Tokata Iron Eyes is beaming. Surrounded by journalists, camera crews and activists, the 13-year-old water protector—what she and other demonstrators call themselves—stands in the snow at a camp near the Standing Rock Sioux Reservation in North Dakota, wearing a heavy gray coat, a large knitted scarf and thick burgundy mittens.

Just minutes earlier, she and the rest of the Standing Rock Sioux Tribe learned that the U.S. Army Corps of Engineers won't grant an easement that would have allowed construction of the Dakota Access Pipeline (DAPL) to cross under Lake Oahe on the Missouri River. For months, Native American activists and allies have argued that the 1,172-mile, $3.8 billion pipeline project would pollute the region's water supplies and desecrate sacred sites.

SEE ALSO: How you can help Indigenous activists fight the Dakota Access Pipeline

"This entire movement was brought up by the youth," Iron Eyes, who lives on the Standing Rock Sioux Reservation, told author and activist Naomi Klein on Sunday in a Facebook video that racked up more than 1 million views in 24 hours. "It just started so small ... And now, the easement for DAPL was denied."

"I feel like I got my future back."

Her joy is tangible, her infectious laugh punctuating every sentence. Klein asks her how she feels about the news.

"I feel like I got my future back," she says. Then, she breaks down in tears.

It's a short video, just over a minute long. But it shows that for a movement largely started and sustained by Indigenous youth—using social media savvy to amplify their voices and garner solidarity—her sentiment is widely shared.

Now, young Native American activists are looking ahead, focused on the very future Iron Eyes mentioned.

While Sunday's victory is historic and certainly cause for celebration, Indigenous people have quickly called for continued vigilance, especially from young activists on social media.

"It took a little bit to set in, because it happened so quickly," Iron Eyes tells Mashable. "We went from being told that we might be raided to the easement being denied."

She says there's been an atmosphere of celebration as well as apprehension over the past few days, especially because they don't know what will happen when President-elect Donald Trump takes office.

Sunday's decision was made by the Obama administration, which will transition power to an administration that supports the completion of the pipeline project.

The pipeline is also almost complete, and Energy Transfer Partners, the company behind the pipeline, called the decision not to grant an easement a "purely political action."

This is a great victory for Standing Rock!!! But we must remain cautious, Trump is right next in line. #NoDAPL... https://t.co/mE3n2K2zQE — Standing Rock Kids (@ReZpectOurWater) December 5, 2016

#NoDAPL is as much about stopping the pipeline as it is recognizing tribal sovereignty, right to land, as well as Native civil rights. And many activists and water protectors say the good news won't erase the reported human rights abuses that have taken place.

While Reuters reported that Dave Archambault II, chairman of the Standing Rock Sioux Tribe, asked those who are not Sioux to leave the area for the winter on Tuesday, water protectors aren't planning to leave anytime soon. And #NoDAPL actions are still planned around the world for the month of December.

"People are not leaving, and that's great," Iron Eyes says with a laugh. "Because it's not over yet ... I'm thankful for the people at the camp who continue to stay in this below-zero weather."

As young activists continue the fight, it's worth looking back at the impact they've had leading up to Sunday's victory—and the lessons they learned using social media to reach it.

The beginnings of a movement

Proving that teenagers can truly make a difference, many people credit Tokata Iron Eyes and her friends with starting the #NoDAPL movement.

"In Dakota/Lakota we say 'Mni Wiconi.' Water is life."

In March, when they heard about plans to reroute the Dakota Access Pipeline away from Bismarck and through sacred land, they took action. As part of the Standing Rock Youth, a group of about 30 young people from the Standing Rock Sioux community, they decided to go online, and make their issue known.

Thirteen-year-old Anna Lee Rain Yellowhammer, also a member of the Standing Rock Sioux Tribe, spearheaded a Change.org petition in late April, simply called "Stop the Dakota Access Pipeline."

"In Dakota/Lakota we say 'Mni Wiconi.' Water is life," Rain Yellowhammer wrote in the petition to the Army Corps of Engineers. "Native American people know that water is the first medicine, not just for us, but for all human beings living on this earth."

