Operable Unit Information
Butte is the Mining City, literally built in the midst of the mines. Families built their homes scattered amongst the mines on the “Hill” and amongst the many waste rock dumps that contain contaminants.
The EPA’s early work at this operable unit was to ensure that those dumps were covered in clean soil and an overlying cover of protective vegetation. The EPA, in collaboration with DEQ, Atlantic Richfield and Silver Bow County established the Residential Metals Abatement Program (RMAP) to protect residents’ health by cleaning up yards and homes that are contaminated by arsenic, lead and mercury.
Because lead (Pb) is one of the primary contaminants of concern, CTEC suggests getting children’s blood lead tested through family physicians or through the free Butte-Silver Bow County lead program.
In 1997, Atlantic Richfield began remediating Silver Bow Creek by excavating the Colorado and Butte Reduction Works Tailings, reconstructing a clean streambed and floodplain and installing a system to capture and treat contaminated groundwater that was degrading the Creek. That work continues.
As with any city in Montana, Butte has a stormwater problem. But it is complicated here because the extensive mine waste contribute high levels of arsenic, cadmium, copper, lead and zinc to the urban storm-drain system that drains to Silver Bow Creek. Under the current Superfund cleanup program, Atlantic Richfield is constructing an extensive system of stormwater ponds that will act as catchment basins and function like wetlands to mitigate those contaminants. The ponds will include recreational amenities such as trails, public venues and playgrounds.
Visit BPSOU’s website for an overview of site history, the cleanup to date and designs for the future.


What’s New
Superfund updates.
ARCO selects Butte Repository to dump toxic dirt in Silver Bow Creek cleanup
Date: Mar 27, 2026 Published By: KXLF News BUTTE -This summer, the plan is to start moving the more than 1 million cubic yards of contaminated dirt from Butte’s Silver Bow corridor and deposit it at the Butte Mine Waste Repository northeast of town. “This is a large…
Silver Bow Creek Greenway: A Legacy Worth Protecting
Date: Mar 24, 2026 Published By: The Montana Standard Guest View, Greenway Service District Board – Montana Standard March 24, 2026 In Superfund communities like ours, progress doesn’t always arrive with fanfare. Often it comes quietly and incrementally — mile…
September – October 2025 Superfund Update
CTEC Sep-Oct update Download the Update