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Protecting aquatic life during construction

August 25, 2022

Four people stand in water with nets prepared to catch fish.
Marie Gaylord, biological field technician with the Wallowa-Whitman National Forest, and Corrina Stadler and Trey Montgomery, biological field technicians with the Grande Ronde Model Watershed, prepare to net fish temporarily stunned by Sarah Brandy (Center-Left), fish biologist with the forest, and move them to a safer place. The net in the background marks the downstream extent of the work isolation area, blocking fish from moving upstream into danger. USDA Forest Service photo by Joseph Black.

OREGON—Guided by scientific research, on the ground experience, nets and a desire to protect aquatic life, employees with the Wallowa-Whitman National Forest and biological field technicians with the Grande Ronde Model Watershed recently conducted a fish salvage project in a portion of Limber Jim Creek.

Two people stand in water to set up a net that will block fish from passing through while stream is under construction.
Sarah Brandy, fish biologist, and Marie Gaylord, biological field technician, set up and secure a block net high above water level in case the water level rises. The team will also need to keep the net clean for the duration that it is up so that it doesn’t become blocked with algae or debris. The net will be in place for the shortest amount of time possible so that fish and aquatic organisms remain unharmed and can pass to upstream and downstream habitats as soon as possible after construction is completed. USDA Forest Service photo by Joseph Black.

Relocating the fish outside of the construction area is an important part of the Limber Jim Creek project, said forest fish biologist Sarah Brandy. 

“When the U.S. Forest Service has project work that occurs in stream channels, we are required to work within a certain timeframe that will have the least amount of impact on fish and aquatic life,” said Brandy, who led the project. “We also follow permits that require isolating a construction area, removing fish from this area and moving them to a safe place upstream until the work is complete.”

Removing fish from the stream includes setting up and securing two block nets, one upstream and one downstream—then relocating the fish in between. These nets are held up using trees along the sides of the stream and large rocks that secure the net to the streambed.

The salvage crew then walks up and down the stream, with an electrofishing device and nets, surveying for any remaining fish in the now blocked off section of stream.

This process, known as electrofishing, uses an electrical current to temporarily stun fish, making them easier to catch. Electrofishing relies on two electrodes that deliver an electric current from the anode to the cathode through the water. The cathode, or tail, is a three-meter braided steel cable that trails behind the operator.

Hands holding a bridgelip sucker fish caught in net.
Marie Gaylord, biological field technician with the Wallowa-Whitman National Forest, holds a large native bridgelip sucker fish (Catostomus columbianus) during fish removal operations. This fish was temporarily shocked using an electrofisher, making it easier to net, but is healthy and unharmed from the voltage. The fisheries biologist that runs the backpack electrofisher is trained to ensure that the voltage is on the lowest effective settings so that fish and aquatic life are not harmed. USDA Forest Service photo by Joseph Black.

“A fisheries biologist with appropriate training in both human and aquatic safety runs the backpack electrofisher, ensuring that the voltage is on the lowest effective settings so that fish and aquatic life are not harmed or damaged,” said Brandy.

Other technicians then capture the fish in nets and relocate them to a place in the stream upstream of the work isolation zone.

“By placing the fish upstream, they are able to migrate freely while remaining safe from the dangers of a construction site,” explained Brandy.

This construction project, funded by the Confederated Tribes of the Umatilla Indian Reservation, Bonneville Power Administration and the Forest Service, is replacing an existing culvert on a forest road. The culvert was undersized and not aligned correctly to the stream, causing the stream to erode the road on the upstream side of the culvert and cause conditions that were not passable to fish and aquatic life at certain flows. The new concrete bridge spans the whole creek and is wide enough for the creek to flow unimpeded at high flows. 

“Correcting obstructed fish passages is a high priority for conserving and restoring fish populations,” said Brandy. “It helps connect fish habitat and gives fish and other aquatic life access to upstream areas.”

The culvert replacement also benefits the local community by protecting native fish resources, correcting problem road sections and utilizing local contractors to boost local economy.

The Forest Service keeps sections of stream blocked for the shortest amount of time possible so that fish and aquatic organisms remain unharmed and can swim to upstream and downstream habitats as soon as possible after construction.

Now that the project has been completed, the fish are able to move freely throughout the stream and the road is open for public use.

More information about the Wallowa-Whitman National Forest is available on the forest website.

Two people walk under culvert in stream in an effort to move fish downstream.
Marie Gaylord, biological field technician with the Wallowa-Whitman National Forest, and Corrina Stadler, biological field technician with the Grande Ronde Model Watershed, walk through a culvert in an effort to move fish downstream to be removed using the process of elctrofishing. Electrofishing uses an electrical current to temporarily stun fish so they can be caught and relocated during construction of the culvert replacement. USDA Forest Service photo by Joseph Black.