Lock and Dam No. 7

Lock and Dam No. 7[1]
Mississippi River Lock and Dam No. 7
Location of the Lock and Dam No. 7 on the border of Minnesota and Wisconsin
Country United States
Location Winona County, Minnesota
La Crosse County, Wisconsin
near La Crescent, Minnesota
Coordinates 43°52′01″N 91°18′26″W / 43.86694°N 91.30722°W / 43.86694; -91.30722Coordinates: 43°52′01″N 91°18′26″W / 43.86694°N 91.30722°W / 43.86694; -91.30722
Purpose Navigation
Status In use
Construction began 1933 (1933)
Opening date April 1937 (1937)
Operator(s) U.S. Army Corps of Engineers, St. Paul District
Dam and spillways
Impounds Upper Mississippi River
Height (foundation) 41 ft (12 m)
Length 10,860 ft (3,310 m)
Spillways 2
Spillway type 5 Roller Gates
11 Tainter Gates
Spillway capacity 273,000 acre⋅ft (0.337 km3)
Reservoir
Creates Lake Onalaska
Pool No. 7
Total capacity 5,000 acre⋅ft (0.0062 km3)
Catchment area 62,340 sq mi (161,500 km2)
Surface area 13,440 acres (54.4 km2)
Normal elevation 636 ft (194 m)[2]
Hydraulic head 25
NIDID# MN00587

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.[3] 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.


See also

Notes

  1. ↑ "The National Inventory of Dams (NID)". nid.usace.army.mil. United States Army Corps of Engineers. Retrieved 26 Mar 2017.
  2. ↑ Lake Onalaska on Topozone.com
  3. ↑ "Lock and Dam 7". United States Army Corps of Engineers. Retrieved 2012-08-19.

Locks and dams of the Upper Mississippi River
Upstream:
Lock and Dam No. 6		 Downstream:
Lock and Dam No. 8
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