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Corps Tests Fish Friendly Turbines

by Mike O'Bryant
Columbia Basin Bulletin - November 19, 1999

Biological testing of a new generating turbine at the Bonneville Dam began this week that will show just how fish-friendly the blades on the new turbine are compared to turbines installed in the 1930s.

While the testing will not determine if the turbines will be installed, it could influence strategies that balance power production and fish passage at the dam in the future.

The "MGR" is a specially-designed turbine that leaves less room around the turbine hub and blades and the outer casing. That, the U.S. Army Corps of Engineers says, should reduce the number of fish that are killed when traveling through a turbine by up to 4 percent. Survival through the turbines now ranges between 89 percent and 94 percent, depending on flow. With the new turbine, survival rates could improve to between 93 percent and 98 percent.

However, the Corps cautions that even though the turbine could be used at other projects to improve juvenile survival, it is not the final answer for downstream migration problems.

"This is not the silver bullet. It is not the only answer to solving juvenile salmon survival," said Debbie Chenoweth, the Corps' Bonneville Dam project director. "Every project is a little different and fish behave differently at various times of the year."

The 10 turbines at power house number one are 1930's technology, she said, so they need to be replaced anyway. One of the MGR turbines is in place and the other nine are being manufactured, all at a replacement cost of $108 million. But, according to Corps literature, it may take as long as until 2007 (one turbine per year) before all ten are in place. Bonneville's other power house was put into service in 1983 and those turbines do not have to be replaced yet.

The conceptual design for the turbine was developed by a regional Turbine Technical Working Group composed of biologists and engineers from the National Marine Fisheries Service, the Corps, the U.S. Dept. of Energy, Bonneville Power Administration, public utility districts, the Idaho National Engineering Laboratory and the Electric Power Research Institute.

Chenoweth said the MGR turbine is a specially-designed Kaplan turbine, which is the type it is replacing. In both the old and the new turbines, the blades move to vary pitch. When the blades of the old turbine design move, gaps widen or narrow depending on the angle of the blade. Fish could be caught, pinched or killed in those gaps. The new turbine minimizes that gap at all times regardless of blade pitch.

Testing juvenile survival through the minimum gap runner turbine at Bonneville's power house number one began Monday, Nov. 15 and will conclude by Jan. 31, 2000. The testing uses live Lewis River hatchery juvenile chinook salmon, a radio tag and two balloons that bring the test fish back to the surface after they pass through dam.

Twenty-two biologists are working on the $2.5 million biological testing project that is paid for by the Corps, DOE and Grant County PUD. Everyday they release 120 of these well-equipped juveniles and retrieve them from four boats waiting downstream.

A biologist first inserts a nearly-microscopic visual implant tag in the skin behind the fish's eye that will identify the fish for life. Then he attaches the radio tag and one of the balloons beneath the dorsal fin and the other balloon in front of the tail. Each item has a number that will identify the fish when it is picked up later in a boat.

Forty fish per day are released into the new MGR turbine chamber and 40 into one of the old turbine chambers to be used as a comparison. An additional 40 fish that are introduced into the tailrace do not go through a turbine and are used as a control group.

Just before the fish are introduced to the turbine or tailrace, a little water is injected into the balloon to activate a gel-cap which acts as a timed-release inflation device. Fish are introduced to the turbine through a tube that puts them either at the hub, at mid-blade or at the blades' tip. Each day that location changes.

Dennis Schwartz, Corps biologist and project manager for the test, said the velocity of water speeds to 12 feet to 15 feet per second near the hub and slows again to about 6 feet to 8 feet per second once the fish leave the turbine and head out towards the tailrace.

At that point, the balloons begin to inflate and biologists in four outboard boats with tracking antennas tuned to the frequency of the radio tag scoop them out of the water, determine their condition and put them in a tank for 48 hours to check for delayed mortality. At the end of this short vacation, the salmon are released to the Columbia River.

According to Schwartz, the testing results will not be available until February 2000, but the results will not determine whether the turbines will be installed. That decision has already been made. The results could, however, be used to determine whether The Dalles or other dams on the Columbia and Snake River system get outfitted with the same fish-friendly turbines. Schwartz said new generators are being installed at The Dalles Dam, but the decision to replace the runners is awaiting the outcome of these tests.

On the other hand, Schwartz said the testing could determine operational strategies after the turbines are in place.

"The tests could show that we get better survivability through the turbines than we get through the spillway," Schwartz said. "That doesn't mean we can say we can reduce spill. That would be up to biologists and operators to decide as a policy."

Still, he said, there are benefits to biology of "speeding up the water that you don't get when slowing water to run through turbines."

Schwartz said they are also measuring things like efficiency and found that the same amount of water is resulting in more power production. According to Corps information, each additional MGR will produce enough additional power to fuel about 15,000 homes in an average year.

Link information:

by Mike O'Bryant
Corps Tests Fish Friendly Turbines
Columbia Basin Bulletin, November 19, 1999

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