Oil and gas companies operating in Colorado have submitted hundreds of environmental impact reports with “falsified” laboratory data since 2021, according to state regulators.

Colorado’s energy and carbon management commission (ECMC) said on 13 December that contractors for Chevron and Oxy had submitted reports with fraudulent data for at least 344 oil and gas wells across the state, painting a misleading picture of their pollution levels. Consultants for a third company, Civitas, had also filed forms with falsified information for an unspecified number of wells, regulators said.

Some of the reports, which were conducted and filed by the consulting groups Eagle Environmental Consulting and Tasman Geosciences, obscured the levels of dangerous contaminants in nearby soils, including arsenic, which is linked to heart disease and a variety of cancers, and benzene, which is linked to leukemia and other blood disorders, among other pollutants, according to the commission.

“I do believe that the degree of alleged fraud warrants some criminal investigation,” said Julie Murphy, the ECMC director, in November.

Regulators first revealed in November that widespread data fabrication had occurred, noting that the companies had voluntarily disclosed the issue months earlier. Last week, as officials specified which sites were known to be affected, the New Mexico attorney general’s office said it was also gathering information about the consulting groups’ testing methods.

“This highlights the whole problem of our regulatory agency relying on operator-reported data,” said Heidi Leathwood, climate policy analyst for 350 Colorado, an environmental non-profit. “The public needs to know that they are really being put at risk by these carcinogens.”

Paula Beasley, a Chevron spokesperson, wrote via email that an independent contractor – which ECMC identified as Denver-based Eagle Environmental Consulting – notified the company in July that an employee had manipulated laboratory data.

“When Chevron became aware of this fraud, it immediately launched an investigation into these incidents and continues to cooperate fully and work closely with the Colorado Energy and Carbon Management Commission,” Beasley wrote. “Chevron is shocked and appalled that any third-party contractor would intentionally falsify data and file it with state officials.”

Jennifer Price, an Oxy spokesperson, also wrote via email that a third-party environmental consultant informed the company about employee-altered lab reports and associated forms. “Upon notification, we reported the issue to Colorado’s Energy and Carbon Management Commission and are reassessing the identified sites to confirm they meet state environmental and health standards,” she added.

In emailed responses, Tasman Geosciences spokesperson Andy Boian said that Tasman’s data alterations were the work of a single employee and were “minor” in nature, and presented “no human health risk”. But Kristin Kemp, the ECMC’s community relations manager, said the commission’s investigation had not yet confirmed whether that was true.

“What we can say already is that the degree of falsified data is vast, from seemingly benign to more significant impact,” she said.

Boian also said Tasman “has filed legal action” against its former employee.

Civitas and Eagle Environmental Consulting did not respond to requests for comment.

Across the US, cash-strapped state regulators have long outsourced environmental analysis to fossil fuel companies, who self-report their own ground-level impacts. But the revelations about widespread data fabrication in Colorado – the fourth-largest oil- and gas-producing state in the US – raises questions about whether operators and their consultants can truly self-police.

“It’s obvious: if you want the oil and gas industry to pay you money for a service, you better not find any big problems, or they’re not going to pay you,” said Sharon Wilson, a former consultant for the oil and gas industry who is now an anti-fracking activist in Texas. She said she left her post after her employer’s findings, which she described as trustworthy, were routinely ignored by industry.

It is not uncommon for hired consultants to misreport numbers in a way that benefits their clients in the fossil fuel industry, said Anthony Ingraffea, emeritus professor of civil engineering at Cornell University. In 2020, he published a study that found widespread anomalies in how methane emissions were reported across fracking sites in Pennsylvania.

“Make sure that the responsibility – the regulatory responsibility, the moral responsibility – is as uncertain as your lawyers can set it up to be,” he said of the practice of outsourcing environmental impact studies. “In other words, point to somebody else.”

In an email, Kemp said that companies, contractors and regulators support one another like legs on a three-legged stool, with each trusting the other to pull its weight. She explained that regulators such as the ECMC will always be at least somewhat dependent on self-reported data, due to the impracticality of monitoring hundreds of operators at thousands of sites – but that existing processes may need reconsideration.

“ECMC’s regulatory workflow is grounded in an expectation that people abide by the law, with reasonable measures in place to ensure that to be the case,” she wrote. “But if we determine we can no longer rely broadly on receiving accurate information, we’d need action – and the scope and scale of that action will be determined by what we learn during the ongoing investigation.”

According to the commission, 278 of the wells disclosed so far to have falsified information are operated by Chevron, which contracted with Eagle Environmental. Sixty-six belong to Oxy, a Houston-based energy firm which contracted with Tasman Geosciences. Civitas, which also worked with Eagle Environmental Consulting, disclosed it too had filed falsified data, but has yet not shared information about which of its sites were affected.

Most of the wells in question are in rural Weld county, in north-eastern Colorado, which is home to 82% of the state’s oil production and contains more than half of its gas wells. However, regulators revealed that some of the sites with falsified data are within miles of Fort Collins, Greeley and Boulder. About half are no longer operational and had been deemed safely remediated by the state.

So far, the only sites shared with the public have been those self-reported by the operators, rather than discovered by the ECMC. “It’s likely more sites will become known as the ongoing investigation unfolds,” Kemp wrote.

Eagle and Tasman, the consultants who allegedly provided false data, also work outside the state, raising concerns their employees may have submitted fraudulent data elsewhere.

“We believe that this is potentially of such danger and magnitude that the situation warrants further inquiry,” said Mariel Nanasi, executive director of the Santa Fe-based non-profit New Energy Economy.

Lauren Rodriguez, director of communications for New Mexico’s office of the attorney general, confirmed on 16 December that the office was indeed looking into the allegations around the consulting groups’ work.

“The single Tasman individual involved in the data alteration did not do any work for Tasman in [New Mexico], or any other states,” Boian said by email.

Kemp, the ECMC spokesperson, said it was still unclear why two independent third-party consultants came forward to self-report data falsification around the same time. But the consequences could be serious: forging an official document filed to a public office is a class 5 felony in Colorado, punishable by one to three years in prison and up to $100,000 in fines. The ECMC will also consider fines and other enforcement actions, she said.

The Colorado attorney general’s office declined to comment on the ongoing investigation. And while the alterations originated with the hired consultants, Kemp noted that the buck ultimately stops with the oil and gas operators.

“Regardless of who’s at fault, the burden of responsibility falls to the operator,” she said.