An eye bolt sunk into concrete holds a ring of iron on Lock & Dam #10 in Guttenberg, Iowa. This anchor is located on the exterior wall of the lock entry wing. Presumably it is used to secure recreational craft to the wall outside of the lock before launching or recovering a boat. These irons may have originated when the L&D system was constructed in Guttenberg in 1937. Despite some pitting the hammered ring is in good shape for being 78 years old.