While air pollution in the Mon Valley has been the focus of environmental concerns and lawsuits for many years, the non-profit Three Rivers Waterkeeper is also looking at water quality, and has a new opportunity to monitor a chemical plant that discharges pollution into the Monongahela River.
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A boat trip to Synthomer Jefferson Hills
On a bright fall day, the Waterkeepers took their boat out on a beautiful stretch of the Monongahela River, near the Elizabeth Bridge, 23 miles from the point in Pittsburgh. People were fishing off one of the banks and geese and a blue heron were in the water nearby. The river, once an industrial powerhouse, still has plenty of industries along its shores.
Captain Evan Clark secured the Three Rivers Waterkeeper’s boat at one spot where Synthomer Jefferson Hills LLC, a chemical resins manufacturing plant, releases stormwater and other wastewater into the river. These outfalls are regulated by a water pollution discharge (NPDES) permit by the Pennsylvania Department of Environmental Protection.
Clark hopped out and started digging in the black-colored muck on the river’s edge.
“There’s a real strong petrochemical type of smell in the sediment right here,” he noticed. His digging created a small pool of water with a colorful sheen.
“Whenever we are moving the sediment around, and seeing that sheen, that is another thing that leads us to believe that this is not a natural process but is because of industrial activities,” said Koa Reitz, an environmental scientist with the Waterkeeper group.
She crouched down to scoop the muck into a jar. They planned to send this sample to a lab. The Waterkeepers want to know whether it contains chemicals, oil and grease.
The chemical plant has exceeded its pollution discharge limits
They’re interested in the Synthomer plant because it’s exceeded its water pollution limits more than any other industry along the Mon, by far, according to the group’s analysis.
The Waterkeepers looked at publicly available data from state and federal government databases, analyzing the compliance reports of industries with Clean Water Act permits to discharge wastewater into the Mon, Allegheny and Ohio river watersheds in southwestern Pennsylvania between 2019 and 2024.
They found that the Synthomer plant, formerly Eastman Chemical until 2023 (and before that, Hercules Chemical), exceeded its permit limits 281 times, accounting for 76% of all the exceedances of the 13 facilities they analyzed along the Mon River watershed. Most of the plant’s exceedances were for aluminum and zinc.
In 2023, Eastman agreed to pay a $2.4 million fine to the U.S. Environmental Protection Agency and the DEP for alleged pollution of the Mon River, including discharges of oil, zinc and xylene. The plant also had violations of the Clean Air Act and for hazardous waste management. Eastman, and later Synthomer, agreed to fix the problems in a consent decree.
But exceedances of its permit continued from January 2024 through 2025. The plant reported exceeding its limit 34 times for aluminum, three times for chlorine, once for oil and grease and twice for total xylenes, according to the U.S. EPA’s compliance history website.
“They’ve been known to exceed for xylenes, which is in a suite of chemicals called B-TEX chemicals, which are volatile organic compounds,” said Reitz. “And so part of the reason that we are concerned about this is because we know that they use these things, we know that there have been exceedances of their permit of these things.”
In an email to The Allegheny Front, Synthomer said it continues to comply with the ongoing 2023 consent decree and “performs reporting in compliance with its 2023 NPDES permit.”
The Elizabeth Dam removal made this monitoring possible
There is another reason the Waterkeepers are now starting to take water and soil samples from Synthomer’s outfalls: because they can. Until now, the river has been too high. Then, last summer, the U.S. Army Corps of Engineers removed the 117-year-old Elizabeth Locks and Dam. With the dam gone, the river level is lower in front of Synthomer’s plant.
“On the upper side, water dropped a ton,” Clark said. “All of a sudden, not only are we able to access outfalls safely, but we’re also able to see a lot of the sediment that was under four feet of water, and we’ve seen some stuff that has caused us to ask a lot more questions.”
Tracking Synthomer’s wastewater to the West Elizabeth Sanitary Authority
While Synthomer’s stormwater and some wastewater move through its outfall points into the Mon, the Waterkeepers are concerned about Synthomer’s industrial wastewater, which comes from its production processes. That waste gets sent to the local sewage treatment plant.
“We’ve been learning a lot more about Synthomer’s connection to West Elizabeth Sanitary Authority,” said Hannah Hohman, environmental steward for the Waterkeepers group.
“We’re trying to learn if there are pollutants that are going from Synthomer or any industrial facility to a wastewater treatment plant that isn’t being properly treated for, or is not being tested for,” Hohman said.
One of their concerns is that zinc and other chemicals in the industrial waste could disrupt the municipal sewage treatment plant.
“That is something that has…happened, for example, with fracking waste going into wastewater treatment plants. Some of that waste could then be discharged out into the river through their outfall there,” Clark said.
The West Elizabeth sewage treatment plant is currently seeking a renewal of its own NPDES water pollution permit from the DEP. The draft of that permit creates, for the first time, a limit for zinc in its discharge, which is meant to protect the Mon River.
“These limits are necessary to achieve water quality standards in the receiving waters,” a DEP fact sheet about the draft permit states. “The permittee has not demonstrated the ability to achieve these limits as of the effective date of the permit.” It gives the sewage plant two years after the permit goes into effect to meet the new zinc standard.
In an email to The Allegheny Front, the West Elizabeth Sanitary Authority (WESA) said Synthomer pretreats its wastewater before sending it to the sewage treatment plant and that “Synthomer has been compliant with all rules and regulations of WESA.”
In a letter to the DEP in August, consultants for WESA said the plant had not been testing the wastewater it receives from Synthomer for zinc, but that it planned to do so.
The letter said the sewage treatment plant also gets wastewater from a former industrial waste landfill, though two samples of that wastewater did not show detectable levels of zinc. The landfill took resin waste in the 1950s and ‘60s and is now a Superfund site. Zinc can also come from corrosion of household plumbing fixtures and pipes.
The draft permit for WESA will be open for public comment, although the timing is not yet known.
The DEP did not answer questions about Synthomer or the new zinc limits in WESA’s draft NPDES permit in time for publication of this story. A spokesperson said answers are forthcoming.
Sampling effluent from the West Elizabeth wastewater treatment plant
Captain Clark and his crew sampled under the Elizabeth Bridge at the outfall of the West Elizabeth sewage treatment plant, where it discharges treated wastewater into the river.
Their results, provided in an email to The Allegheny Front, found detectable levels of zinc and numerous other industrial chemicals. At Synthomer, the Waterkeepers’ soil samples had detectable levels of oil and grease, aluminum and some metals.
“It’s a big learning curve of trying to understand how waste is moving and then how it’s interacting with our waterways,” Hohman said.
They plan to do more sampling in this part of the Mon, keeping an eye on Synothomer and other industries to track water pollution in Pittsburgh’s rivers.
Correction: According to the Three Rivers Waterkeeper, Eastman/ Synthomer had 281(not 282) exceedances of its NPDES permit limits from 2019-2024. The story has been edited to reflect this correction.
Note: Three Rivers Waterkeeper receives funding from The Heinz Endowments, the Foundation for Pennsylvania Watersheds and the Pittsburgh Foundation, as does The Allegheny Front.
