Federal officials trace the first big dump to 1989, when tribal member Geraldine Ibanez, who has since died, made a deal with now-defunct Chino Corona Farms to compost sewage on her land. But the company composted only a fraction of the sewage, which originated in San Diego, and left the rest in a giant, growing pile.
In 1994, a federal court in Los Angeles barred further shipments to the site, though illegal dumping has persisted on a smaller scale. Two years later, the two owners of Chino Corona Farms were convicted for illegal dumping in Imperial County and were sent to prison, according to state officials.
Mt. San Diego stands just a half-mile from three schools and directly beside an empty lot advertised as a future Pardee Home site. According to state environmental documents, it still "poses a significant threat not only to the ... reservation but also to the neighboring communities." Cleanup efforts began last year and will continue at least through 2008.
Three years after Ibanez opened her dump, fellow Torres Martinez member Kim Lawson started a "recycling center" on tribal land.
Little if any recycling went on, investigators say. Semi-trucks dropped off loads of palm trees, treated wood, plastics, paint and oil, among other things.
"Kim Lawson used to burn twice a month, and it would last for hours or days," said EPA attorney Letitia Moore. "You could see the smoke for 50 miles."
Citing a total lack of permits, the BIA issued Lawson a cease-and-desist order in 1994. Yet he continued to operate. It took more than a decade to shut it down. Lawson could not be reached for comment.
Unlike in some other states, the BIA in California has no police officers to enforce its will.
"It would be a lot easier to have a law enforcement officer standing with you when handing out cease-and-desist letters," said Lisa Northrop, natural resources officer for the BIA's Southern California Agency. "If they ignore the letters, we hand them out again. We need to create a record before taking someone to court."
Torres Martinez tribal leaders insist they have no power over members such as Lawson because they run businesses on private land allotted to their families by the government.
The BIA and legal experts dispute that.
"The tribe does have jurisdiction over these allotments, but it's complicated for tribes to exercise coercive authority over them because of intertribal relationships," said UCLA law professor Carole Goldberg, an expert on Indian law who has written extensively about dumping on tribal lands. "It is very delicate."
James Fletcher, BIA superintendent for Southern California, said the Torres Martinez tribe, which has 400 members on the reservation, has largely cooperated in efforts to stop dumping but hasn't done all it can.
"The tribe has ordinances, but they choose not to use them," he said.
One tool the tribe could use, Fletcher said, is cutting off gaming money to lawbreakers.
Tribal Chairman Ray Torres refused to comment, citing instructions from his tribal council. Tribal Manager Maxine Resvaloso did not return repeated calls seeking comment. The tribe's environmental director, Alberto Ramirez, also declined to comment.
Aside from internal politics, violence and intimidation also remain serious problems.
"People who have objected to the running of an illegal dump have had their families threatened," said Lt. Mark Barfknecht of the Riverside County Sheriff's Department, whose deputies patrol the reservation. "As recently as 18 months ago there was a school project where kids living in and around the reservation filmed the burning in the illegal dumps and were chased off by armed men."
Cesar Rafael, 17, of Thermal was one of those kids.
"They shot a gun into the air," he said. "I was trying to film when it happened."
A virtual Wild West atmosphere prevailed at the AuClair dump. Methamphetamine use was common, deputies said. At least 13 people lived in makeshift shelters. On a recent visit, a man pulled up and warned that two other men were shooting at each other around the corner.
Back in the brush, Tonetta Torro, 50, tended the four wolves she keeps tied up for protection. She has spent four years here in a tent but plans to leave soon.
"I hear gunshots all the time," she said. "Still, I feel sad to go."
The arrival of trailer parks on the reservation in the 1990s heightened a sense of urgency about the dumps.
More than 12,000 people, mostly farmworkers, live in five ramshackle parks. The biggest sits beside the Lawson dump site.
In 2003, the EPA issued an internal memo reporting dioxin levels 20 times the national average at the dump.
Last year, a federal judge in Riverside shut it down and fined Kim Lawson $47 million. He has declared bankruptcy.
As for AuClair, his dump may be closed, but his shame lingers.
"We are destroying our environment," he said, picking up a piece of Indian grinding stone lying in the sand. "I don't have the money to pay for it, but I'll be damned if I won't clean this up. Look at this place. My ancestors would roll over in their graves if they saw it."