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Flow Augmentation: Does So, Does Not, Help

by N.S. Nokkentved
Times-News, December 14, 2000

TWIN FALLS -- Scientists agree that more water in the lower Snake River benefits endangered salmon as they migrate to the ocean.

But some state officials have questioned the benefit of using stored water from federal reservoirs in Idaho to boost the flow.

At issue is a federal study that officials say shows that using water stored in federal reservoirs to increase the flow in the lower Snake River -- known as flow augmentation -- helps improve salmon survival.

Others disagree, saying the study is flawed and proves nothing.

While scientists argue about what the study did or did not prove, they agree that higher flows in the lower Snake River mean more adult salmon return to Idaho.

Idaho Department of Water Resource Director Karl Dreher recently told the Twin Falls Rotary Club that the study used by the National Marine Fisheries Service to justify flow augmentation doesn't support the conclusion that flow augmentation benefits salmon.

A report Dreher helped write says the Fisheries Service's study is flawed.

But the study doesn't disprove benefits of flow augmentation either, said one of the report's co-authors, Ed Bowles, now director of the fisheries division at the Oregon Department of Fish and Wildlife.

Bowles recently resigned his position as head of the salmon and steelhead program with the Idaho Department of Fish and Game.

Though he is not surprised by Dreher's criticism, Paul Wagner, fishery biologist with the National Marine Fisheries Service in Portland, disagrees.

Wagner, in an interview Wednesday, said the study shows a strong correlation between flow in the lower Snake River and the survival of juvenile salmon migrating to the ocean. As the flow went down, so did the rate of survival, he said.

He was pretty convinced by the results, and other studies strengthened the conclusion that there is a high correlation between flow and survival, Wagner said.

Southern Idaho has supplied 427,000 acre-feet of stored water from southern and eastern Idaho and eastern Oregon for recovery efforts each year since 1993. Of that, about 232,000 acre-feet comes from federal irrigation reservoirs on the Snake River above Milner Dam. The federal reservoirs can hold 4.1 million acre-feet of water.

An acre-foot is enough water to cover an acre with one foot of water -- or 325,850 gallons.

With additional water from Dworshak Dam on the Clearwater River, the Bureau of Reclamation supplies more than 1.5 million acre-feet of water for so-called "flow augmentation" from Idaho.

Earlier this year, the governors of Idaho, Oregon, Montana and Washington in a joint statement said they would support continued flow augmentation only if federal officials could show a benefit for fish.

"No problem," said Will Stelle, regional director for the National Marine Fisheries Service. Contemporary scientific data shows a high correlation between flow, water temperature and survival of Snake River fall chinook salmon.

But Bowles said significant flaws in the Fisheries Service's study renders it useless to justify flow augmentation. The study neither proves nor disproves the benefit of flow augmentation. To really determine whether the fish benefit from flow augmentation, a study needs to tally the adults that return, he said.

Wagner noted that in a similar study by another agency, tiny electronic tracking tags were inserted in wild fish and counted at Lower Granite Dam. The results showed higher survival during high flows and low temperatures, Wagner said.

But tracking groups of fish through a portion of the hydro system doesn't really prove anything except they were still alive at the checkpoint, Bowles said.

"It doesn't say anything about their survival through the rest of the system," he said.

Here the two agree. Counting returning adult salmon supports the conclusion that increased flow help the fish, Wagner said. A study of fish passage records shows that more adult salmon return from runs that migrated to the ocean during high flow years, he said.

There is no question that high flows help the fish, Bowles said.

Because the dams create slow-moving, warm-water reservoirs it makes sense to tackle that problem, he said. Though flow augmentation won't make up for the effect of the dams, it is the only tool that deals with flow and temperature. But current flow augmentation efforts are only an incremental improvement, he said.

Incremental improvements are not going to be equal to breaching the four federal dams on the lower Snake River in southeastern Washington, and the approach is more risky to the fish than breaching the dams, Bowles said.

"It's not even close," Bowles said.

That's a point echoed by most other Northwest fishery scientists, who continue to say that recovering Snake River salmon will have to include breaching the four federal dams on the lower Snake River in southeastern Washington.

The recent efforts of improving habitat and hatchery operations are helping but they are not enough. The Oregon chapter, Idaho chapter, and the western division of the American Fisheries Society say salmon recovery must include breaching.

Current incremental improvements include habitat improvements, additional restrictions on fishing, changes in hatchery operations, increased predator controls, increased spill at hydroelectric dams and a shift in the region's flood control regime to release water in the spring to benefit fish.

These are conservation measures, and though they help, people should not fool themselves into thinking they are anything other than conservation measures, Bowles said.

"This is not recovery," he said.


N.S. Nokkentved
Flow Augmentation: Does So, Does Not, Help
Times-News, December 14, 2000

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