On Oct. 18, he decided to walk his camera down to the University Avenue bridge that crosses the river to snap a few pictures of ice forming on the water's surface.
But instead of finding just snow and ice, McCaa saw a "strange thing" moving back and forth in the current of the murky river.
"It never fully revealed itself," he said in a phone interview Tuesday.
McCaa took a video and posted it to the "Bureau of Land Management – Alaska" Facebook page Tuesday afternoon. By evening it had been watched about 20,900 times. Speculation has run rampant on what the creepy object — or creature — swaying in the water might be.
McCaa said there were some minor alterations to the video — it's slightly sped up, with a camcorder view screen and some minor sound effects added — but that the movement of whatever is in the water is not enhanced.
He said he watched the object — which he said was between 12 to 15 feet long — swirl back and forth in the current for several minutes, though it remained stationary. McCaa, who has lived in Fairbanks since 1994, said he has yet to show it to BLM biologists to get their opinion.