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Scientists Take Issue with Old Flow Augmentation Paradigm by Bill Rudolph NW Fishletter, February 21, 2003

New information no longer supports the prevailing flow-augmentation paradigm in the Columbia Basin "that in-river smolt survival will be proportionally enhanced by any amount of added water," according to the Northwest Power Planning Council's Independent Scientific Advisory Board.

The assessment was included in the ISAB's update and clarification of an earlier review it conducted for the council. As part of its continuing dialog on mainstem operations, the Power Planning Council had given the science panel a list of questions on the topic last November. Fish agency managers later added a few questions of their own.

Old-line fish managers probably won't like what the ISAB has to say. "Incremental flow augmentation of the magnitude presently mandated within a year is not likely to have a dramatic beneficial effect on inriver smolt survival of outmigrants," the ISAB said in the Feb. 10 report. Its conclusion "most likely" holds for spring chinook and maybe for fall chinook as well, "particularly if the water is provided by intermittent dam discharges, rather than provided as steady flow," the ISAB said.

The panel also seemed to support Montana's position that BiOp flow mandates shortchange the state's resident fish populations. The council's preferred alternative called for steadier water releases from Montana's federal projects in most years than those included in the BiOp.

The group focused mainly on fish survivals in the lower Snake, saying no flow-survival relationship was evident from data in the upper Columbia River. In the Snake, the ISAB said the latest data from the National Marine Fisheries Service showed no benefit from added flows above 100 kcfs. Below that level, steady flows or other alternatives "may be needed to avoid deleterious effects."

The panel's conclusion is fairly consistent with the current BiOp's 85 kcfs spring flow target for the Snake, but conflicts with the council's preferred alternative, which calls for doing away with BiOp flow targets. Decreases of 10 percent in spring and summer flows in the lower Snake weren't likely to have "deleterious effects" on juvenile fish survival, provided flows were around 100 kcfs, the scientists said.

However, the council asked the group if augmented flows would produce the same fish benefits as higher flows under natural conditions. The scientists said not necessarily.

The ISAB said the correlation between gross measures of smolt survival and flow "remain unexplained" and that "we have no way of knowing whether the flow increments that are provided by the present flow augmentation policy will or will not induce conditions that enhance smolt survival."

The panel seemed to make more inferences from data federal scientists released in December than the feds did themselves, when the ISAB embraced a graph of several years' worth of flow and survival data first exhibited by NMFS scientists during a power council presentation. The ISAB called it the "broken stick" model, referring to the shape of the graph when the feds plotted 1995-2001 fish survivals. With the drought year 2001 included, when juvenile chinook mortality in the lower Snake more than doubled from other years in the period, the plot angled steeply downward, hence the appearance of a "broken stick."

At the December council presentation, NMFS scientist John Williams said that "above some threshold average, [spring chinook and steelhead] survival appears to vary little, is relatively high and does not correlate with flow." Below that threshold, as indicated by data from the extremely low flow year of 2001, fish survival is a good deal lower, Williams said. But even at the lower levels, the relationship between flow and survival "is not strong," he said.

Williams' take-home message was that most juvenile mortality occurred at the dams, not in the reaches between dams, so flow improvements might have little benefit for riverine survival. But he suggested that since fish travel times through the hydro system are much longer than in the pre-hydro era, increased flows might reduce travel times and improve survivals to the estuary and ocean. But Williams also said the impact of travel times was still largely unknown.

The ISAB panel said the idea that faster migration improved smolt survival needed evaluation, though they noted increased migration rates in the higher reaches didn't ensure survival in the lower reaches.

Panel Puzzled
The independent science panel admitted it was puzzled that a "significant" relationship had been found in analyses of annual average estimates of survival and flow, since only one year demonstrated a clear "within-year" relationship. "Continuing observations are necessary," the panel said.

Meanwhile, an alternative to these analyses has just gone public. The Idaho Water Users Association has released a study by Prof. Jim Anderson of the University of Washington, who claims to demonstrate that any relationship between reduced water transit time, a surrogate for flow, and survival of spring chinook is driven by the 2001 data. "Excluding the warm low-flow year 2001 from the group, results in the relationship disappear," Anderson said. "Thus, 2001, with its high temperature and correspondingly low flow and survivals, drives the regression." He said the high temperature of 2001, not flow, was enough to "explain the survival pattern between years and within each year."

The panel also reviewed analyses by the Fish Passage Center, which has been a longtime advocate of flow augmentation. The ISAB concluded that the FPC reviews of data are substandard, saying that the FPC's "basic model and methods of presentation are now inadequate to make confident predictions for management, and other interpretations of the accumulated data are needed."

As part of its review, the panel speculated that higher flows with frequent hourly interruptions from power operations could lead to decreased smolt survival. They included a long appendix that outlined their alternative hypotheses "for Explaining Current Data on Smolts and Flow," which had one longtime river watcher, who wished to remain unidentified, highly irritated.

"I think they stepped way outside the box that they're supposed to be operating in," he told NW Fishletter. "They're supposed to be helping the region identify what the scientific information is telling us, what are the key messages, what do we know and not know, where are the legitimate uncertainties." He said it certainly wasn't their role to advise NMFS "and come up with recovery measures that they promote and advocate with no data to indicate that their measures would, in fact, be successful."

The Power Planning Council is accepting public comments on the ISAB flow augmentation review until Feb. 25.