After years of considering the idea, the U.S. Environmental Protection Agency (EPA) is proposing to add natural gas processors to a list of industrial facilities that must report annually information on chemical discharges and other waste management activities.

Under a proposed rule, EPA would add natural gas processing facilities to the list of industrial sectors currently required to send information annually for the agency’s Toxics Release Inventory (TRI) public database. The rule was published in Friday’s edition of the Federal Register. Public comments will be accepted until March 7.

EPA said it estimates at least 282 natural gas processing facilities in the U.S. would be affected by the proposed rule because they have at least 10 full-time employees and manufacture, process or otherwise use at least one chemical listed by the TRI. The agency said processors use more than 21 different chemicals listed by the TRI, including n-hexane, hydrogen sulfide, toluene, benzene, xylene and methanol.

The proposed rule was first suggested in October 2012, when environmental groups filed a petition with EPA to add oil and gas extraction activities, including hydraulic fracturing (fracking), to its TRI reporting requirements. After the agency didn’t respond to the request, a coalition of nine environmental groups, led by the Environmental Integrity Project (EIP), sued EPA in January 2015.

Nine months later, EPA Administrator Gina McCarthy wrote a letter to EIP stating that EPA “has determined that natural gas processing facilities may be appropriate for addition to the scope of TRI.”

EPA said a survey conducted by the U.S. Energy Information Administration found that there were 517 natural gas processing facilities in the Lower 48 in 2012. The agency estimates more than half of those facilities would meet the TRI reporting requirement threshold.

But in a statement Friday, the EIP said between 281 and 444 natural gas processing facilities would be affected by the proposed rule.

“Today’s proposal by EPA marks significant progress for public health, the environment, and the right to know,” said Adam Kron, a senior attorney for the EIP. “The oil and gas industry releases an enormous amount of toxic pollutants every year, and communities deserve to know what they’re facing. We hope EPA will move swiftly to finalize and implement this simple yet vital public-reporting rule.”

GPA Midstream Association spokeswoman Crystal Myers told NGI on Friday that the organization was still reviewing the rule and had no comment.

EPA said it declined to add fracking chemicals to TRI because producers were already required to disclose the chemicals to state regulators, and the information was subsequently available to the public. The agency also said it wanted to avoid being overwhelmed by TRI reporting from hundreds of thousands of oil and gas sites.

TRI tracks how certain toxic chemicals are managed. Facilities in different industry sectors in the United States are required to submit annual reports over how much of each chemical is released to the environment, recycled or used in energy recovery and treatment operations. TRI was established by Section 313 of the Emergency Planning and Community Right-To-Know Act of 1986 and covers more than 650 toxic chemicals.