Iron King Mine Humboldt Smelter

⚠ Superfund · Cleanup underway

On October 20, 2023, EPA issued a record of decision to clean up the site. The Record of Decision documents the cleanup option EPA has chosen after considering and responding to public comment. In the next steps in the process, EPA will comprehensively design the cleanup action and then implement it.

Location

CityDewey-Humboldt
CountyYavapai County
StateArizona
Coordinates34.50000, -112.25000

Contaminants of concern

Contaminated media

Cleanup timeline

  1. Initial Assessment Completed — 09/28/1998
  2. Proposed to the National Priorities List — 03/19/2008
  3. Finalized on the National Priorities List — 09/03/2008
  4. Remedial Investigation Started — 06/19/2008
  5. Remedy Selected — 10/20/2023
  6. Remedial Action Started — 09/27/2024
  7. Final Remedial Action Started — Estimated Jun - Aug 2028
  8. Construction Completed — Not Yet Achieved
  9. Deleted from National Priorities List — Not Yet Achieved
  10. Most Recent Five-Year Review — Not Yet Achieved

EPA references

EPA-regulated facilities nearby

Understanding this Superfund site

Iron King Mine Humboldt Smelter is a federal Superfund site in Arizona. The Superfund program, created by Congress in 1980, addresses sites where hazardous substances have been released or threaten release into the environment. EPA scores potential sites using the Hazard Ranking System; those that score high enough are placed on the National Priorities List.

Current status: Cleanup underway. Active cleanup is underway, meaning EPA has approved a remediation plan and work is in progress. Cleanup timelines vary widely — some sites take decades depending on contamination depth, groundwater involvement, and funding availability.

EPA has identified 10 contaminants of concern at this site, including aluminum, antimony, arsenic. Contamination has been detected in surface water, solid waste, soil, groundwater.

If you live near this site and have health concerns, your state health department can provide site-specific guidance. EPA maintains a community involvement program for most NPL sites, and site documents — including the Record of Decision, five-year reviews, and public health assessments — are typically available through EPA's Superfund site profile.