When Aliens Attack

by Heather Millar

Our team has pushed way beyond the Grand Canyon's tourist zone, past the usual river-trip loop hikes or backpacker routes.

We're working five or six miles up the Lava Canyon drainage from the Colorado River, farther up, we hope, than any seeds of alien tamarisk trees have managed to blow and germinate. We've left camp and the river so far behind that the North Rim's red wall looks attainable, if not exactly close. Then, we turn a corner and see a brambly, twisted stand of the dreaded shrub. Drat.

"Kamikaze!" The most enthusiastic team members start to yell in pseudo-Japanese gibberish and fall upon the larger plants with samurai fervor.

The tree they're assaulting, Tamarix ramosissima, aka tamarisk or salt cedar, originates far from northwestern Arizona, in Eurasia. In the 19th century, settlers imported these dense, shrubby trees to create windbreaks and stabilize eroding riverbanks in the arid West. The species adapted so well that it has spread to other parts of North America and invaded every river system in the Southwest.

Growing in thickets where plants were once sparse, tamarisk increases fire frequency and crowds out native cottonwood and willow. It also guzzles precious water in the species-rich riparian zones. Each year, tamarisks in the United States suck up about three times more water than is used by all the households in the city of Los Angeles.

As early as the 1920s, tamarisk had established itself in the main Colorado River corridor of Grand Canyon National Park. Along its banks, tamarisks now form a band of green that would take millions of dollars and as many hours to remove. More recently, perhaps in the last two decades, the invader has begun to creep up the side canyons formed by the Colorado's tributaries. There, though, in remote places like Lava Canyon, the tamarisk takeover is not yet complete.

I drop into the red dust, pull out my folding saw, and try to ignore my sweaty knees, which are scraped despite my double-ply work pants. This side canyon "flashed" a few months before, and the rushing water partly snapped this smaller tree. Looking for the main trunk, I scratch at the dirt and rocks that cover the roots and branches, obscuring their growth pattern.

A fuzz of sprouts has grown up around the jagged stump and through the thatch-like deadwood. Where the soil has remained wet, even partly severed twigs have put down roots. It's difficult not to admire the sheer determination of tamarisk, even as you're trying to kill it. Finally, I find the crackled gray bark of the central root and start sawing.

Across a small stream, one of the larger trees, about 10 or 12 feet tall, starts to creak, then falls with a whump! "Kill tammys!" someone yells. "Boy, that was satisfying," says a fellow tammy warrior, holding her saw in one hand and wiping her sweaty, dirt-smeared forehead with the other.

The Union of Concerned Scientists has called the spread of alien species like tamarisk "one of the preeminent environmental problems of the 21st century." And the journal BioScience points to invasives as a major cause of animal and plant extinction, second only to habitat destruction and significantly higher than pollution, overexploitation, and disease combined. But invasive species have yet to sink into the public's environmental consciousness the way clearcuts and oil spills have, and government has yet to devote substantial resources to the problem. The National Park Service now has 17 rapid-response teams that try to snuff out infestations at their onset, but they still cannot keep up with the demand.

It's a problem that is changing the very meaning of conservation, and one that raises confounding questions. Just how "saved" are our national parks if they're overrun with exotic species? How many invasives are too many? What should be done if an endangered native species begins to rely on an alien species for food or habitat?

"It's 3:30, and it's a three-hour hike back to camp," announces Lori Makarick, a National Park Service restoration biologist and leader of our 18-day river raft trip. "We're going to have to turn around."

"Oh, man!" everyone whines.

Lori ignores the group's reluctance to leave. "FAN-tastic. Let's go."

Lori has spent the previous three years researching and planning these tamarisk-removal trips, a $250,000 effort bankrolled by the state's Water Protection Fund, the national park, and the Grand Canyon National Park Foundation. Since October 2002, she has brought park staffers, river guides, and volunteers to dozens of the side canyons that support perennial streams—repeating some trips as many as five times. Tamarisk is a stubborn foe that must be cut back again and again.

