As of June 18, 2004 the wire you mention is still there.
The flow was about 2000 cfs and I saw what seemed to be a power line reaching towards the middle of the river from a boulder it is snagged on river right, below the main Barrel Springs rapid.
It appears to be looped, possibly creating a lasso for catching things that don't want to be caught.
I spotted it while scouting the rapid and I did not know about it in advance. It was easy to see from the bike path at 2000 cfs but I imagine people who boat there frequently don't scout as closely as I did. This was my first time down.