Inside Climate News - Opponents of the Dakota Access Pipeline won an important victory on Sunday when the U.S. Army Corps of Engineers denied the final permission to cross Lake Oahe near the Standing Rock Sioux Reservation. But even as Native American protesters celebrated, they acknowledged the larger battle is far from won.

The Army Corps' decision keeps the pipeline from crossing a spot the tribe has vowed to protect, and called for a more comprehensive environmental review of alternative routes. But an incoming Trump administration could not only reverse this decision, but could also strike back at a core environmental law that has governed fights like this for more than half a century.

There are many in the oil industry, Congress and President-elect Donald Trump's inner circle ready to target the process of repeated reviews under the National Environmental Policy Act. That law resulted in the years-long review of the Keystone XL tar sands pipeline, eventually ending in President Obama's rejection of a cross-border permit.

The question is how aggressively, and how soon, they will move to rein in the law, a potent tool for two generations of environmentalists.

The Dakota Access Pipeline's opponents are happy to claim their victory, even if it is only temporary. For months, they have gathered under the banner of water protectors, facing down forceful tactics by authorities while demanding relief from Washington.

"While this is clearly a victory, the battle is not 'over,'" said a statement from four organizations supporting the encampment: Honor the Earth, the International Indigenous Youth Council, the Indigenous Environmental Network and the Sacred Stone Camp.