Abandoned Mine Lands Unit

Desert landscape with Division of Mine Resources vehicle  parked outside entrance of an abandoned mine

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Abandoned Mines in California

Did you know that California’s mining history left California with tens o​f thousands of abandoned mines, many dating back to the Gold Rush?​

​In California, you have likely passed within a few miles of legacy abandoned mines.  These mines are present in all 58 counties on federal lands (~64% statewide), privately owned lands (~32%), ​and lands owned or managed by state agencies and local governments (~4%). 

1 Map of known mine hazards, Department of Conservation.

Abandoned mines are a threat to public health and safety. Almost every year people, pets, livestock, or wildlife are killed or injured in accidents at abandoned mine sites​(PDF).
2 clockwise from top: Sacramento Bee story of cow rescued from mine shaft, San Bernadino Cave and Technical Rescue Team in action, and FJ Cruiser in mine shaft.

Some mines are sources of mercury, arsenic, acid rock drainage, or other pollutants that contaminate watersheds and degrade water and air quality.
While abandoned mines are dangerous to people, they have become important habitat for wildlife, including bats, tortoises, owls and snakes. Many of the sensitive and endangered species that use the mines perform critical ecological functions including pest control and crop pollination.
3 Townsend's Big Eared Bats, common California mine inhabitants.  Photo Credit: J. Danielson NDOW

About the Abandoned Mine Lands Unit 

Created in 1997 and comprised of a team of geologists, scientists, and GIS professionals, DMR's Abandoned Mine Lands Unit (AMLU) mission is to collaborate with partner agencies to protect people from abandoned mine hazards in California, while preserving mining history and wildlife habitat.

AMLU employs specialized expertise to inventory mines and their use by wildlife, then assists public agencies with science-based solutions to design, contract, and install remediations. We broaden our impact by collaborating and coordinating with people nationwide working on abandoned mine land issues in academia, government, and advocacy groups.

We envision a California where abandoned mine lands are safe and a benefit to Californians, celebrated for their historical significance and biodiversity.​​

Quick ​​​Fa​​​​​cts

  • AMLU partners with multiple state, federal, and local agencies and nongovernmental organizations (PDF), making thousands of hazardous shafts and adits (vertical and horizontal openings) on public lands safer for residents and recreationists. 
  • Mine closures typically target hazardous sites near homes and high visitation areas such as campgrounds, trails, and Off Highway Vehicle parks. 
  • Sources of funding to remediate abandoned mines include state fees collected on gold and silver mined in California, federal funds, and other special funds. 
  • AMLU projects ​(PDF) include fences, backfills, polyurethane foam (PUF) closures, and a variety of gates and other structures that allow access for bats and other wildlife that use abandoned mines for habitat or shelter while keeping humans safely out
  • Wildlife protections, which are often built by small businesses under contract to the AMLU, bolster local economies that benefit from safe public recreation areas and help to maintain the natural pest control services that bats provide to California’s working lands.


​To report an abandoned mine, call DMR on our toll-free hotline at 1(877) ​​​OLD-MINE​ (1-877-6​53-6463) or email us at DMR@conservation.ca.gov

 When contacting us, include:
  1. location (e.g., GPS point with latitude and longitude, name of nearest road and Assessor's Parcel Number), and 
  2. description of the mine site or feature. 
​​Remember: Stay Out – Stay Alive!

 In an emergency situation, call 911 or contact your local sheriff's office.

If someone is injured due to a fall or is trapped in an abandoned mine, do not try to rescue the victim yourself. Rescue attempts should only be made by professionals with proper training and equipment to avoid further injury to the victim or yourself.


​Additional Abandoned Mine Resources​

AMLU F​​acts Sheets

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