The ELJ construction uses 12 logs (five vertical and seven horizontal), which vary in size. They are installed in the Truckee River just upstream of the plunge pool located beneath the output pipe, where fish will enter the river following passage through the fish screen. Wood is an important fish habitat component in most river systems. The ELJ will serve three main purposes: 1) helping to induce scour and ensure proper depth of the plunge pool, 2) provide cover for fish from predators, and 3) protect the pipe outlets from debris.
“Working in waterways is always challenging,” explains Cody Cummings, Granite’s project manager for the Derby Dam Horizontal Fish Screen Project. “It was crucial to coordinate our installation efforts with the river’s low flow. Once we created the diversion, our crew started the dewatering process allowing for us to start placing the logs that will form a protected area for the LCT to exist upon entering the Truckee River,” Cummings adds.
This type of ELJ is used in many different scenarios and applications throughout stream environments. However, this is only the second FCA screen design that features an ELJ as part of the project design.
“The ELJ plays an important role in the Derby Dam Fish Screen Project. It provides a safe place for fish to transition back to the Truckee River after passing over the screen,” explains Alexis Vaivoda, Farmers Conservation Alliance project manager.
The Derby Dam Fish Screen Project is scheduled for completion in fall 2020. The next project steps include installing walkways, grating, and electrical equipment, final earthwork, and screen panel installation.
To learn more about the Derby Dam Horizontal Fish Screen Project visit the Farmers Conservation Alliance website.
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