Oil and Gas Companies in Colorado Used Banned Toxic Chemicals, Part Two

This story by Jennifer Oldham was originally published by Capital & Main on October 17, 2025. We are sharing it in two parts.

Read Part One

Health researchers in Colorado had a head start on chemicals used in fracking after the state was among the first to require operators to disclose chemicals to FracFocus. Even so, it allowed companies to designate substances as trade secrets. But the state’s new chemical disclosure law does away with this loophole, providing an unprecedented look at the slew of toxic compounds operators use to coax oil and gas from deep underground.

A search of the Energy and Carbon Management Commission’s chemical disclosures database showed that operators reported using chemicals known as “quaternary ammonium compounds” at 59 locations over the last 15 months. Scientists say that these substances carry higher risks of exposure for children and pregnant women. The list surprised public health researchers.

“I was really shocked,” said Tracey Woodruff, a professor and director of a program on reproductive health and the environment at the University of California, San Francisco. “Quaternary ammonium compounds are quite toxic from a reproductive and developmental standpoint.”

Woodruff added that transparency requirements for chemicals used in fracking should be “standard” across all states. They are not. Besides Colorado, only California currently requires companies to report all chemicals they are using in operations. Ohio and West Virginia require the disclosure of most chemicals used in drilling.

The elimination of the trade secret loophole in Colorado’s chemical disclosure law prompted operators to list chemicals left off FracFocus documents. For example, on one well pad in Weld County, the state’s busiest oil and gas field, 30 chemicals listed in the ECMC database did not appear in FracFocus. The public health effects of some of these materials are essentially unstudied.

Even so, gaps in chemical disclosures remain, Capital & Main found. Colorado regulators, researchers and public health advocates disagree on whether the 2022 law requires the state’s oil and gas agency to collect disclosures from operators for chemicals used in the drilling process.

Drilling occurs prior to fracking. Physicians and environmental groups say that it’s important to disclose such substances because drilling machinery penetrates aquifers without any concrete casing around the bit, potentially exposing groundwater to contamination.

“We are particularly concerned about the lack of reporting on chemicals used during the drilling phase,” wrote Ramesh Bhatt, conservation chair for the Colorado Sierra Club, in an August letter to the Energy and Carbon Management Commission. “We know from disclosures in other states, as well as from safety data sheets for drilling products, that drilling chemicals can differ significantly from fracking chemicals.”

Lack of disclosure
In Ohio and West Virginia, where companies are required under state law to disclose drilling chemicals, records show that companies used toxic substances that are banned under Colorado law.

“Disclosures of drilling chemicals in Ohio and West Virginia … show that it is especially important for oil and gas companies to disclose their drilling chemicals in Colorado so that residents are not unknowingly exposed to toxic chemicals,” said Dusty Horwitt, an attorney with FracTracker Alliance who has studied state chemical disclosure laws.

Colorado’s oil and gas regulatory agency is focused on implementing the “legislative intent” of the state’s disclosure law, which requires companies to report chemicals used in “oil and gas production operations that are conducted underground,” which it interprets as the fracking process, said Kristin Kemp, the agency’s community relations manager. She added that the agency is also “engaging with stakeholders to evaluate the costs and benefits of extending the reporting requirements beyond the initial focus on production operations.”

Physicians for Social Responsibility Colorado, FracTracker Alliance and Colorado Rising were signatories to the Sierra Club’s August letter. These groups also sponsored a groundbreaking report released in May that revealed the halting rollout of the state’s chemical disclosure law. The analysis found that operators reported chemicals used in only 39% of their operations as of May 1 and that about two-thirds of the firms fracking wells in the state had not made any disclosures at all.

The lack of disclosure meant that “at least 30 million pounds of secret chemicals were injected into more than 600 of the state’s oil and gas wells operated during the first 21 months covered by the law should have been disclosed but were not,” wrote Allison and Horwitt, both with FracTracker Alliance. After the report’s release, ECMC commissioners expressed concern about operators’ lack of compliance with the disclosure law.

“This was, and continues to be, a very long, drawn out process,” said Commissioner Mike Cross at a July 9 public meeting.

During the meeting, Julie Murphy, director of the state’s oil and gas regulator, responded that creating and implementing a new chemical disclosure database was a “complex project that involved many team members.”

Some companies remained out of compliance in July, Murphy said, prompting regulators to issue more than a dozen warning letters. Most of the cases were closed after the firms filed their chemical disclosure reports.

In the months after the study’s release, the rate at which companies disclosed chemicals increased markedly, with compliance hitting about 97% as of early September, Murphy said during a public meeting on September 3.

With Colorado’s chemical disclosure database firmly off the ground, physicians and consumer advocates are turning their focus back to a years-long push to persuade officials to test fracking fluid that flows back out of wells when fracking is completed.

By analyzing chemicals in what’s known as “produced water,” and matching them to what operators reported putting down the well, regulators could determine the veracity of information in the chemical disclosure database, said Bhatt, the Sierra Club conservation chair. Among the substances doctors and researchers are asking regulators to test for is a class of chemicals known as PFAS, or “forever chemicals,” that don’t break down in the environment and are harmful to humans in microscopic concentrations.

Colorado law requires energy companies to provide a written declaration to regulators that the fluids they use contain “no intentionally added PFAS.” In response, the state oil and gas regulatory agency’s Kemp said that as the implementation of the new chemical disclosure law “continues, we will evaluate whether it is necessary to test flowback water to assess compliance.”