The three Warm Springs Ponds cover 2,400 acres at the confluence of Silver Bow, Mill, Willow, and Warm Springs creeks. The ponds were constructed by the Anaconda Company between 1911 and 1959 in an attempt to trap tailings before they entered the Clark Fork River, which begins immediately below the ponds. An investigation of the ponds was completed in 1989.
The EPA Record of Decision (ROD) for the Warm Springs Ponds from 1990 below. An EPA Explanation of Significant Differences for the site was issued later in 1991. A separate EPA Record of Decision for the Inactive Area of Warm Springs Ponds was issued in 1992. All documents can be download via the Superfund Library, or using the links below. While geographically distinct, the ponds are considered to be part of the Silver Bow Creek Streamside Tailings Operable Unit by EPA.
Public comments were extensive and led to a decision to speed up cleanup plans in the Mill-Willow Bypass. The bypass contained approximately 200,000 cubic yards of tailings and contaminated soils that were a principal cause of fish kills. In 1990 and 1991, the tailings and contaminated soils were excavated and consolidated in Pond 3.
The ponds contain 19 million cubic yards of tailings and contaminated soils. The selected remedy to cleanup the two active and one inactive Ponds included:
- Removing the Mill-Willow Bypass tailings and placing them on top of tailings in the berms of Pond 3
- Reinforcing all ponds and upgrading their treatment capabilities
- Dry closing Pond 1 by covering it with a cap and vegetation
- Wet-closing (flooding tailings areas) Pond 2
- Enlarging Pond 3 to handle a 100-year flood event
Groundwater interception trenches were installed to divert ground water to Pond 3 for treatment. The Potentially Responsible Parties (PRPs) designed the selected remedy in late 1991, and began cleanup activities in mid 1992; construction was completed in 1995.
Five Year Review (2010-2011)
In 2010-2011, EPA conducted a five year review of the remedy. The review report can be downloaded below or via the Superfund Library. EPA concluded that although the Warm Springs Ponds have not always performed as dictated by the Record of Decision, the remedial action has been protective of human health and the environment.
The area is generally perceived as a success, and is now also a Wildlife Management Area renowned for the many species of birds that utilize the clean waters of the ponds.
- Visit the website of the Arrowhead Foundation, the EPA-funded TAG group for the Anaconda area.
- Additional information and site documents can be found on the EPA Superfund Website.
- The Clark Fork River Technical Assistance Committee (CFRTAC) also provides information and outreach in regards to the Clark Fork River Superfund sites and Operable Units.