People delay putting their tools away, and busy themselves with piling up brush and rocks to camouflage the cut stumps. During the environmental-impact hearings for the tamarisk effort, some visitors commented that they didn't want to hike past stumps, even if they were the remains of an invasive species. So wherever we can, we cover up our work. Watching her crew, Lori shifts her pack to one side and sighs. Fact is, she shares their masochistic zeal for these grueling 14-hour days. "No, really guys," Lori says. "Let's get going."

Some 230 national parks have problems with invasive species. Alien plants have invaded approximately 2.6 million acres of Park Service land, a figure that is growing by over a million acres each year. The agency spends $2 million annually trying to control them. Invasive animals are harder to track, but anecdotal evidence of their impact abounds.

Fallow deer have overrun Point Reyes National Seashore in Northern California. And invasive insects–fire ants, gypsy moths, Africanized honey bees, and Asian tiger mosquitoes, to name just a few–cause problems nationwide. (See "Unwelcome Guests," page 38.) In the Grand Canyon alone, over 100 non-native plants, 26 fish, and 4 birds have established themselves in the Colorado River corridor. Stocked trout compete with native chub for food. Besides tamarisk, invasive plants like Russian olive take over delicately balanced ecosystems more quickly than most native flora can adapt. The result is simpler bio-communities that support fewer species.

But control efforts in Grand Canyon National Park have worked before—against wild burros, tree of heaven, Mediterranean sage, and Himalayan blackberry. One member of our group, ecologist Larry Stevens, detected the explosion of Ravenna grass in the canyon in the early 1990s. Since 1993, the Park Service and volunteers have removed over 25,000 plants. Ravenna grass is now rare in the Grand Canyon.

It's probably impossible to duplicate that success everywhere and weed out every exotic species in the park. But if control efforts begin early, as they did with Ravenna grass, some non-natives can be beaten back. The side canyons where tamarisk doesn't yet dominate are part of the 2 percent of river habitats nationwide that remain pristine. There's still time to make a difference there.

Our crusade to stamp out tamarisk begins in early October, 65 river miles upstream at Lees Ferry, the starting point for most Grand Canyon boat trips. A few of the side canyons might be accessible by hiking from the rim, but the fastest and easiest way is by water. What's more, tamarisk spreads from the Colorado out into the tributaries. By following the river, we're following the invasion's path.

I watch as my 15 trip mates scurry around the launch ramp rigging the five rafts that will take us down canyon; everyone but me seems to know what to do. In a few hours, everything imaginable has been packed into nets that hang from the boat frames, or lashed to the rafts with carabiners, cinches, and nylon straps: a veritable armory of tamarisk-killing tools, 32 gallons of herbicide in double-sealed containers, first-aid kits, safety goggles, rubber gloves, a satellite phone, grids and GPS devices for record-keeping, two camp stoves, folding seats, five rectangular boxes that serve as toilets, even flourishes like guitars, tiki torches, flowered oilcloth table covers, more than 40 cases of beer, an assortment of top-shelf liquor, and a Virgin Mary votive candle that Simone, the devout camp cook, has christened with a label reading, "Our Lady of Biodiversity."

Things we need to access easily—sunglasses, cameras, medicine, ChapStick, and so on—go into waterproof ammunition cans tied to the boat frame. The rest of our personal gear is stuffed into "dry bags," flat-bottomed, impermeable cylinders that seal by rolling the open end like a toothpaste tube and then securing the corners. Huge piles of dry bags rise in the back third of each raft. The boatmen take their places on the coolers in the center. Passengers perch on the front third. We push off at dusk in a light rain as a bank of thunderclouds advances. We look like the Joads in a bizarre aquatic remake of The Grapes of Wrath.

Since it's almost dark, we float just a couple hundred yards downstream, to a ten-acre sandbar that was choked with tamarisk only three years earlier. As part of the feasibility study for the side-canyon project, the alien trees were bulldozed and the area replanted with native cottonwood and willows. (Many studies suggest that it's not enough to kill tamarisk; you need to plant something else in its place.)

After that success, Lori and her partners at the Grand Canyon Wildlands Council won approval from the National Park Service for this first phase: removing tamarisk from 63 canyons formed by tributaries beginning within the park. Funding has recently been allocated for a second phase that will tackle 100 more areas. A planned third phase will move into eight larger tributaries, including the lower reaches of the Little Colorado.

