ANN ARBOR — After nearly four decades of environmental monitoring and legal battles, the U.S. Environmental Protection Agency has officially designated the former Gelman Sciences site and its spreading 1,4-dioxane groundwater plume in Ann Arbor and Scio Township as a federal Superfund site.
The designation places the contaminated area on the National Priorities List, unlocking additional federal resources and oversight aimed at containing and ultimately cleaning up one of Michigan’s longest-running groundwater pollution problems.
The contamination originated at the former Gelman Sciences manufacturing facility on Wagner Road, where the industrial solvent 1,4-dioxane was disposed of between the 1960s and mid-1980s. The chemical seeped into groundwater and eventually formed a plume that now stretches several miles beneath western Ann Arbor and Scio Township.
Local officials say the new federal designation could finally accelerate a cleanup effort that has stretched across multiple generations of residents.
“Ann Arbor has been fighting for decades to protect our drinking water,” said Mayor Christopher Taylor. “This decision ensures the federal government will now play a larger role in protecting our community and future generations.”
A Pollution Problem Dating Back Nearly 60 Years
The Gelman contamination traces back to 1966–1986, when the company manufactured medical filtration products and used large quantities of the solvent 1,4-dioxane during production.
Waste solvent was disposed of onsite, a common industrial practice at the time. The chemical migrated through soil into groundwater and began spreading underground.
The contamination was first detected offsite in the mid-1980s, triggering investigations by the Michigan Department of Environmental Quality (now EGLE).
Since then, monitoring wells have tracked a slow-moving underground plume that now extends several miles west of Ann Arbor, moving generally toward the Huron River watershed.
Over the years, regulators have required pump-and-treat systems and groundwater monitoring, but critics argue those measures have failed to fully contain the pollution.
Why 1,4-Dioxane Is So Concerning
The chemical at the center of the contamination, 1,4-dioxane, is a synthetic industrial solvent used in manufacturing and laboratory processes.
It is particularly difficult to remove from groundwater because it:
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dissolves easily in water
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does not easily break down naturally
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travels quickly through soil and aquifers
The U.S. EPA classifies 1,4-dioxane as a likely human carcinogen.
Michigan regulators have established strict groundwater cleanup standards for the chemical, and concentrations detected in parts of the plume have historically exceeded those limits.
Because the compound is highly mobile, environmental scientists say it can migrate long distances underground.
Concerns About Ann Arbor’s Drinking Water
The contamination has long raised concerns about potential impacts on Ann Arbor’s municipal drinking water system.
The city draws drinking water from the Huron River, and officials have taken steps over the years to monitor the plume and prevent contaminated groundwater from reaching the river or municipal wells.
Ann Arbor’s water treatment system now includes advanced monitoring programs and testing for 1,4-dioxane.
City officials say current testing indicates the city’s drinking water remains safe.
Results are posted publicly through the city’s environmental monitoring program.
Still, the presence of the plume near municipal water sources has been a point of concern for residents and environmental groups.
What Superfund Status Means
Placement on the EPA’s National Priorities List (NPL) is the most serious designation under federal environmental cleanup laws.
It allows the EPA to:
• conduct expanded investigations
• require responsible parties to fund cleanup
• use federal cleanup funds if necessary
• accelerate long-term remediation planning
The designation also gives federal regulators greater authority to oversee the site and coordinate cleanup strategies.
Environmental advocates have pushed for Superfund designation for years, arguing that state-level oversight had not been sufficient to contain the plume.
A Long Legal and Political Battle
The Gelman plume has been the subject of decades of regulatory negotiations, lawsuits, and cleanup orders.
Gelman Sciences, which was later acquired by Pall Corporation, has been responsible for cleanup under state oversight.
Critics, including local environmental groups and some state lawmakers, have argued the cleanup has moved too slowly and allowed the plume to expand.
U.S. Rep. Debbie Dingell and other federal officials have pushed for stronger EPA involvement in recent years.
With the Superfund designation now in place, federal authorities will take a larger role in directing future remediation efforts.
What Happens Next
EPA officials will now begin the formal Superfund cleanup process, which typically includes:
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Detailed environmental investigation
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Risk assessment
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Evaluation of cleanup alternatives
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Selection of a long-term remediation plan
The process can take years, but federal designation often brings greater resources and stronger enforcement authority than state-led cleanup programs.
For residents in Ann Arbor and surrounding communities, the hope is that the move will finally bring a long-awaited solution to one of Michigan’s most persistent groundwater contamination problems.
Why This Is a Big Michigan Environmental Story
The Gelman plume is widely considered:
• one of Michigan’s largest groundwater contamination cases
• a multi-decade environmental battle
• a major test of state vs. federal environmental oversight
For Ann Arbor residents, the issue has become closely tied to concerns about drinking water protection, environmental accountability, and corporate responsibility.
The EPA’s decision to elevate the site to Superfund status marks the most significant escalation in cleanup efforts since the contamination was first discovered nearly 40 years ago.
