Despite a federal appeals court ruling on Sunday that allowed construction of the Dakota Access Pipeline to continue on both sides of the Missouri River, Native American and environmental activists are far from giving up. In fact, they have been redoubling efforts on a bigger and perhaps unprecedented goal—permanently shutting down the entire 1,172-mile project, which is already more than half built.

The pipeline's opponents are buoyed by an announcement last month by the Obama administration that it was withholding a permit for the pipeline to cross federal land beneath and immediately adjacent to the Missouri River. Despite Sunday's court ruling, opponents believe that crucial link can keep the pipeline from being completed.

A loose coalition of roughly two dozen mainstream and grassroots indigenous and environmental groups has formed in the last month to argue that the project should not be finished. The coalition is trying to build on the unexpected success of the Native Americans who opposed the pipeline because it threatened sacred cultural sites and the drinking water supply of the Standing Rock Sioux reservation—which sits a half-mile downstream of the pipeline's proposed Missouri River crossing.

The groups, however, have expanded their argument, saying the pipeline also threatens the treaty rights of Native Americans elsewhere along its route, the property of private landowners, the drinking water of millions of Americans and the Earth's climate.

The pipeline, which would carry roughly half a million barrels of crude oil per day, traverses four states, crossing the Missouri and Mississippi rivers, before connecting to other pipelines in Illinois that would likely carry the oil to Gulf Coast refineries or export terminals. One assessment by environmentalists found the oil's carbon footprint would be equivalent to that of 30 coal-fired power plants.

"We need to find a way to keep dirty fuels in the ground...and this pipeline is the highest-profile fight in that larger struggle," said Michael Brune, executive director of the Sierra Club, one of the national organizations that has made shutting down the North Dakota-to-Illinois pipeline a top priority.

Brune's Sierra Club, the Natural Resources Defense Council and Bold Alliance—a grassroots organization that grew out of the successful fight against the Keystone XL oil pipeline—take turns hosting a weekly conference call to coordinate pipeline opposition. Many members of the coalition were leaders in the six-year Keystone fight and they're applying what they learned from that campaign.

The coalition is coordinating civil disobedience demonstrations at construction sites in North Dakota and Iowa, waging legal battles in federal court, challenging the permitting process of the Army Corps of Engineers, which approved the Dakota Access Pipeline's construction, and pressing administration officials in meetings with tribal leaders. They are also tying the project to climate change as part of a nationwide effort to connect the boom in new energy infrastructure to sustained fossil fuel dependency.

"Everyone told us in the beginning that Keystone XL was a lost cause, maybe it's worthy that we are fighting it, but we are never going to stop it," said Jane Kleeb, the president of Bold Alliance. "That's exactly what the Big Oil corporations want us as advocates to believe. We are not playing with those set of rules anymore."

Not Necessarily a Keystone Sequel

The two pipelines have different circumstances, however, affecting the chances of a successful halt.

While Keystone XL's builder, TransCanada, never broke ground on the hotly contested northern half of the route, Dakota Access LLC already has spent more than $1.6 billion to build more than 60 percent of its pipeline. More than 98 percent of the pipeline's route through North and South Dakota has been cleared and graded.

Pat Parenteau, an environmental law professor at Vermont Law School, said that because too much of the pipeline already has been built, placing it elsewhere is no longer a "reasonable alternative."

"This is a classic case of steamrolling the approval process," he said.

In addition, while the Keystone project required numerous federal permits, the Dakota Access pipeline only required federal permission from the U.S. Army Corps for key water crossings, including the Missouri River. More than 99 percent of the land needed for the pipeline is privately owned, where no federal permits are required.

"The Corps has no real options," Parenteau said. "They could say, 'Well, sorry you don't get the permit, too bad.' But that's billions."

Unlike the Keystone effort, the fight against the Dakota Access pipeline is decentralized, driven in part by limited phone and Internet connectivity at the camps and demonstration sites in North Dakota. More than 1,000 demonstrators reside in four semi-permanent camps. "It's definitely different than Keystone where we had a coordinating table where all actions were being organized," said Kleeb, who launched Bold Alliance's predecessor, Bold Nebraska, to oppose the Keystone XL pipeline.

The pipeline company argues, like TransCanada did in defending Keystone, that activists are overplaying the risks to drinking water and other environmental concerns.

"As with all of our pipeline projects, safety is the company's top priority—the safety of our employees who build and operate them, the safety of those who live in the communities through which our pipelines pass, and the safety of the environment which surrounds them," Dakota Access spokesperson Vicki Granado said in a statement.

Delays Seen as Mini-Victories

Hope for a halt to the pipeline came on Sept. 9, when the Justice Department, the Department of the Interior and the U.S. Army announced that they would withhold a permit that would allow the pipeline to cross beneath the Missouri River near the Standing Rock reservation, where nearly half the population lives in poverty. The Army Corps would re-evaluate whether or not this project needs further examination it said.

Even if the coalition doesn't win in court or through a denial of permit from the Army Corps, other lawsuits, demonstrations and challenges could derail the project.

