Lock and 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 ft long with five roller gates and 11 tainter gates, a segment of earth embankment 8100 ft long from the dam to French Island separated by a concrete spillway 1000 ft long, and another embankment 2400 ft long from French Island to Onalaska which has a concrete spillway 670 ft long. The lock is 110 ft wide by 600 ft 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.