OSWER/OSRTI 

Washington, DC 20460 

NATIONAL PRIORITIES LIST (NPL) 

***Final Site*** December 2014

COLORADO SMELTER Pueblo, Colorado

Pueblo County

 Site Location:

The site is a former silver and lead smelter located within a residential and commercial area of south Pueblo, in Pueblo, 

County, Colorado. 

 Site History:

The Colorado Smelter was constructed in a ravine between Santa Fe Avenue and the Denver & Rio Grande railroad tracks 

and operated from 1883 to 1908. From 1883 to 1888, 37,659 tons of bullion containing 4,436,099 ounces of silver and 

11,887 ounces of gold was produced. In 1899, the Colorado Smelter was merged into the American Smelting and Refining 

Company; the facility closed in 1908. The site was originally reported to the EPA via a citizen complaint of an orange 

discharge to the Arkansas River. In 2010, the Colorado Department of Public Health and Environment conducted a focused 

site inspection (SI) at the former Colorado Smelter, including nearby residential areas and the Arkansas River. 

 Site Contamination/Contaminants:

Residential soil and the remaining slag onsite contain lead and arsenic. An onsite seep is contaminated with arsenic, 

cadmium, copper, lead, manganese and zinc. Historical information indicates that the height of the main smelter stack was 

200 feet; therefore, past smelter stack emissions are an additional source of lead and arsenic contamination in nearby soils. 

 Potential Impacts on Surrounding Community/Environment:

Exposure to contaminated slag and soil is the primary concern at the former Colorado Smelter. The site is accessible and 

there are remnants of former buildings and slag piles at the site. Sampling of soil in the residential areas found arsenic and 

lead significantly above health-based concentrations and above levels that would be considered naturally occurring in soil. 

 Response Activities (to date):

There have been no response activities. 

 Need for NPL Listing:

The site consists of an approximately 700,000 square foot slag waste pile and many residential yards with high levels of 

lead and arsenic that pose a risk to residents. The size of the slag pile and the large number of contaminated yards indicate 

that listing the site on the NPL, as opposed to addressing the site through other programs, would be the most effective 

approach for cleaning up contamination.The EPA received a letter of support for placing this site on the NPL from the state. 

[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. See 56 FR 5600, February 11, 1991, or subsequent FR notices.] 

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/toxfaqs/index.asp or by telephone at 1-888-42-ATSDR or 1-888-422-8737.