"They're actually the first ones that evolved, and they are able to tolerate the warmer waters that we have in Southern California," Goode said. "This is really significant because of climate change. The fish up north cannot tolerate the warm waters, so as northern streams become warmer, we may hold the key to having steelhead trout."
Knite also said the Topanga Creek restoration will give scientists an opportunity to study how the southern trout adapts to changing habitats. She said that within a year or two, the effects of the berm's removal will be evident. "Fish show up in places they haven't been in years as soon as you give them a place to come," Knite said.
The 1,600-acre parcel called Lower Topanga was acquired by the state parks department from the Los Angeles Athletic Club for about $40 million in 2000. In the process, the agency also became the landlord to a community of about 50 homes, the same community that decades earlier built the berm.
The state paid about $5 million to relocate the residents, Goode said. Buildings in the area were demolished over the last few years in preparation for the creek restoration.
The 12-acre project to remove the berm and some nonnative plants, and restore the riparian system with native plants, will cost about $3 million, Goode said.
Workers will plant willow, mule fat, alders, cottonwoods, sycamores and oaks, and remove the highly flammable and bamboo-like arundo plant, jacaranda, an orange tree and palm trees. Some nonnative plants will stay to address concerns of people living further up the canyon who don't want vegetation uprooted.
"There's exotic grasses, crab grass, fruit trees; it looks sort of like people's backyards," Goode said. "Then you have dry creek bed for thousands of feet that has these arundos growing on both sides instead of the willows that it should have."
Residents were also concerned that some of the asphalt in the berm was probably dumped there after Lincoln Boulevard was repaved and might contain lead, Goode said.
Decades ago, when gasoline was still leaded, the lead would often drip onto the asphalt on roads or near gas stations, she said. Officials decided that all materials from the berm will be tested for lead. Lead-free dirt will be sent via a covered truck to a nearby dump. If any debris tests positive for lead, it will be trucked to a special landfill in the San Joaquin Valley.
The area will remain open to the public while workers restore it. The rainy season will probably bring water back to the creek later this year.
Officials envision a future in which the creek will run year-round and the area will look as it did in the 1920s and '30s. The bubbling creek would be free to choose its own path down the canyon's crevices, full of silvery steelhead trout and other fish swimming back and forth from its headwaters to the Pacific. Around the creek lush green native plants will hopefully provide a thriving habitat.
"Restoring this area is the work of a lifetime," said Goode, who is one of the managers on the restoration project. "It will not be done when I retire."
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tami.abdollah@latimes.com
