Mammoth Stamp Mill Site Closed

The Inyo National Forest has closed the Mammoth Stamp Mill Site due to elevated levels of metals that were determined to pose a risk to human health and the environment. Antimony, arsenic, lead and mercury were identified as the primary chemicals of concern.

Records can be viewed at:
Inyo National Forest
Supervisor's Office
351 Pacu Lane
Bishop CA 93514

Contact: Colleen Garcia

Document Links

Technical Memo: Data Gaps Sampling Investigation - June 6, 2022

Forest Closure Order: Mammoth Mill, 5/16/2022 - Expires 5/15/2024      (Previous Forest Order expired 5/16/2022)

Mammoth East Area Site Investigation, 07/2021

Work Plan for Data Gap Sampling Mammoth Stamp Mill Site 11/2020

Supplemental Characterization Report for the Cabins Area at Mammoth Mill 12/2019

Map: Figure 11. Extent of Metals-Impacted Soil in Cabins Area

Map: Figure 2. Cabin Area Definition

Mill City Tract Public Meeting Minutes, 11/16/2019

Mammoth Mill Site Update : Public Meeting 11/16/2019

Focused Site Inspection (Focused SI) for the Cabins Area Mammoth Mill Site 01/12/2018

Unilateral Administrative Order (UAO) for Time Critical Removal Action 11/03/2017 PDF (3MB)

Mammoth Mill Fact Sheet 04/05/2017

Frequently Asked Questions for Mammoth Stamp Mill CERCLA Site 04/05/2017

Technical Memorandum for Refinement of Streamlined Human Health Risk Assessment. 1/23/2017