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Corps Moving Forward on Ice Harbor Spillway Weir

by CBB Staff
Columbia Basin Bulletin - January 23, 2004

Funding "is a problem, a challenge" but a Corps of Engineers-led initiative to have a "removable spillway weir" operating at the lower Snake River's Ice Harbor Dam in time for the 2005 spring salmon outmigration remains on track, according to the Corps' Witt Anderson.

Even though the project does not have the total support of the region's salmon managers, the Corps plans to issue a solicitation for construction bids at month's end. The construction bid award is scheduled May 15 with installation planned in March of next year.

"It's a tight schedule," the Corps project leader, Kevin Crum, said of the process necessary to accelerate the installation of the fish passage devices at Snake River hydroelectric projects. An RSW installed two years ago at Lower Granite has proven effective at moving migrating salmon and steelhead through a spillbay with a lesser amount of water than traditional spill.

As a result, regional heads of the federal agencies that operate the hydroelectric projects, sell the power and require operations that improve fish survivals decided last year to press for speedy implementation of the once-tried technology. The weirs allow for more water to be channeled through the powerhouses because "comparable" biological benefits can be provided with a lesser amount of spill. It's also believed to be a more benign route of passage.

Ice Harbor was chosen as the next installation target, but higher than expected spillway mortality at the dam caused decision makers to hesitate. Why, they reasoned, put a device draws more fish toward that surprisingly fatal passage route -- and costs about $12 million to build.

During a presentation this week on the progress of the project, Northwest Power and Conservation Council member Tom Karier asked the same question.

"Why wouldn't you find the reason for the problem before committing millions of dollars," said Karier, one of two Council members from Washington. His state's fish and wildlife department, and that of Oregon, have advised that the project be delayed until the cause of the spill passage problem is determined.

Crum said that the Corps feels that the cause of the problem should be identified through testing this spring. It is suspected that the cause of the injury and mortality, particularly at low flows, could be from contact with flow deflectors that were installed to reduce the amount of total dissolved gas produced by the spill. It could also be something else in the spill bay.

Crum said that spill survival at Ice Harbor for summer migrants had been in the "upper 80 percent" range, much lower than is experienced at other projects.

"It's caused a lot of concern," Crum said. A 2003 experiment employing bulk spill -- concentrating the water in fewer spillbays rather than across all 10 -- bumped the survival rate to 96 percent. Engineers fear, however, that continued bulk spill will impact the dam itself.

Crum says that the Corps reasons that two processes should run concurrently so that, after the problem is identified it would only have to be corrected in the spillbay that houses the RSW, not all 10 spillbays.

The design phase for the project is about 80 percent complete. The schedule for the project includes several so-called "off ramps" where the project could be stalled. Anderson said that at this point he did not think any off ramps would be taken for technical reasons. Financial or policy considerations could force a change of plans.

The 2004 budget for the Columbia River Fish Mitigation Program is $85 million. But $19 million is held out by the Corps national headquarters as "savings and slippage." In years past some or all of the savings and slippage has been retrieved nearer year's end if it is not needed elsewhere in the country. But that is unlikely this year, Anderson said. The Corps' CRFMP funds research and construction projects intended to improve fish survival through the system.

The Corps "reprogrammed" $2.8 million in other funding to the CRFMP, to bring the total available to nearly $68 million. But the list of projects prioritized for funding by the System Configuration Team would require $71 million if $3.5 million were spent to launch the Ice Harbor RSW project.

"We're $2 million short," Anderson said. The SCT, which includes participation from the state, federal and tribal fish and hydro managers, would likely have to cut or defer other projects to fit the Ice Harbor project in.

The Corps, BPA, NOAA Fisheries and Idaho Department of Fish and Game favor pushing the Ice Harbor project this year.

According to a Bonneville cost analysis, spill passage provided at Ice Harbor has an average annual cost of $34 million because of the foregone generating opportunities. The spill is required as a passage option under the terms of a NOAA Fisheries biological opinion. The BiOp outlines actions the agency feels must be taken in order to avoid jeopardizing the survival of salmon and steelhead listed under the Endangered Species Act. Snake River sockeye, steelhead and fall and spring/summer chinook are all listed.

BPA estimates that the RSW would allow those costs to be reduced from $13 million to $22 million.

"Ice Harbor has a robust spill program," Crum said. It is the only hydro project on the lower Snake that does not have transportation capabilities -- meaning the fish can't be collected and barged downstream as many of them are at the other three Snake River dams and McNary Dam on the Columbia.

Councilor Larry Cassidy pointed out that the construction costs would effectively be paid back in one year with increased generation.

"Let's get the crazy thing in place because I think it's one of the best pieces of equipment I've seen on the river in a long time," Idaho Councilor Jim Kempton said.

The RSW at Lower Granite during normal operations employed about 19,000 cubic feet per second of water for fish passage at the RSW 24 hours per day. Roughly 12 kcfs of that went goes through the RSW and 7 kcfs goes through adjacent spillbays as "training spill." The training spill creates conditions in the tailrace that facilitate fish egress. The BiOp spill is 60 kcfs at night.

Tests conducted in 2003 indicate that the survival probability through the Lower Granite RSW was 98 percent as compared to 93 percent via BiOp spill. And the RSW attracted 69 percent of all juvenile migrants approaching the project, as compared to 59 percent for the BiOp spill.

Crum called those results for RSW and BiOp spill passage "comparable" because the differences (98 percent vs. 93 percent and 69 percent vs. 59 percent) were within the error band for the study. The fish/flow ratios -- fish passed per volume of water -- were not comparable, however. The Lower Granite RSW fared much better with an 8.3-9.9:1 ratio as compared to BiOp spill's 1.6-1.8:1 ratio.

"It's around five times more efficient," Crum said. He said he believes the devices have many other side benefits. The normal spill is released 50 feet below the surface of the water, well below the 30-40 foot level where the fish normally travel. The fish are subjected to additionally water pressures as they sound. They also seem to delay for as much as a day before taking spill route.

The RSWs raise the crest of the spillway 40 feet, making it easier for the fish to find. The passage delay at the RSW is just a few hours. The reduced flows means less dissolved gas -- which can be harmful to the fish -- created in the river below.

CBB Staff
Corps Moving Forward on Ice Harbor Spillway Weir
Columbia Basin Bulletin, January 23, 2004

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