Acoustic tags and numerical river models are two technologies developed by researchers at the Department of Energy’s Pacific Northwest National Laboratory to help improve salmon passage at the Columbia Basin’s hydroelectric dams.
An average of 76 percent of juvenile Chinook salmon that pass through the lower 100 miles of the Snake River and its three hydroelectric dams survived the trek in the spring of 2008, according to a joint study between PNNL and the U.S. Army Corps of Engineers’ Portland District.
The information was gathered by surgically implanting 4,140 young salmon with a tag that’s part of the Juvenile Salmon Acoustic Telemetry System (JSATS). The JSATS-tagged fish were released from the Lower Granite Dam on the Snake River, where hydrophone receivers in the river picked up small sounds, or “pings,” that the tags emit. PNNL and NOAA Fisheries began developing JSATS in 2001 to determine the survival rate of subyearling Chinook salmon in the Columbia River estuary.
Migrating salmon will soon be directed away from predatory fish near The Dalles Dam, thanks in part to a detailed 3-D computational fluid dynamic model created by researchers at PNNL and the Corps’ Portland District. The Corps is building a concrete guide wall downstream of the dam’s spillbays. The researchers’ computer model showed such a wall would help move fish away from shallow waters downstream.
Predatory fish like northern pikeminnow gather in the shallow waters and eat passing salmon. The new guide wall should direct salmon toward the Columbia River’s deeper channels, where predatory fish are less abundant.
The 3-D model was unusual because it included breaking waves on the surface, while most other river models use flat “lids” at the water surface. One of PNNL’s supercomputers processed the model, while commercially available software helped create the model.