While they did extensively modify the river during the late part of the 1800's and the early part of the 1900's it is well known around here that the split in the river there is natural. It wasn't caused by the damming and the dykes and all of that. It was there before any of that happened The village of Skagit City, was actually built right where the river forks. It was built there because the river forked there. But I didn't know it was one delta, nor anything about it switching. Still, it is a very visible split and it is totally natural.