Silver Bow Creek

Remediation and Restoration

Silver Bow Creek

The cleanup of Silver Bow Creek has been ongoing since 1999 as part of a Superfund remedial action being coordinated by the Montana Department of Environmental Quality (DEQ) in consultation with the U.S. Environmental Protection Agency (EPA). In 2000, the Natural Resource Damage Program (NRDP) of the Montana Department of Justice formed a partnership with DEQ, bringing a restoration component to the project that goes beyond remediation required under Superfund. Provided below is a brief history of the project, updates regarding the current status of the project, and descriptions of activities planned in future years.

PROJECT BACKGROUND

The Problem
Silver Bow Creek extends from Butte approximately 23 miles to the Warm Springs Ponds, a water treatment facility located at the headwaters of the Clark Fork River (see corridor map). Since the late 1800s, tailings and other mine wastes containing elevated concentrations of metals have been discharged to or otherwise entered Silver Bow Creek. These toxic discharges impacted the stream and floodplain with heavy metals and virtually eliminated aquatic life in the stream. Tailings deposited in the floodplain are toxic to plants and have resulted in a floodplain that is largely devoid of vegetation and is generally incapable of supporting wildlife.

The Remedial Response
In 1983, EPA listed the Silver Bow Creek/Butte area as one of multiple Superfund sites in the Upper Clark Fork River Basin. The agency later designated the approximately 23 stream miles of streamside tailings along Silver Bow Creek as an operable unit (OU) within this overall Superfund site. The Streamside Tailings Operable Unit (SSTOU) has become one of the areas of focus for Superfund cleanup in the Butte area. Initially, EPA named ARCO as the primary party responsible for remediation of the SSTOU and other Superfund sites in the Upper Clark Fork Basin through its acquisition of the Anaconda Company. EPA and DEQ issued a Record of Decision (ROD) for the site in November 1995 that identifies the final site remedy and the agencies' rationale for selecting that remedy. The major remedial action that resulted from issuance of the ROD is excavation of tailings and related impacted soils from the floodplain of Silver Bow Creek and reconstruction of the stream channel and floodplain. For planning purposes, the SSTOU was divided into four subareas, each with a distinct geologic and geographic character.

The NRDP Connection
In a 1999 state, federal and tribal settlement, ARCO agreed to pay $215 million to the State to resolve certain claims. From the settlement amount, $80 million plus interest was set aside for DEQ and EPA to implement the remedy for Silver Bow Creek. Some of the remaining amount is being used to enhance the cleanup of Silver Bow Creek through various habitat improvements and restoration actions. DEQ and EPA are coordinating the cleanup of the Silver Bow Creek remedy with NRDP.