Report 29303: Man and dog enjoying the evening on a river have rocks thrown toward them near Yelm

Went out near Nisqually River with dog to build camp fire and enjoy nice night weather alone. In a remote spot on the river on Joint Base Lewis McCord I was with my dog Oscar. The fire had just started to catch up and my dog started barking toward the river ferociously. This is very out of character for him. I told him to be quiet and come back to me. I then heard large rocks being thrown into the river. I went to inspect with my flashlight and saw nothing. They were large rocks because I could hear them hitting the rocks on the bottom of the river. There were more than 5 rocks thrown. The experience was so creepy that I immediately put my dog in my Jeep and left. I am an avid outdoorsman and notice details always, on the way in I observed that no one had been in the area since the last rain because there were no tracks. In this area there is no access to the other side of the river other than walking in. I observed no evidence of other humans such as lights, fire, or sounds. I had heard of the rock throwing on TV shows about bigfoot sightings so I immediately thought of this and I left.