150 MULTIPLE PURPOSE RIVER DEVELOPMENT 



dams would provide up to 1.3 million acre-feet of usable storage, 

 develop 602 feet of head, and provide for initial installed capacity 

 at site of 783,400 kilowatts. This plan can be considered inter- 

 mediate in size in the sense that it would provide more storage 

 than the three-dam plan, and would permit a greater amount of 

 power generation downstream, more flood control, and more 

 improvements to navigation. However, in terms of investment 

 outlays and annual costs, it represents the smallest of the three 

 plans. 



The estimated annual average benefits from the intermediate, 

 two-dam plan are shown in Table 23. 



TABLE 23. Average Annual Value of Project Services of Brownlee 

 and Medium-Height Hells Canyon Dams, 

 Assuming Public Development 



Item Two dams 



(kilowatts) 

 Prime power ': 



At site 566,000 



Downstream 145,000 



Total 711,000 



($ thousand) 

 Value of prime power at $41.58 per kw.*": 



At site 23,534 



Downstream 6,029 



Increment to system 29,563 



Value of flood control benefits « 1 ,800 



Value of navigation benefits * 150 



Total average annual value of project services 31^13 



Increment of average annual benefits of High Dam over two dams 11,295 



» Estimates of nominal prime power were taken from Witness Meadowcroft's 

 estimate (FPC, StaQ Brief, op. cit.. Appendix A, p. 16), and adjusted to conform 

 with estimates for the High and three dams (i.e., a critical period of thirty-two 

 to thirty-four months, 366,650 additional acres irrigated and all downstream 

 generation credited to the Hells Canyon Reach) to achieve results based on 

 assumptions consistent among all three plans. 



"See note b. Table 21. 



'See note c. Table 21. 



