Abandoned Mine Remediation

The California State Lands Commission works internally, as well as cooperatively, with the California Department of Conservation’s Office of Mine Reclamation to inventory and remediate abandoned mine hazards on school Lands in the California desert.  Many of these abandoned mines are nearly 100 years old and existed prior to the state’s acquisition of the lands and enactment of state laws requiring reclamation of lands impacted by mineral exploration or production.  Many mine features, which include vertical shafts and horizontal adits, are used as habitat by wildlife, such as bats, desert tortoise, owls, rodents, etc.  However, some features such as vertical shafts may pose a physical hazard to the public that uses the lands for recreation, and can also entrap animals.  Preliminary sampling has been conducted at five abandoned mine sites on lands under the Commission’s jurisdiction to look for potential chemical hazards typically associated with some types of mining activity. 

Addressing physical hazards associated with abandoned mines is a complex process that includes remedies ranging from signage to permanent closure.  Upon discovery of a mine feature that may pose a hazard, staff installs warning signs to “Stay Out and Stay Alive,” which advises the public of the many dangers associated with old abandoned mines.  Prior to any mine closure, surveys are conducted on the biologic and historic attributes along with the physical characteristics to determine what closure technique may be physically possible and best suited for each feature.  Commission staff consults with the California Department of Fish and Wildlife and the State Office of Historic Preservation’s State Historic Preservation Officer (with detailed information and closure plans. 
As an example, when internal or external surveys reveal the presence of either significant biological or historical resources, bat gates or cupolas have been built to protect the public and wildlife.  Bat gates conforming to the standards of Bat Conservation International can be installed on horizontal adits, such that bats, owls, desert tortoise, and other animals can continue to use the mines for habitat while precluding and safeguarding the public.  Similarly, for vertical shafts, a cupola (or basically a box made of steel angle iron) can be installed over the shaft allowing continued wildlife access.  Both closure techniques protect and preserve historic resources, and can be designed in a way to allow biologists and archeologists to perform surveys or geologists to prospect for a valuable mineral deposit. 

Mine shafts that are relatively shallow and have no horizontal workings generally provide poor wildlife habitat, but may still pose a fall hazard to the public and wildlife.  Such shafts typically have little historic value in comparison to the public hazard they may pose.  When shafts such as these have the original waste rock dump adjacent to them, staff has contracted for a small front end loader to backfill the shaft with the original waste rock.  When waste rock is not available, a polyurethane foam plug may be used that is later covered with native rock and soil to protect the foam from sunlight and obscure the original location. 

Some mines may not be suitable for bat gates, cupolas or foam plugs due to unique circumstances or they cannot be reached by vehicle.  Wire fences are commonly employed on these mine features or as a temporary measure until a more permanent solution can be sought.  Cable netting is occasionally used on complex mine structures with large or irregular shaft openings that are not readily amenable to cupolas.  Remote mine closures requiring the use of a helicopter may be employed in the future after the more accessible hazards have been remediated. 

In August 2009, the Office of Mine Reclamation completed an inventory of abandoned mine lands managed by state agencies, including those managed by the Commission.  Lands under the Commission’s jurisdiction were identified as having approximately 143 sites with more than 1,200 individual mine features on them and were ranked based on  the physical and chemical hazard that they may pose.  Since then, staff has been inventorying those sites that were ranked as posing the greatest physical hazard to the public.  Warning signs are being installed as plans are formulated so that more permanent closure techniques can be used.  Unfortunately, many of these signs are quickly stolen or vandalized.  Recently, Commission staff inventoried and installed warning signs at the Leiser Ray, New Trail, Pacific Fluorite and Shadow Mountain Mines in San Bernardino County and at the Baxter Mine in Inyo County.  In addition, wildlife surveys were completed at the Leiser Ray Mine and work has begun to determine appropriate closure measures for the 13 shafts located there. 

