the film
Economic and dam related articles

Science Panel Likes Mainstem Passage Report

by Bill Rudolph
NW Fishletter, June 6, 2002

The Independent Scientific Advisory Board has released its review of a report on mainstem Columbia fish passage strategies. The report was commissioned to help the Power Planning Council amend the section of its fish and wildlife program that deals with how best to use water for migrating fish. The ISAB said the report did a good job explaining current strategies and uncertainties of the program, which is used to help fish move through the federal hydro system.

Since 1980, when the four-state Power Council was created out of the NW Power Act, the group has been responsible for helping fish runs through a "water budget," which dedicates a certain amount of water for improving flows. That budget has risen over the years since salmon and steelhead stocks were listed under the ESA. But the jury's still out on just how beneficial the strategy has been for Columbia Basin fish populations.

The Council itself has estimated that from 1978 until 1998, BPA spent nearly $1.4 billion on the flow augmentation strategy through a combination of foregone revenues ($698 million) and power purchases ($668 million) needed to meet load demands that the hydro system would have been able to handle if not for the fish obligation.

Consultant Al Giorgi presented his own report to the Council last January, which said that after nine years of NMFS research, the agency has found no "apparent" flow/survival relationship for ESA-listed salmon and steelhead stocks. Council members seemed a bit stunned by the straight talk, though it wasn't really news. With salmon stocks showing a 10-fold increase in survival rates over the past 10 years, Giorgi said that "conventional wisdom" holds that the boost isn't anything that could be expected from the fresh water system, but resulted from changes in oceanic conditions.

Giorgi's remarks drew a slew of comments from fish and wildlife managers and environmentalists, whose flow-based fish recovery agendas seemed threatened by the results of federal survival studies. In fact, the flow targets in the feds' own hydro BiOp seemed to be on shaky scientific ground. The Council debated whether it should send Giorgi's report out for independent peer review and decided to get the ISAB to take a look at it.

The ISAB's review, released June 4, supports most of Giorgi's conclusions. "The comments from the public and agencies provided additional useful technical information," said the ISAB, "usually amplifying points made in the Giorgi et al. report, but often, it is our impression, from more of an advocacy position for certain management strategies. Contrary to what was suggested in some of the comments, we did not see any pervasive tendency for selective use of data or misinterpretation of results by authors of the Giorgi et al. report. Genuine technical disagreements occur over possible interpretations of available information for methods of analysis and implementation measures. Giorgi et al. were criticized for not providing the full range of scientific 'opinion' on the key issues, yet the intent of the report was to summarize information, not opinion."

But the ISAB also said the Giorgi report's "statistical conservatism affects its value as a synthesis of current understanding." The panel said "tests that fail to show statistical significance in data can be definitive in stating that no effect was found, yet these tests do not definitely prove the absence of effect." The science panel went on to say that it was possible that new studies or "further rigorous analysis" of existing data "could generate statistically significant results or a different answer."

However, a recent paper in the peer-reviewed North American Journal of Fisheries Management (Smith et al, 22:385-405, 2002) by NMFS scientists found little correlation between flow or travel time to fish survival through impounded sections of the lower Snake-- "neither strong (within or between years) nor consistent from year to year." The scientists said they used PIT-tag data from 1995 through 1999 because 1995 was the first year the detection system was sufficiently developed to allow survival estimates to McNary Dam from the lower Snake.

NMFS Weighs In
Yet NMFS itself, in comments to the Council, says the Giorgi report is "fairly complete, factual, and supports the short-term Reasonable and Prudent Alternatives" in its hydro BiOp, which includes the current flow augmentation strategy. The agency even cited the Smith et al paper, pointing it out as "a comprehensive analysis related to travel time and river conditions for spring migrants." But the May 28 NMFS letter signed by Brian Brown, assistant regional administrator for the agency's hydro program, took issue with Giorgi's characterization of the value of spring flow.

"The comment that 'there is little evidence supporting a flow/survival relationship across the water years experienced from 1993-2000' followed by a discussion of the negative survival impacts of the low flows in 2001 stops short of the next step," said the agency, "and is thus incomplete, potentially leaving the reader with the impression that it has been demonstrated there is no flow/survival relationship. There was only one low flow year in the 1993-2000 period. Now, with 1994 and 2001 providing two low flow years, additional analysis can and is being conducted."

The ISAB agreed with Giorgi's conclusion to expand NMFS' PIT-tag based survival studies to help answer other questions raised by commentors about possible delayed mortality effects from passage through the hydro system. But they pointed out that the studies reviewed in the Giorgi report were "aimed at estimating mortality within the hydro system, not outside it."

The value of flow augmentation is still a matter of debate and drew more comments than any other part of Giorgi's report, the ISAB said. Some Power Planning Council members want an evaluation of flow augmentation added to their mainstem amendment package because of the apparent disconnect between current policy and scientific support for the strategy.

The ISAB paraphrased Giorgi's conclusion as follows: "Surprisingly few, if any, comprehensive evaluations of flow augmentation have been published, which address all or even most of the significant issues. The annual reports of the Fish Passage Center are deficient in that they fail to estimate the extent to which flow augmentation, increased water velocity or decreased water temperature, as compared to base condition; nor do they predict the magnitude of fish response in terms of smolt migration speed or survival, as attributable to that incremental change in flow and temperature. The NMFS BO is deficient in this regard, as well. The BO specifies volumes (MAF) for flow augmentation, and prescribes seasonal flow (KCFS) targets, but provides no quantitative analysis describing changes in water velocity, smolt speed or survival benefits that are to be expected as a result of flow augmentation."

Other uncertainties about augmented flows that Giorgi mentioned are whether such strategies could improve river estuary and ocean plume characteristics within a given year, optimize the time fish reach the ocean, or if more flows really add much to summer fish survival in the lower Snake. Giorgi suggested updated evaluations for flow augmentation that balance benefits and risks between anadromous and resident fish resources.

Giorgi's review also looked at the value of spilling water to help fish over dams and using barges to transport them downstream. He told Council members that spillways are generally the safest passage route, but total effects on fish must be included in a proper analysis, including possible adverse effects on adult fish migrations from spill. He also recommended that models used to estimate fish survival be updated with the latest information, and he stressed the difficulties inherent in isolating effects of spill in field studies.

Barging seems effective from Lower Granite and Little Goose dams, but "questionable" at Lower Monumental and possibly McNary, said Giorgi, who noted that small sample sizes have made it impossible to determine whether barging helps wild fish or not. But with increasing survival rates that have exceeded the 2 percent minimum recovery threshold, Giorgi's report noted that "neither transport nor inriver migrations may be a bottleneck to recovery, when marine-based survival is at some adequate level."

Bill Rudolph
Science Panel Likes Mainstem Passage Report
NW Fishletter, June 6, 2002

See what you can learn

learn more on topics covered in the film
see the video
read the script
learn the songs
discussion forum
salmon animation