The petition was the cornerstone of the Standing Rock Youth's #ReZpectOurWater campaign. Expertly navigating Twitter, Instagram, Facebook and YouTube to elevate their voices and those of others at Standing Rock, the young people's petition spread across social media with the #NoDAPL, #ReZpectOurWater and #StandWithStandingRock hashtags. By now, it has more than 460,000 signatures, including endorsements from celebrities and influencers like Leonardo DiCaprio, Shailene Woodley, Bill McKibben and Ndaba Mandela.

By tapping into the power of social media, the Standing Rock Youth were able to capture the attention of other young people—the digital generation. And those are the very people they wanted to galvanize.

"Our ancestors are the ones that died fighting for this land, so that makes me think that we have a duty to fight for our land," Iron Eyes told Truthout in June. "Whatever happens with the pipeline and climate change—that is going to be affecting us, this generation. And it will affect the next generation, too."

Native American Kids Standing Up Against Big Oil Company. READ, SIGN & SHARE our petition. Link in bio A photo posted by #RezpectOurWater (@rezpectourwater) on Apr 28, 2016 at 9:12am PDT

Soon after the petition launched, Standing Rock Sioux historian LaDonna Brave Bull Allard founded the Sacred Stone Camp, granting permission to the first tepees and tents of people protesting the Dakota Access Pipeline to set up on her land.

Meanwhile Iron Eyes, Rain Yellowhammer and the rest of the Standing Rock Youth held rallies and organized a 500-mile spiritual relay race from Cannon Ball, North Dakota, to the district office of the Army Corps of Engineers in Omaha, Nebraska. On July 15, the group also organized a 2,000-mile relay race to Washington, D.C. to deliver their petition. They used YouTube and Twitter to cover the race as a means of "[elevating] our campaign into national awareness" and "[attracting] media coverage."

That same day, the camp received notice that construction on the pipeline would begin.

Like the young people before her, Ladonna Brave Bull Allard grabbed her iPhone, made a video and posted it to Facebook. Her message? "Please come stand with us."

"And people came and people are still coming," she told Canada's CBC Radio in November. "We have people from all the tribal nations. I couldn't imagine this in my whole lifetime to ever see this."

While Native-led news outlets, such as The Last Real Indians and Indian Country Today, have covered the pipeline and its threat of sacred land since the beginning, most mainstream news outlets didn't give the story attention until August.

That's when thousands of water protectors and allies assembled to physically block construction, and when the U.S. District Court for the District of Columbia heard the Standing Rock Sioux Tribe's lawsuit.

Since then, the movement's grown exponentially. Media attention followed suit.

Hashtag activism at its most effective

The role social media played in Standing Rock is so substantial that the movement itself is now often referred to by its hashtag: #NoDAPL.

When the situation at Standing Rock became especially tense in September, as North Dakota law enforcement unleashed dogs and pepper spray on water protectors, those at Standing Rock uploaded videos to Facebook and Twitter to show the rest of the world what was happening.

In October, Native American activists and allies started using Facebook Live and other videos on the social network to further broadcast standoffs with police.

"Facebook Live, I think, has really helped shape this movement," Eryn Wise, of the International Indigenous Youth Council, told Mashable.

Wise, who is Jicarilla Apache/Laguna Pueblo and works as the media coordinator at the Sacred Stone Camp, distinctly remembers watching a Facebook Live on Oct. 27. She witnessed, in real-time, a police officer macing her little sister in the Youth Council with a large canister for an extended period of time. She immediately drove over.

"Facebook Live, I think, has really helped shape this movement."

"I was screaming at the police officers," Wise said. "I was telling them, 'You know, I just watched you on a video with 32,000 other people.' And they seemed pretty shaken by that. I think Facebook Live has really threatened their ability to hide."

The tool, Wise says, has allowed large numbers of people to understand what's actually happening on the ground.

"They can see it for themselves, through our eyes—or at least through a lens we're looking through as well," she says.

Later that month, thousands of allies started checking in to the Standing Rock Reservation on Facebook, in an attempt to confuse police after rumors that they were monitoring the social network to keep track of water protectors. However, local law enforcement denied this, which meant the effort, while well-intentioned, didn't achieve what allies hoped.

However, some Indigenous organizers didn't see it as useless "slacktivism."

Dallas Goldtooth (Mdewakanton Dakota and Dine), an organizer with the Indigenous Environmental Network, told Mashable in October that he felt the Facebook check-ins actually helped generate support.

"The real positive outcome is it's a cool, positive way to stay engaged in the fight," he said.

