The Oahe Dam, just north of Pierre, South Dakota in the United
States, is a large man-made dam along the Missouri River. The
9,300-foot-long rolled-earth dam creates Lake Oahe, the 4th largest
man-made reservoir in the United States and the 14th largest in the
world, which extends over two hundred miles up the Missouri River
to Bismarck, North Dakota. Lake Oahe has 2,250 miles of
shoreline--more than the state of California. The dam's power plant
provides electricity for much of the north-central United States.
It is named for the Oahe Indian Mission established among the
Lakota Sioux in 1874.
Construction of the Oahe Dam on the Missouri River started in
1948 with the relocation of towns, roads, and bridges that would be
flooded by creation of the reservoir. Work dam then proceeded, with
closure taking place in 1958.
One–third of the Missouri River has been transformed into
lake environments due to the construction of six dams along the
river.
These changes have significantly altered the Missouri River. In
the upper river, deep-water reservoirs replaced the
free–flowing river. This has also caused lower water
temperatures and reduced sediment loads. In the lower river, the
sandbars are disappearing, and there are now varying degrees of
depths. The river is now regulated to reduce water flow in the
spring and augment the river flow in the summer and fall.
The drastic changes in the river have lowered populations for
many river fish and bird species; some are now even federal or
state–listed as endangered species.
As a result of the dam's construction the Cheyenne River Indian
Reservation lost 150,000 acres. Standing Rock Reservation lost
55,993 acres. In addition to the land loss, most of the
reservations' prime agriculture land was included in the
loss.
The changes have had positive impact on the land as well. With the
dam in place the Army Corps of Engineers can now control and
prevent flooding along the Missouri river. The forming of Lake Oahe
has created recreational areas where people can enjoy a variety of
activities. The Army Corps of Engineers can also control the water
level to aid in the navigation of ships along the river. The
damming of the Missouri river has also aiding in irrigation of the
surrounding land. Last but not least the Oahe dam provides
hydroelectric power to much of the upper central United
States.
The first official filling was achieved in April 1962, and all
seven generators in the powerhouse were online in 1963. The U.S.
Army Corps of Engineers designed and built the dam for flood
control, power generation, irrigation, and navigation. The
reservoir holds 23.5 million acre-feet of water. President John F.
Kennedy officially dedicated it on August 17, 1962.
Power plant Tours:
Tours are given daily Memorial Day through Labor Day. Tours start
at the Visitor Center, with check in at 10:00 a.m, 1:00 p.m, and
4:00 p.m. Plan an hour and a half per tour, and bring a photo ID.
Groups of 10 or more should call to schedule a tour. Tours in the
off-season by special appointment only. For large groups and
off-season tours, please call (605) 224-5862.
There are several signs nearby, please read them all.
To log this Earthcache please answer the following questions:
1. What does the word Oahe mean?
2. According to the historical marker how long is the lake?
3. On the historical marker is a map. What is at point "I"?
4. Who painted the pictures that are displayed near the small
shelter?
Please send the answers to me in an email and do not post them
in your log. In addition to answering the questions please take a
picture of yourself or your GPS with the dam and power plant in the
background and post it here.
References: (visit link) (visit link) (visit link)
