RedactedNarrative: The operator stated that he was navigating the boat down stream (west) on the Payette River and went to go under bridge on the south side.  The operator stated that this was where the deep channel was in this stretch.  As he went under the bridge he observed that someone had built a fence out of wire cow panels partially across the channel. The boater stated that the last panel was held in place by strings tied to the top of the panel and to the top rail of the bridge. The operator stated that he put the boat into "full" reverse to avoid hitting the panel and when he did the rear of the boat hit the cement pier of the bridge damaging the right rear portion of the boat. The operator stated that it "caved in the rear quarter panel". Damage was observed to the right side swim deck and corner area of the boat.