Region 8

Carpenter Snow Creek Mining District

Carpenter Snow Creek site location map

Site Type: Final NPL
City: Neihart
County: Cascade
ZIP Code: 59465
EPA ID: MT0001096353
SSID: 089X
Congressional District: At Large

What's New?

Updated June 2013

An open house/public meeting will be held at the Monarch/Neihart Senior Center beginning at 6:30 p.m. on Thursday, June 27, 2013 to discuss upcoming site activities. A fact sheet summarizing our planned 2013 field activities was sent out to interested parties and is posted in the Site Documents section below.

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Site Description

James Neihart, a local prospector, was the namesake for the small mining town of Neihart. Mining began in the area in the 1880s when silver deposits were discovered near the future Neihart town site. Mines yielded primarily silver, lead and zinc ores. During the 1920s, lead and zinc were produced in large quantities. The mining district has been largely inactive since the 1940s, although some mines have reported mine development work and some sporadic production.

map of the Fort Benton/Denton/Stanford area

The Carpenter Snow Creek Mining District Superfund Site (CSCMD) lies in the Little Belt Mountains of southern Cascade County. The site encompasses approximately 9,000 acres with mine tailings, waste rock and acid mine drainage present throughout the site, due to the many inactive and abandoned mines. The State of Montana’s Abandoned Mine Bureau identified, inventoried and sampled these inactive mines in the Carpenter Snow Creek area in the early 1990s. Sampling showed the presence of a variety of metals in the area surface water and soil that are found in concentrations known to produce risk to human health and the environment. The CSCMD site was listed on the Superfund National Priorities List in 2001.

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Site Risk

Approximately 96 abandoned mines have been identified in the Carpenter Snow Creek Mining District, and at least 21 of these have been identified as probable sources of contamination to surface water. There are documented impacts from mining waste to soil, surface water and stream sediments in Carpenter Creek, Snow Creek and Belt Creek.

Media Affected Contaminants Source of Contamination
groundwater, sediment, surface water, soils lead, arsenic, copper, cadmium, zinc mining activity

Since 2001, the EPA has and is continuing to collect soil/mine waste, surface water, sediment and groundwater samples throughout the entire site, with expanded efforts in and around the town of Neihart. Concentrations of lead and arsenic in soil have been identified above the action levels in the Record of Decision in residential yards and alleys throughout Neihart. Preliminary sampling did not identify contaminant levels above drinking water standards, or levels that the EPA considers unhealthy for aquatic life, in the surface water of Belt Creek as it flows through Neihart. Similarly, contaminant levels in the sediment of Belt Creek as it flows through Neihart did not exceed levels considered safe for recreational use. Recent sampling in the Carpenter Creek and Snow Creek drainages revealed elevated levels of lead and zinc in sediments along Carpenter Creek and throughout the various tailings piles present in the watersheds. Sampling in 2012 indicates that contaminated soils that were deposited in the floodplain during historic Belt Creek flood events extend all the way to Monarch. In addition, several adits that are discharging from abandoned mines continue to contribute to the degradation of the water quality throughout the mining district.

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Cleanup Progress

The site has been delineated into three operable units (OUs). OU1 includes the Neihart Community Soils Area, which encompasses the urban area of the town that contains contaminated soils associated with residential and public-use property. OU1 also includes the mine waste adjacent to residential property, where waste is accessible to the general public, and the Neihart Tailings that were addressed as part of an EPA time-critical removal action in 2004. The EPA has also established preliminary study area boundaries for the purpose of planning and developing the initial scope of the Remedial Investigation/Feasibility Study (RI/FS) for OU2 and OU3. As the site is characterized further, these OU boundaries are subject to change.

OU2 is the Snow Creek watershed, which is characterized by ore that has low base-metal content and higher gold content. OU2 also includes the lower Carpenter Creek basin below the confluence with Snow Creek as well as the abandoned mine sites, mill sites and associated wastes at the base of the Neihart slope that are not easily accessible to the public. Belt Creek flows from south to north through Neihart and its named tributaries within the Neihart slope, where known historic mining operations occurred, include Broadwater Creek, Compromise Creek and Rock Creek. OU2 also contains the abandoned mines and mills within Lucy Creek, MacKay Creek and Burg Creek in the Upper Carpenter Creek basin. Carpenter Creek enters Belt Creek north of town.

OU3 is the Silver Dyke Mining Complex, located in the Squaw Creek drainage in the Upper Carpenter Creek basin above the confluence with Snow Creek. The Silver Dyke Mining Complex includes the Silver Dyke adit, mill and tailings piles. The ore in this complex is characterized by a wide body of low grade ore containing zinc and lead and a high proportion of copper, but which also resulted in a large quantity of tailings and refuse. A tailings dam, co-located next to the Silver Dyke Mill, was damaged by an earthquake in 1925 and caused a flood of tailings into the valley below, now known as the Silver Dyke Tailings. In 1926, Silver Dyke Mining Company developed two new impoundments (upper and lower) for collection of mine tailings. These tailings, now known as the Carpenter Creek Tailings, were placed into the impoundments by slurry from the upstream Silver Dyke Mill and are thought to have originally spanned the entire valley. All tailings depositions above Snow Creek are included in OU3.

