Iron Mountain Mine NPL Site

State TrusteeState of California
Federal TrusteeDepartment of Commerce
AO Bureau

Also Known As

Incident Type




Case Status



Spring Creek and Sacramento River


Contaminants of Concern Include

Affected DOI Resources Include

Anadromous Fish, Threatened and Endangered Species, DOI Managed Lands

Financial Summary

Restoration Funds Collected:


*Restoration Funds Allocated:


*Restoration Funds Remaining:


* Restoration Funds can contain multiple settlements/projects. All collections are placed in interest bearing accounts. For detailed information on individual settlements/ projects please visit: NRDAR Status Report

Visit the Withdrawal Request Form to request restoration funds. Login required.

Case Description

The Iron Mountain Mine Complex (IMM) is located 9 miles northwest of Redding, California. From the 1860s through 1963, the 4,400-acre IMM site was mined for iron, silver, gold, copper, zinc, and pyrite. Though mining operations were discontinued in 1963, underground mine workings, waste rock dumps, piles of mine tailings, and an open mine pit still remain at the site. The mining activities resulted in acidic conditions and the release of heavy metals (copper, cadmium, arsenic and zinc) to the Sacramento River watershed. Before remediation IMM was identified as the single largest point source discharge of metals to surface waters in the nation. The low pH level and the heavy metal contamination from the mine have caused the virtual elimination of aquatic life in sections of Slickrock Creek, Boulder Creek, and Spring Creek. In 1983 IMM was placed on the EPA Superfund National Priority List. Remediation began in 1989 and includes on-site treatment of IMM drainage, capping certain areas of the mine complex and diversion of surface waters away from sources of contamination. The remediation actions and the careful regulation of flows to the Sacramento River from a reservoir impacted by the mine have greatly reduced the risk of metal toxicity in the Sacramento River. Drainage from IMM caused injury to aquatic and riparian habitats in four creeks in the vicinity of the mine and contaminated Spring Creek Reservoir. Heavy metals in IMM drainage have caused at least 39 documented fish kills in the Sacramento River since 1940, copper from IMM alone killed an estimated 20 million salmon fry in the Sacramento River between 1980 and 1999. In addition to ecological injuries the mine drainage and mine operations caused closures and lost recreational use of public lands impacted by the mine. The U.S. and California reached a $9 million settlement agreement in 2000 with Aventis CropScience USA, Inc., the company with primary responsibility for IMM. The Trustee Council, including the U.S. Fish and Wildlife Service, California Department of Fish and Wildlife, the National Oceanic and Atmospheric Administration, the Bureau of Land Management, and the Bureau of Reclamation produced a Restoration Plan in 2002. Four projects were completed to compensate for injuries to salmonids, instream and riparian habitats and lost human recreation use.

Credit: USFWS

Page 1 of 1

Case Documents

 Document TypeDocument NameDocument Date


 Consent Decree Consent Decree 12/08/2000


 Restoration Plan Restoration Plan 04/01/2002

Map View

Case Contact

San Francisco Bay-Delta Fish and Wildlife

Sacramento, CA | (916) 930-5603 |

If you have any problems, suggestions, or comments about our website please notify

Content Protected Copyright © 2021 NRDAR. Reproduction in whole or in part in any form or medium without express written consent of NRDAR is Strictly Prohibited.