On April 1, 2016, LaDonna Brave Bull Allard, an elder member of the Standing Rock Sioux tribe, and her grandchildren established the Sacred Stone Camp to protest the DAPL, which they said threatens the upper Missouri River, the only water supply for the Standing Rock Reservation. The camp was on Allard's private land and served as a center for cultural preservation and spiritual resistance to the DAPL. Protests at the pipeline site in North Dakota began in the spring of 2016 and drew indigenous people from throughout North America, as well as many other supporters. It was the largest gathering of Native Tribes in the past 100 years. A number of planned arrests occurred when people locked themselves to heavy machinery in civil disobedience.