In 2004, a Removal Action was completed for select properties in Neihart where areas of higher contamination were prioritized to be removed and/or stabilized. Although this was successful for the areas of high contamination, larger remediation efforts are still being planned pursuant to the Record of Decision issued in 2009 for the Neihart Community Soils. Field efforts in 2012 almost completed the Remedial Design for the properties and roads in and around Neihart. In addition, metals concentration in tailings, soil, sediment, surface water and groundwater throughout the mining district is being characterized to identify the extent of material that may require a response action.

An appropriate repository for the waste from the entire CSCMD is still being determined, so the planned remediation schedule for Neihart is delayed. The Evening Star Mine and Mill Site, located just outside Neihart on Highway 87, was evaluated as a potential repository. The site was determined not to be feasible because of the cost to develop the property as a repository and insufficient size to handle all of the waste. Without a place to move the waste from the entire CSCMD, the EPA will not be able to begin the Remedial Action, as planned, in 2013. There are two additional repository locations in the Carpenter Creek watershed currently being evaluated. The EPA can’t confidently state what the new schedule will be for the Remedial Action for Neihart until a potential repository within the mining district has been identified to accept all the waste and an agreement is negotiated with the property owner(s).

Multiple important sampling efforts took place within the watershed in 2012. One of the efforts was to determine the types and amount of metals in the creek-side mine waste. Another important part of the sampling was to better understand the actual volume and chemical composition of mine tailings and waste rock in the Carpenter Creek, Snow Creek and Neihart slope drainage areas. As part of the 2012 sampling efforts, our contractors took over 1,000 field measurements using X-ray fluorescence.

The EPA also sampled all the remaining abandoned mines in the watershed during 2012 that were not sampled in 2011. A sampling of native plants, small animals, insects and aquatic organisms that are in contact with mine waste was also collected for the ecological risk assessment. Additionally, groundwater and surface water samples were collected during two different sampling events to better understand mine waste contact with water. These sampling efforts greatly improved our understanding of the nature and extent of contamination within the watershed. A Remedial Investigation (RI) report is anticipated to be completed in 2013.

A 2012 Field Update presentation from the November 2012 meeting is available in the Site Documents section below.

View a map of site and operable unit boundaries, April 11, 2012

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Community Involvement

Community involvement plays an important role in the Superfund process. The EPA uses a number of different tools and resources to promote effective, on-going, meaningful community involvement. The goals of the Superfund community involvement program are to:

  • Keep communities affected by sites informed throughout the cleanup process.
  • Provide opportunities for communities to comment and offer their input about site cleanup plans.
  • Facilitate the resolution of community issues tied to a site.

A Community Involvement Plan was prepared in 2011 for the Neihart Community Soils area (OU1) and is being updated in 2012 to include the entire site. The plan provides a history of the site, a brief background and description of the community of Neihart, and identifies issues of concern to the local community regarding the site. The EPA interviewed home and business owners and local government officials in the preparation of the Community Involvement Plan. The interviews provided community members and officials the opportunity to voice concerns and issues related to the Superfund site. In the Community Involvement Plan, the EPA specifies objectives and future plans for community involvement and communication at the Carpenter Snow Creek site. The EPA plans fact sheets, news releases and focused meetings for community members as part of the agency’s efforts to keep the community informed of site progress. In addition, the EPA will maintain an accurate mailing list for those interested in receiving information about the site. If you would like to be on the mailing list, please contact the EPA Remedial Project Manager listed below. The 2012 Community Involvement Plan will be available in the Site Documents section once it has been finalized.

An open house/public meeting will be held at the Monarch/Neihart Senior Center beginning at 6:30 p.m. on Thursday, June 27, 2013 to discuss upcoming site activities. A fact sheet summarizing our planned 2013 field activities was sent out to interested parties and is posted in the Site Documents section below.

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The EPA places a high priority on land reuse as part of its Superfund response program mission. The agency tries to select cleanup options that encourage and support future use of a site. The EPA uses two fundamental methods to facilitate reuse of Superfund sites:

  • Exploring future uses before the cleanup remedy is implemented, an approach that gives the Agency the best chance of designing cleanup remedies to support the likely future use of a site.
  • Working with landowners and communities to remove barriers not considered necessary for the protection of human health or the environment at those sites where remedies are already in place.

One option for reuse is the siting of clean and renewable energy projects on contaminated (or formerly contaminated) lands. As part of this effort, the EPA is evaluating the potential for energy projects on these properties and working with landowners and communities to identify ways to remove barriers to such projects.

