In the first case, I'd Ctrl+z after Plow Terrain...
The image taken from overhead may help explain why I'd decided not to Plow Terrain.
After more testing, I now believe this
might be caused by using the single giant 'S' curved river path.
Also for a different issue I've seen, I've included a zipped dump file from the Paths tab.
![](http://bbs.hitechcreations.com/smf/index.php?action=dlattach;topic=393529.0;attach=30085)