The rain turns into a lightning storm, and we pitch camp, trying to anchor our tents on rolling sand. At dawn, the sky remains gunmetal gray. As we silently eat cold bagels, cream cheese, and bananas under a canopy held aloft by two oars, Jeri Ledbetter gives the river safety talk. She knows the legendary pull of the Grand Canyon. Her first river trip 15 years ago convinced her to leave her husband in the Midwest and bring her kids to Arizona so she could become a river boatman. She married another guide and has run the Colorado River more than 60 times.

"Your main job as a passenger is to stay in the boat," Jeri says. "Make sure you hold on in two places...Cinch your lifejacket tight. It’s your friend...

Lean into the waves. It helps to stabilize the raft...If you’re thrown out of the boat, your first choice is to get back in the boat ...last choice is to swim for shore...This has been a public-service announcement. Thank you."

After a shivering morning sitting in Jeri’s boat and berating myself for not re-treating my Gore-Tex rain shell, we stop to scramble up a rocky bluff just upstream to scout the first big whitewater: House Rock Rapid. Between them, the people standing around me have logged tens of thousands of Grand Canyon river miles.

Larry, the president of the Wildlands Council’s board of trustees, has done hundreds of trips. Kim Crumbo, the council’s wilderness policy coordinator, worked for Grand Canyon National Park for 12 years and has lobbied for longer than that to bar motors from the Colorado. Other trip members earned their stripes on different rivers. Matt Wallace, an Australian guide with long blond dreadlocks, will kayak the rapids as "safety," in case someone goes overboard.

That possibility seems less and less far-fetched as my experienced cohorts stand and "read" the raging rapid. How high is the water? Where does the "tongue," where the water flattens into a smooth arrow just before the rapid, point? Where are the "holes," the foamy pits behind big rocks, the "haystacks," the "rooster tails"? What about the eddies, the crosscurrents, the riffles? The boatmen could be speaking a foreign language; the water looks all white to me.

"Rapids are only scary about the first 20 or 50 times," Lori says.

Jeri eases our raft into House Rock Rapid backwards. The technique, developed in the 1890s by Utah trapper Nathaniel Galloway, seems crazy to me. But Jeri explains that pulling, rather than pushing, into the rapid gives her more power, and thus more control. The raft starts to heave, then to undulate. Jeri stops talking. Whoosh! The first big wave rises ominously. Though it’s counterintuitive, I lean toward the wave and it breaks over us. It’s shockingly cold; the river water draws from the bottom of Lake Powell about 30 miles north. Midway through the rapid, Jeri pivots the raft so that we’re pointing downstream again. Whoosh!

The next morning, Lori calls a post-breakfast meeting to talk about tamarisk and how to kill it. We’re sitting at the mouth of North Canyon, one of the most popular hikes on commercial river trips. Lori tells us that all kinds of control methods have been tried across the Southwest. Crews have burned the trees, then come back to cut and poison the post-fire sprouts. Botanists have injected pellets of slow-release herbicide into them; pilots have sprayed the chemicals from helicopters. Rangers have used chainsaws, axes, and bulldozers to rip them out. None of these methods worked perfectly. Some tamarisk always seems to grow back.

Tamarisk may be pretty, but it’s a formidable foe. Throughout the Southwest, it has foiled the efforts of eradication crews armed with fire, poison, or chainsaws. In sensitive areas like the Grand Canyon, volunteers and park staffers rely on hand tools to cut tamarisk off at its root, and then carefully apply Garlon herbicide to individual plants.

"Tamarisk is really the perfect weed," Ken Lair, a Bureau of Reclamation biologist, had told me before I’d left for Arizona. One of the most aggressive alien species, it can survive total inundation or extreme drought for prolonged periods. "A forest fire can burn it to the ground and it will grow back," Lair continued. "It hogs space, light, and nutrients. It has no natural enemies in North America to help control its spread."

For this tamarisk trip, we’re armed only with saws and little herbicide sprayers that look like cappuccino foamers. As with most things in national parks, it wasn’t simple to get the OK to cut and spray. A small migratory bird, the endangered southwestern willow flycatcher, poses one big conundrum. Flycatchers, which travel north from Latin America to breed, nest in brushy vegetation near rivers. They prefer the cottonwoods and willows native to the Grand Canyon, but some studies show that they—along with half a dozen other birds—have switched to tamarisk because it’s so dominant among most Southwest rivers.

