Threatened juvenile salmon get scientific assistance
August 11, 2003
RICHLAND, Wash. –
Research has found that thousands of miles of essential juvenile salmon habitat are blocked by tens of thousands of culverts that lay beneath Pacific Northwest roadways. Many of these culverts - that for years have successfully channeled water under roadbeds - are acting as barriers to young salmon preventing them the upstream passage required for growth and development.
To find a more ‘fish friendly' design for future stream crossings and for the thousands of retrofits expected to be completed in coming years, the Washington State Department of Transportation (WSDOT), representing West Coast transportation agencies, has hired Pacific Northwest National Laboratory (PNNL), to design and install a culvert test bed in southwestern Washington. PNNL, located in Richland, Wash., is operated by Battelle for the U.S. Department of Energy.
"We're blending the expertise of hydraulics engineers, mechanical engineers, statisticians, fish biologists and fish behavior specialists to find a solution to a problem that faces the entire Northwest, and has implications for culverts throughout the country," said Walter Pearson, PNNL fish behaviorist and program manager.
The full-scale, one-of-a-kind culvert test bed system is located at the Washington Department of Fish and Wildlife Skookumchuck Hatchery near Tenino, Wash.
The system allows scientists to adjust and measure the hydraulic conditions - water velocity, turbulence and depth - of various culvert designs being evaluated. By assessing different slopes and flow regimes, scientists can determine how these conditions influence fish behavior and the ability of the fish to pass through a variety of culvert designs being considered as retrofits.
"There are hundreds of possibilities for bed configurations," Pearson said. "A particular design may stop passing fish at some flow rate or some slope and that's what we'll be looking for. This will help us design stream crossings that accommodate fish in all life stages."
The ability to quickly receive research results on these configurations is very appealing to transportation agencies. "Testing culvert designs in a controlled setting will help us better understand how we can meet fish passage needs in a variety of conditions," said Jon Peterson, from WSDOT's Environmental Services Office. In coming years, tens of millions of dollars will be spent improving culvert fish passageways in Washington State alone.
U.S. Rep. Norm Dicks (D-Wash.) has recognized the need for greater federal involvement in removing these barriers to fish passage, initiating a new program to identify problems and replacing culverts that obstruct salmon migration on national forests and other federal lands. He said better science is required, however, and that the culvert test bed is needed for a more thorough understanding of the dynamics of stream flow and how adjustments based on credible data-gathering will help improve culvert design and construction. "This is a critical issue requiring solid science to help maintain the health of our streams and the well-being of our fish runs," said Dicks. "Decisions made based on research at this facility will benefit us for decades to come."
Attempts to retrofit culverts are not new. Baffles, weirs, ladders and other physical structures have been added to enhance fish passage over the years, but there is insufficient data to demonstrate the effectiveness of these efforts. The program will provide decision-makers scientifically sound data to retrofit existing culverts and develop better designs for new culvert installations. "Investing in this system provides WSDOT with improved scientific data to ensure that we're spending money on solutions for fish passage that will work to provide long-term benefits to our environment," said Peterson.
A transportation consortium that includes the states of California, Oregon, Washington and Alaska, and the Federal Highway Administration pooled funds totaling $1.16 million to contract with PNNL to conduct the first phase of a five-year $3.4 million interdisciplinary program. Scientists with extensive natural resources and hydraulics expertise were selected from PNNL's Marine Sciences Laboratory in Sequim, Wash., and from PNNL's Hydrology Group in Richland, Wash., to design, install and operate the culvert test bed. PNNL recently completed installation of the test bed, has tested the mechanics of the device, and is currently performing hydraulic characterization.
Passage of juvenile salmon through culverts is a significant Endangered Species Act issue for Pacific states. Scientists recognize fish passage both up and downstream is crucial for the rearing and feeding of young salmon. The test bed enables controlled experiments that will yield the behavioral and hydraulics data to address this ESA issue.
The consortium members led by WSDOT include PNNL, the departments of transportation in California, Oregon and Alaska, the Federal Highways Administration, Washington Department of Fish and Wildlife, and Alaska Fish and Game.
Tags: Energy, Environment