Groups like 350.org and Climate First! are standing in solidarity with the North Dakoka occupation. Here is an email alert from Jason Kowalski at 350.org:

Today's the day when a federal judge could decide the fate of the Dakota Access Pipeline. The Standing Rock Sioux Tribe have bravely resisted this pipeline for months, and now is our opportunity to show solidarity and gratitude. 

Join me in front of the U.S. District Court today from 1:00-2:00pm for a rally and press conference in solidarity with frontline fighters.

We'll be joined by tribal representatives from the Standing Rock Sioux Nation including Wiyaka Eagleman and Joseph White Eyes, as well as activists Josh Fox, Shailene Woodley and Susan Sarandon. 

We know we need to keep fossil fuels in the ground and that means #NoDAPL.  

See you there, 

Jason

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Friends,

We know that to defeat a pipeline, it takes a movement of people from all corners of the nation.

Right now, the Standing Rock Sioux Tribe are standing up against a pipeline comparable to Keystone XL. The Dakota Access Pipeline threatens sacred land and water, and would carry half a million barrels of crude oil per day across four states.

Over 700 indigenous activists have gathered at the Sacred Stone Camp along the pipeline route in a historic moment of nonviolent resistance. In the last week, 18 people have been arrested for blocking construction – and now they’re asking allies for support in Washington D.C. as they battle this pipeline in court.

Will you join us tomorrow outside the U.S. District Court for a rally and press conference in solidarity with frontline fighters?

The Tribe filed a lawsuit in federal court against the Army Corps of Engineers for approving the project – and this Wednesday will determine whether or not the permits for the project can move forward. We know we need to keep fossil fuels in the ground and that means no more fossil fuel pipelines like this one.

Here are the details:

What: Rally and press conference against the Dakota Access Pipeline
When: 1:00 – 2:00pm on Wednesday, August 24th
Where: Outside the U.S. District Court, 333 Constitution Ave, NW, Washington DC
RSVP: Join the Facebook event here and invite your friends!

So far, the speaker lineup includes activist Josh Fox, actress and activists, Shailene Woodley and Susan Sarandon, as well as tribal representatives from the Standing Rock Sioux Nation.

Together, we can show solidarity and honor the warriors who are fighting with everything they have to protect what impacts all of us.

Hope to see you there,

Jason Kowalski, and the 350.org team

As reported by Petro Global News in an article entitled "Susan Sarandon joins Dakota Access Pipeline protest as judge hears injunction request":

...[actors] Susan Sarandon, Riley Keough and Shailene Woodle were protesting outside the U.S. District Court for the District of Columbia during a hearing related to the $3.7 billion project.

Sarandon told Reuters she joined the protesters to bring attention to “this horrible thing that is happening to their land.”

Sarandon has long had a keen interest in nuclear power matters as well, including security, safety, health and environmental protection (or lack thereof) at Entergy Nuclear's Indian Point nuclear power plant, very near her home in New York City.

The article also mentioned additional Hollywood stars opposing Dakota Access Pipeline, Ltd. (DAPL):

The project has garnered attention from Hollywood players before Wednesday’s hearing.

Earlier this year, Leonardo DiCaprio shared images on Instagram and Twitter voicing support the Standing Rock Sioux Tribe’s efforts to oppose the Dakota Access Pipeline.

Jason Momoa, who will star as Aquaman in the upcoming “Justice League” film, also took to social media to protest the project’s route.