Callahan Mine

Overview

The Callahan Mine operated from 1968 to 1972 as an open-pit mine extracting zinc, copper, lead, arsenic, and cadmium ore near Brooksville, Maine. The site sits on the EPA's National Priorities List and includes a submerged open pit, about 1.7 million cubic yards of waste rock, a 21-acre tailings impoundment holding roughly 700,000 cubic yards of tailings, and portions of the former Goose Pond estuary that were used as a settling basin during mining.

EPA has identified 20 contaminants of concern across soil, sediment, groundwater, surface water, and leachate. Heavy metals, including arsenic, cadmium, copper, lead, manganese, thallium, and zinc, appear across multiple media. Two PCBs, Aroclor 1242 and Aroclor 1248, were found in soil. Groundwater in some areas holds metals at levels unsafe for drinking. In Goose Pond, copper, lead, and zinc from mine waste threaten shore wading birds and bottom-dwelling organisms, and clams contain elevated lead levels. Waste rock with unsafe arsenic and lead levels was also found on nearby residential properties before cleanup began.

The site is divided into three operable units (OUs). OU1 addressed residential PCB contamination. Soil cleanup on residential properties finished in 2011, and PCB work in the mine operations area was done by September 2013. OU3 covers sediments and a cap. A horizontal drain and passive treatment system went in during fall 2015, a stone buttress was completed in 2020, and a cover system was installed in 2021. In 2023, EPA began excavating contaminated salt marsh and Goose Pond sediments, finishing in 2024 and installing a subaqueous cover in Dyer Cove. Salt marsh and upland restoration wrapped up in fall 2024. Final grading and a permanent geomembrane cap for the waste rock piles are scheduled to start in spring 2026. OU2 addresses sitewide groundwater and is still in the investigation phase, with a remedial investigation and feasibility study estimated to conclude between March and May 2028.

Human exposure to contaminants in soil, sediment, and groundwater has been brought under control per EPA assessments, but groundwater migration is not yet stabilized and physical construction is not complete. A sitewide removal action is planned for mid-2026. Institutional controls restrict land uses that could expose people to remaining hazards. EPA conducted water and groundwater sampling in summer 2024 and plans additional sampling between May and August 2025. The most recent five-year review was completed on April 16, 2026.

Site records are available at the Brooksville Free Public Library and at the EPA Region 1 Records and Information Center in Boston.

(NOTE: This summary was created based on all information available on the EPA's official site profile page as of May 29, 2026. To see the most up-to-date information provided by the EPA, visit the EPA's official profile page for this site. For questions, or to politely encourage the EPA keep their profile pages current, contact the EPA Community Involvement Coordinator or Remedial Project Manager assigned to this site.)