In March of 2014, staff inventoried the Piper Mountain Copper Mine in Inyo County and inspected several mine closures near Mojave.  In April 2014, staff surveyed five additional mine areas in the San Bernardino and Inyo Counties and established a priority list for mine closures during the biologic window of late summer/early fall following consultation with the California Department of Fish and Wildlife and the California State Office of Historic Preservation.  Bat gates, cupolas and fencing are the preferred closure options to alleviate concerns over biological and historical impacts.  Consultation was completed in late September, followed by a contractor walk through in mid-October to solicit bids in conformance with state contracting protocol.  Of the two contractors participating in the walk-through, only one submitted a bid, in part due to the difficult road conditions that make accessing the site with proper vehicles, equipment and materials difficult.  The Office of Mine Remediation subsequently issued a contract to Frontier Environmental Solutions for the installation of six cupolas, four bat gates and four cable nets at the five mine locations, scheduled to be completed this summer.  Also in December 2014, Commission staff constructed five fences around shafts at the Leiser Ray, Shadow Mountain and Pacific Fluorite mine sites.  Additional fencing and inventory work is planned prior to the commencement of the work by Frontier Environmental this summer.

The following list is a summary of many of the more prominent mine features staff have safeguarded on school lands with bat gates, cupolas, foam plugs, fences, and signage.  Much work remains to be performed.  At some sites, a few of the mines were closed, while others require other solutions due difficulty accessing the area.  Some of the names used are for mines located on adjacent federal or private lands, as mine sites can contain dozens of mine features located with a complicated patchwork of ownership.  In other cases, a name is used proximal to a nearby community as many of the mines were simply prospects and never given formal names. 

Mines Remediated

Mine Name


Closure Completed

Calico Mountains San Bernardino Backfills  
Crown Uranium Mine Imperial Two Bat Gates  
Fry Mountains San Bernardino Backfills and Fence  
Gold Standard San Bernardino Cupola  
Golden Bee Riverside Bat Gates  
Guadaluupe Mine Imperial Foam Plug  
Iron Chief Riverside Features not on State Lands  
Los Padres San Bernardino Foam Plug, Backfill, Fence  
New Trail Mine Prospects San Bernardino Signage  
Rosamond Mine Kern County Backfill  
Rusty Gold San Bernardino Fence and Backfills  
Scouts Cove San Bernardino Foam Plug  
Ship Mountain San Bernardino Bat Gate and Backfills  
Standard Hill Kern County Backfill  
Stone Cabin San Bernardino Backfill  
Trade Rat Mine San Bernardino Backfills  
Turtle Mine Imperial Fence  

Mines Partially Remediated

Mine Name


Remediation Work Accomplished

Future Closure

Arnold Edward San Bernardino Fence Cupola
Baxter Inyo Features not on State Lands Sign Prospect Pits
Golden Queen Imperial Two Backfills Two Bat Gates
Iron Horse San Bernardino Fences Two Cupolas
Little Dove San Bernardino Fence Cupola
Mohawk Hill San Bernardino Fence Cupola
New Deal San Bernardino Signage One Bat Gate, Two Cupolas
Pacific Fluorite Mines San Bernardino Cupola One Bat Gate, One Cupola
Shadow Mountain San Bernardino Fences One Bat Gate, Three Cupolas
Signal Hill (Leiser Ray) San Bernardino Signage Backfills
CSLC/OMR Abandoned Mine Warning Sign Installed at Los Padres Mine

  CSLC/OMR Abandoned Mine Warning Sign Installed at
Los Padres Mine.  Many signs are vandalized or quickly stolen.

Photo of Trade Rat Mine Trade Rat Mine Trade Rat Mine

Fence Installed at the Trade Rat Mine in San Bernardino County in May 2004. Mine was Backfilled with Waste Rock in October of 2007

Wildlife Survey Conducted by Dr. Pat Brown Revealed Several Desert Tortoises 200’ back in Adit at Mohawk Hill


Bat Gate with Tortoise Door at Mohawk Hill Bat Gate with Tortoise Door at Mohawk Hill

Wildlife Survey Conducted by Dr. Pat Brown
Revealed Several Desert Tortoises
200’ back in Adit at Mohawk Hill

Bat Gate with Tortoise Door at Mohawk Hill

Bat and Owl Compatible Cupola Installed Over Gold Standard Mine Bat and Owl Compatible Cupola Installed Over Gold Standard Mine

Bat and Owl Compatible Cupola Installed Over Gold Standard Mine

Scouts Cove Opal Mine - May 2001

Scouts Cove Opal Mine - May 2001

Scouts Cove Opal Mine - April 2003

Scouts Cove Opal Mine - April 2003

Plugging of Mine Shaft with Polyurethane Foam

For further information please contact Greg Pelka of the Mineral Resources Management Division at 562.590.5227 or by e-mail at Greg.Pelka@slc.ca.gov

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From TTY Phone 1-800-735-2929
From Voice Phone 1-800-735-2922