Taming the Wild
River
Ever since
Americans recognized the Upper Mississippi River’s potential as a
transportation route, they have been trying to improve it for
commercial navigation. One such improvement is the Lock and Dam
system that is visible from this location.
The first attempt
to improve the Upper Mississippi for navigation began in 1878, when
Congress authorized the Corps to create a continuous for-foot
channel from St Paul to the mouth of the Ohio River at Cairo,
Illinois. To accomplish this, the Corps constructed hundreds of
wing dams – long, thin piers of rock that jutted out from one shore
or the other- - and closing dams, which resembled wing dams but ran
from shore to island or island to island.
In 1907, the
minimum depth of the channel was increased, and even more wing and
closing dams were built. By 1930, when Congress authorized the
current channel depth, more than 1000 of these simple dams had been
installed.
By constricting
the river’s flow, the wing and closing dams eliminated many side
channels and backwaters that provided habitat to wildlife. The
modern lock and dam system had submerged most of these older dams,
including the ones on this stretch of the river, thereby flooding
the backwater areas again. Because the river is no longer free to
meander, many of these areas are gradually being filled with
sediment.
Lock and Dam No. 5
is a lock and dam located in Winona County, Minnesota on the Upper
Mississippi River around river mile 738.1. It was constructed and
placed in operation May 1935. The site underwent major
rehabilitation from 1987 through 1998. The dam consists of concrete
structure 1,619 feet (493.5 m) long with six roller gates
and 28 tainter gates and an earth embankment 18,000 feet
(5,486.4 m) long. The lock is 110 feet (33.5 m) wide
by 600 feet (182.9 m) long.
This lock and dam,
built by the U.S. Army Corps of Engineers, is one of 29 between
Minneapolis and St. Louis. Designed to keep the depth of the main
channel from falling below a specific level, these structures have
tamed the once-wild river, effectively transforming it into a long,
long stairway. With the input of the 29 dams, the river was slowed
and the water levels between each dam are maintained at a specific
level. With the levels being maintained, this allowed the fishing
habitats to grow and the living conditions for other water dwelling
creatures to flourish.
The lock and dam
system has been a fortunate thing to commercial navigation. River
commerce, less than one million tons a year in the mid-1920’s now
exceeds 70 million tons annually.
Although
significantly altering the environment of the upper Mississippi,
the project also served as an forward motion for the upgrading of
municipal drinking water and sewage disposal systems, as well as
providing new recreational opportunities, thus, in the end, proving
generally beneficial to public welfare.
Good Habitat = Good
Fishing
Plentiful food,
good cover, and lots of clean water add to ideal living
conditions….and great fishing for the refuge’s visitors. Over half
of the 3,000,000 annual visitors are by anglers, who fish
year-round.
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BookMarks.
To get credit
for this
Earthcache:
You must post a
picture of yourself
with the lock and
dam in the background.
Answer the
following questions:
The system of dams was
designed to keep the main channel from falling below what
depth?
How many miles/km of
the Mississippi River are in Minnesota?
Estimate how wide the
river is from your location?
The sign talks about a
reptile that lives in the river,
What is the reptile
and how long is its life span?