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Science Panel Finds Big Holes in Summer Flow Analyses

by Bill Rudolph
NW Fishletter, November 18, 2004

At last week's flow symposium in Portland, an independent panel of scientists said the region needs to get a much better handle on measuring both water flows and fish survival before it can hope to implement a policy sure to benefit ESA-listed fall chinook.

Panel members, who were charged with making a recommendation about Montana's proposal to modify current hydro operations, panned a federal fish passage model that links summer flow augmentation with improved fish survival. They also questioned the accuracy of current survival rate data after hearing about recent research that found half the ESA-listed Snake River fall chinook returning as adults had never been counted as juveniles migrating to sea.

The symposium was the brainchild of NOAA regional administrator Bob Lohn. In July, Lohn suggested the region should meet so the flow/survival debate could be brought up to date and reviewed by the ISAB [Independent Scientific Advisory Board] before NOAA Fisheries finishes its final version of the hydro BiOp, promised by Nov. 30. The ISAB is a group of Northwest scientists who are occasionally convened to judge the scientific merit of different aspects of salmon recovery research.

Lohn was on hand to kick off the Nov. 9-10 proceedings, noting that the region had suspected a flow-survival connection for 30 years or so. But direct proof has been elusive, especially in the case of summer migrants, where flow-survival correlations are often confounded by other elements like river temperatures and turbidity.

Lohn was skeptical that any short-term research could detect changes in fish survival from "modest" changes in flow as called for in the Montana proposal. And after a presentation by Northwest Power and Conservation Council staffer John Fazio, the ISAB heard those modest reductions may be much smaller than most hydro policy wonks had even thought.

The Montana proposal, now an amendment to the Council's fish and wildlife program, calls for an experiment that would evaluate a change from current BiOp operations that drains the top 20 feet of its two largest federal reservoirs in July and August. The operation adds about 1.2 MAF of flow augmentation to the Columbia River for aiding the juvenile migration of ESA-listed Snake River fall chinook.

The proposal calls for drawing down only 10 feet in most years (80 percent of the time) and extending those water releases through September to stabilize flows and reduce adverse effects on resident fish below Libby and Hungry Horse dams, which include ESA-listed bull trout and sturgeon.

Dampened Expectations

Fazio cautioned that his results were preliminary, but looking at the Montana proposal relative to the BiOp, he pointed out the dampening effects from other projects like the Corra Linn Dam at the outlet to Kootenay Lake. Corra Linn Dam may reduce average flows by the time the water reaches the lower Columbia (at McNary Dam) to about 8 kcfs from a 10-kcfs reduction at Libby and Hungry Horse during July, when average flows at McNary are in the 200-kcfs range.

Fazio said average flows in August at McNary (140-180 kcfs) could be reduced by 5.6 kcfs to 7 kcfs from Montana reductions, with a slight boost in September. According to his analysis, when all BiOp actions are included, the net effects to system flows from potential changes in Montana range from a 2-kcfs increase in July to a 2-kcfs loss in August. The small changes in flow from the Montana proposal might add only a few hours of travel time for fish migrating between McNary to Bonneville dams, Fazio said.

An analysis by Fish Passage Center staffers Margaret Filardo and Tom Berggren of fish survival between Rock Island and McNary dams concluded that a 10-kcfs reduction in August would likely have a negative impact on fall chinook survival. But the flow/survival relationship exhibited by Berggren in a graph came in for criticism by ISAB members, who wondered how a curve could be developed from the data points since fish survival between the dams was actually a bit lower this year, about 25 percent, than in 2001 when flows averaged only at 60 kcfs, compared to the 100-kcfs average summer flows in 2004.

Temperature Bugaboo

The ISAB also got updates from salmon passage modelers at the University of Washington and NOAA Fisheries. Former U.W. programmer Chris Van Holmes explained the latest version of the CriSP model, which includes a relationship between river temperature and juvenile fish survival. The U.W. modelers say their latest model fits the survival data, including the extremely low flow year 2001, better than any (14 in all) others that have been used to model Columbia and Snake River salmon passage.

NOAA hydro branch chief Jim Ruff described his agency's SIMPAS model as an accounting spreadsheet with a flow/survival relationship built into it that is being used to estimate fish survival in the new BiOp, evaluating proposed hydro operations compared to a hypothetical reference operation that maximizes fish survival.

Panel member Prof. Charles Coutant, a resource ecologist at the Oak Ridge National Laboratory, took issue with the SIMPAS model because it lacked a temperature input and needed a better accounting of the system's water. He said using monthly flow averages doesn't get to the level of detail needed to answer the question posed before the panel. He also questioned the legitimacy of NOAA's modeling assumption that "absorbed temperature into flow," pointing out that adding flow from Idaho's Brownlee Reservoir likely reduces fish survival because the water is so warm.

ISAB member Prof. Dan Goodman of Montana State University called Ruff on the carpet for extrapolating fall chinook survivals from the lower Snake to the lower Columbia, where data were lacking. "You've got a bad regression," Goodman said.

But NOAA Fisheries statistician Steve Smith pointed out that his own analysis of fall chinook survival in the lower Columbia approximated the SIMPAS analysis.

"We recognize that models are lacking at this point to do those sorts of predictions, which doesn't mean we should ignore it," Smith said. "I think that, specifically, for the Montana plan that's under consideration, I would probably have as much confidence in the SIMPAS model to predict that tiny little difference as I would with any other possible model at this point with the data we have, which is saying they're all equally bad."

U.S. Fish and Wildlife Department scientist Billy Conner explained his work that has turned Snake fall chinook survival studies upside down since he and others have found that many returning adults over-winter before heading to sea. This may have huge implications for current survival estimates that have assumed all the fish migrate as sub-yearlings.

Ruff also acknowledged his agency has a major uncertainty in regard to the "life-history question" of fall chinook.

Prof. Goodman said a whole new data collection system is needed, since at this point, no one can say whether fish survival is lower at lower flows, or whether it correlates to higher survival of the reservoir-type fall chinook.

Coutant said with daily flow fluctuations, the flattening process, the peaks over time, "and a whole lot of other stuff that is going on out there, that's going to make it next to impossible, I suspect, to really tease out the effects downstream of this [proposal]."

Retired University of Washington fisheries professor Richard Whitney, and the ISAB's "grand old man," called the long-standing view that flow was good for fish survival simply a belief system. "It's a cult," he said drawing laughter from spectators. "We might need a counselor to de-program us."

The ISAB spent the rest of the afternoon discussing research possibilities with Basin researchers. NOAA Fisheries' Bill Muir said a transport study for fall chinook had been stalled by "roadblocks" from other agencies for five years. Others pointed out the startling fact that fish managers had also refused to let federal researchers take scale samples from 400 returning fall chinook to investigate the yearling/subyearling question. The ISAB asked whether the managers had a scientific reason for turning down the request. The researchers said no, it was a policy issue.

Federal scientists said they were tagging more fish to get more answers, but Montana State Prof. Goodman summed up the current situation that's likely to be the gist of the panel's report to Lohn.

"We're in a startling state of ignorance regarding these fish," Goodman said, who also noted that if harvest rates were cut back significantly, "you'd have fish to burn." He said tremendous numbers were being taken in Canada.

Bill Rudolph
Science Panel Finds Big Holes in Summer Flow Analyses
NW Fishletter, November 18, 2004

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