An update on this: in the last month, Denver Water, who owns the 'rights' to the land in question, has allegedly put up a private property sign on the south side of the bridge. This is all according to the Flies and Lies staff.
I was down there yesterday and looked hard for the sign, but did not see it on the south side, but it very could be hidden in the tall willows. The sign on the north side next to hwy 67 junction is still there, and appears to be fairly new.
So, the message is clear: don't fish upstream from the bridge.
On a different note, This lovely 23" rainbow specimen ate my golden stone pattern near Trumbull:
Have fun out there!