A federal judge ordered the U.S. EPA to review and potentially propose updates to its rules for Class II oil and gas waste injection wells by March 2019. Environmental groups have complained that the rules have failed to keep pace with the boom in the number of injection wells resulting from horizontal drilling and hydraulic fracturing.

In a Dec. 28 consent decree, Judge John Bates of the U.S. District Court for the District of Columbia said the EPA, which would have to review its regulations at least every three years, with revisions made as warranted, has more than two years to conduct the initial review and possibly adjust its regulations on injection wells.

"No later than March 15, 2019, EPA shall either (a) sign (and thereafter expeditiously transmit to the Office of the Federal Register) a notice of proposed rulemaking for the revision of the Subtitle D criteria regulations pertaining to oil and gas wastes, 40 C.F.R. Part 257, or (b) sign a determination that revision of the regulations is not necessary," wrote Bates, an appointee of President George W. Bush.

If the EPA finds a need to update its rules for the injection wells, it will have until July 15, 2021, to publish the new regulations.

The plaintiffs in the case, who said the regulations on injection wells have not been altered in 30 years, welcomed the decision.

"This consent decree is a step in the right direction toward fulfilling EPA's duty to the public," said Adam Kron, senior attorney at the Environmental Integrity Project. "EPA has known since 1988 that its rules for oil and gas wastes aren't up to par, and the fracking boom has made them even more outdated. Our communities deserve the best possible protections for their health and the environment."