Some of the most dangerous mines have been fitted with bat gates that keep people out and let wildlife in. Others have metal netting stretched over openings.
The financially strapped National Park Service estimates the total cost of making mines safe at about $233 million, with an immediate need for $60 million. Sen. Dianne Feinstein (D-Calif.) has introduced legislation to establish a cleanup fund by requiring all hard-rock mining firms operating on public land to pay a 4% royalty on existing operations and 8% on new ones.
The inspector general recommended that parks request enough money to mitigate the worst sites and share resources to shore up their programs for abandoned mines.
Despite warnings, people continue to explore mines and occasionally post their exploits on YouTube. In one video, a middle-aged man heads into a Death Valley mine. At the point when he sees danger signs, a message on the video reads: "Danger. . . . That's my middle name! Let's check out this mine."
"It's not a matter of if we have another death, but when," said Mike Cipra, California Desert Program manager with the National Parks Conservation Assn. "This year, Death Valley got no money for mine reclamation. All national parks are competing for that money. There is an $8-billion maintenance backlog in the national parks."
The job is daunting, especially in Death Valley.
Miners once moved like termites over this harsh landscape, blasting and boring their way through sand and rock. Everything was taken -- uranium, silver, talc, borax.
When the Earth stopped yielding its treasures, the miners simply packed up and went away, leaving gaping holes behind.
Deciding how to balance this rich if treacherous history with public safety is complicated, said Linda Greene, who works for the park's cultural and natural resources department.
"Mining has been going on in Death Valley for more than 100 years," she said. "They are good educational spots, and we consider that when we decide whether to close them or not."
Greene and Manning were searching for old mines in the remnants of Skidoo, once home to 700 people and one of the most productive gold camps in California. The site is one of dozens scattered across an epic, near-biblical landscape.
It didn't take long to find mines. Some were mere holes in the ground, others yawning chasms in the desert crust. Trails led to a largely intact old mine, with signs warning visitors not to enter.
