405 



$5,000,000 in hydropower recapture. 



BPA has commissioned several studies which demonstrate a 

 considerable potential for water savings in improvements in the 

 application of irrigation water. Irrigation efficiencies on the 

 Basin now range from 40% in primitive flood operations, most often 

 found on Reclamation-served projects where 60% of depletions occur, 

 to 90% in the most highly capitalized center-pivot operations 

 typically found on privately-financed corporate farming operations. 

 One BPA-commissioned study indicates that water conservation from 

 a scheduling program, implemented by the Umatilla Electric 

 Cooperative, decreased water use by 39% for alfalfa.* 



In some cases improvements in efficiency of water application can 

 lead to increased consumption of water by crops. However, even in 

 such cases the hydropower value of water savings may exceed the 

 increased amount of water utilized, or depleted by crop 

 consumption. E.g., a flood irrigated farm may currently divert 7 

 feet per acre, of which 3 acre-feet is consumed by the crop and 4 

 acre-feet per acre returns as runoff: a 40% - 50% efficiency level. 

 The result of a conversion to more efficient sprinkler irrigation 

 may increase the amount of water consumed by the crop to 4 acre- 

 feet per acre, but because of the efficiency increase to 70% with 

 sprinkler irrigation, the actual diversion may reduce to 6 acre- 

 feet or less, providing a potential hydropower recapture at the 

 point of diversion of one foot per acre. Where substantial 

 differences in total dynamic head exist between the point of 

 diversion and the point of return flow, as in the Columbia Basin 

 Project, significant hydropower benefits may thus be derived from 

 the conversion despite the increased uptake by crops. The increased 

 efficiencies may also decrease the non-beneficial consumption of 

 water on the farm, and improve water quality. 



SocioeconoBic eind Environaental Considerations Influencing a 

 Hydropower Recapture Strategy on the Columbia Basin 



A distinction must be made between economic and technical 

 inefficiencies in irrigation's usage of water resources on the 

 Basin. It appears that a signficant cunount of water now diverted 

 and depleted in irrigation in the upper reaches of the system is 

 now or will soon be worth more to the regional economy in low water 

 years if it is left in the river for hydropower production, 

 regardless of the efficiency of water application. In such cases 

 of uneconomic usage, inefficiencies in irrigation technique are 

 irrelevant. The purchase of such water with public funds for 

 public purposes will probably constitute the most cost-effective 

 conservation measure available, on the basis of principles similar 



* Potential Conservation Opportunities from the Use of 

 Improved Irrigation Scheduling in the Pacific Northwest Region. 

 PNL-5416; UC-95C, March 1985. 



