Lock and Dam No. 7
Encyclopedia
Lock and Dam No. 7 is a lock
and dam
located near Onalaska, Wisconsin
on the Upper
Mississippi River
. It forms pool 7 and Lake Onalaska
.
The facility is located on Mississippi River mile
702.5 near La Crescent, Minnesota
. It was constructed and placed in operation in April, 1937 and underwent major rehabilitation from 1989 through 2002.
The entire system consists of a concrete structure 940 feet (286.5 m) long with five roller gates
and 11 tainter gate
s, a segment of earth embankment 8100 feet (2,468.9 m) long from the dam to French Island separated by a concrete spillway
1000 feet (304.8 m) long, and another embankment 2400 feet (731.5 m) long from French Island, Wisconsin
to Onalaska, Wisconsin
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.
Lock (water transport)
A lock is a device for raising and lowering boats between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water level can be varied; whereas in a caisson lock, a boat lift, or on a canal inclined plane, it is...
and dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
located near Onalaska, Wisconsin
Onalaska, Wisconsin
Onalaska is a city in La Crosse County, Wisconsin. The 2011 Census Bureau estimates the city had a population of 18,097. It is part of the La Crosse Metropolitan Area....
on the Upper
Upper Mississippi River
The Upper Mississippi River is the portion of the Mississippi River upstream of Cairo, Illinois, United States. From the headwaters at Lake Itasca, Minnesota, the river flows approximately 2000 kilometers to Cairo, where it is joined by the Ohio River to form the Lower Mississippi...
Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
. It forms pool 7 and Lake Onalaska
Lake Onalaska
Lake Onalaska is a reservoir located on the Mississippi River between Wisconsin, and Minnesota. It is approximately across, and is the widest point on the Mississippi River. Located in La Crosse County in the state of Wisconsin, its latitude and longitude are . The lake is and is shored by the...
.
The facility is located on Mississippi River mile
River mile
In the United States, a River mile is a measure of distance in miles along a river from its mouth. River mile numbers begin at zero and increase further upstream. The corresponding metric unit using kilometers is the River kilometer...
702.5 near La Crescent, Minnesota
La Crescent, Minnesota
As of the census of 2000, there were 4,923 people, 1,940 households, and 1,367 families residing in the city. The population density was 1,634.4 people per square mile . There were 2,014 housing units at an average density of 668.6 per square mile...
. It was constructed and placed in operation in April, 1937 and underwent major rehabilitation from 1989 through 2002.
The entire system consists of a concrete structure 940 feet (286.5 m) long with five roller gates
Roller dam
A Roller dam is a type of hydro-control device specially designed to mitigate erosion. They are most often used to divert water for irrigation but the largest and most notable examples are used to ease river navigation.- Use :...
and 11 tainter gate
Tainter gate
The Tainter gate is a type of radial arm floodgate used in dams and canal locks to control water flow. It is named for Wisconsin structural engineer Jeremiah Burnham Tainter....
s, a segment of earth embankment 8100 feet (2,468.9 m) long from the dam to French Island separated by a concrete spillway
Spillway
A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...
1000 feet (304.8 m) long, and another embankment 2400 feet (731.5 m) long from French Island, Wisconsin
French Island, Wisconsin
French Island is a census-designated place in La Crosse County, Wisconsin, United States. The population was 4,207 at the 2010 census. It lies on an island of a similar name, with which it is not coextensive; most of the island is part of the city of La Crosse, but all are part of the La Crosse...
to Onalaska, Wisconsin
Onalaska, Wisconsin
Onalaska is a city in La Crosse County, Wisconsin. The 2011 Census Bureau estimates the city had a population of 18,097. It is part of the La Crosse Metropolitan Area....
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.