A Texas Commission on Environmental Quality investigator tested wastewater from the Tesla Inc. lithium refinery near Robstown on Feb. 12. The state regulator didn’t look for contaminants since found in samples tested by the county wastewater district.
Travis Prater/Texas Commission on Environmental Quality
After Texas regulators said Tesla Inc.’s lithium refinery near Corpus Christi wasn’t violating its permits by discharging glack wastewater into a drainage ditch, independent water testing commissioned by a local drainage district found two toxic metals and other contaminants..
Eurofins Environment Testing, an accredited lab with locations across the globe, reported traces of hexavalent chromium, a well-known carcinogen, and arsenic, an environmental poison. Nueces County Drainage District No. 2, which manages the ditch, commissioned the test.
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Neither hexavalent chromium nor arsenic is included as an allowable discharge pollutant in Tesla’s wastewater permit.
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“The results are quite disturbing,” Frank Lazarte, an attorney representing the drainage district, wrote in a cease and desist letter to Tesla’s associate general counsel. It is asking Tesla to stop discharging wastewater into the ditch until the lab results can be discussed.
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Jason Bevan, senior manager of site operations for the plant in Robstown, said the company remains in compliance with all requirements of its state-issued wastewater discharge permit, including applicable water quality standards.
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“Tesla routinely monitors and tests its permitted wastewater discharge,” he said in a statement. “Tesla is currently reviewing the letter from Nueces County Drainage District #2 and looks forward to working cooperatively with the district to address their concerns.”
Tesla’s lithium refinery is seen in Robstown, Texas, on Sunday, Aug. 24, 2025.
Andrea Leinfelder/Houston Chronicle
The Teaxas Commission on Environmental Quality sampled and tested Tesla’s wastewater discharge in February and said the company was in compliance with its permit, Bevan said.
But the state environmental regulator didn’t look for heavy metals in February. Its water sample tested for dissolved solids, oil and grease, chlorides, sulfates, temperature and oxygen — all of which were within the bounds of Tesla’s permit.
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Victoria Cann, a spokesperson for TCEQ, said Tesla’s facility was required to conduct initial sampling of the wastewater discharged from its outfall pipe for conventional and non-conventional pollutants, including metals used at the facility and toxic pollutants believed to be present in the discharge.
The TCEQ industrial permits team reviewed those initial submitted results and had no concerns, Cann said. Therefore, it didn’t require an amendment to the permit to include additional wastewater limitations or monitoring requirements.
The regulator initiated its February investigation after workers for the drainage district found an unfamiliar pipe stretched across its easement. The workers reported black liquid expelling into the ditch. The drainage district, which manages the ditch area, was unaware that the state had given Tesla permission to use it.
District officials said they were confused about how the state could allow Tesla to discharge an average 231,000 gallons of lithium refinery wastewater each day into the district’s ditch without notification. TCEQ said it doesn’t communicate directly with local drainage districts as part of the permitting process.
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Independent test finds metals, other contaminants
Volunteer drainage district engineer Aref Mazloum said TCEQ didn’t test for heavy metals in its compliance investigation because that hadn’t been part of a complaint filed by the district earlier this year. When the investigation concluded, he said he requested the results and commissioned the third-party wastewater testing to see what else might be in the water.
Eurofins conducted its testing earlier this month, according to its report. It placed a sampling machine in the wastewater for 24 hours to monitor and collect the discharge, then sent the results to its San Antonio lab on April 7.
The unnamed drainage ditch is less than a mile upstream of the discharge pipe from the Tesla Inc. lithium refinery near Robstown.
Travis Prater/Texas Commission on Environmental Quality
The state’s wastewater permit requires that sampling be conducted at the outfall pipe. The third-party report sampled water from the drainage ditch, Cann stated, which is inappropriate for use by TCEQ for permitting decisions.
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As soon as district staff saw the lab results, they notified a raft of local elected officials, said Mazloum, who also recently started working as an engineer in the water supply division at TCEQ and is a mechanical engineering assistant professor at Texas A&M University-Corpus Christi.
He said he does not want to be seen as driving Tesla out of Robstown but that heavy metals must be remediated from the county’s wastewater. He said he wouldn’t be able to sleep if he were to keep quiet about the information.
“Public safety is my highest priority,” Mazloum said. “Secondly would come the economy.”
Concerns about environmental and infrastructure impacts
To safely manage its hyper-saline and toxic discharges, the electric vehicle company should design and fund an on-site multi-stage wastewater treatment plant, he said. The process would remove heavy metals and use industrial reverse osmosis technology. Then, Mazloum said, Tesla could use district infrastructure to discharge wastewater again.
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“The resulting clean water will then be discharged and nothing will happen to the infrastructure, the ditches, the plants, the fish, the frogs, the animals, the people from that water,” he said.
The concentrated brine solution created by that on-site treatment would have to be hauled to a hazardous waste facility or processed through a zero-liquid discharge system, he added.
