The first major structure at this location is the auxiliary lock, which was built as part of the US Army Corps of Engineers 6-foot navigation channel. A canal was built around the west side of Smith's Island and around a major rapids on the Mississippi River to feed this lock. When the 9-foot navigation channel was built, a new lock and dam was built across the main channel of the river, submerging the rapids forever.

The problem is that there was no way to get vehicles out to the area where the new lock and dam was built. The solution is a temporary bridge, which is placed across the auxiliary lock during the months of low recreational boat traffic. When the lock is needed, the barge in the lock simply lifts the bridge, and floats it away for storage. The bottom photo shows the bridge tender barge, and the black brackets that make up the lifting mechanism.