Groups Take Legal Action to Stop Aluminum Factory’s Illegal Mercury Pollution in Ohio River

Alcoa Smelting Plant Hit with Notice of Intent to Sue for Violating Legal Limits for Toxic Metals

Edward Smith, 

Tom Pelton, Environmental Integrity Project, (443) 510-2574 or

Evansville, IN -- The Sierra Club and Environmental Integrity Project sent a notice of intent to sue the Alcoa Warrick aluminum smelting plant in Indiana for repeated violations of the Clean Water Act, including dumping illegal amounts of mercury, a potent neurotoxin, into the Ohio River.

Under federal law, plaintiffs must send such a notice to defendants at least 60 days before filing a lawsuit under the Clean Water Act, and also notify the Indiana Department of Environmental Management and U.S. Environmental Protection Agency.

Located in the southwestern corner of Indiana near Evansville, the 63-year-old Alcoa Warrick smelter was highlighted in a recent Environmental Integrity Project report as the aluminum industry’s worst violator of water pollution laws in the U.S. Aluminum is vital for a clean energy future, but the U.S. plants that produce this light-weight and durable metal are old and have failed to invest in modern pollution controls.

The Warrick smelter violated its water pollution control permit at least 101 times between 2018 and 2023. Thirty-two of these violations in 2022 and 2023 were for releasing illegal amounts of mercury pollution into the Ohio River. 

“This aluminum smelting facility is blowing past limits for mercury that have been put in place to protect the water quality of the Ohio River,” said Meg Parish, Senior Attorney for the Environmental Integrity Project. “It is past time for Alcoa to comply with the Clean Water Act and install modern wastewater treatment systems to reduce this pollution.”

Under the federal Clean Water Act, Alcoa could be required to take action to reduce its pollution to meet legal limits and face penalties of up to $64,618 per day for each of numerous violations.

"The Ohio River doesn't belong to Alcoa to pollute with impunity; it belongs to everyone to use and enjoy without fear of being poisoned," said Joab Schultheis, Energy Committee Chair, Hoosier Chapter Sierra Club. "I'm hopeful this notice will be enough for Alcoa to agree it needs to comply with our clean water safeguards."

The notice of intent to sue sent by the two organizations today said that toxins from the Warrick smelter have repeatedly exceeded permitted limits for not only mercury, but also several other pollutants that threaten aquatic life and human health, including aluminum, chlorine, copper, fluoride, nickel, zinc and the acidity of its discharges.

At one Warrick plant outfall monitored on June 30 of this year, the amounts of mercury and zinc discharged from the plant were about 20 times the legal limit, and the amount of copper more than triple permitted levels, according to the notice. On May 31, effluent from the plant had more than 13 times the legal limit for aluminum discharges.

“Members of the Sierra Club Hoosier (Indiana) chapter are avid bird watchers along the Ohio and in the area around Newburgh, regularly walk along the Ohio River, drink treated Ohio River water and otherwise use the Ohio River downstream of the Alcoa Warrick complex and discharges,” the notice states. “These members have been injured and continue to be injured by the [Alcoa] pollution.”

The waters downstream from the plant have been designated as “impaired” (or unusable) by the state for fishing or recreation because of their high levels of mercury and other pollutants.

For a copy of the notice, click here.

The Environmental Integrity Project is a nonprofit organization, based in Washington, D.C. and Austin, Texas, dedicated to enforcing environmental laws and strengthening policy to protect public health and the environment.

About the Sierra Club

The Sierra Club is America’s largest and most influential grassroots environmental organization, with millions of members and supporters. In addition to protecting every person's right to get outdoors and access the healing power of nature, the Sierra Club works to promote clean energy, safeguard the health of our communities, protect wildlife, and preserve our remaining wild places through grassroots activism, public education, lobbying, and legal action. For more information, visit