The Clear Creek Management Area straddles the San Benito and Fresno County lines. The area was closed because of high levels of asbestos, but some say they're being robbed of their right to enjoy public land by an overblown risk.
Ken Deeg of Santa Clara likes to spend his spare time riding the trails of the Hollister Hills Vehicular Recreation Area with his 12-year-old daughter. Deeg only wishes he could take her some 50 miles away where he spent his childhood learning to ride off-highway vehicles, also known as OHVs.
"It was an OHV paradise," Deeg said.
The Clear Creek Recreation Area covers 48-square miles of former mining roads and trails. The sparse vegetation and scarred landscape are unlike any other in California.
"The amount of mileage you could ride in a day was incredible," Deeg said. "You could ride 50 to 60 miles, come back, have lunch, ride another 50 to 60 miles and not cover the same terrain twice."
In 2008, the federal government abruptly closed Clear Creek. The Bureau of Land Management controls the land and ordered all off-road vehicles out after the Environmental Protection Agency found potentially-dangerous levels of naturally-occurring asbestos in the soil.
"That risk assessment of the recreation activities that we were authorizing on public lands were exposing the public to levels of asbestos that was going to increase their lifetime risk of cancer," said Rick Cooper with the Bureau of Land Management.
"What we were concerned about was the public's health impact from the asbestos exposure," said Jere Johnson with the EPA. "And, frankly, we were surprised at how high the levels were."
The three-year-long EPA study concluded that just five visits a year over three decades could lead to lung cancer or other crippling diseases. The effects of asbestos exposure often takes decades to appear.
"It's not safe for children to be participating in those activities, and it's not safe for adults to participate in them on a frequent basis," said Johnson.
But off-roaders, like Deeg, are skeptical of the EPA's findings.
"For many years, it was just about every weekend," said Deeg.
Deeg says most of the EPA's tests were done in dry conditions, not the wetter conditions that off-roaders like.
With that in mind, Deeg started reaching out to other off-roaders who had spent significant time at Clear Creek. Deeg has yet to identify a single case of cancer or asbestos-related illness.
The EPA admits no studies have been conducted on cancer rates among Clear Creek's dirt bike riders, but a 2005 U.C. Davis study did find that people living near naturally-occurring asbestos had a significantly-higher cancer rate than those who did not.
The EPA says any exposure is not worth the risk.
Deeg isn't the only one who questions the closing of the park.
"The people of California have an investment in this area," said Phil Jenkins with the OHV Recreation Division.
The state agency that oversees off-highway motor vehicles has worked in partnership with the BLM for decades. California has spent millions of tax dollars over the years maintaining Clear Creek's roads and trails, so the state commissioned a Harvard scientist to investigate whether the risk is lower when the ground is wet.
"They found that the risk to human health is below the danger levels, that it was an acceptable level of risk," said Jenkins.
The state is now hoping to work out an agreement with the BLM to allow limited use of Clear Creek. Jenkins says all extreme sports come with risks, whether it's mountain climbing, surfing or off-road vehicles.
There are an estimated four million off-road vehicle users in California. Whether to re-open Clear Creek is an issue the BLM will decide.
Written and produced by Ken Miguel