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 located in Butte, Montana and covers about 26 miles of stream and streamside habitat. Since the late 1800s, mining crews dumped mining wastes into on-site streams and wetlands near mining operations. These activities contaminated soil, groundwater and surface water with heavy metals.
What Is Being Done to Clean Up the Site?
To better address cleanup, the site is currently divided into seven active operable units (OU). EPA has completed four five-year reviews of the site’s remedy to ensure that the remedies put in place for each OU are protective of public health and the environment and function as intended by site decision documents.
Streamside Tailings OU1 – includes the 26-mile, mine-waste impacted Silver Bow Creek floodplain. Continued protectiveness of the OU1 remedy requires completing implementation of the selected remedy; filling in data gaps; implementing enforceable institutional controls; and updating and implementing the monitoring and maintenance plan.
Butte Mine Flooding OU3 – includes contaminated groundwater in the flooded underground mine workings below the city of Butte along with contaminated water in the Berkeley Pit. The West Camp/Travona Mine OU6 was previously part of this OU, but treatment of the West Camp groundwater was transferred to OU8 with the BPSOU ROD. Continued protectiveness of the OU3 remedy requires resolving treated effluent water quality issues before discharge to Silver Bow Creek becomes necessary.
Rocker Timber Framing and Treating OU7 – includes soils and groundwater contaminated with arsenic from a former timber treating facility. Continued protectiveness of the OU7 remedy requires ongoing monitoring; continued implementation of institutional controls, site access controls, updated conceptual site model; and operation and maintenance activities.
Warm Springs Ponds (WSP) Active Area OU4 – includes the portion of the 2,600-acre WSP that actively treat the entire flow of Silver Bow Creek prior to its confluence with Warm Springs Creek, forming the start of the Clark Fork River. It also includes the reconstructed Mill-Willow Bypass. Continued protectiveness of the OU4 remedy requires remedy implementation progress at other upstream OUs.
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. To ensure protectiveness, remedy implementation must be completed and municipal storm water contributions to Silver Bow Creek must be addressed.
Warm Springs Ponds Inactive Area OU12 – includes the portion of the 2,600-acre WSP that are not part of the active treatment of Silver Bow Creek water. Continued protectiveness of the OU12 remedy requires remedy implementation progress at other upstream OUs.
West Side Soils OU13 – 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. This OU was not included in the last five-year review.
A site wide protectiveness statement will not be issued until construction of the remedy is complete at all OUs.
What Is the Current Site Status?
Many cleanup actions have been completed, including several removal actions, or short-term cleanups, 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 long-term remedy includes long-term environmental monitoring; removal of contaminated soil, sediment and tailings; placement of contaminated materials in repositories; management of wastes left in place; institutional controls; long-term operation and maintenance; treatment of contaminated surface and groundwater; and removal of lead and arsenic-contaminated soil and attic dust.
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).
EPA’s Involvement at the Site
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.
In 2006, EPA selected a remedy in a Record of Decision (ROD) for the BPSOU that essentially includes the "uptown" city of Butte where most of the mining activity occurred. The selected remedy for the BPSOU addresses potential or actual threats to human health or welfare of the environment resulting from heavy metals and arsenic in soils, indoor dust, surface water and groundwater through long-term remedial response actions. In 2011, EPA issued a unilateral administrative order to implement most aspects of the 2006 ROD.
EPA is working with the Montana Department of Environmental Quality and the BPSOU responsible parties on the evaluation and implementation of additional best management practices (BMPs) to protect Silver Bow Creek from contaminated storm water.
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, About PDF) 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 most aspects of the 2006 ROD for the portions of the cleanup where there was agreement between EPA and the State of Montana. This enforcement tool required the responsible parties for BPSOU to implement parts of the 2006 ROD.