62 



SCIENCE 



[Vol. LVI, No. 1438 



tions to this plan. Keservoirs above the. can- 

 yon region, while in the long run intercepting 

 the major portion of the waters, leave unreg- 

 ulated the sudden floods to which the lower 

 and more arid portion is subject. The Gila 

 Ba.sin alone, while comprising less than one 

 fourth of the area of the basin, sometimes fur- 

 nishes floods which at their maximum may 

 equal or even exceed those of the main stream 

 above its mouth with nearly four times the 

 drainage area and about fifteen times the mean 

 annual dischai-ge. Complete regulation there- 

 foi'e requires the control of the waters of the 

 Gila as well as those of the Colorado, and the 

 same is true of any other large portion of the 

 basin. If we confine storage to the streams 

 above the Arizona line we can intercept over 80 

 per cent, of the mean annual flow, but we 

 leave unregulated about 150,000 square miles 

 of drainage area or three fifths of the basin. 

 This area while arid and unreliable as to water 

 supply, is, like the Gila Basin, subject to tor- 

 rential rains and would in the aggregate leave 

 a flood menace that would have to be met in 

 some other way if the lands are to be pro- 

 tected.. 



It is obvious that the nearer the re.servoir 

 can be built to the lands in the lower valley 

 the more complete will he its flood regulation, 

 and it also happens that the lowest reservoir 

 site of adequate capacity, v/liich is at Boulder 

 Canyon, lies at a point within transmission 

 distance of the Pacific Coast and thus i-enders 

 available for its construction the vast power 

 as-et which is not available to any adequate 

 reservoir site existing above this point. For- 

 tunately it i.s possible here to build a dam as 

 high as maj' be required and to furnish there- 

 ))y not only complete regulation of the river 

 flow but a surplus capacity which will store 

 the sediment for centuries to come without 

 impairing the head on the power plants to be 

 served therefrom. In the distant future it 

 will become necessary to furnish additional 

 storage by building reservoirs above, but thi.s 

 requirement will be more than a century away 

 and in that time certain regulation of the 

 river is likely to be accomplished by reservoirs 

 on its tributaries and the problem eaii be 

 easily and practically met when it arises. 



Investigations have demonstrated the feasi- 

 bility of building a dam of sufficient height to 

 form a reservoir in Boulder Canyon of more 

 than 30,000,000 acre-feet capacity, which is 

 more than actually required to accomplish the 

 proposed solution of the consei'vation prob- 

 lems that are no\v imminent. The feasibility 

 and perfection of this accomplishment and the 

 economy with which it will conserve the waters 

 of the Colorado River for their best uses, are 

 in strong contrast to the results that would be 

 obtained by reservoirs in the upper basin. 

 Good sites for storage and the development of 

 power exist on the Green, the Grand and the 

 Yampa, all of which have been carefully sur- 

 veyed by the Reclamation Service, and their 

 possibility estafljlished. These reservoirs could 

 be built one at a time as needed and individu- 

 ally would cost much less than a large reser- 

 voir on the lower liver, but if their construc- 

 tion were undertaken to meet the present needs 

 of the lower valleys, they would necessarily be 

 operated in accordance with those needs and 

 this would destroy their usefulness for power 

 development and irrigation in the upper basin 

 where they are needed and for which purposes 

 there are no substitutes. To attempt such a 

 solution would therefore interpose obstacles of 

 a legal and financial nature to the proper 

 development of the upper states and virtuallj' 

 destroy a large part of the potential resources 

 of those states because most of the projects 

 would become infeasible if loaded with the 

 additional burdens of the extinguishing rights 

 which such a program woidd establish. The 

 preservation of the resources of the upper 

 states and the elimination of serious obstacles 

 to their development is the strongest argument 

 in favor of storage on the lower river and 

 the preservation of the reservoir sites in the 

 upper basin for local use. It is thus seen that 

 the conservation and proper use of the waters 

 of the Colorado Basin are in some sense one 

 great problem which must be considered as a 

 whole, otherwise there is danger of virtual 

 destruction of natural resources by throwing 

 obstacles in the way of the development which 

 at best is in many eases clifiicult and expensive. 



The recognition of this relation has led to 

 common action on the part of the seven states 



