Environmental Protection Agency Administrator Scott Pruitt, who has been methodically weakening air pollution rules over the past year, is now taking control of key decision-making on the protection of streams and wetlands from the agency's regional administrators, an internal memo shows.

At issue is something known as "geographic jurisdiction," agency speak for which bodies of water do, or do not, fall under the Clean Water Act. Historically all waters, including major waterways, tributaries and wetlands were regulated under the Act. This broad jurisdiction was reaffirmed by the Waters of the U.S. rule in 2015.

In the memo, Pruitt notified EPA staff that he would now be in charge of such decision-making.

"Authority previously delegated to regional administrators to make final determinations of geographic jurisdiction shall be retained by the Administrator," Pruitt wrote to EPA employees on March 30. The memo was made public on Wednesday by Public Employees for Environmental Responsibility (PEER), a non-profit organization of government employees.

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Pruitt, who suspended the Waters of the U.S. rule (WOTUS) in January, has been clear about his plans to significantly reduce the scope of the Clean Water Act. The recent memo may be a first step toward that goal.

"If Scott Pruitt's record over last year is any indication, the reason he is pulling this decision making away from the local EPA staff is so he can hand over a lot of our natural resources to polluting interests, which has been his M.O. since day one," said Dalal Aboulhosn, deputy legislative director for the Sierra Club.

Regional EPA Offices Would Lose Leverage

Pruitt, who has also drawn scrutiny and calls for his resignation in recent weeks over alleged ethics violations, wrote in the memo that the change was part of an ongoing effort to "restore regulatory certainty and promote the rule of law."

"This memo explains that jurisdictional determinations that raise significant issues or technical difficulties should be handled in a consistent and uniform manner, particularly during the WOTUS rulemaking," EPA spokeswoman Liz Bowman said. "Regions will absolutely be involved in the process and work closely with the administrator's office when doing the work to assess jurisdiction for very select, and often rare, cases."

However, PEER warned that the new directive would reduce the influence of locally based EPA scientists and specialists in reviewing projects and making determinations on wetlands and other water-related issues.

Under the changes outlined in the memo, regional offices of the EPA would lose their ability to "veto" activities by the Army Corps of Engineers, which oversees permitting of oil pipelines and mine—projects that could adversely impact drinking water supplies, fisheries, wildlife habitat or recreation areas, PEER said.

"It takes away the one bullet that EPA had in its gun to stop a project," Kyla Bennett, PEER's New England director and a former EPA employee, said. "Any case, including coal, oil, power plants, nuclear, whatever it may be, anything that involves significant impact to wetlands and waters, this could have been used, and now it's been relocated to someone who will never use it."

Such veto power by EPA officials has been used 13 times since it was first allowed under the Clean Water Act in 1970, according to the EPA. The most recent case was in 2010, when the agency revoked an Army Corps permit for one of the nation's largest mountaintop removal projects, a coal mine in West Virginia that agency officials said would jeopardize the health of surrounding communities and the water on which they depend.

Though rarely used, the veto was a powerful stick that EPA officials used to coax the Army Corps to deny or revise permits, Bennett said.

Another Worry: Future of the Clean Water Act

Because the veto was so rarely exercised, the transfer of its power to Pruitt may not be that significant, Pat Parenteau an environmental law professor at Vermont Law School, said.

When viewed against the backdrop of a larger, ongoing effort to significantly reduce the power of the Clean Water Act, the consolidation of decision-making power outlined in the memo is, however, cause for concern, he said.

"What Pruitt is ultimately trying to do is significantly reduce the scope of the Clean Water Act," he said. "It all has to do with the geographic reach. We don't know how far back Pruitt wants to cut that."