SILVER BOW CREEK/BUTTE AREA
On this page:
- What Is Being Done to Clean Up the Site?
- What Is the Current Site Status?
- EPA’s Involvement at the Site
- Sampling and Monitoring
- Emergency Response and Removal
- Enforcement Information
On related pages:
The Silver Bow Creek/Butte Area site is in Butte, Montana and includes 26 miles of stream and streamside habitat. Since the late 1800s, mining wastes have been dumped into streams and wetlands near mining operations. These activities contaminated soil, groundwater and surface water with heavy metals.
Removal and cleanup actions have been completed to address immediate threats to human health and the environment in Butte. Cleanup, operation and maintenance, sampling, and monitoring actions are ongoing.
What Is Being Done to Clean Up the Site?
Over the past 20 years, several cleanup actions have been completed, including removal actions, to address immediate threats to human health and the environment.
Contaminated soil has been removed from waste dumps, residential areas, railroad beds and rail yards. In addition, rail yards and residential properties have been reclaimed, a waste dump has been capped and protected, and cement channels and sedimentation ponds have been put in throughout Butte to address storm water contamination. Contamination has been removed from stream sides and channels and local area groundwater has been treated.
The cleanup plan includes further removal of lead and arsenic-contaminated soil and attic dust in homes and yards; removal of contaminated soil, sediment and tailings from around Butte; placement of contaminated materials in repositories; management of remaining wastes left in place; institutional controls; long-term operation and maintenance; treatment of contaminated surface and groundwater; and long-term environmental monitoring.
In 2016, EPA completed the fourth five-year review of remedial actions performed at the site. Five-year reviews are conducted to determine how the remedy is working and if the remedy remains protective of human health and the environment.
- Fourth Five-Year Review Report for the Silver Bow Creek/Butte Area Site (PDF) (324 pp, 24.7 MB, About PDF).
What Is the Current Site Status?
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To better address cleanup, the site is currently divided into seven active operable units (OU).
Streamside Tailings OU1 consists of about 26 linear miles of Silver Bow Creek and deposited tailings along the Creek. The boundary begins at the upstream end just outside of the Butte city limits and continues until Silver Bow Creek enters the Warm Springs Ponds. Remedial activities have addressed exposure pathways that could result in unacceptable risks.
- 1998 Explanation of Significant Differences for Streamside Tailings (PDF) (32 pp, 12 MB)
- 1995 Record of Decision for Streamside Tailings (PDF) (679 pp, 70 MB)
Butte Mine Flooding OU3 is the Berkeley Pit and contaminated groundwater in the flooded underground mine workings below the city of Butte and Walkerville. The boundaries are the Continental Divide to the east, Silver Bow Creek to the south, Missoula Gulch to the west, and the Yankee Doodle Tailings Pond and upper Silver Bow Creek to the north.
Rocker Timber Framing and Treating Plant OU7 covers about 16 acres and includes the contaminated groundwater resulting from site operations under and near the land surface. It is located south of U.S. Interstate 15/90 near Rocker, Montana, about 3 miles west of Butte, in Silver Bow County. The community of Rocker is just north of Silver Bow Creek.
- 2014 Explanation of Significant Differences for Rocker Timber Framing and Treating Plant (PDF) (27 pp, 37.6 MB)
- 1995 Record of Decision for Rocker Timber Framing and Treating Plant (PDF) (249 pp, 11 MB)
Warm Springs Ponds OU4 & 12 is in southwestern Montana at the lower end of Silver Bow Creek approximately 27 miles downstream of Butte. This 2,600-acre area consists of a series of three sediment settling ponds. OU 4 includes the portion that actively treats the entire flow of Silver Bow Creek prior to its confluence with Warm Springs Creek that forms the start of the Clark Fork River. OU 12 is the portion that is not part of the active treatment of Silver Bow Creek Water.
- 1992 Record of Decision for Warm Springs Ponds (PDF) (179 pp, 61.5 MB)
- 1991 Explanation of Significant Differences for Warm Springs Ponds (PDF) (16 pp, 48 MB)
- 1990 Record of Decision for Warm Springs Ponds (PDF) (455 pp, 16.3 MB)
OU8, Butte Priority Soils OU8 (BPSOU): – includes impacted soils, mine wastes, and contaminated attic dust located within portions of the city of Butte, along with mining-impacted alluvial groundwater and surface water associated with the historic and current Silver Bow Creek floodplain within the City of Butte.
- 2011 Unilateral Administrative Order (PDF) (134 pp, 30.6 MB)
- 2011 Explanation of Significant Differences for Butte Priority Soils (PDF) (35 pp, 10.7 MB)
- 2006 Record of Decision for BPSOU (PDF) (731 pp, 161 MB)
In 2011, EPA issued a unilateral administrative order to implement most aspects of the 2006 Record of Decision.
OU13, West Side Soils: includes the mining-impacted areas in and around the city of Butte that are not included in the BPSOU or the permitted active mining area. A comprehensive investigation to characterize the nature and extent of contamination will start in 2018.
Over the timeline of Superfund cleanup in Butte, EPA has completed four five-year reviews to determine how the remedy is working and if it remains protective of human health and the environment. The last Five-Year Review was completed in 2016.
EPA’s Involvement at the Site
In 1982, EPA proposed the Silver Bow Creek site to be added to the National Priority List (NPL) and it was listed as a Superfund Site in 1983. The Butte Area was added to Silver Bow Creek site in 1987. From 1988 to 2005, EPA completed several removal actions to clean up areas around former smelter sites, mine waste dumps, railroad beds, stream banks and channels, and residential yards to address immediate human health and environmental risks.
EPA continues to work with the community, project stakeholders, and responsible parties to oversee the ongoing cleanup work.
Sampling and Monitoring
Comprehensive sampling and monitoring actions are ongoing at the site.
The 2008 to 2013 Surface Water Characterization Report (406 pp, 71.4 MB) presents a summary and interpretation of surface water quality data collected at the Butte Priority Soils Operable Unit.
Emergency Response and Removal
Eleven time‐critical removal actions and expedited response (Non‐Time Critical Response) actions were conducted from 1987 through 2005 to address immediate and significant human health and environmental risks at BPSOU. One removal action, the Lower Area One tailings removal, was a large scale removal of wastes within the Silver Bow Creek floodplain at the site of two former smelters and resulted in substantial improvement to Silver Bow Creek water quality and a reconstructed floodplain.
In 2011, EPA issued a unilateral administrative order (UAO) to implement parts of the 2006 Butte Priority Soils Record of Decision for the portions of the cleanup where there was agreement between EPA and the State of Montana.
- 2011 Butte Priority Soils Unilateral Administrative Order (PDF) (134 pp, 30.6 MB)
In January 2018, EPA, the U.S. Department of Justice, Montana DEQ, Butte Silver Bow, and the Atlantic Richfield Company reached a conceptual agreement to address future cleanup work at the site. EPA will be working with all parties to develop a proposed plan to amend the existing Record of Decision. The proposed plan will be made available for a 60-day public comment period.