3 great heroes: Eryn Wise, @BernieSanders and Ladonna Allard discussing Standing Rock in DC. Strength and solidarity pic.twitter.com/MWlP5t9lUJ — Bill McKibben (@billmckibben) November 16, 2016

On Twitter, relevant hashtags gained more momentum. A Twitter spokesperson told Mashable that from Oct. 1 until Monday morning, more than 5 million tweets used the hashtags #NoDAPL or #StandWithStandingRock.

"We need people to not only see our side of things and to have our story told, but for us to be the ones to tell it."

Beyond media attention, the impact of these social media campaigns is felt within Indigenous communities, too. Wise says the movement has very much been about the youth reclaiming their own power, especially since many elders may not live to see the true impact of their decisions.

"Obviously many of our elders don't know about social media in the slightest. So, we're really teaching people how to not only use social media, but teaching them how to use it in a way that will help share their story," she says.

"We need people to not only see our side of things and to have our story told, but for us to be the ones to tell it."

But it's also about showing the incredible solidarity across various Indigenous communities that have converged on Standing Rock, and the powerful moments they share.

"I want people to see that it's not just the violence—that it really is a rekindling of so many beautiful things and inter-tribal solidarity that people would otherwise be missing out on, had there not been social media there actively displaying it," she says.

The fight ahead

The Army Corps of Engineers' denial of a federal permit on Sunday is by no means the end of #NoDAPL. The wide sentiment among activists is that it's a temporary victory, especially as a Trump administration looms.

"There have been presidents who have been very vocal in the past about not liking Native Americans and not supporting our rights," Wise says. "This is just another person we will actively survive and stand up to. Because the only thing white men [and] the United States government seem to acknowledge is strength. And we intend to stand very strongly in the face of adversity."

That includes further honing their social media skills. Wise says one thing Indigenous youth and other water protectors have learned is to make hard copies of everything they post online. They've encountered instances in which Facebook has removed posts, or technical issues randomly shorten or delete posts.

They're also learning how best to navigate Facebook's algorithm, working to make sure people can see what's happening in real-time and remain educated.

The fight is NOT OVER. Now more then ever we need people to take action for #NoDAPL. Let's kill the Black Snake. https://t.co/fngekb0m3r pic.twitter.com/ze1naKsgb0 — Sacred Stone Camp (@SacredStoneCamp) December 5, 2016

The Black Snake, a term referencing a Lakota prophecy that says a great black snake will run through the land and end the world, is not yet dead. The Sacred Stone Camp released a series of 10 questions water protectors encourage everyone to ask in the coming days and weeks, including when the Army Corps will conduct an Environmental Impact Statement, and to what extent will there be tribal input.

Wise says "once we kill this Black Snake," water protectors will fight other pipelines around the country, such as Proposed Line 3 in northern Minnesota, the Sabal Trail Pipeline in Florida and the Pinon Pipeline in New Mexico.

"This isn't just the one fight, or the one last stand," she says. "This is a struggle to continue reclaiming Indigenous rights and lands and languages and resources."

The Int'l Indigenous Youth Council on the banks of the Cannonball River, Sicangu Camp side, fighting for your right to clean agua. #NoDAPL✊🏽 pic.twitter.com/I0DTu1WVNv — Samakuu (@erynwisegamgee) November 7, 2016

"I think we're looking at completely ending this pipeline, but then also continuing to speak out about climate change and then just Big Money and Big Oil," Iron Eyes says. "Trying to spread the word, and help out in any way we can to change what's wrong in this world."

For now, water protectors at Standing Rock are standing firm, showing no signs of going anywhere and making sure their allies know the fight isn't over.

"We're going to remain here as long as we can and as long as we're welcome."

"I'm honestly very scared," Wise says. "What's next? I don't know. And that uncertainty is terrifying. Not knowing what's going to happen is terrifying."

But she also feels that the water protectors' prayers have gotten stronger. She wants the Trump administration, and people in general, to not underestimate younger generations that are "awake and alive and watching."

"We've come further than anybody thought we would, and yet we're somehow still here, even in 5-degree weather with 45 mile-per-hour winds," she says. "We're all still here, and we're going to remain here as long as we can and as long as we're welcome."

Indeed—the hours listed on Sacred Stone Camp's Facebook page read as "Always Open." For the foreseeable future, they still will.