While water in the ditch does not reach the drinking water supply, people can be affected in other ways such as by eating fish caught nearby or by facing increased flood risk if the ditch infrastructure erodes, Mazloum said. Wastewater pooling in the drainage ditch flows to Petronila Creek and ultimately to Baffin Bay, a longtime fishing spot suffering from decades of deteriorating ecosystem health.
Nueces County groundwater is known to contain some arsenic, said Chris Cuellar, a retired chemical plant worker who spent 10 years managing wastewater operations at one of the region’s largest industrial facilities. Eurofins tested the wastewater from the ditch, rather than from Tesla’s outfall pipe, so it’s possible there was residual arsenic from a nearby pond overflow that leached into the ditch, for example, rather than coming from the industrial process itself, Cuellar said.
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The metallic particles of arsenic in the sample measured 0.0025 milligrams per liter, a fraction of the federal limit for drinking water, which is 0.01 milligrams per liter.
The Eurofins sample is good to have, Cuellar added, but offers a one-time baseline of that day. “It’s not what it always is or what it has been,” he said.
Debate over source and risks of contaminants
In the wastewater sample Eurofins tested, the concentrations of lithium, strontium and vanadium were abnormally high compared to levels in rainwater or groundwater, according to Lazarte, the attorney. “The three metals/chemicals act like a chemical signature pointing back to the battery processing facility,” he wrote.
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Lithium is the active material inside rechargeable batteries. Tesla is seeking to increase the domestic supply of battery-grade lithium hydroxide at the nearly $1 billion lithium refinery plant that began operating in late 2024. It processes spodumene, an often yellowish mineral and a commercially important source of lithium.
A report written by Mazloum that’s been distributed to legislators and will soon be discussed with Robstown residents calls the traces of lithium a “fingerprint at a crime scene.”
The electric vehicle company’s wastewater permit does not monitor for lithium and TCEQ did not test for it in February. In the first 60 days of the facility’s operation, Tesla had to test for a variety of metal and chemical pollutants not listed in its permit, but lithium was not among them.
When the permit was being considered and public comments expressed concern about how the facility would affect the environment, Kelly Keel, TCEQ’s executive director, said the wastewater wasn’t expected to contain any residual lithium, chemical runoff or other harmful pollutants.
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No surface water intake for domestic drinking water supplies is located within five miles downstream of the wastewater discharge point so there would be no impact on water wells or drinking water, Keel said at the time.
Before the permit was issued, TCEQ determined that Tesla’s wastewater discharge plan would meet state requirements and protect the environment, water quality and human health.
Tesla’s lithium refinery is seen in Robstown, Texas, on Sunday, Aug. 24, 2025.
Andrea Leinfelder/Houston Chronicle
Mazloum’s report noted that Eurofins detected 1.17 milligrams of strontium per liter of water in the sample and said long-term exposure could affect bone density and kidney function in humans and wildlife.
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His report also flagged heightened levels of several chemicals consistent with industrial discharge including manganese, iron, phosphorus, calcium, magnesium and potassium. Manganese, a battery process tracer, can have neurological effects at chronic doses, the report stated. Too much iron can stain the ditch’s infrastructure and too much phosphorus can cause algae blooms that starve waterways of oxygen.
The risk of algal growth is amplified by ammonia, which the lab results found in the form of nitrogen at 1.68 milligrams per liter of water. “At this level,” Mazloum’s report said, it is “directly toxic to fish and aquatic invertebrates. Imagine a slow-acting suffocant for anything that lives in the water.”
The high sodium concentrate, combined with elevated calcium, magnesium and potassium, creates a near-brackish water condition that’s from 10 to 20 times saltier than normal surface water, according to Mazloum’s report.
“This directly threatens the drainage ditch’s ability to protect the neighborhoods,” Lazarte wrote. “Plants hate salt the same way you’d hate drinking ocean water when you’re thirsty.”
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As salt draws out the moisture of plant roots, it kills the grass and ground cover lining the walls of the ditch. Then the bare soil washes away in rain, Mazloum said, and as the drainage ditch walls collapse, the channel loses the capacity to carry stormwater away from homes and raises the risk of floods during heavy rains.
When a state investigator went to test the wastewater in February, it appeared clear as it flowed downstream, according to state records. Along the banks and in the ditch, there was a heavy growth of algae and vegetation.
News of the contaminants Eurofin found in the wastewater sample comes as South Texas faces a serious water crisis. Corpus Christi is in the midst of developing groundwater projects to try to stave off imminent depletion of its dwindling reservoirs, and it expects to enact emergency water-use restrictions in September if weather patterns don’t change.
Robstown is 16 miles west of Corpus Christi. The Tesla situation is the first time the drainage district has had to deal with discharge water quality, said Steve Ray, a consultant for the district. The drainage district typically focuses on maintaining the integrity of its ditches and flood preparedness, he said.
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“We want to make sure that this is environmentally safe for our citizens and for our employees who have to work in those ditches,” Ray said. “We also want to make sure it’s environmentally safe and sound for the future—for our kids, our grandkids.”
Mazloum recommended that Robstown residents stay away from the ditch. It’s off U.S. 77 and County Road 28.