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MARIETTA – The City of Marietta has placed a proposal for groundwater monitoring wells on the back burner after determining they would provide little early warning of contamination from injection wells and could create another potential pathway into the city's aquifer.
Marietta Water Superintendent Steve Eddy said he discussed the monitoring wells with the Ohio Environmental Protection Agency because one would have been close to an existing oil or natural gas production well. It was determined that contamination would likely be detected in the production well first.
The monitoring wells were proposed in response to concerns over potential contamination of the city's drinking water wells by injection wells, into which production waste from oil and gas wells mixed with salt water, called brine, is placed for disposal. Some residents and community leaders have said they believe the large number of injection wells in Washington County pose a threat to drinking water, as injection well waste has migrated to production wells in at least one instance.
Drilling a monitoring well deep enough to provide useful information could also create a conduit for brine to reach the aquifer, Eddy said.
"The risk kind of outweighs any benefits that we would see from it," he said.
The city tests selected wells monthly for volatile organic compounds, or VOCs, which the U.S. EPA identifies as common groundwater contaminants. Eddy said the department has not detected any changes. The city also tests monthly for chloride and conductivity.
Eddy said PFOS has been detected in all or most of the city's wells. Used for decades in the Teflon-production process at the Washington Works plant in Wood County, PFOS is part of a larger group of long-lasting manufactured chemicals known as per- and polyfluoroalkyl substances, or PFAS. The city samples for PFOS annually to build a data set and monitor trends, he said.
The testing is occurring as the city considers an assessment from its Ad Hoc Injection Well Committee. The assessment was presented Monday by former Councilman Ben Rutherford, who was also on the committee.
It ranked five potential contamination sources from highest to lowest risk: surface spills, the Muskingum River, an active oil and gas well within the water field, atmospheric deposition and possible vertical infiltration from nearby Class II brine injection wells.
The assessment said vertical migration is possible and that the region's drilling history and faults mean a pathway to the surface may exist. However, it said "no evidence or data of vertical risk to the city's water wellfield is established by Exhibit F's arguments."
That language does not conclude that injection wells pose no threat. It limits the finding to whether Exhibit F established evidence of vertical risk to the city's water field. Exhibit F is a technical report by geologist and geophysicist Catherine M. Helm-Clark filed in an the Ohio 10th District Court of Appeals challenging permits for the proposed Stephan No. 1 injection well near the Bramblewood Heights and American Growers No. 4 well along Ohio 7 south of Marietta.
Stephan No. 1 is classified as a Class I injection well, which according to the U.S. EPA and the Ohio EPA are wells that inject waste thousands of feet below drinking water aquifers into isolated rock formations. These wells are subject to stricter siting, construction, monitoring and testing requirements than Class II wells. Class II wells are federally regulated under the Safe Drinking Water Act and are used only for fluids associated with oil and gas production. They dispose of brine and other liquid waste by injecting it deep underground into porous rock formations, sealed off from groundwater by layers of rock and casing. More than 180,000 Class II wells operate nationwide.
According to the court petition, Helm-Clark identified 116 water wells within 2 miles of Stephan and 44 within 2 miles of American Growers. She identified 191 oil and gas wells near Stephan and 202 near American Growers.
The petition cited an ODNR investigation finding that approximately 4.2 million gallons of waste from the Redbird No. 4 Class II injection well near Dunham Township migrated to at least 28 production wells, some as far as 5 miles away. ODNR found that none of the sampled water wells was affected by Redbird brine.
Mike Chadsey of the Ohio Oil and Gas Association said the association maintains that properly located and inspected injection wells operate safely. Possible pathways involving inactive conventional wells should be addressed by plugging orphaned, abandoned and non-producing wells, he said.
Chadsey said ODNR's decision to halt operations at four wells and examine water chemistry, pressure and geology shows the regulatory process is functioning.
"We've got 230," he said, referring to Ohio's Class II disposal wells. "We're talking about four, right? So this is not a widespread, systematic problem."
Closing injection wells would not eliminate oil and gas wastewater, Chadsey said. It would require more brine to be trucked elsewhere, increasing traffic and placing additional demands on other disposal facilities.
Roxanne Groff, a Buckeye Environmental Network advisory board member, called the city committee assessment incomplete and questioned the scientific basis for its rankings.
"If it isn't linked to a scientific study, then somebody just made up that ranking list," she said.
Groff pointed to the Southeast Ohio Regional Water Study as a potential source of additional data. According to the Ohio Water Development Authority's 2025 annual report, the authority awarded Ohio EPA $2.25 million for the study.
The project will assess water availability, use, quality and drinking-water access through 2050. Groff said she believes the data will help inform future industrial development. The official description refers broadly to future development but does not identify particular industries.
A preliminary Washington County groundwater map from the regional study includes data on bacteria, nutrients, total dissolved solids, metals, PFAS, arsenic, VOCs and bromide. Total dissolved solids, or TDS, include minerals, salts, metals and organic matter dissolved in water.
Groff said her reading of the preliminary map showed an area near the Muskingum River in the "exceeding criteria" category for six of the eight groups. The preliminary data do not identify the contamination sources or establish a connection to injection wells.
Eddy said Marietta's new water-treatment facility is approximately 30 to 45 days from full operation. A contractor is preparing a bid for additional PFOS treatment, which Eddy said is not expected to increase costs for Marietta or Reno water customers.
Rutherford was not immediately available for comment. ODNR and DeepRock Disposal Solutions also were not immediately available.