"Wing Dam"
This is one of many wing dams on the Columbia, but the only one on the island. The point of this structure is to direct the flow of the river to the middle and cause the sand to accumulate on the banks. They also do a good job of catching debris like trees and boats. Very often during the Spring someone will cut between the shore and the outer pier, not seeing the picket of submerged pilings they just ran over until their hull or prop hits the wing dam. This is refered to as a wing damnit, which is very quickly followed by a frantic call on channel 16 for someone who is sure to laugh at them after promising to come help.
A few things to note. You can see the radar reflector on top of the outer pier, just like Pier One. Wing dams show up really well on radar (thank God). Also, it's easy to note the water level relative to the cross piece. When the water is at or above the cross piece, you can get through the South End channel. When it's like this, forget it, you probably couldn't drag your boat through. The good news is, you are very near the North End, which you can always get through. Also note the RV lot across the river, on the far left side of the picture, and you look really closely, you can see another wing dam across the river on the far right side of the picture, just above the rightmost post in this wind dam. In fact, if you go
back to the satellite picture you should be able to count three wing dams on the East (left) side of the river.