Club members say their motive is a little selfish: They enjoy seeing the native species return and the creeks flow when the intruders are removed. “We love to hike in those canyons, and we’re environmentalists,” Erskine-Hellrigel said. “It’s amazing when you see creeks running longer in the year because the tamarisk is gone.” Some 40 volunteers have shown up at past tamarisk pulls, and she expects at least that many when the group meets at 8 a.m. Saturday near an abandoned oil boom town called Mentryville, deep in Pico Canyon. A similar effort involved the La Crescenta-based Habitat Works, whose member backpacked some 40 miles along Piru Creek to uproot a stand of tamarisk. “They removed 10,000 seedlings,” Teresa said. The strategy has been to kill the plants upstream so seeds won’t wash downriver and germinate, creating a bigger problem. Pico Canyon, where the volunteer crew will work Saturday, is upstream from the South Fork of the Santa Clara. “If we don’t stop it above, that constant source of seeds will keep coming down,” Teresa said. Tamarisk and another pesky nonnative, the bamboolike Arundo donax, were imported during the Civil War era from Mediterranean countries for use in landscaping and to prevent erosion. Since 1993, the U.S. Forest Service has been laboring to annihilate tamarisk and arundo from the Santa Clara and its largest tributary, San Francisquito Creek. Nancy Hanson, a wildlife biologist for the Forest Service who is headquartered in Saugus, leads the local eradication effort. She, too, has seen water return to parched riverbeds when the water-sucking tamarisk and arundo are removed. Hanson is in the midst of applying for a grant of up to $12 million to work with the city of Santa Clarita to remove the weeds from the Santa Clara as it cuts through town. “The objective is to eradicate all arundo and tamarisk on the Santa Clara River watershed, from Acton to the Ventura County line,” Hanson said, and she knows it can be done. The Forest Service has taken out about 75 percent of tamarisk and arundo where the Santa Clara River and San Francisquito Creek meander through the Angeles National Forest. Pesticides are monitored by the U.S. Department of Fish and Wildlife to ensure chemicals don’t damage the river environment. “When we are able to eradicate, it frees up that water, and the native vegetation returns on its own and flourishes,” Hanson said. Further downstream, federal and state agencies are working with The Newhall Land and Farming Company to eliminate tamarisk and arundo from the river where it passes the developer’s planned 21,000-home Newhall Ranch. As the river heads to the Pacific, it’s filled with thick stands of both weeds. Authorities fear flooding in wintertime when the heavy foliage blocks the flow of the river. They also note that arundo, in particular, dries to a crisp under the sun and becomes perfect fuel for brush fires. In 2003, swaths of brittle arundo fed fire that swept from the Castaic area downriver through the Ventura County cities of Fillmore and Santa Paula. “The magnitude of the problem – you cannot imagine,” Teresa said. “It’s a phenomenal propagator. It crowds out the native species.” Still she holds out hope. “We have to be really creative and extremely careful. There’s a wasp that eats tamarisk, but if we introduce that and it’s successful, what’s that going to do? Will the wasps be a bigger problem? “I’m dismayed at the magnitude of the problem, but I’m hopeful it can be handled. We’re fighting on a lot of fronts.” [email protected] (661) 257-5251160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set! Their prize? A dry stream begins to flow again, wildlife put off by the intruder returns, and native plants abound. “We did a removal at a dry creek in the Coachella Valley, and now the creek flows,” Teresa said. “The water’s come back. It’s amazing.” On Saturday, dozens of volunteers from the Community Hiking Club will attack a wall of tamarisk in Pico Canyon west of Santa Clarita. A creek there feeds tributaries of the Santa Clara River, which stretches through the area, with its headwaters in the High Desert and its mouth at the Pacific near Oxnard. The weeds flourish in the Santa Clara and its feeders, and club members have successfully attacked the weed in nearby Towsley, Whitney and Placerita canyons, club leader Dianne Erskine-Hellrigel said. The volunteers must remove the tamarisk by hand because they are not licensed to use pesticides in a creek bed. The labor is grueling. “We’ll pull out the bushes, follow the roots, dig them out. We’ll move boulders, if we have to, to make sure we get all the roots,” Erskine-Hellrigel said. NEWHALL – Laden with tools, they’ve hiked dozens of miles and padded through muck with the goal of eradicating an enemy, one that boasts flowers in a variety of colors. Tamarisk, a common shrub with white, yellow or pink blooms, is sucking the life out of waterways in the West. The nonnative bush, which has invaded the rivers and other streams of Santa Clarita’s watershed, chokes out indigenous plants and wildlife and absorbs extraordinary amounts of water – some 300 gallons a day – at a time when it’s needed most. “It’s a huge water hog,” said Sherry Teresa, executive director of the nonprofit Center for Natural Lands Management. “It’s all over the West, drying up creeks and rivers.” An army of “soldiers” from the public, private and volunteer sectors has been battling the weed for more than a decade – pulling it, poisoning it and coming back to clean up seedlings from the 500,000 microscopic seeds a single bush can produce.