So we’ll only be weed-whacking above the Colorado’s highest waterline. Where we do cut, we are allowed to use only the simplest implements. About 1.1 million acres of the park, including the canyons where we’ll be working, are proposed wilderness. Park Service policies require that proposed wilderness be treated as wilderness, and the Wilderness Act mandates that the "minimum requirement" of tools be used there. So our crews can forget about chainsaws.

Lori yields the floor to Kim Fawcett, who grew up on rivers with parents who were champion kayakers. She guides raft trips in Idaho, and is one of four on our trip who are certified to spray herbicide. "We’ll be using Garlon 4 and Garlon 3A," Kim says. "They’re nonrestricted chemicals, so anyone can go out and buy them."

Triclopyr, the active ingredient, degrades rapidly in soil. It poses a low toxic threat to mammals, birds, fish, and invertebrates. It’s also relatively safe for humans. Even so, Kim continues, "we’re extra careful. We each have two sets of Garlon clothes—long pants, long sleeves—and we’ll always wear gloves, and glasses or goggles. Remember what the label says: ‘Danger! 3A can cause irreversible eye damage.’"

Lori cuts in. "It’s important to call us as soon as you’ve finished a tree. We need to get herbicide on the cut within 20 minutes, before the plant can send its own chemicals to heal the wound," she says. "OK, there’s lots more to talk about, but I’m excited to get to work. Let’s go."

After our first trip up North Canyon, life on the river settles into a rhythm. The days begin at dawn as camp cook Simone yells out, "Hot COOFF-ee!" Within moments, everyone has stirred to life: striking tents, rolling up sleeping bags, shaking out boots to check for scorpions, filtering drinking water, packing lunches, sealing dry bags, packing up the toilet (all human waste is carried out), loading the five boats. Depending on the day, we hike from camp or don river gear and float down to a work site. Then we cut tamarisks for 10 or 12 hours, calling for Kim and the other certified sprayers to apply "tammy jammy" on the trees.

We stumble back to camp smelling like dead things, bathe in the freezing river, rinse out our work clothes. Simone always has a hearty dinner ready: fish tacos, or steak, or grilled chicken. Beer and tequila shots fuel raucous after-dinner talk. The Australian, Matt, makes haunting sounds on his didgeridoo during jam sessions around a driftwood fire. Many nights, the throng calls for Larry Stevens to strum his signature song, "The Ballad of the Humpback Chub." Later than our mothers would advise, we collapse into our sleeping bags. Then we wake to Simone’s siren call to caffeine and do it all over again.

After a few days, you begin to dream of tamarisk, of the Invasion of the Tammy Snatchers, of Garlon sprayed in your eyes. You begin to twist tunes like this from the Wizard of Oz: "We’re off to kill some tammys, with loppers and hatchets and saws..."

You also begin to understand that what makes the canyon grand are the humble drainages where we’re working. I had been to the Grand Canyon once before, to the North Rim, but I hadn’t really seen the canyon at all on that first trip. Each side canyon is a little world unto itself, an oasis of lush vegetation and diversity bounded by the stark desert landscape. This is especially true of the canyons with perennial streams, the focus of this first round of tamarisk removal.

"The perennial streams are mostly paradise," Larry says as he pulls his boat up to the mouth of Saddle Canyon at river mile 47. "It’s not too difficult to believe in a guiding spirit when you see the profusion of life in these canyons. When tamarisk moves in, the diversity plummets."

With the boats tied up, about five of us start hiking up the canyon with Larry, who is taking his usual taxonomic census of everything around him, muttering species and their Latin names: "Catclaw, Acacia greggi; redbud, Cercis occidentalis; hackberry, Celtis reticulata . . ." All these native trees will thrive if tamarisk can be kept at bay. So will the dizzying array of flora and fauna that populate these side canyons, including McDougall’s flaveria, orchids, blue-eyed grass, stone flies and mayflies, grosbeak, Grand Canyon rattlesnake, and bighorn sheep.

