It sounded like a hot tip. “They’re breaking up the first concrete in the L.A. River today,” Lewis MacAdams told me over the phone one morning last week. “Today?” “Yes,” he drawled assuringly. “You really ought to go up there.” As the founder of Friends of the L.A. River, MacAdams has long fought to break up the concrete in which the U.S. Army Corps of Engineers entombed the river over the last five decades and bring it back as much as possible to its natural state. He gave me the cell-phone number of Lynne Dwyer, co-founder of North East Trees, who was supervising the project. Shouting over the construction noise, Dwyer was giddy. “When are you coming out?” she wanted to know. I arrived around 2 at a northern stretch of the Arroyo Seco under the Devil’s Gate Dam. “Right down that road,” Dwyer shouted from her shiny red late-model Volkswagen Beetle, directing me down a dirt road behind a “trail temporarily closed” sign. We met again in the parking lot. Dwyer wore a hardhat over her perky blond bob; her cheeks were truly red like apples, and she was beaming. “This isn’t the L.A. River,” I observed. “Oh, yes, it’s a tributary!” said Dwyer. “It’s all the L.A. River.” And there was concrete being broken up, just as MacAdams had promised. The sound of jackhammers split the air, and friendly little Bobcat tractors crawled up and back, depositing slabs in a truck. But it wasn’t a whole flood-channel tomb being destroyed, just a long slab under a 210 freeway overpass. And it wasn’t put there by the legendary Army Corps of Engineers. “But it’s still the demolition of concrete,” Dwyer insisted. “I love demolishing concrete!” “But where did it come from?” I wanted to know. “Well, it’s of mysterious origin,” Dwyer said. “Some people think it ended up here when the freeway collapsed in the earthquake in 1971. But we don’t believe that. Another theory is that a flood-control wall overturned when they rebuilt the freeway and they just left it there. But we really think this piece of concrete was put here to stage scaffolding during construction. “It’s not like we’re dechannelizing the Tujunga Wash,” she admitted. “But it’s still significant. We’ve developed a process and a management precedent for restoring river habitats. That’s historic.” Dwyer and MacAdams were in cahoots. “I think Lewis tricked me to get me up here,” I told Dwyer. “Yes, well, Lewis is good that way,” she said with a laugh, and invited me on a hike. The 20-acre Arroyo Seco Restoration, Dwyer explained, was pioneered by a Pasadena city supervisor named Rose Laveaga, who lost several nights’ sleep writing grants for the $1 million required for the first phase of restoration. Dwyer, a landscape architect and the co-founder of North East Trees, was hired by the city to oversee the restoration. The state put up the funds; city and county agencies cooperated; the county closedthe dam — “and they sure didn’t have to,” said Dwyer. Caltrans signed off after lengthy negotiations. “They had real concerns about destabilizing the overpass,” Dwyer said, “but we convinced them.” I told her she seemed awfully happy about all of it. “Oh, I’m all into it,” she said with a little shudder of joy. “I’m way into it.” She and her team had been working for a while already on the first 10 acres, below the Rose Bowl; the concrete slab had fallen in the upper 10. “What we’re doing here is removing debris,” Dwyer said. “We’ve found tires, shoes, lampposts — every time the water shifted, more stuff has accumulated.” She includes non-native plants among that debris: “Most of our work,” she said, “has been removing exotics from these natural areas, and restoring native plants through seeding and cutting.” Exotics had been branded with pink paint so crews could come through and tear them out. “At one point there was so much pink up here that people were freaking out — ‘Who is the graffiti artist?’ ” Dwyer isn’t after perfect wilderness here; this is an urban ecosystem, in which some concrete — like the walls that shore up the overpass — has a place. Still, as we navigated our way through mud and over boulders, Dwyer established the hierarchy of plant life in restoring a native habitat, a system in which simple ornamental beauty has no value. Willows, artemisia, sage and sumac remain, but equally elegant fern-leafed acacia gets torn out (unless a bird has nested in the trees — “then we wait until next year”). Aggressively parasitical cucumber vine, or “man-root,” as it’s more accurately called, stays: “Not just because it’s native, but because it stabilizes the hillside.” Poison oak becomes wholesome, said Dwyer, “because it keeps the people out.” By the end of my walk with Dwyer, it had ceased to matter to me that I wasn’t witnessing storybook history — this was something altogether more subtle and somehow more profound. “Sure, it’s a small thing,” Dwyer admitted. “It’s not like we’re trying to take apart the L.A. River. But it reflects the agencies bending, working together. “And for me,” she added, “it’s just really fun.”

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