the film
Commentaries and editorials

Sciences Slowly Come to Favor Dam-Breaching

by Rod Taylor, Seattle Post-Intelligencer-Reporter
Seattle Post-Intelligencer - April 16, 1999

Scientists have reached a tentative consensus that dam-breaching offers by far the best chance of restoring strong Snake River salmon runs.

But like so much in the Columbia Basin salmon debate, this conclusion is neither simple nor certain.

Science, in short, offers policy-makers gamblers' odds, not answers -- and the 20-year debate over Columbia Basin fish runs grinds on.

The broadest analysis to date comes from about two dozen Northwest scientists, Indian tribes, federal agencies and other groups. The scientists' effort, called the Program for Analysis and Testing of Hypotheses (PATH), analyzed options for improving salmon and steelhead survival in the lower Snake River.

The team used sophisticated mathematical models and was reviewed by four leading scientists from outside the region. Under every modeled scenario, the virtual fish fared better without dams than with them, even with extra efforts to barge or divert salmon past the dams.

With dams bypassed, the simulations showed spring and summer chinook salmon runs recovering to healthy numbers in about a half-century some 80 percent of the time, compared with half the time with the dams in place. The healthy margin remained large even if dams were made more fish-friendly by boosting water flows or barging young fish.

Environmental groups greeted the simulation results prepared by the panel of independent scientists as decisive.

"It is fairly clear that under virtually all assumptions, dam removal is the only option that meets both the survival and recovery goals," said Tim Stearns of Save Our Wild Salmon.

But Wednesday, in a broad review of the science, the National Marine Fisheries Service cautioned that the apparent advantage of breaching could evaporate.

Under a small minority of the computer simulations, dam-breaching appeared to afford "negligible advantages," said the review's director, Peter Kareiva. Moreover, he said, tentative new findings hint the dam-breaching advantage may be overstated.

The PATH report assumed that salmon that are barged through the lower Snake River dams are considerably less likely to survive a round-trip to the Pacific Ocean than non-barged fish.

Initial returns from a new line of research tends to show that barged fish actually may return almost as well as those that migrate freely.

If that tentative finding proves right, the mathematical advantage of dam-breaching over other salmon improvements would drop from 30 percent to a more modest 11 percent, the Fisheries Service said. If barging doesn't weaken fish at all, the edge drops to a negligible 2 percent.

Those caveats aside, the Marine Fisheries Service confirmed that "breaching meets recovery and survival goals over the widest range and highest proportion of assumptions" for the spring-summer chinook, the best-known and most numerous salmon the Snake River. And it appears even more advantageous for fall chinook, though less is known about that run.

Scientists said more study might answer questions about barging.

But delay has risk, too.

If dam operations remained unchanged for 24 years, scientists calculated that the chance of fish runs going practically extinct would rise about 8 percent.

The decline of Snake River salmon has been sharp since the lower Snake River dams went up in the 1960s and 1970s. Spring and summer chinook, which numbered about 1.5 million a century ago, have fallen to less than 10,000 fish.

The main problem generally isn't with returning adult salmon, but with juveniles. As they pass the dams on their migration to the sea, young salmon are bumped and scraped, injured by water pressure fluctuations, and exposed to lethal levels of nitrogen gas in the water below the dams. In reservoirs, they are exposed to water that is too warm for them, and delays getting to sea may affect how they survive in salt water.

Dam defenders say these problems have been reduced and the practice of collecting young salmon in the upper Snake River and barging them below Bonneville Dam is an effective antidote.

But decades of extensive barging of fish have failed to reverse the salmon decline.

Last month, 200 scientists signed a letter drafted by an Idaho environmental group urging President Clinton to lower the Snake River to natural-river level to save salmon and steelhead runs.

They included two current members and one former member of an influential group of scientists that advise the Northwest Power Planning Council.

The letter concluded: "Enough time remains to restore them, but only if the failed practices of the past are abandoned and we move quickly to restore the normative river conditions under which these fish evolved.

But dam supporters -- and some scientists -- loudly disagree.

Bruce Lovelin, director of the Columbia River Alliance, a consortium of dam-dependent businesses, claimed that the PATH study underemphasized evidence that dams and barging may not be as harmful to fish as in the past.

Lovelin dismissed many scientists as advocates for breaching. And so do many audiences in Eastern Washington.

When federal biologist Tom Cooney explained the panel's findings in Pasco in January, he was derided by his audience.

"You're using assumptions as facts, weighting the inputs the way you want so the dams need to be removed," one elderly man said.

Related Pages:
Illustration showing dam-breaching plan
Farmers stand to see lifetime investment bulldozed

Rod Taylor, Seattle Post-Intelligencer-Reporter
Sciences Slowly Come to Favor Dam-Breaching
Seattle Post-Intelligencer, April 16, 1999

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