"Every delay here that increases the public attention and the public sympathies is going to decrease the likelihood that the project goes forward and also make the project more expensive," said Jessica Owley, a law professor at the State University of New York at Buffalo.

Dakota Access would lose $1.4 billion in its first year of delays, wrote attorneys for the company —a subsidiary of Energy Transfer Partners—in a Sept. 14 court filing. "Even a temporary or limited injunction would have devastating long and short term impacts to the DAPL project," the brief submitted to the U.S. Court of Appeals for the District of Columbia Circuit said.

As delays mount, so does support for the pipeline's opposition.

More than half of the nation's 567 federally recognized tribes and a number of municipalities, including Los Angeles, Oakland, Seattle and Minneapolis, have passed resolutions or made formal pledges in support of the Standing Rock tribe. Nineteen members of Congress urged a stop to the pipeline in a Sept 29 letter to President Obama.

On Tuesday, activists who said they were supporting the Dakota Access opposition, temporarily shut down five pipelines that carry tar sands crude from Canada to the U.S.

While the biggest challenge to stopping completion of Dakota Access may be how much of it already has been built, Owley said there have been times when major infrastructure projects were stopped even after construction had begun.

For example, the Elk Creek dam in Oregon was one-third complete when construction was halted by a court order pending further environmental review. The project ultimately passed the review and was approved, but the delays made the project prohibitively expensive and the dam was never built.

Conversely, the Tellico Dam in Tennessee was nearly 90 percent complete when the Supreme Court determined its completion would violate the Endangered Species Act. Congress, however, subsequently passed legislation in favor of the dam and the project was completed.

"We've got examples of wins and losses here," Owley said.

Besides continued demonstrations, which were critical in pressuring President Obama over Keystone and making the project a litmus test for his climate legacy, Dakota Access opponents are employing three other strategies to attempt to further delay, and even permanently derail the pipeline: Calling for a full environmental impact assessment, Native American consultation and lawsuits in three of the four states it would cross.

Here's a breakdown of each:

Environmental Impact Assessment

The Standing Rock tribe, the Sierra Club and others want the government to drop a fast-track process for pipeline approval and conduct a full environmental impact statement of the Dakota Access project. Such an assessment would include consideration of a project's climate impact and detailed analysis of what would happen in the event of a spill.

The Standing Rock tribe filed a lawsuit against the Army Corps on July 27, calling on the court to force the agency to complete an environmental impact statement. The suit is still making its way through a federal district court. (A related, temporary halt to construction for 20 miles on either side of the Missouri River is what was overturned by the U.S. Court of Appeals for the District of Columbia Circuit on Sunday.)

Completing an environmental impact statement could delay the project for a year or more, or its findings could derail the project entirely.

A memorandum by President Obama in March 2012 called on federal agencies to approve domestic pipelines as quickly as possible, which resulted in the Army Corps approving pipelines for the first time under an expedited review process known as nationwide permit 12.

The expedited review, which the Army Corps used to evaluate the Dakota Access Pipeline, does not require an environmental impact statement, but is currently being re-evaluated as part of a 5-year renewal process that will be completed in March 2017.

Sierra Club and Standing Rock submitted detailed public comment this summer calling for an end to the use of such permitting for large pipeline projects.

The future of such fast-tracking was further called into question in August, when the Obama administration called on federal agencies to fully consider greenhouse gas emissions and the costs they impose on society in their decisions on major projects.

Lawsuits

In addition to the Standing Rock lawsuit, the Yankton Sioux tribe in South Dakota sued the Army Corps and the U.S. Fish and Wildlife Service over damage to similar sacred sites and water issues posed by the pipeline.

Landowners in Iowa are also suing to challenge Dakota Access's use of eminent domain to seize their land.

Sacred Sites and Treaty Rights

Native tribes led by Standing Rock and the National Congress of American Indians are asking the Obama administration to revise the federal permitting process to give greater consideration to sacred sites and treaty rights.

As outlined in their Sept. 9 directive on Dakota Access, the Interior Department, Justice Department, and the U.S. Army, are holding a series of formal government-to-government consultations with tribal leaders that began with a listening session on Tuesday.

The meetings provide pipeline opponents an added venue to call on President Obama to block the pipeline.

"While formally, the President doesn't have final approval over the permit, he still is the leader and the employer of all of these people within these agencies," Kleeb said. "There still is a presidential target just like on Keystone XL."

The meetings which will take place over the next two months, will focus on how the federal government can better account for and integrate tribal views on major infrastructure decisions.

The Congress of American Indians will call on tribes from across the country to weigh in, not only on the Dakota Access pipeline, but also on other projects.

"It doesn't matter what industry or what corporation is doing it, we have to make a stand because for far too long we have seen our homeland [negatively] impacted and we never had a voice like we are seeing now," congress president Brian Cladoosby said.

No matter how many environmental groups get involved, the pipeline opposition will always be centered around the Native American activists who brought it to the world's attention. And they are definitely not ready to give up anytime soon.

"The Standing Rock Sioux Tribe is not backing down from this fight," David Archambault II, chairman of the Standing Rock Sioux tribe said in a statement. "We will not rest until our lands, people, waters and sacred places are permanently protected from this destructive pipeline."