President-elect Donald Trump’s pick to head the U.S. Environmental Protection Agency pledged Wednesday to enforce the Chesapeake Bay “pollution diet,” even saying it should be “commended and celebrated” despite his earlier participation in a lawsuit challenging it.

In a Senate hearing on whether to confirm his nomination as the EPA administrator, Oklahoma Attorney General Scott Pruitt praised the way in which the federal regulatory agency had worked with the Bay watershed’s states to develop a plan that set binding pollution reduction targets for improving the Chesapeake’s water quality. He brushed aside his earlier objections to the EPA’s role in developing that plan, and vowed to see that it is carried out.

That plan — known officially as a “total maximum daily load,” or TMDL — prompted farming and home-building industry groups to file a lawsuit challenging its legality shortly after the EPA issued it at the end of 2010. The groups contended that the EPA had overstepped its authority and that it should be up to the states to decide how best to reduce water pollution affecting the Bay. 

Pruitt joined 20 other state attorneys general in 2015 in filing a legal brief supporting the lawsuit and asking the U.S. Supreme Court to hear an appeal. The high court declined to do so last year, letting stand lower court rulings that solidly upheld the legality of the EPA’s action.

Under questioning by Sen. Ben Cardin, a Maryland Democrat, Pruitt said he had been concerned that EPA might take similar action to address pollution elsewhere, particularly in the Mississippi River basin, which includes Oklahoma. As happens in the Chesapeake, the Gulf of Mexico experiences oxygen-starved “dead zones” every year as a result of nutrient pollution from sewage plants and farm runoff in its watershed.

“There were some concerns about the precedent, the role that the EPA was playing initially,” Pruitt said. “But through that litigation,” he added, “EPA has acknowledged that their role is more informational.”

Now, Pruitt said, he believes that the EPA’s role in helping the states clean up the Bay is “something that should be commended and celebrated. And in relation to enforcing that TMDL, I can commit to you that I will in fact do so.”

Under the TMDL, the states have the primary responsibility of enacting and enforcing programs that achieve cleanup goals. But the EPA can take “backstop” actions if states fail to meet their pollution reduction obligations. It did temporarily withhold some grant funding from Pennsylvania after finding that state significantly lagging in fulfilling its cleanup requirements.

Later in the hearing, Pruitt repeated his praise for the Chesapeake Bay Program, saying he applauded how the six states joined with EPA to address the estuary’s water quality problems.

“The effort they engaged in is something states ought to model,” Pruitt said, adding that EPA “is providing assistance to those states.”

Pruitt's remarks about the Bay took just a few minutes in a day-long hearing where he fielded largely friendly questions from Republican senators and took sometimes testy grilling from Democratic committee members over his views on climate change, air and water pollution, his record of suing to challenge EPA regulations and his ties to fossil fuel companies and other industries that EPA regulates.

In response to Pruitt’s remarks at the hearing, Chesapeake Bay Foundation President William Baker issued a statement saying that “the federal government, led by EPA, plays an essential role” in what is often described as a federal-state partnership to clean up the Bay. Baker added that CBF “looks forward to working with Mr. Pruitt, should he be confirmed, to build on the progress that has been made and achieve the goal of restoring this national treasure.”

Cardin had said earlier that he was troubled by Pruitt’s record of suing EPA, but vowed to withhold judgment on whether to support or oppose his nomination until after the hearing.

But Sen. Bob Casey, a Pennsylvania Democrat, issued a statement Wednesday saying he would oppose Pruitt’s nomination, citing Pruitt’s role in challenging the Bay TMDL and other other EPA initiatives as Oklahoma’s attorney general. If Pruitt is confirmed, Casey said he was “concerned that the standards that protect the quality of the water Pennsylvanians drink and the air Pennsylvanians breathe will be weakened and our Commonwealth’s children will pay the price.”