Monte Cristo Mining Area
4 Mi SE Barlow Pass Mtn Loop Hwy, Silverton, WA 98241

Monte Cristo Mining Area - Circa 1912
Please click on the photo for a larger view


The Monte Cristo Mining Area (MCMA) site is in the Cascade Mountains. It is part of the Mt. Baker-Snoqualmie National Forest in Snohomish County, Washington, near the Henry M. Jackson (HMJ) Wilderness Area. The Monte Cristo Mining District and the surrounding area have a rich mining history. Monte Cristo Mine peak production was in 1897.

Most ore production came from eight mines: Mystery, New Discovery, Pride of the Mountains, Pride of the Woods, Golden Cord, Comet, Justice, and Rainy Mines. The District processed mined ore for delivery to the Everett Smelter. By 1894, it could process up to 300 tons of ore per day. The Monte Cristo Mining District produced mainly gold, silver, copper, lead, and zinc.

The American Smelting and Refining Company (ASARCO) bought the mining operations in 1903. In 2009, Ecology and the United States Department of Agriculture Forest Service (USFS) received ASARCO bankruptcy settlement funds to clean-up hazardous materials and contamination from historic mining activities.

Property ownership in the area is complex. As a result, the United States and the State of Washington divided the settlement funds equally to pay for cleanup. The USFS conducted the removal action under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and is also known as Superfund. Ecology will continue cleanup of private landholdings under Model Toxics Control Act (MTCA) authority.

Non-time critical Removal Action (RA) activities:

The USFS used their authority to determine how much waste rock be removed and contained in the repository. After many years of planning and preparations, the USFS began the removal action in April 2015. The repository was grubbed, cleared, and logged in late April and early May 2015. Approximately 2.5 acres were cleared for construction of the repository; the actual repository covers approximately 1.15 acres.

After the construction of the repository was completed, approximately 8,067 bank cubic yards (bcy) of mine tailings were excavated from the former mine Concentrator area, 12 bcy of which was designated Dangerous Waste.

The following is a list of approximate bcy and pounds of waste rock excavated from other areas:

    •  1,099 bcy of waste rock was excavated and removed from the Ore Collector are

    •  955 bcy of waste rock was excavated and removed from the Comet Terminal and Haulage Ways

    •  213 bcy of waste rock was excavated and removed from the Assay Shack area

    •  2,148 bcy of waste rock was excavated and removed from the Rainy Mine area

    •  Pride of the Woods waste rock pile excavation and removal required transport via heavy lift helicopter of equipment, fuel, materials and supplies to the HMJ Wilderness Area. the total weight of waste rock removed from the HMJ Wilderness Area was approximately 6, 415,000 pounds.

    •  Mine adit diversion activities were completed at Mystery Mine #3 and Justice Mine

All disturbed areas at the MCMA were recontoured and revegetated during the 2016 and 2017 field seasons.

Complete details regarding the Removal Action are located at this link:

Ongoing Activities and MCMA:

Long-term monitoring by the USFS continues at the Site. In 2019, activities for long-term monitoring included:

    •  Surface water sampling to evaluate levels of arsenic in the South Fork Sauk River

    •  Inspection of the mine drainage diversions

    •  Groundwater monitoring at the repository

    •  Inspection of slope stability at the repository

    •  Continued revegetation of disturbed areas, as needed

MCMA - Mine Opening - around 2014
Please click on the photo for a larger view


USFS contractors were unable to visit the MCMA in 2020 due to the COVID-19 pandemic. Long-term monitoring will begin again during the 2021 field season. Ecology continues to work with private landowners to cleanup to MTCA human and ecological health standards. Institutional controls (signage) are expected to be installed during the 2021 field season.


Ecology wants to keep you involved!  You have the opportunity to review and comment on key documents during the cleanup process.  The documents are available for review here at this "View Electronic Documents" link as well as in the right navigation pane under "SITE INFORMATION" and at the repository locations (when open) listed to the right as they become available.


Map showing site location as Snohomish County, WA SITE INFORMATION


View Electronic Documents

Cleanup Site Details Report

Facility Site ID: # 2251399

Cleanup Site ID: 4550

Silverton, Snohomish County

Status: Cleanup Started   Get definitions of Status terminology

Mary Monahan
Site Manager
(509) 454-7840

Document Repositories:

Central Regional Office
1250 W Alder St
Union Gap, 98903-0009

Darrington Public Library
1005 Cascade St
Darrington, 98241