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May 2, 2000

Engineers study Columbia dams for alternatives to breaching

By SUSAN JANKOWSKI
Journal environmental editor

Seventy Seattle area engineers toured the Rocky Reach, Rock Island and Wanapum dams on the Columbia River last weekend to look at ways to improve fish passage that might reduce pressure to remove Northwest dams.

"We're trying to raise awareness in engineers' minds for future designs for reconstruction and dissuade them from dam removal -- if we can achieve successful fish passage," said Felix Kristanovich, an engineer with Shapiro & Associates who coordinated the tour. The tour was sponsored by the American Association of Civil Engineers-Washington Chapter. Kristanovich helped design outflow pipes to facilitate fish passage at Rocky Reach.

Engineers from Golder Associates, R2 Resource Consultants, Inca Engineers, R.W. Beck, Ecology and Environment, Inc. and Ridolfi Engineers were among those who attended.

"The designs of these dams are locally unique. We have to examine particular elements of each dam to find out where to put safe fish passages. There have been several changes and quite a bit of problems in the last 20 years," said Kritstanovich. Rocky Reach and Rock Island dams supply electricity to Chelan County, and Wanapum supplies power to Grant County.

There is consensus that Wells Dam, upriver from Rocky Reach, has the best design for fish passage on the Columbia -- by default because physcial constraints dictated the design at this facility. At Wells, juvenile salmon pass directly over the dam without having to be diverted to another route for passage. Also, Wells' generator turbines operate parallel, instead of perpendicular, to the flow of the river and the turbine intakes are below the level where fish pass through spillway gates.

Rocky Reach Dam. The Chelan County PUD has spent millions of dollars since the mid-1990s to make Rocky Reach more fish friendly. There are three ways migrating salmon can get past this dam: the fish bypass system which is comprised of gates and pipes and diversion areas; spillways; or through the turbines.

The PUD has spent approximately $50 million constructing a fish bypass system prototype and has committed to spending another $130 million over the next 15 years to develop and build a permanent system. So far, this model has resulted in a high percentage passage rate for steelhead, but less for chinook, sockeye and coho.

In 1998, Rocky Reach expanded its surface collection pools, part of the bypass system, with a 60 percent successful passage rate. The entrance was expanded again last year and tests now reveal a 95 percent successful passage rate. The entrance is adjustable to accommodate varying flows to continuously attract migrating salmon with the right degree of turbulence.

In 1995, Rocky Reach began replacing its 11 aging turbines for more efficient power generation at a cost of $76 million. Officials took this opportunity to design turbines that are more fish friendly. In the new design, engineers tried to minimize the gap between the hub and runner blades where some migrating juvenile salmon are killed.

Reducing gases, such as nitrogen, to protect salmon from getting fish bubble disease as they move through spillways is a challenge at several dams. To address this, Rocky Reach installed a new outfall pipe as part of its bypass system. Fish are collected along the surface, then put into the outfall pipe, which takes them around the dam and deposits them farther downriver, below the dam and away from gases.

Two hatcheries operate adjacent to Rocky Reach. Here, a combination of state Fish & Wildlife, Chelan County PUD and contracted biologists tag juvenile salmon, collect data and conduct testing. Predicting the behavior of migrating salmon has been these scientists' greatest dilemma.

"Although each dam is completely different, everybody's looking at everybody else to see what works," said Tracy Yount, a spokesman for the Chelan PUD. "It's always a give and take; it's tough coming up with biological engineering solution. How many people really know what a fish does?"

Wanapum Dam. Wanapum Dam's salmon conservation plan includes a hatchery at the nearby Priest Rapids Dam. This program has been successful, in part, because hatchery fish mingle with wild salmon to produce a genetically healthier stock, officials said. Consequently, Wanapum has been able to boast of its "disease-free" stocks for several years.

"Generally, at Priest, we're looking at rearing seven million (chinook) eggs there each winter for our own stock and we send out an additional seven million eggs to state hatcheries. We get a return that's quite good," said Gary Garnant, a spokesman for Grant County PUD.

Wanapum regularly measures gas levels below each dam and adjusts spill rates around the clock to accommodate migrating salmon. "We spill just for fish survival, so they go over the gates, rather than through turbines," he said. According to Garnant, Wanapum has an agreement with government agencies to achieve a 95 percent survival rate for fish passage and controlling spills is helping to achieve this.

Grant County PUD is also involved in research on fish friendly turbines with the U.S. Army Corps of Engineers and the Bonneville Power Administration. "We are essentially refining our turbine designs by participating in this research," Garnant said.

One progressive design feature at Wanapum is its method of reducing underwater gases. Flow detectors monitor the depth and pressure of spilled water and, when necessary, signals when to spray water out over the river. Spraying dissolves gases, as opposed to what happens when the force of falling water strikes the bottom of the river. This past winter marked the first time this spraying system has been fully operative. According to Garnant, other dams are interested in this model for gas reduction.

Rocky Reach. Predatory birds also threaten salmon. At Rocky Reach, propane canons randomly fire to scare away gulls. At Wanapum, stainless steel lines are hung across the downstream-side of the dam, to temporarily snag gulls as they dive for fish. While these lines do not hurt the birds, it deters them.

The first hydroelectric plant was built by the federal government at Niagara Falls in 1879.

At their peak, hydroelectric dams supplied power to a third of the U.S. poplution. However, fossil fuels proved cheaper and many communities adopted that type of power instead. Later, some states chose nuclear power. Today, about one-sixth of the nation's power is hydroelectric. Proponents of hydroelectricity say if engineers can design ways to mitigate fish passage, this source of power is among the cleanest and cheapest available.




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