TSF study reveals potential for health exposure while recreating on Sierra Nevada public lands

SACRAMENTO, 22 June 2010 – Today on the West Steps of the State Capitol, The Sierra Fund released the Gold Country Recreational Trails and Abandoned Mines Assessment, which documents that outdoor enthusiasts including Off Highway Vehicle (OHV) riders, mountain bikers, hikers and equestrians are recreating in abandoned mine areas that are contaminated with dangerous levels of lead, arsenic and asbestos.

In some cases, these outdoor recreationists are being encouraged to visit contaminated sites because officially sanctioned recreational trails in National Forests have been routed on, through and into abandoned mine lands, old mill sites, mine tailings and waste rock piles.

“More than 100 years after the end of the Gold Rush era, the environmental, cultural and health impacts of that time have still not been assessed or addressed,” states Elizabeth Martin, CEO of The Sierra Fund. “Our study documents that these abandoned mines pose a toxic health threat on public lands that are widely used for recreational activities. The time has come for a serious assessment of abandoned mines, and the public needs to be informed about potential exposure to toxic heavy metals and asbestos in areas with abandoned mines.” 

The Sierra Fund’s Gold Country Recreational Trails and Abandoned Mines Assessment identifies specific recreation areas around Downieville, Nevada City and Foresthill where popular trails intersect with known abandoned mine sites. In these areas, samples were taken to learn whether recreationists may be encountering hazardous substances. Contaminants of concern (COC) include heavy metals including lead and arsenic, and also other hazardous materials such as asbestos.

According to Dr. Carrie Monohan, The Sierra Fund’s Science Director and principle author of the report, “The purpose of this study was to learn whether people are potentially being exposed to dangerously high levels of heavy metals while engaging in dusty recreation activities in and around abandoned mines. Our results show that this is in fact the case in some areas, and more assessment is urgently needed.”

At certain locations, toxins were found at levels that could affect human health:

  • In the Nevada City area, arsenic was found at levels of concern on Banner Mountain trails, and asbestos in one location on the Newtown Ditch trail used for biking and hiking. 
  • At the Foresthill OHV Area in and around the abandoned Marrall Chrome Mine pit, samples showed up to 40% asbestos and off-the-charts levels of lead in the soil on trails where families ride OHVs.
  • In the Downieville area, certain biking, hiking and OHV trail locations tested high for arsenic, lead and asbestos. 

There is also good news: the study found that several popular areas including the “Downieville Downhill” mountain bike trails, the Eureka Diggings OHV Area, and the Western States Trail near Foresthill, while they pass several abandoned mines, do not pose a health threat to recreationists. 

The results of this study are meant to help identify areas that require further evaluation. Key recommendations include.

A dust exposure study that looks at exposure scenarios of different recreational activities, and

  • Clear, visible advisories in areas that are known to be contaminated by substances that are dangerous to human health,
  • Additional sampling of contaminated areas,
  • In the Downieville area, certain biking, hiking and OHV trail locations tested high for arsenic, lead and asbestos, 
  • A survey of people recreating in these areas to learn more about their exposure, and effective outreach and education methods.

    The full report and executive summary may be downloaded from The Sierra Fund’s Mining Initiative Resources page