While trawling his boat further down the river, Castor points to odd-looking clusters resembling dirty foam floating by.

“There’s just a slurry of a foam that looks like oil or some kind of chemical in there,” says Castor, a 42-year-old father, construction business owner and member of the Athabasca Chipewyan First Nation (ACFN).

He’s been a traditional hunter, trapper and fisherman for nearly 20 years and has documented strange changes in the water, the land and animals.

Something’s going on in the river, he says.

“They say that it’s natural, well, I know that that’s not natural because I’ve been on the river my whole life,” he explains as he points to brown and white foam, oil sheens and other discoloured formations floating on the river.