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Testing Impacts of Less Summer Spill
Won't Be Systemwide

by Barry Espenson
Columbia Basin Bulletin - December 12, 2003

Any attempt in 2004 to measure the effect of reducing summertime spill on juvenile salmon survival would likely take place at a project or two, not across the system of Columbia River federal hydroelectric projects, the Northwest Power and Conservation Council was told this week by staff and by the regional chief of the federal agency charged with protecting salmon and steelhead populations.

"A systemwide study is not feasible in 2004," Bruce Suzumoto, NPCC special projects manager, told the Council's fish and wildlife committee. The task of estimating juvenile survival through the portion of the hydrosystem where spill is provided for passage has to be done over a long period, and at great cost, to achieve the statistical validity that is desired.

The Council in amendments earlier this year to the mainstem portion of its fish and wildlife program called for an evaluation of spill within the federal hydrosystem to determine what level brings the optimal biological benefit. The Council staff has estimated that, because of the foregone power generating revenue, the summer spill program alone amounts to one-quarter of the total cost impact of all mainstem operations designed for fish and wildlife protection -- about $68 million based on a 50-year average water year and a $28 per megawatt hour power price.

The current spill program is rooted in the 2000 Federal Columbia River Power System biological opinion written by NOAA Fisheries. That opinion's reasonable and prudent alternative actions, such as spill, are designed to assure hydrosystem operations don't jeopardize the survival of salmon and steelhead listed under the Endangered Species Act.

The Bonneville Power Administration, which markets power generating in the hydrosystem, estimated that last August's spill reduced revenues by $1 million per day. Power customers criticize the program, saying it has the result of driving up rates while bringing little benefit to listed fish.

An effort blossomed this summer and fall to produce a viable research alternative that could be implemented next year and would begin an evaluation of modified spill levels. An ad hoc committee is continuing technical and feasibility analysis for five different approaches to the research. Federal, state and tribal officials have been involved in the process to work on study designs and logistics, performance measures, levels of precision and study costs.

A subcommittee is also fine tuning a list of "offsets" that potentially could be implemented to improve fish survival at a rate equal to or better than any losses that might be incurred because of reduced spill. The analysis is now proceeding to determine how much benefit could be gained from various measures, such as reducing predation on juvenile fish and harvest on adults.

"Only Option 2B can be implemented in 2004 and that would be a project specific study," Suzumoto said. Option 2B would involve reducing spill levels at one or more of the projects, modifying planned spill studies, and performing additional summer spill studies and monitoring. Such studies would provide project specific survival information.

The cost, assuming the purchase of about 48,000 radio tags, would range from $2-3 million per project, Suzumoto said. Bonneville Dam would be the most likely 2004 study target.

A systemwide study would compare survival at various spill levels through the entire hydrosystem or a particular set of hydro projects. The BiOp calls for spill at Ice Harbor Dam on the Snake and at Bonneville, The Dalles and McNary Dams on the lower Columbia.

The systemwide approach poses numerous logistical, statistical and financial problems.

"The working group looked at what it would take to measure a survival difference for summer migrants on the order of 3 percent. The advice we have gotten is that it is something that is scientifically doable but it would be expensive and we would need to tag 1 to 2 million juveniles with PIT-tags. That by itself would cost $4-5 million and then you would have very extensive monitoring," Bob Lohn, NOAA Fisheries regional administrator, told the Council Thursday.

"In order to detect this in an 80 percent confidence interval, you would need to this for more than one year. In fact the best estimates would be that you would need to do it between 500 and 600 years," Lohn said. "Which is a polite scientific way of telling us that we are unlikely to get systemwide survival data at a level of accuracy capable of measuring those nuances in a time that's going to be important for the decisions that need to be made."

Project-specific studies are an often-used method utilizing small radio tags that are placed in the bellies of juvenile fish, Lohn said.

"The fish are released some place above a project and they are tracked as they pass down through the project and tracked as they exit the tailrace," Lohn said. "It gives you a piece by piece snippet of what survival is and hopefully some indication of the differences between different passage methods if in fact those differences are present."

Both Suzumoto and Lohn stressed that there are scientific limitations or uncertainties to the project-specific research as well. The research in large part assumes that the tagged fish behaviors replicate those of untagged fish.

"The fish we tag have to be relatively large for juvenile migrants. Fall chinook, depending where they are coming from, are almost at the size of fry, relatively small fish. There may be a difference in effect between these small fish and these large fish," Lohn said.

A project-specific study also does not allow an assessment of indirect or delayed effects on fish passing through the hydrosystem, Suzumoto said. And the fact that the study can not be carried out in August -- when spill provides benefit to the fewest number of fish -- could bias the results. Researchers would have to decide whether July survival tests fairly represent August survivals. Currently, survival testing is ended July 20. Because of warm temperatures, handling the fish in late summer can cause harmful stress.

Suzumoto said that the Corps of Engineers, which guides much of the mainstem research, is developing a scoping document to help clarify the assumptions and uncertainties surrounding project specific studies. It will be submitted to the regional technical forum process for review. That forum was created under the BiOp.

Barry Espenson
Testing Impacts of Less Summer Spill Won't Be Systemwide
Columbia Basin Bulletin, December 12, 2003

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