Mississippi River Lock & Dam No. 7

Lock and Dam No. 7 is a lock and dam located on the Upper Mississippi River at river mile 702.5 near the cities of La Crescent, Minnesota and Onalaska, Wisconsin. It forms pool 7 and Lake Onalaska. The facility was constructed in the mid-1930s and placed in operation on April, 1937. It underwent major rehabilitation from 1989 through 2002. The lock and dam are owned and operated by the St. Paul District of the United States Army Corps of Engineers-Mississippi Valley Division.

The lock and dam system consists of a concrete structure 940 feet (286.5 m) long with five roller gates and 11 tainter gates, a segment of earth embankment 8,100 feet (2,468.9 m) long from the dam to French Island separated by a concrete spillway 1,000 feet (304.8 m) long, and another embankment 2,400 feet (731.5 m) long from French Island to Onalaska which has a concrete spillway 670 feet (204.2 m) long. The lock is 110 feet (33.5 m) wide by 600 feet (182.9 m) long. The lock and dam is one of the most visited because of its proximity to Interstate 90, and is clearly visible to travelers crossing the I-90 Mississippi River Bridge.

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