12 is a lock and dam located on the Upper Mississippi River at Bellevue, Iowa, United States.

The movable portion of the dam starts at the locks adjacent to the Iowa shore and is 849 feet (258.8 m) long, consisting of seven tainter gates and three roller gates.

It connects to a 200-foot (61.0 m) storage yard and continues toward the Illinois shore with a 2,750-foot (838.2 m) non-submersible dike, a 1,200-foot (365.8 m) submersible dike and a 3,130-foot (954.0 m) non-submersible dike.

[2] In 2004, the facility was listed in the National Register of Historic Places as Lock and Dam No.

12 Historic District, #04000172 covering 1,017 acres (4.1 km2), 1 building, 3 structures, and 4 objects.