EPA warns of eating fish caught near Windham’s Keddy Mill Superfund Site

By Ed Pierce

Because of the presence of hazardous chemicals called PCBs in sediments resulting in impacts to fish tissue, the Environmental Protection Agency is advising the public not to eat fish from the "Target Reach" of the Presumpscot River between Little Falls and Mallison Falls near the Keddy Mill Superfund Site in South Windham until a comprehensive remedial action there has been completed.

The Environmental Protection Agency is advising residents
not to eat fish caught in the Presumpscot River near the
Keddy Mill Superfund Site in South Windham because
of the presence of hazardous cancer-causing chemicals
called PCBs there. PHOTO BY ED PIERCE

According to an update from the EPA, pending completion of the remedial action, reduction of risks posed by contaminated fish consumption will be achieved using Institutional Controls such as fishing restrictions, fish consumption advisories and engineering controls such as signage to prevent contaminated fish consumption.

“Following the collection and analysis of supplemental fish tissue samples in July 2025, EPA worked with the Maine Department of Environmental Protection (MEDEP) and Maine Center for Disease Control & Prevention (Maine CDC) to determine an appropriate fish advisory,” the bulletin reads. In August 2026, a "Do Not Eat" guideline was posted on the Maine Department of Health & Human Services website for the segment of the Presumpscot River between the Little Falls Dam and the Mallison Falls Dam. EPA will continue to work with various stakeholders to update and enhance engineering controls at the Superfund site adjacent to the Presumpscot River.

Polychlorinated biphenyls, or PCBs, are a group of man-made organic chemicals consisting of carbon, hydrogen and chlorine atoms. PCBs do not readily break down once in the environment and can remain for long periods cycling between air, water and soil. The types of PCBs likely to be bioaccumulated in fish and bound to sediments are the most carcinogenic and studies have shown direct links to cancer.

Manufacturing of PCBs and importation was banned in the U.S. in 1979 based on mounting evidence that they were toxic to human health and the environment.

A note posted on the EPA’s New England website in February 2026 says that following regulatory review and revisions, the Pre-design Investigation Report for the Keddy Mill site was conditionally approved by EPA in August 2025. The results of that report will support development of the design to demolish and remove the mill complex.

Design planning including the work schedule, Project Management Plan development and design of the mill building demolition is underway and is expected to be completed by the end of this year. The EPA estimates that Removal Action implementation consisting of mill building demolition will commence following EPA approval of the design submittals and procurement of a construction contractor by late 2026 or early 2027.

Located at 7 Depot St. in South Windham, the Keddy Mill complex includes a 6.93-acre abandoned mill complex property adjacent to the Presumpscot River. The mill building was constructed in the early 1900s although a sawmill existed there previously.

The sawmill closed in 1822, and the Keddy Mill property was then used as a grist and carding mill. In 1875, the Sebago Wood Board Company acquired the mill site and constructed a pulp mill complex, which included a three-story main mill building, machine room, drying rooms, and a wood preparing house. Between the late 1800s and 1922 additional process buildings/facilities were added, including storehouses, a second railroad siding, the finishing and shipping building, a water tank, machine room, and engine room. The mill was used for pulp and box-board manufacturing through the 1940s.

In 1945, the Keddy Mill shifted from manufacturing paper to steel products such as heavy equipment buckets. Scrap metal was transported by rail cars to the mill and melted into steel billets, which were then used to manufacture steel parts.

By the 1960s and early 1970s, manufacturing included flanges and fire suppression materials. EPA officials say that it was during this period that significant disposal of hazardous substances, including harmful PCBs, may have occurred at the site. A large oil-based fire in 1969 damaged the mill complex and destroyed several blast furnaces and by 1974, a scrap recycler launched operations in the mill building. The property was used as a machine shop and for equipment storage until 1997. 

In 2014, the Keddy Mill site was placed on the EPA’s National Priority List, also known as the Superfund, recognizing it as contaminated and hazardous to human health. In 2023, after years of conducting environmental studies, the EPA Superfund adopted a cleanup and remediation plan based upon an EPA Remedial Investigation Report, human health and ecological risk assessments, the Feasibility Study, and comments received on EPA's Proposed Plan during a 30-day public comment period.

According to the EPA, the Keddy Mill Superfund Site will be cleaned up in multiple phases. The first phase includes demolition and removal of the building, with the potential exception of the westernmost wall, under a Non-Time-Critical Removal Action. Following this work, soil, sediment, and groundwater will be cleaned up under a remedial action. The primary building contaminants which have been determined to exceed acceptable human health standards include PCBs and asbestos.

The complex clean-up will take an additional two to four years following the demolition of the Keddy Mill building, EPA officials say. The Superfund Site cleanup involves excavation and off-site disposal of contaminated soil and debris from the mill property; targeted treatment of soil in support of groundwater cleanup; treatment of groundwater contaminants and contaminated sediments from the Presumpscot River; and restoration of the portions of the Presumpscot River altered by remedial clean-up actions. Once that has been completed, the EPA will mandate land use restrictions to prevent exposure to site-related contaminants in groundwater and fish tissue until clean-up levels are met, and monitoring of groundwater and fish tissue to evaluate the achievement of cleanup levels, followed by Five-Year Reviews to assess the protectiveness of the remedy.

EPA’s Superfund is the federal program that investigates and cleans up the most complex, uncontrolled, or abandoned hazardous waste sites in the country to protect human health and the environment.

In December 2025, the Town of Windham and Maine Department of Environmental Protection signed a Declaration of Environmental Covenant, restricting activities associated with the potential for exposure to contaminated groundwater and associated vapors at the 7 Depot St. parcel. Specifically, the Environmental Covenant restricts the installation of wells and use of groundwater, disturbance of existing monitoring wells, discharge or injection of liquids to the subsurface, construction of structures without appropriate sub-slab vapor barriers and ventilation systems, and excavation without approval from the regulatory agencies. The Environmental Covenant runs with the town-owned 7 Depot St. property is for perpetuity unless the appropriate entities agree to amend or terminate the agreement.

Banning consumption of fish caught from the Presumpscot River near the Keddy Mill will play an important role in site remedies because they reduce exposure to contamination by limiting land or resource use, the EPA says. The ban is intended to limit the public’s exposure to contaminated groundwater and associated vapor that pose threats to future residents and construction workers until groundwater cleanup levels are achieved and fish tissue within the segment of the Presumpscot River between Little Falls (upstream) and Mallison Falls risk-based standards are achieved.

The total cost of the EPA Superfund cleanup for the Keddy Mill site is expected to be about $17 million. <