The Hells Canyon Case 149 



TABLE 22. Comparative Costs of Hells Canyon High Dam and 



Three Low Dams, Assuming Federal Development and 

 Imputed Interest Rate of 5.5 per cent 



Interest and amortization" 23,721 12,040 



Interim replacements "^ 1,545 1,074 

 Payment in lieu of state and local 



taxes 2,145 1,089 



Operation and maintenance ^ 1,495 1,666 



Total average annual costs 28,906 15,869 



Increment of average annual costs of 



High Dam over three low dams 13,037 



» The investment figures were obtained in the same manner as in Table 20, 

 except for the use of an interest rate of 5.5 per cent instead of 2.5 per cent. 

 *" Interest at 55 per cent over a 100-ycar amortization period. 

 •" FPC, StafJ Brief, op. cit., Appendix B, p. 87. 

 ^Ibid., Appendix B, p. 88. 

 * Ibid., Appendix B, pp. 89-90. 



Feasibility of an hitermedinte, Two-Dam Plan 



Since the plans for the High Dam and three low dams are so 

 nearly equal in comparative efficiency (when the higher oppor- 

 tunity cost is employed), despite the fact that they are so different 

 in scale, it appears that the resources committed to the develop- 

 ment of the incremental opportunities represented by the High 

 Dam would be employed over some range of diminishing total net 

 returns. A plan of development intermediate between the two, 

 therefore, may be economically superior to both. 



Details of such a plan of development were prepared by one of 

 the expert witnesses for consideration at the FPC hearings. The 

 plan involved two structures — a dam of medium height (.S2.5-foot 

 head) to occupy the site proposed for the High Dam, and a second 

 structure identical in location and characteristics to the Idaho 

 Power Company's proposed Brownlee Dam.^o Together, the two 



^'FPC. Staff Brief, op. cit., pp. 6-7, and Appendix A, pp. 3 1; also /:\hil>its, 

 op. cit.. No. 186. 



