OSWER/OSRTI 

Washington, DC 20460 

NATIONAL PRIORITIES LIST (NPL) 

***Final Site*** September 2011 

CHEVRON QUESTA MINE Questa, New Mexico 

Taos County 

 Site Location: 

The Chevron Questa Mine site, called the MolyCorp, Inc. site when it was proposed, is a molybdenum mining site located 

near the village of Questa, Taos County, New Mexico and consists of two separate areas: the mine area and the tailing 

ponds. The mine itself is approximately 3 square miles in size and is surrounded by the Carson National Forest and the 

state-designated Latir Peak Wilderness Area, which is located approximately two miles north of the mine. The tailing 

facility, which is approximately one square mile in size, is located 6 miles west of the mine site in the village of Questa. 

The mine is located near the Red River and includes several side drainages, including Sulfur Gulch, Spring Gulch, Goathill 

Gulch and Capulin Canyon. 

 Site History: 

Chevron Mining, Inc. (CMI), currently owns and operates the MolyCorp mine site. The mining operation has been active 

for the last 90 years, with three distinct operational phases: (1) conventional underground mining, which occurred from 

about 1919 to 1958, (2) open pit mining, which was conducted from 1965 to 1981 and (3) underground block cave mining, 

which started in 1983 and continues to the present. As part of the current operations, the facility also consists of a mill, a 

tailing facility and a tailing pipeline that runs between the mine and the tailing facility. 

 Site Contamination/Contaminants: 

Sources evaluated include the open pit mine, waste rock piles, contaminated soil in the mill area, tailing impoundments and 

the tailing pipeline. Primary site contaminants include polychlorinated bi-phenyls (PCBs), molybdenum and other heavy 

metals. Antimony, boron, cadmium, cobalt, manganese, molybdenum, nickel, vanadium and zinc were detected in the Red 

River. 

 Potential Impacts on Surrounding Community/Environment: 

Hazardous substances, contaminants and pollutants from the mining-related sources have released into the soil, ground 

water, surface water and sediment at and in the vicinity of the mine site and tailing facility, including the surface water of 

the Red River. A release of hazardous substances has been documented in both surface water and sediment within the Red 

River, including the Red River Fish Hatchery, which is located downstream of the site. Both a Human Health and 

Ecological Risk Assessment have been completed at the site, and identified unacceptable risks to human health and the 

environment. 

 Response Activities (to date): 

A Remedial Investigation and Feasibility Study (RI/FS) has been conducted through an Administrative Order on Consent 

between EPA and Chevron. Chevron currently is working in conjunction with the State and EPA to address ongoing 

releases. 

 Need for NPL Listing: 

The site was initially proposed to the NPL in May 2000. EPA is re-proposing to ensure that the Hazard Ranking System site 

score more accurately reflects current site conditions obtained since the May 2000 proposal. EPA received a letter from the 

state supporting listing of the site on the NPL. 

[The description of the site (release) is based on information available at the time the site was evaluated with the HRS. The description may change 

as additional information is gathered on the sources and extent of contamination.] 

For more information about the hazardous substances identified in this narrative summary, including general information regarding the effects of exposure to these 

substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on the Internet 

at http://www.atsdr.cdc.gov/toxfaq.html or by telephone at 1-888-42-ATSDR or 1-888-422-8737.