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Even after its hotly anticipated restoration, the L.A. River will likely remain dominated by non-native species.

The cement-lined urban waterway—a symbol of future hope and past environmental harm for many Angelenos—is getting a massive makeover. A number of small revitalization projects are in various stages of completion, and a planned $1.6 billion Army Corps of Engineers effort would remove concrete and replant native habitat along an 11-mile section.

But it’s not clear exactly what that will mean for local wildlife.

LA River.

LA River.

This Sunday, historian Patt Morrison joins a panel of experts to explore the issue of “Life in the L.A. River” with the Natural History Museum and the UCLA La Kretz Center for Conservation Science.

Brad Shaffer, a panelist and UCLA ecologist, says it’s not surprising that the river is dominated by non-natives, having been so heavily modified.

“In terms of all aquatic species, I’d be shocked if 10 percent were native,” he says.

Some activists, including one prominent group that has long advocated the waterway’s restoration—Friends of the L.A. River—say they’ll only be satisfied when California steelhead trout once more call the river home.

But would a healthy, functioning river be a failure if native fish and amphibian species weren’t part of it? Shaffer doesn’t think so. To him, efforts to restore habitat and wildlife need to be realistic given how drastically people have changed things.

Flooding on 43rd Place near Leimert Boulevard, downtown L.A., 1938.

Flooding on 43rd Place near Leimert Boulevard, downtown L.A., 1938.

After a series of floods devastated property and claimed lives in the rapidly growing metropolis, the Army Corps of Engineers began a project in 1938 that would eventually seal fifty-one miles of the river in 13 million barrels of concrete. The endeavor halted the floods but destroyed ecosystems and transformed the river into a flood channel that fast-tracks polluted runoff into the Pacific Ocean.

Non-native fish such as carp have an advantage in an urban landscape: People continuously release them. Many native fish could only return with a similar helping hand and strategies to maintain them once re-stocked.

Such interventions are not included in the $1.6 billion restoration. But after masterminding the river’s initial paving, the Army Corps of Engineers aims to make the river much more wildlife-friendly.

“We’re trying to replicate the physical conditions that native species like as much as possible, but we aren’t proposing to bring animals back,” says Eileen Takata, lead planner with the agency.

However, there is a bright spot for one native fish. A heavy El Niño rainfall could wash the Santa Ana sucker, which currently lives further upstream, down to the project area.

Great blue heron, LA River.

Great blue heron, LA River.

Whatever the long term outcome, UCLA’s Shaffer sees the river as a fascinating example of urban ecology, where species’ adaptive resilience can be observed in the presence of dense human development.

Having been involved in conservation projects across California, Shaffer says success metrics vary with differing levels of human population density. A project in Yosemite’s Tuolumne Meadow, for example, would aim for 100 percent native species.

A more likely scenario in L.A. is an ecosystem in which non-natives and increasing numbers of native species live in harmony—and that’s not a bad thing, Shaffer says. Food webs of predominantly non-native turtles, crayfish and snails could support increasing populations of native birds, such as cormorants and great blue herons.

This article originally appeared on UCLA’s Institute of the Environment and Sustainability.

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