60 



SCIENCE 



[Vol. LVI, No. 1438 



irrigated from the tributaries of the Colorado 

 River and their aggregate use of its waters is 

 very important. The largest valley which the 

 Colorado irrigates is the Imperial Valley in 

 southern California. Smaller diversions from 

 the river are in the Palo Verde Valley of Cali- 

 fornia and the Yuma Valley of Arizona. 

 These valleys can of course receive only the 

 waters left after the diversion in the basin 

 above and in years of low water the entire 

 available flow of the river is utilized in the 

 lower valleys. A much larger quantity is 

 needed to fully develop these valleys and this 

 can not be secured without the storage of the 

 flood flow at some point above. Hence arises 

 the problem of the conservation of the waters 

 of the Colorado River. 



This prcyblem has been under investigation 

 by the Reclamation Service ever since the year 

 of its organization, 1902. In this it has had 

 the cooperation of the Geological Survey in 

 the measurement of streams and of the Agri- 

 cultural Department in the examination of 

 soils. The investigation has been carried on 

 in all parts of its vast basin, many dam sites 

 have been explored with diamond drill, and 

 the results have been condensed in various re- 

 ports, the latest and most comprehensive of 

 which has been recently published as Senate 

 Document No. 142 entitled "Problems of 

 Imperial Valley and vicinity." 



The topography of the Colorado River 

 Basin is admirably adapted to the conservation 

 of its waters and their use for power. Several 

 good reservoir sites have been found at ad- 

 vantageous locations. The main stream below 

 its junction with Green River has a total fall 

 of nearly 4,000 feet to sea level, fully three 

 fourths of which are physically capable of 

 being developed for power, and the greater 

 portion of the waters of the 'basin can be made 

 available for use in this stretch. The main 

 trunk of Green River above the junction falls 

 over 2,000 feet and the upper fork or Grand 

 River has a fall of nearly 4,000 feet. The 

 average potential power in the basin at 

 present is over 8,000,000 hor.se power. Some 

 of this is unavailable for development for 

 various reasons and some of the water will 

 ultimately be consumed in irrigation, so that 



the ultimate available is about 6,000,000 horse 

 power, of which more than two thirds is on 

 the main stream, mostly within the state of 

 Arizona or on its boundaries. 



During the past twenty j'ears many engi- 

 neering examinations of the main stream of 

 the Colorado River have been made by power 

 interests, with a view to the estimation of its 

 power possibilities, and though these were uni- 

 formly reported as great, the engineers have 

 until recently agreed in the conclusion that 

 there was no available market; but the mar- 

 kets have been growing and the feasibility of 

 transmitting large blocks of power has also 

 been improving. It is believed that the time 

 has at last arrived when the development of 

 power on the lower Colorado River has be- 

 come feasible at such points as are most acces- 

 sible and nearest to adequate markets. 



The use of the waters of the Colorado for 

 irrigation presents problems of considerable 

 difficulty. Most of the river is in canyons 

 where no valleys are adjacent and its use in 

 irrigation is impossible. In the lower reaches 

 the river has formed some alluvial valleys 

 which are in part being irrigated by the nat- 

 ural flow of the stream, but which for full 

 development require a much larger flow of 

 water than is available in the late summer and 

 fall. The present irrigated area can be more 

 than trebled if the water supply is conserved 

 and the complete regulation of the river will 

 furnish a supply greater than the available 

 valley areas. Their reclamation, howevei-, 

 presents great engineering difficulties and im- 

 poses upon those lands heavy charges for con- 

 struction which would be difficult if not impos- 

 sible for settlers to pay if the entire burden 

 of the conservation and diversion had to be 

 borne by those settlers. Fortunately, however, 

 the conservation for power purposes will so 

 nearly fit with the requirements for irrigation 

 that the utility of the storage sites for the de- 

 velopment of power may be utilized as an 

 asset to defray the expenses of regulating the 

 river and thus through the power asset I'ender 

 feasible irrigation enterprises that would not 

 otherwise be feasible. 



One of the greatest, and by far the most 

 pressing problems on the Colorado, is the eon- 



