Protesters gathered in northern Minnesota where a Canadian company is poised to replace an aging pipeline that would carry oil through the state’s watersheds and tribal lands.

Over the weekend and into this week, demonstrators took part in drum circles and prayer gatherings to express their opposition to the $9 billion Enbridge pipeline expansion, dubbed Line 3. Others took more disruptive action geared toward blocking the construction efforts, leading to law enforcement action. Activists estimate that more than 160 people have been arrested.