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Release: Jan. 31, 2003

Iowa Engineers Receive $6.87 Million To Study Pacific Salmon

Photo: Larry Weber

Researchers at the University of Iowa College of Engineering’s IIHR—Hydroscience and Engineering world-renowned water research center have received a three-year, $6,872,566 contract extension from Public Utility District No. 2 of Grant County, Wash. to study how Pacific Northwest salmon can co-exist with hydroelectric dams on the Columbia River.

At present, the two appear to be incompatible, with fish mortality at the dams ranging from a few percent to 50 percent, according to regional fisheries biologists. Fish that swim through the turbines emerge highly stressed and disoriented, making them vulnerable to predatory birds and fish waiting downstream. In addition, excess nitrogen in the bloodstream -- a situation known to deep-sea divers as "the bends" -- occurs in fish near the dams when water crashes over spillways, taking nitrogen from the air and compressing it into the river water below.

While some environmentalists and others have called for dismantling some of the dozen or so Columbia River dams, the Iowa engineers believe the billion-dollar hydroelectric power industry (which generates 75 percent of the region’s electricity) can live side-by-side with the billion-dollar fishing industry, if the power industry can improve the fish survival rate.

“The solution is to route the young salmon around the turbines and to reduce levels of excess nitrogen at the base of the dams. Our work supports a variety of experimental studies and numerical simulations in support of fish passage design,” says Larry Weber, project director, IIHR researcher and associate professor of civil and environmental engineering.

“What is driving our work is the fact that Grant County, Wash. is undergoing a license renewal with the Federal Energy Regulatory Commission. We’re helping Grant County in their license application by sharing study results with fisheries experts and developing plans and concepts they will implement once their license is renewed,” he says. “At present, we’re taking a broad view on how to help the dams co-exist with the fishing industry over the next 40 years.”

Once the Grant County license has been successfully renewed, Weber and his colleagues will focus on the details of saving the salmon. Although they cannot duplicate the actual amount of nitrogen compressed into the water at the base of a real dam or the behavior of migratory salmon, laboratory scale models and numerical, or computerized, models can do a good job of estimating the effects of certain modifications.

IIHR researchers use several large-scale models, including an indoor, 100-foot-wide-by-160-foot-long model of the Wanapum Forebay dam on the Columbia River and a one-mile length of the Wanapum downstream waterway, also called the "tailrace." Under terms of the new funding, modifications will be made to existing reservoir models of the Wanapum and Priest Rapids dams and the Wanapum tailrace, and a new model of the Priest Rapids tailrace will be built and tested. Researchers can limit the amount of water flowing through the scale model dams and the angle at which spillway water enters the river to see whether they can likely reduce the nitrogen content of the water. Likewise, the reservoir models are used to explore the hydraulic signature created by various non-turbine passage facilities.

Weber and his colleagues are also using a software program developed at IIHR, U2RANS, to simulate water flow and fish passage along the Columbia River and, in turn, determine the effectiveness of water deflectors and non-turbine passage facilities. Increasingly, the virtual environment is able to replicate the natural environment as mathematical expressions portray the absorption of nitrogen and the response of salmon to the dams. IIHR researchers have earned a reputation as national leaders for their advances in numerical modeling for hydraulic and fisheries engineering.

Ultimately, Weber says, the challenge will be to reduce the nitrogen content to meet the Washington state standard of 110 percent of the amount of nitrogen normally present in river water and provide non-turbine passage for 95 percent of the migrating salmon.

In addition to Weber, UI researchers working on the project are: Yong Gen Lai, associate research engineer, Pete Haug, engineer 2; Troy Lyons, engineer 1; Songheng Li, postdoctoral research associate; eight graduate students; four undergraduate students; and several UI support staff members, including Doug Hauser, Darian DeJong, Mark Wilson, Brian Miller and Mike Kundert.

The new funding brings the total amount received to about $16 million since the current contract began in 1990. The project is a continuation of earlier fish passage studies initiated by UI engineering professor Jacob Odgaard in 1980 with a $6 million dollar contract.