The reasonably anticipated future land use is determined during the RI/FS process. This information is considered during the development and selection of the remedy for the site. Many properties in Neihart are already in continued use as residential or commercial properties.

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Land Use Controls and Other Institutional Controls

Land use controls are the most common type of institutional control (IC). ICs are administrative or legal controls that help reduce the likelihood for human exposure to contamination. ICs can also help protect the integrity of the remedy. Examples of ICs are:

  • Zoning ordinances.
  • Environmental covenants.
  • Deed notices.
  • Well-drilling restrictions.
  • Building permits.
  • Informational advisories.

Options for institutional controls are developed as needed during the RI/FS process and selected in the Record of Decision as a part of the remedy. The EPA will determine the specific ICs later in the cleanup process, following the remedial action.

Options for institutional controls are developed as needed during the RI/FS process and selected in the Record of Decision as a part of the remedy.

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Five-Year Reviews

The EPA or the lead agency conducts five-year reviews following the start of a Superfund cleanup when contamination is left on the site. These reviews are repeated every five years. We use these reviews to determine:

  • How the remedy is working.
  • If the remedy remains protective of human health and the environment.

Remedial action has not begun, therefore five-year reviews are not yet required at this site.

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Site Documents

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2012 Field Update presentation from the November 5, 2012 public meeting

Presentation from the May 3, 2012 public meeting

Map of site and operable unit boundaries, April 11, 2012

2011 Sampling Activities Report, March 2012

2010 Sampling Activities Report (SAR), February 2011 (PDF, 171 pp, 253 MB, located on the FTP site)

Record of Decision (ROD) text, appendices and figures, March 2009 (PDFs located on the FTP site; see individual files)

Revised Proposed Plan for Neihart Community Soils, December 2008
- Public Comments on the Revised Proposed Plan
- Transcript of the Public Hearing for the Revised Proposed Plan, January 13, 2009

Public Comments on the original Proposed Plan for Neihart Community Soils
- Transcript of the Public Hearing for the original Proposed Plan, November 30, 2008
- Transcript of the Public Hearing for the original Proposed Plan, October 25, 2008

Fact Sheets

Site Update Fact Sheet, June 2013

Neihart Community Soils (OU1) Fact Sheet: Introducing EPA’s Pre-Remedial Assistance for Property
Owner’s Soil Management,
December 2012

Site Update Fact Sheet, October 2012

Site Update Fact Sheet, April 2012

EPA Issues A Revised Proposed Plan for Cleanup of Soils in Neihart, MT, December 2008

EPA Issues Its Proposed Plan for Cleanup of Soils in Neihart, MT, October 2006

EPA Project Update for Neihart, Montana, March 2005

Site Update: Carpenter Snow Creek Superfund Site, August 2004

EPA to Interview Neihart Residents and Property Owners in February, February 2004

Remedial Investigation Begins in Neihart in September 2003, August 2003

Additional Sampling Begins in Neihart in June 2003, June 2003

Soil Sampling Results and Plans for Additional Work in Neihart, March 2003

EPA to Conduct Sampling in Neihart, September 2002

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Tillman McAdams
Remedial Project Manager (for OU1)
U.S. Environmental Protection Agency, Region 8
Montana Office
Federal Building
10 West 15th Street, Suite 3200
Helena, MT 59626
866-457-2690 (toll free)

Roger Hoogerheide (for OU2 and OU3)
Remedial Project Manager
U.S. Environmental Protection Agency, Region 8
Montana Office
Federal Building
10 West 15th Street, Suite 3200
Helena, MT 59626
866-457-2690 (toll free)

Montana DEQ

Keith Large
State Project Officer
Montana Department of Environmental Quality
Remediation Division
1100 N. Last Chance Gulch
PO Box 200901
Helena, MT 59620-0901

Site Information Repositories:

EPA Superfund Records Center
Montana Office
10 West 15th Street, Suite 3200
Helena, MT 59626
866-457-2690 (toll free)
Hours: M-F, 8:00 a.m.-4:30 p.m.

Cascade County Health Department
115 4th Street South
Great Falls, MT 59401

Belt Creek Ranger Station
c/o Neihart, Montana 59465

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Photo/Video Gallery

Click on a thumbnail below to view the full size image.

Collecting a water sample at Haystack mine
Runoff of lower Carpenter Creek tailings during a thunderstorm
Carpenter Creek entering Belt Creek after a storm
Montana Fish, Wildlife and Parks collecting fish in Belt Creek below Carpenter Creek
Big Seven mine during a winter reconnaissance
Silver Dyke Mine Glory Hole during a March reconnaissance
Adit discharge from the Compromise mine
Looking out at the Lexington #4 from the collapsed adit
Looking down at Upper Rebellion from the Ripple mine
Silver Dyke Mill

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Montana Department of Environmental Quality, Remediation Division Exit

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