SEQUOIA NATIONAL PARK, CALIF. — Even Br'er Rabbit couldn't make it through this briar patch. With their M-16 rifles and their backpacks snagging on every bramble, three national-park rangers in commando gear spit out mosquitoes on a pathless mountainside of manzanita thickets and dense brush. Gun barrels raised to give each other cover, they advance using hand signals, pausing only to sip water in the 100-degree heat and gasp for air through mesh masks.
After 2-1/2 hours, one mile, and a thousand-foot gain in altitude, they come across evidence of large-scale activity that officials call the biggest threat to national parks since their creation over a century ago. Beside an abandoned camp scattered with trash and human waste, lie empty bags of fertilizer, gardening tools, irrigation tubing - and spent rifle casings. Illegal marijuana farming, once the province of small-time growers, has become big business on the nation's most visited public land: national parks.
"This is massive-scale agriculture that is threatening the very mission of the national parks, which is to preserve the natural environment in perpetuity and provide for safe public recreation," says Bill Tweed, chief naturalist at Sequoia National Park. "[Growers] are killing wildlife, diverting streams, introducing nonnative plants, creating fire and pollution hazards, and bringing the specter of violence. For the moment, we are failing both parts of our mission, and that is tragic."
For decades, park rangers have stumbled into small cannabis stands. But now, desperation and opportunity have combined to move larger-scale illicit marijuana farming to Sequoia, Glacier, Big Bend, and other jewels of the American landscape.
Since the late 1990s, marijuana cultivation has escalated dramatically in the more remote public areas such as national forests - many of which permit mining, forestry, grazing, and other activities - and areas under the stewardship of the Bureau of Land Management. Marijuana seizure in California national forests has jumped tenfold, from 45,054 plants in 1994 to 495,000 plants last year.
But since Sept. 11, drug farming has increasingly spread from remote forests to more-public national parks. Tighter security on US borders has raised the incentive for domestic cultivation. That makes for more armed growers - and potential clashes with those traipsing into the wilderness for nature at its most pristine.
As well as growing more common, the enterprise has become more organized. International drug cartels - made up largely of Mexican nationals - seem especially drawn to the bounty. And their harvests can be huge: last year, officials here seized the biggest stash of all, with 34,000 plants in five locations at an estimated street value of $140 million. Complicating the task for law enforcement is the strain on resources. Park budgets have tightened, and many of the available rangers have been shifted to more popular haunts.
"The most [visitors] used to worry about is running into a grizzly bear. Now there is the specter of violence by a masked alien toting an AK-47," says David Barna, chief spokesman for the National Park Service (NPS). He and others say the problem is national, but most pronounced in California, Utah, and Arkansas, and in parks with international borders such as Big Bend in Texas and Glacier in Montana.
Here in California, the biggest problems have been at Sequoia, Whiskeytown National Recreation Area and Point Reyes National Seashore. Officials say the accouterments of cannabis farming - black tubing, drip-irrigation techniques, terraced gardens, booby traps, look-out posts, and weapons - are so similar across the plots that the same organizations are probably at work. "Intelligence gathering ... up and down the state suggests these are the same groups expanding their operations into different areas," says Steve Prokop of Whiskeytown, near Mount Shasta.
Sequoia officials began concerted efforts to comb remote areas in 2001, when a fisherman reported meeting masked operatives toting automatic rifles. Since then, officials have discovered five camps and several acres of marijuana stalks, typically in areas with natural water sources. Last year, officials destroyed eight tons of crops and counted thousands of plants that had already been harvested - and they surmise that many other plots exist undetected. Eight Mexican nationals are due for trial in September.
For years, drug enforcement in national parks was focused on scouting out methamphetamine labs. Marijuana gardens were few in comparison and were rarely large-scale enterprises, according to Holly Bundock, chief NPS spokeswoman for California.
"We used to find smaller gardens every once in a while, but what is going on now is far more organized," says Al DeLaCruz, chief criminal investigator for Sequoia. "The impact [on] resources is very dramatic in terms of the refuse left behind; the damage to vegetation, soil, and water."
Besides clearing trees and brush to plant marijuana, growers often terrace the land, stirring up soil - and attracting plants that wouldn't otherwise take hold. Officials fear those exotic newcomers and the havoc they could wreak, reminiscent of an influx of star thistle on California ranch land that rendered millions of acres useless.
