That pointy big rock down there on the river bank saved the rest of my riverbank and the bridge. The bank to the left of it was eroded because an eddy formed right there, swirling into the river bank. But because the big rock was there, and the various trees and bushes, it didn't go any further.
To fix it, we will cut those downed trees to about 10 feet from the root end, and put those stumps at the bottom of the bank with the roots facing out into the stream. Big rocks will go on top, and then we'll put the tree tops and branches in the hole vertically, like a fence. Fill dirt will go on top of that, and we'll plant bushes and trees in it.
My neighbor's riverbank will probably stay the same - it won't all erode away, even though it looks like it might. When the water rises for the summer, the river channel will move away from their bank toward my side of the river.
This next step is the most interesting because it's not the expected:

This is where the side stream jumped its banks and went across the yard to the river. Since this was a natural effect caused by our culvert, if we try to go back to the way it was, this will happen again. We need to keep a small depression, like a very shallow ditch, where you see that current trench, and build up a higher area as it crosses the yard to steer the water away from the house. Once past that tree, the yard will be contoured to encourage the water to either go across the bridge or in front of the Brown Palace along the riverbank and find its natural way to the river.
The principle behind this is: 'the river will go where it wants to go' or maybe 'don't try to fight mother nature.'
And I'm supposed to place a couple of large boulders at the end of the bridge.
That's it. Not much at all, compared to some people around here.