— Oil and gas drilling would be banned indefinitely throughout millions of acres of the Atlantic and Arctic oceans under a sweeping decision announced Tuesday by the Obama administration that could force a showdown with President-elect Donald J. Trump.
Relying on a rarely invoked provision of a 63-year-old law intended to protect environmentally sensitive areas, the Obama administration said the decision would prohibit drilling in 31 underwater canyons extending offshore from New England to the Chesapeake Bay as well as 115 million acres in the Arctic.
While the move may help cement Obama's environmental legacy during his final days in office, it met with swift resistance from Republicans and the energy industry. Trump has vowed to increase oil and gas production and reverse federal environmental regulations that he has said harm the economy.
Drilling off the U.S. Atlantic coast was abandoned decades ago, but the Obama administration proposed opening millions of acres from Virginia to Georgia last year. The president later reversed course following an outcry from environmentalists, including in Maryland, who were concerned about the effect a spill would have on beaches and the fishing industry.
Obama made the announcement in conjunction with Canadian Prime Minster Justin Trudeau, who imposed a similar moratorium on oil and gas licensing in his country's Arctic waters.
"These actions, and Canada's parallel actions, protect a sensitive and unique ecosystem that is unlike any other region on earth," Obama said in a statement.
"They reflect the scientific assessment that, even with the high safety standards that both our countries have put in place, the risks of an oil spill in this region are significant and our ability to clean up from a spill in the region's harsh conditions is limited," he said.
White House officials and environmental advocates stressed that the 1953 Outer Continental Shelf Lands Act contains no provision for a future president to reverse the decisions of a sitting president. A senior White House aide said the administration is confident the move will withstand legal challenge and argued that presidents of both parties have invoked the law previously to withdraw offshore land from drilling.
But there also does not appear to be anything — aside from political pressure — that prevents Congress from changing the law. Trump and Republican leaders who will control both the House and the Senate could attempt a legislative change, or fight the issue in court.
Trump transition spokesmen did not respond to a request for comment.
Rep. Andy Harris, Maryland's only Republican in Congress, generally has supported drilling as an important element of U.S. energy independence.
"Unfortunately, the lame-duck president is making one last futile effort to handcuff the American energy economy," said Harris, who represents the Eastern Shore as well as portions of Baltimore's northern suburbs. "Thankfully, the incoming president understands that American leadership and ingenuity in the fossil-fuel energy industry will lead our economy's rebound under the new administration."
Obama's administration has acted unilaterally on a host of environmental issues in recent years through new regulations, including efforts to improve air and stream quality. Republicans, including Trump, have described those efforts as job-killing red tape and have fought in Congress and the courts to revoke them. In most cases, Trump will have broad authority to pull those regulations back once in office.
But the permanency of Tuesday's announcement is less clear.
Oil industry leaders disputed the White House's interpretation that the actions Tuesday will be difficult to unravel. An official with the American Petroleum Institute said Obama's actions could be reversed through a presidential memorandum, saying President George W. Bush did just that in 2008.
"Our national security depends on our ability to produce oil and natural gas here in the United States," said Erik Milito with the trade group. "Blocking offshore exploration weakens our national security, destroys good-paying jobs, and could make energy less affordable for consumers."
The Obama administration's announcement was applauded by some Democratic lawmakers and environmentalists who have warned of the potential for spills, particularly following the 2010 Deepwater Horizon oil accident in the Gulf of Mexico. Maryland Democrats such as Attorney General Brian E. Frosh and U.S. Sen. Ben Cardin criticized the earlier federal proposal to open some Atlantic waters to drilling, arguing a spill in Virginia could affect Maryland beaches and the bay.
"This final act should permanently end any and all misguided attempts to endanger the economic viability and environmental health of the region," said Cardin, a member of the Environment and Public Works Committee, of the latest effort Tuesday.
"Oil spills and the damage associated with seismic exploration do not respect state boundaries, making drilling anywhere on the Atlantic Coast a threat everywhere on the Atlantic Coast," he said in a statement.
A spokesman for Republican Gov. Larry Hogan did not respond to a request for comment.
The area withdrawn from potential drilling leases in the Atlantic totals 5,990 square miles, or 3.8 million acres, officials said. The largest of the canyons, located off the coast of New Jersey, reaches depths of more than 10,000 feet and is comparable in scale to the Grand Canyon. The Baltimore, Washington and Norfolk canyons, off the coast of the Eastern Shore, also are included.
The administration described the canyons as "hot spots" of biodiversity, biologically unique, and ecologically and economically valuable for fisheries.
Chesapeake Bay Foundation President Will Baker said that the bay's sensitive ecosystem extends hundreds of miles inland and tens of miles into the ocean. Larvae from blue crabs can float miles out into the ocean and so an entire yearly class of blue crabs could be wiped out from one major oil spill, he said.
"Were an oil spill to occur even 30 to 50 miles offshore in the Atlantic, the bay could be traumatized," Baker said in a statement. "While the bay states continue to work to reduce the pollution fouling the bay, we must assist them by not unnecessarily adding new threats that could undo the progress being made."