The diversion of water can also debilitate wildlife, especially in the dry season when many species come from far afield for summer's paltry trickles. Without water, animals will migrate elsewhere or die. And fertilizer in water is a major problem. When polluted runoff flows into lakes and streams, varying nitrate levels can kill fish species, launching a domino effect on the food chain.
"We have found evidence of insecticide contaminating groundwater, which can be devastating," says Colin Smith, a ranger at Point Reyes National Seashore.
Beyond agriculture's toll, there's the wear and tear of humans fending for themselves. DeLaCruz and others have found the remains of deer and bear that growers killed for food and of snakes and rodents they killed for sport.
To rangers, the most galling part of the story is that the National Park backcountry where marijuana is cultivated is designated wilderness by the 1964 Wilderness Act. Unlike the portions of national parks with campsites, roads, and restrooms, such areas are supposed to "retain their primeval character," preserve solitude, and keep man's imprint unnoticeable. Even rangers can't use saws or other motorized tools here. Regulations forbid clearing brush for campsites or fires, and guns are prohibited.
"Wilderness Designation is the highest possible protection for land under US law," says Ms. Bundock.
A hike through dense underbrush to the most accessible of the illicit camps gives a taste of how hard it is for growers to haul food and equipment. The sites are so remote, in fact, that harvests often must be helicoptered out.
Besides ammunition and guns, there are tents, cooking utensils, propane cylinders, and stacked 50-pound bags of fertilizer. Though a 10- to 15-foot canopy of dense trees conceals the camps' whereabouts, growers take the added precaution of camouflage tarping.
One ranger, who asked to remain anonymous, marveled at "how impossible this is to find from above. There is no other way to find [it] except on foot. And we don't have the staff or resources to ... scour these regions." Rangers say that cartels hire illegal immigrants to work and live in the camps, probably for months on end. They use public roads to access parks by night, scurry into the underbrush with supplies, and lug goods up steep hillsides by moonlight.
One advantage for authorities is that they believe marijuana grows best at elevations of 3,000 to 5,000 feet, eliminating most of the park's 15 million acres as optimal sites. Still, that leaves 100 square miles to monitor in Sequoia.
"Law enforcement is spread thin already," says Mr. Barna. Parks and memorials nationwide are transferring 200 rangers - mostly from Western parks - to help meet the general security demands of the summer surge in tourism. Nor does policing the park system come cheaply: The recent terror-alert switch from Code Yellow to Code Orange cost the Park Service $63,500 a day.
And the forces left behind are stretched ever thinner. DeLaCruz says he spends a significant portion of his time on the marijuana battle, and two rangers accompanying him on a recent day say their time for other duties, from search and rescue to interpretive work, is dwindling. "There are people all over the park who want to find a ranger for all the usual reasons, from historical questions to what kind of flora and fauna they are seeing," says one. "It's sad that we are frequently out of sight for them, because we're off chasing marijuana growers."
Given the growth of marijuana farming in national parks over the past decade, officials fear the problem will worsen before it improves. "The whole trend is that these groups are moving around more and head[ing] to areas which are more populated," says Laura Mark, an agent for the US Forest Service. "They are going after public land meant for families, where they threaten people and cause untold damage. And they don't care because they are making more money than [most] will see in a lifetime."
Marijuana growers keep themselves heavily armed, officials say - partly out of worry about rival growers, partly because the street value of marijuana can be so high. Several shootouts have erupted between growers and law enforcement. A hunter and son were shot in El Dorado County recently, and a hunter was killed two years ago in Butte County. Last year, officers were shot in Tehama and Glenn counties in the Central Valley. "One of our primary concerns is for our employees," says Sequoia's Mr. Tweed.
Officials say public exposure is one of the only solutions. They hope more citizens will pressure lawmakers for funding and personnel to stop covert cultivation, in part so that perpetrators' fears of capture might curtail the activity. Though park officials are reluctant to reveal the number of staff assigned to ferret out marijuana plots, estimates at Sequoia are in the dozens. For the clearing of debris and plants, the Park Service has had to rely on other organizations, from the National Guard to the California Highway Patrol to the Tehama County Sheriff, using up to 60 people per operation.
"This is everyone's problem," says Tweed. "It's not just a question of the moral and legal issue of marijuana. It's an issue of commercial-sized agriculture devastating the mission of national parks to preserve land ... for generations.