The hydropower cost of irrigation development and fisheries enhancement in the Columbia river basin

Abstract

Competition for water in the Columbia River Basin is increasing. It is becoming more difficult to satisfy all desired instream and out-of-stream uses of water in the Pacific Northwest. All available water is now employed and increasing any future use will require the reduction of some other uses . . This condition is unlikely to change at any time in the future

given the finite nature of the Columbia-Snake River system and the increasing demands being placed on the river system. This study estimates the quantity and value of lost hydropower due to increased irrigation development and enforced minimum instream flow requirements. As water is allocated to agriculture for irrigation and to fisheries for anadramous fish enh~ncement, the potential to generate hydroelectricity in the Columbia-Snake River system is reduced. The value of this electricity is measured as the opportunity cost of replacement with thermal power plants, coal or nuclear power losses were estimated for each phase of irrigation development in combination with four different minimum in stream flow requirements for fish enhancement. The flow requirements for fisheries ranged from an average daily flow of zero to levels as high as those recommended by the Columbia Basin

Fisheries Technical Committee. Given these assumptions, a total of 12 irrigation-stream flow alternatives were compared. The power losses were estimated with the Hydro System Seasonal Regulation program (HYSSR) developed by the Corps of Engineers. The losses due to irrigation dep~etions ranged from 402 MWs for Phase I (2,163,651 acres), 565 MWs for Phase II

(3,323,673 acres), and 956 ~vs for Phase III (5,527,246 acres).

Only the highest minimum flow level for fish enhancement resulted in significant losses of power production. The losses accruing to this stream flow condition after meeting irrigation needs were 0, 10, and 95 MWs, respectively. The total annual hydropower replacement costs ranged from $123,253,200 for Phase I to $322,236,600 for Phase III using 35 mills/KWH and from $176,076,000 in Phase I to $460,338,000 in Phase III using 50 mills/KWH. These are the costs which will be absorbed by consumers of electricity in the Pacific Northwest for replacing lost hydropower due to diverting water to alternative uses.