This is amazing, outstanding project! Interestingly, I got it "stuck" when I clicked somewhere random in California (Pope Valley, apparently): https://i.imgur.com/deOsIt2.png
The path, having almost reached the mouth of the Sacramento River, seems to have been captured by the very artificial Mallard Reservoir in Concord, Contra Costa. As to be expected, it seems that anything draining into the Sacramento will do the same.
