Once the victim is freed, they will head downstream - perhaps pretty quick. If this was a foot entrapment, they will probably be injured. If they have been trapped for awhile, they may be too tired to grab a throw rope. Be ready with a pre-set live bait rescuer. Basically, a rescuer wears a rescue vest and is attached to a line with a fair amount of slack. The rescuer needs to time a shallow water entry and potential quick ferry to meet the victim and safely grab them. The line will get taught real quickly and the belay person better be in a good brace so they can pendulum both quickly to shore. Consider having an extra person assist with a vector pull.

This film from the 2010 Green River Race shows several "Live Bait" rescues: Green River Race Live Bait Rescues.