writer, ''Nature has accomplished for the valley what man 

 and his dikes have done for Holland," but vastly more human 

 effort must yet be brought to bear before the Imperial farms 

 and ranches can be thoroughly secured against the danger 

 incident to an act of malice, or to a surcharged river combined 

 with an exceptionally high tide in the estuary. At the present 

 time a huge dam is being constructed to block a possible 

 breach at Volcano Lake, Lower California, which has a higher 

 altitude than much of the country to the northward. But 

 south of this, and also west of the Cocopahs, lies perhaps the 

 better portion of an American Nile flood-plain, where the only 

 inhabitants are a handful of Indians, and where a readily 



