Designing Safe Passage for Steelhead Trout Through the L.A. River

The Southern California steelhead was added to the federal endangered species list in 1997. Today, planners are working to create a new home for the trout in the L.A. River.

2 minute read

October 7, 2020, 10:00 AM PDT

By Lee Flannery @leecflannery

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"Biologists and engineers are setting the stage for an environmental recovery effort in downtown Los Angeles that could rival the return of the gray wolf, bald eagle and California condor. This time, the species teetering on the edge of extinction is the Southern California steelhead trout and the abused habitat is a 4.8-mile-long stretch of the L.A. River flood-control channel that most people only glimpse from a freeway," reports Louis Sahagún.

According to scientists, the global population of southern steelhead has declined from an estimated 36,000 to 46,000 to less than 400 adults. The L.A. River now separates the remaining steelhead trout from their original spawning grounds in the San Gabriel Mountains.

The Los Angeles River Fish Passage and Habitat Structures Design Plan will modify the depth of the river and provide pools where steelhead can rest during their migratory trips to provide safe passage through Downtown Los Angeles. 

Among the difficulties in planning the project is the velocity of the river's waters. "It can contain a discharge of about 104,000 cubic feet per second during a 100-year flood event," Sahagún says. Finding funding and gaining necessary permits to work on the flood-control system are also challenges. 

"Design phases of the project are being funded by the California Wildlife Conservation Board under a Proposition 68 grant of $1.3 million," writes Sahagún. The total cost of the project is not yet clear, but Sahagún says the project would be a compliment to the "along-awaited river revitalization project north of downtown approved by the Army Corps of Engineers."

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