In hopes that action would discourage President Barack Obama from permitting an extension to the Canadian Keystone pipeline – also known as the “Keystone XL” – a group of First Nations and American Indian activists protested in front of the White House on Friday.

Before being arrested, the protesters insisted that the extension – which will run from Alberta Canada to Nebraska, Oklahoma, and Texas – will harm ancestral homelands.

“Our Lakota people oppose this pipeline because of the potential contamination of the surface water and of the Oglala aquifer,” said Deb White Plume, a Lakota activist. “We have thousands of ancient and historical cultural resources that would be destroyed across our treaty lands.”

Even the New York Times’ editorial board came out against the pipeline, writing that it was concerned about oil spills along the route and carbon emissions. “[T]he extraction of petroleum from the tar sands creates far more greenhouse emissions than conventional production does,” the board wrote last month.

The approval process for the Keystone XL was set in motion in September 2008, and while the National Energy Board of Canada approved it in 2010, 50 members of Congress have opposed it. Obama will have until the end of the year to decide whether to approve the extension.

In the meantime, those affected are speaking up. “Our First Nations in Alberta have been concerned of the lack of consultation of the pipelines and tar sands expansion,” Chief George Stanley, Cree Regional Chief of Alberta said at the protest. “President Obama can do what’s right. For the president to approve this pipeline is not in the national interest of U.S. or Canada.”