river biome error ether biome but says in f3 its a river

Put the summary of the bug you're having here

What I expected to happen was...:
Describe what you thought should happen here

What actually happened was...:
As shown in the attachment there is a large 'blockage'  in the river including a tree and the blockage touching both sides for a reasonably large area

Steps to Reproduce:
1. Use seed -4191120372260684700
2. ...tp to cords in photo
3. ...