In three years of cleanups, government agencies, volunteer groups and an American Indian tribe have removed only a fraction of the millions of pounds of trash left behind by immigrants sneaking across the border into southern Arizona.

About 250,000 pounds of trash were hauled away from thousands of acres of federal, state and private land across southern Arizona from 2002 to 2005, according to the U.S. Bureau of Land Management.

Nearly 25 million pounds of trash were thought to be on those lands.

"We're keeping up with the trash only in certain locations, in areas that we've hit as many as three times," said Shela McFarlin, Bureau of Land Management's special assistant for international programs.

The trash includes water bottles, sweaters, jeans, razors, soap, medications, food, ropes, batteries, cell phones, radios, homemade weapons and human waste.

It has been found in large quantities as high as Miller Peak, more than 9,400 feet in the Huachuca Mountains, as well as in low desert such as Organ Pipe National Monument and Cabeza Prieta National Wildlife Refuge.

It's even started turning up in smaller amounts in hiking areas closer to Tucson.

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"In the Huachucas, you are almost wading through empty gallon water jugs," said Steve Singkofer, president of the Southern Arizona Hiking Club. "There's literally thousands of water jugs, clothes, shoes. You could send 1,000 people out there and they could each pick up a dozen water jugs, and they couldn't get it all."

Most of the garbage is left at areas where immigrants wait to be picked up by smugglers. The accumulation of disintegrating toilet paper, human waste and rotting food is a health and safety issue for residents of these areas and visitors to public lands, according to a new report by the Bureau of Land Management.

The trash also isn't good for wildlife, said Arizona Game and Fish spokesman Dana Yost.

Birds and mammals can get tangled up in it or eat it, causing digestive problems, Yost said. It's not at all uncommon to find the trash in bears' stomachs, he said. Plastic bags, foil wrappers and certain foods are all problems.

But McFarlin said clear inroads are being made into the trash problem.

Various local and federal agencies, the Tohono O'odham Tribe, the conservationist Malpais Borderlands Group and student youth corps remove trash from the most obvious and accessible areas, she said.

What needs tackling now are more remote areas such as wilderness, mountains and deserts far from major roads, she said. A couple of times, authorities have had to use helicopters or mules to haul stuff out of such areas.