By TRACIE CONE, Associated Press Writer Sat Oct 11, 4:20 PM ET

PORTERVILLE, Calif. - National forests and parks — long popular with
Mexican marijuana-growing cartels — have become home to some of the
most polluted pockets of wilderness in America because of the toxic
chemicals needed to eke lucrative harvests from rocky mountainsides,
federal officials said.

The grow sites have taken hold from the West Coast's Cascade
Mountains, as well as on federal lands in Kentucky, Tennessee and West
Virginia.

Seven hundred grow sites were discovered on U.S. Forest Service land
in California alone in 2007 and 2008 — and authorities say the 1,800-
square-mile Sequoia National Forest is the hardest hit.

Weed and bug sprays, some long banned in the U.S., have been smuggled
to the marijuana farms. Plant growth hormones have been dumped into
streams, and the water has then been diverted for miles in PVC pipes.

Rat poison has been sprinkled over the landscape to keep animals away
from tender plants. And many sites are strewn with the carcasses of
deer and bears poached by workers during the five-month growing season
that is now ending.

"What's going on on public lands is a crisis at every level," said
Forest Service agent Ron Pugh. "These are America's most precious
resources, and they are being devastated by an unprecedented
commercial enterprise conducted by armed foreign nationals. It is a
huge mess."

On Tuesday, the nonprofit High Sierra Trail Crew, founded to improve
access to public lands, plans to take 30 people deep into the Sequoia
National Forest to carry out miles of drip irrigation pipe, tons of
human garbage, volatile propane canisters, and bags and bottles of
herbicides and pesticides.

"If the people of California knew what was going on out there, they'd
be up in arms about this," said Shane Krogen, the nonprofit's
executive director. "Helicopters full of dope are like body counts in
the Vietnam War. What does it really mean?"

Last year, law enforcement agents uprooted nearly five million plants
in California, nearly a half million in Kentucky and 276,000 in
Washington state as the development of hybrid plants has expanded the
range of climates marijuana can tolerate.

"People light up a joint, and they have no idea the amount of
environmental damage associated with it," said Cicely Muldoon, deputy
regional director of the Pacific West Region of the National Park
Service.

As of Sept. 2, more than 2.2 million plants had been uprooted
statewide. The largest single bust in the nation this year netted
482,000 plants in the remote Sierra of Tulare County, the forest
service said.

Some popular parks also have suffered damage. In 2007, rangers found
more than 20,000 plants in Yosemite National Park and 43,000 plants in
Sequoia Kings Canyon National Park, where 159 grow sites have been
discovered over the past 10 years.

Agent Patrick Foy of the California Department of Fish and Game
estimated that 1.5 pounds of fertilizers and pesticides is used for
every 11.5 plants.

"I've seen the pesticide residue on the plants," Foy said. "You ain't
just smoking pot, bud. You're smoking some heavy-duty pesticides from
Mexico."