Computers Favor Breaching Dams Models Show Almost 100 Percent Chance Of Salmon Recovery If Four Dams Breached

Two major computer-modeled fish-recovery studies now agree Snake River spring chinook are almost certain to recover within 48 years if the river’s lower four dams are breached.

Revised results from the complicated computer models show fish stocks are more likely to revive under “natural river” conditions than by barging ocean-bound juveniles downstream. Previously, the two models were at odds.

There’s still a big split about whether saving the dams by barging young fish downstream also would do the job.

Opponents of dam breaching downplay the significance of the recent revisions, and “natural-river” advocates say the changes are an important step toward fish recovery.

Those who represent river industry and commerce are cautious about interpreting the results.

“Clearly, we are concerned about it,” said Bruce Lovelin, executive director of Columbia River Alliance, a group of river users. “It’s really hard to jump to any conclusions based on this right now.”

In any case, the models are likely to change. “There’s a lot of uncertainty yet,” said Jim Geiselman, environmental engineer for the Bonneville Power Administration. For at least the next six weeks, Geiselman and a group of scientists will try to give the proper weights to the hypotheses used in the models and add benefits from hatcheries and habitat improvement.

What they eventually determine could prove critical as the National Marine Fisheries Service prepares its 1999 report to Congress about the best ways to revive fish stocks in the Columbia River system.

One option is to breach the four dams in an effort to improve salmon habitat and make downstream passage easier, though that is predicted to undermine the mid-Columbia economy. Another option is to continue barging fish downstream past the dams.

Rick Taylor, spokesman for the Columbia River Inter-Tribal Fish Commission, said the revised study will “make the federal agencies and their contractors squirm a bit more” about current barging policy.

“The evidence is mounting day by day that transportation simply won’t cut it, and this analysis is part of that evidence,” Taylor said.

“It’s really another whack at barging and gives much stronger support to the concept of breaching the dams,” said Chris Zimmer at Save Our Wild Salmon, a Seattle alliance of environmental groups.

The complex fish models - widely known by their acronyms CRiSP and FLUSH - have been at odds for years, with CRiSP showing better results from transportation and FLUSH favoring breaching.

Earlier this month, the scientific group called Plan for Analyzing and Testing Hypotheses - PATH - released an updated version of its ongoing study that shows the models aren’t as far apart as in earlier versions.

The two fish-survival models used in PATH represent fundamentally different approaches to estimating mortality throughout the juvenile salmon corridor.

And they differ widely on how well spring chinook population would do in the next 48 years under a program of maximum barging, giving the fish between a 12 and 73 percent chance of recovery.

But if the dams are breached, they give the fish either a 99 or 100 percent chance of meeting recovery levels.

According to the revised document, the scientists found errors in preliminary results and altered some assumptions.