Growing in number and spirit, the Standing Rock Sioux protest against the Dakota Access Pipeline is swiftly gaining strength ahead of a federal hearing on the controversial project. Support has spread across the country, and thousands have descended on the peaceful "prayer camps" in recent days, prompting state officials on Monday to remove the demonstrators' drinking water supply.

North Dakota homeland security director Greg Wilz ordered the removal of state-owned trailers and water tanks from the protest encampment, despite the sweltering heat, because of alleged disorderly conduct, according to the Bismarck Tribune, including reports of laser pointers aimed at surveillance aircraft.

"People are getting overheated now already," said Johnelle Leingang, the tribe's emergency response coordinator, as temperatures hovered around 90º F on Monday. "It's very hurtful."

The supplies were provided last week by the North Dakota Department of Health at the tribe's request to support the roughly 2,500 people now gathered along the Standing Rock reservation's border on the Cannonball River, near where the pipeline is slated to cross.

Standing Rock spokesman Steven Sitting Bear said he's received "notifications from tribes all over the country that have caravans in route, so it’s continuing to grow."