Tesla faced environmental scrutiny after drainage district workers in Texas discovered a pipe discharging black liquid from the company's $1 billion lithium refinery. The workers found the unannounced discharge during routine ditch maintenance in January 2026. Tesla had marketed the Robstown facility as an "acid-free clean process" with sand and limestone as main byproducts, but failed to inform local authorities about the 231,000 gallons of treated wastewater daily.

State regulators initially found no permit violations after testing conventional pollutants. However, independent testing commissioned by the drainage district revealed concerning levels of hexavalent chromium—a known carcinogen—as well as arsenic, strontium, and lithium. The 231,000 gallons of daily discharge contained metals not accounted for in Tesla's permit, which lacked requirements for heavy metal testing despite the facility processing lithium.

Tesla disputes the findings, arguing the sampling methodology was inappropriate since it occurred downstream rather than at the outfall pipe. The company maintains compliance with all permit requirements. The dispute centers on what the permit should have covered, with the drainage district's lab detecting a chemical fingerprint matching Tesla's processing. No laws have been violated, raising questions about permit adequacy for industrial wastewater from battery processing facilities.