64 MULTIPLE PURPOSE RIVER DEVELOPMENT 



as it contributes to the prime powei generation of hydroelectric 

 power plants downstream. For example, storage provided at the 

 Hungry Horse site on the Flathead River of the Columbia River 

 tributary system can be used to generate 212,000 kilowatts of prime 

 power at the Hungry Horse powerhouse. Its contribution of prime 

 power under co-ordinated system operation, at downstream plants 

 currently built or under construction, is nearly three times as great. 

 (See Figure 12.) Table 1 illustrates this in detail. 



The difference between at-site prime power for which an enter- 

 prise unit could collect compensation under the assumptions of 

 the competitive model, and the total resulting from the direct 

 interdependence between investment undertaken at the Hungry 

 Horse site and downstream power plants, suggests the extent of 

 the difference between the private and the social marginal efficiency 

 of investment in this hydroelectric site. 



It is recognized that the hydraulic measurements in establishing 

 stream-flow regulation provided by the storage depend on assump- 

 tions as to the quantity and time profile of additions to storage on 

 the system. 23 Yet these are matters which are not essential for our 



" For example, the data in the illustration above are based on the current 

 seven-month critical period from the standpoint of storage releases for prime 

 power generation. During the remaining five months, production at Hungry 

 Horse is lower and other plants in the system carry the load. As additional 

 storage is constructed in the Columbia Basin, the critical storage drawdown 

 period will increase and the prime power from Hungry Horse will be smaller. 

 If we take an alternative measure, dependable capacity at site (available in 

 sixteen out of twenty years) and the average annual salable energy at site and 

 downstream, the following data are indicative of the annual kilowatt-hours 

 attributable to Hungry Horse by the two methods. 



Dependable capacity 

 Prime power and salable energy 



Site (million kw-h) (million kw-h) 



Hungry Horse 1,857 700 



Downstream federal plants, U.S 3,399 783 



Downstream private plants, U.S 1,489 358 



Downstream private plants, Canada 613 178 



Total 7,358 2,019 



Both sets of data, computed by alternative methods, clearly reveal that power 

 made available by Himgry Horse storage downstream greatly exceeds the amount 

 available at site alone. 



