July 2001 issue

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Council OKs summer water spills at dams, but only if power system reliability is not jeopardized

Water could be spilled at Columbia and Snake river dams this summer to help juvenile salmon and steelhead migrate to the ocean, but only if the reliability of the region’s electricity system is not jeopardized, the Council advised the Bonneville Power Administration in late June.

Water that is spilled over dams cannot be used to generate power, and that is a critical consideration given the ongoing drought that has reduced Columbia River flows to about 53 percent of normal and reduced the region’s hydropower generating capacity by more than 4,000 megawatts. At the same time, summer spill at the dams has some benefit for juvenile fish that migrate in the river and are not collected for transportation in barges, particularly for Snake River fall chinook salmon, a threatened species, and for fall chinook that originate in the Hanford Reach of the Columbia, the Council acknowledged.

Bonneville’s acting administrator, Steve Wright, asked the Council for guidance on summer spill in light of the power system reliability issue. The Council recommended that spills be provided if power system reliability is not further eroded, and if the lost energy can be made up with power purchases at costs that do not jeopardize Bonneville’s financial stability.

"Based on our latest analysis of the power supply, the region appears to be in about the same position it was at the end of May — right on the cusp of a reliable power system next winter if no water is spilled this summer," Council Chairman Larry Cassidy said. "However, wholesale power prices have dropped significantly in the last month, and so if replacement power for later this year can be purchased now for a reasonable price, spill should be provided this summer."

In a discussion with the Council at its June 26-27 meeting in Pendleton, Oregon, Wright outlined several alternatives for providing summer spill. He said, for example, that increasing the outflow from Dworshak Dam in Idaho could provide water for spilling at dams on the lower Snake and Columbia rivers without decreasing power system reliability. But Idaho Council members Jim Kempton and Judi Danielson objected to the idea. Wright also offered out-of-region power purchases as an option, but said there is some financial risk because the price is not known today.

Council members responded that they were reluctant to get involved in day-to-day decision-making, which they see as the responsibility of dam operators. Additionally, many river-operating options for the summer currently are being negotiated by federal agencies, utilities, Indian tribes, state fish and wildlife agencies and others. For those reasons, the Council decided instead to amend a policy it adopted in April to state that "the summer operating plan should not decrease the currently forecast level of electrical reliability," and that "any additional water storage should be deployed to assure the best benefit to fish."

According to the Council’s analysis, there is about a 17 percent probability of power deficits next winter if no water is stored this summer and fall for electricity production next winter. The probability decreases as the amount of water storage increases. If 1,500 megawatt-months of water can be stored, the probability drops to about 12 percent (a megawatt-month is one megawatt delivered for a period of one month). That amount of storage provides the maximum power benefit; storage above that amount doesn’t provide much additional benefit because of the rate at which water can be released from the dam.

The analysis acknowledges that such predictions are inexact. For example, reduced demand for power or additional energy conservation could improve the outlook; spilling water, lower runoff and higher-than-expected demand for power could worsen the outlook.

The issue of whether to spill water at dams during spring and summer has biological implications as well as implications for the power supply. Spill is an effective means of moving juvenile salmon and steelhead past the Snake and Columbia river dams, particularly in the spring when the migration peaks, but spilled water can’t be used to generate electricity.

Spring and summer spills to help juvenile salmon and steelhead migrate to the ocean are recommended in the 2000 Biological Opinion on hydropower operations issued by the National Marine Fisheries Service (NMFS) on behalf of 12 Columbia and Snake river fish populations that are protected under the Endangered Species Act (ESA). Only one of the 12 listed species, Snake River fall chinook, migrates to the ocean in the summer, but there are other important — but not ESA-listed — salmon and steelhead species that migrate in the summer.

The Biological Opinion allows for spills to be reduced or eliminated if there is a power emergency because water that is spilled cannot be used to generate electricity. Federal dam managers, including the Bonneville Power Administration, declared a power emergency earlier this year, and water spills were drastically reduced from Biological Opinion levels in April and May.

According to a biological analysis of summer spill operations by the Council’s fish and wildlife staff, summer spill has little or no benefit for juvenile Snake River fall chinook generally because most of those fish are collected and transported downriver in barges for release below Bonneville Dam. But spill has benefits for Snake River fall chinook that are not barged, and also for fall chinook that originate in the Hanford Reach of the Columbia River just upstream of the Tri Cities. The Hanford Reach fish have only one opportunity for collection, at McNary Dam.

An analysis of summer spill options by the NMFS suggests that eliminating spill would reduce survival of non-listed salmon species that originate in rivers downstream of McNary Dam by up to 17 percent, depending on the species and river of origin. That is because those fish cannot be collected for barging — the last dam with a collection system for downstream migrants is McNary. So fish from the John Day, Deschutes, White Salmon, Klickitat and other rivers downstream of that dam must be spilled or go through the turbines.