While Larry reapplies Garlon to trees at Saddle Canyon’s mouth, I hike to the upper canyon with Matt and Jess Cortright, an Idaho river guide, to see if any tamarisks have gained a toehold that far up. Soon, the redrock closes in, and the humid air embraces us. At the very top, we have to wade through hip-deep aquamarine pools. Maidenhair ferns feather the erotic curves of the stone above us. Helleborine orchids and crimson monkey flowers bloom. A small waterfall marks the end of the canyon. If I crane my head back, I can see the arid landscape above, at the fringe of the robin’s-egg sky: spikes of banana yucca and Engelmann’s prickly pear, and clusters of bristling Mormon tea. It’s good news: We find no tamarisk.

On the trail, we pass a tour group following a guide whom Matt and Jess know. "What do you think about tamarisk?" Matt asks.

"Kill ’em all!" the guide says without hesitation.

At river mile 69 a few days later, we stop at Basalt Canyon. "This canyon is notoriously hot," Lori reminds us. "Make sure you carry at least three quarts of water." About a mile up the drainage, the canyon forks. Lori takes a team to the right. I go with Larry to the left. Our group finds nothing and returns to the boats by noon. We wait for Lori: one hour, then two, then three. Larry goes back up the drainage with a first-aid kit. We stay with the boats and begin to fear the worst. But in the late afternoon, everyone returns.

"We found a bunch of tammys where there had been none last time," Lori explains. "We ended up pulling more than 4,000 seedlings!" As always, she seems most happy when a staggering amount of work has been done.

The current phase of the project—which ends this fall—will set back the tamarisk invasion about 50 years, the Grand Canyon Wildlands Council estimates. But as the day’s surprise seedlings show, it will take sustained vigilance to keep tamarisk out of the side canyons. A single tree can produce over 250,000 seeds each year.

For the long term, Lori aspires to start an "adopt-a-side-canyon" campaign that would raise funds for continued control and recruit volunteers to help keep tamarisk from returning to cleared areas. "We hope we’ll be able to enlist river guides," Lori explains. "They could inform their clients about the problem, and then pull any tamarisk seedlings they might see during side-canyon hikes."

Partnerships are vital to combating invasive species nationwide. National Park Service staff and 50 volunteers from the Pillsbury Company helped clear alien plants in Florida’s De Soto National Memorial and Loggerhead Key in Dry Tortugas National Park. In Hawaii, the Park Service is working with the National Guard, the U.S. Forest Service, and local conservationists to prevent invasives like pampas grass and miconia trees from overwhelming Maui’s delicate ecosystem. A similarly broad group is trying to keep the tenacious zebra mussel out of Wisconsin’s St. Croix River, a national scenic riverway in the upper Mississippi River basin.

On my last workday, we tie up the rafts just north of Vishnu Canyon at river mile 81. We must pick our way up and over a dizzyingly steep saddle to the canyon mouth, spotting each other through an angled, narrow slot. Then we have to find shallow toeholds in sheer walls of black schist ribboned with rose quartz. We climb past a series of rock pools and around several waterfalls. Other tamarisk sites demand mountaineering gear. Vishnu simply requires determination and some nerve. OK, a lot of nerve, I mutter as I strain to pull myself up an eight-foot wall mottled salmon gray and pink. Below me, canyon tree frogs hop in and around a green pool.

I’m not exactly sorry that this is my last day sawing and chopping in my vile, stinking work clothes. Yet as I watch the frogs, I do feel a pang that this is my last side canyon. I had thought that the Colorado’s rapids would be the highlight of this trip, but the miniature worlds formed by each of the river’s tributaries took me by surprise. I had had no idea that the Grand Canyon’s awesome, arid stonescapes were studded with these fragile jewels.

As we follow the canyon upward, the angular schist walls widen slightly into a cool, shaded bowl. Acacia, agave, and prickly pear cactus grow out of the rock, creating a hanging garden. A huge, multi-trunked tamarisk stands at the top of the clearing. Three team members saw away at its main roots. It falls.

"That’s a good way to end it," Lori says, spraying the exposed cuts. Then she turns back toward the Colorado River, eager to get to work on the next canyon.

Heather Millar has written about environmental issues for Smithsonian, the Atlantic Monthly, BusinessWeek, and other publications.