Lock and Dam No. 9 is a lock and dam located near Lynxville, Wisconsin and Harpers Ferry, Iowa on the Upper Mississippi River around river mile 647.9. The lower portion of Pool 9 was formally named Lake Winneshiek. The normal pool elevation behind the dam is 620 feet (189.0 m). It was constructed and placed in operation in July 1937. The site underwent a major rehabilitation from 1989 and 2006. The dam consists of concrete structure 811 feet (247.2 m) long with five roller gates and eight tainter gates. Earth embankment 9,800 feet (2,987.0 m) long with a grouted overflow spillway 1,350 feet (411.5 m) long. The lock is 110 feet (33.5 m) wide by 600 feet (182.9 m) long. Lock and Dam No. 9 is located 12 miles upstream from Prairie du Chien, Wisconsin.