(CNN) - Oil is now flowing through the controversial Dakota Access Pipeline, but opponents say the fight isn't over.
After months of protests, lawsuits and occasional clashes, oil is now moving through the pipeline. The pipeline's developer says the nearly 1,200 mile pipeline that stretches across four states is now in full commercial use.
The $3.7 billion project drew fierce resistance from the Standing Rock Sioux Tribe in North Dakota, its allies and environmentalists. Opponents say the pipeline could contaminate the drinking water of communities downstream.
Several Native American tribes also say the pipeline would destroy burial and prayer sites as well as culturally significant artifacts. A tribal leader vowed to keep fighting on Thursday to stop the pipeline, even though it has already gone into use.
Efforts to complete the Dakota Access Pipeline were reinvigorated following President Donald Trump's executive action in January that advanced its approval.
Trump's actions cast aside efforts by former President Barack Obama to block the pipeline's construction.
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