Thousands of people have gathered at the Standing Rock Sioux Reservation in North Dakota, trying to stop construction of a massive oil pipeline. The Dakota Access Pipeline would carry 500,000 barrels of oil a day from North Dakota to Illinois. "Water Protectors" are concerned it will destroy sacred tribal land and contaminate drinking water. This weekend, they were subjected to water cannons at the hands of police. Dr. Michael Lerma is a professor of Native American politics at Northern Arizona University.