Lock and Dam No. 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 feet (61.0 m) foot storage yard and continues toward the Illinois shore with a 2,750 feet (838.2 m) non-submersible dike, a 1,200 feet (365.8 m) submersible dike and a 3,130 feet (954.0 m) non-submersible dike. The non-submersible sections are separated from the submersible section with two 120 feet (36.6 m) transitional dikes. The main lock is 110 feet (33.5 m) wide by 600 feet (182.9 m) long. There is also an incomplete auxiliary lock. In 2004, the facility was listed in the National Register of Historic Places as Lock and Dam No.