Gavins Point Dam
Missouri River Hydroelectric Dam
Yankton, SD
| • Location: |
River Mile 811.1 |
| • Structure Type: |
Earth Fill |
| • Structure Width: |
8,700 Feet |
| • River Elevation (Pool): |
1,208 Feet |
| • River Elevation (Outflow): |
1,165 Feet |
| • Waterfall: |
45 Feet |
| • Date Built: |
Built 1952 To 1955 |
The Gavins Point Dam is located just west of Yankton, South Dakota.
It is the first of the six major Missouri River dams when heading
upstream, or the last of the six when heading downstream. It was
authorized in 1944 as part of the Pick-Sloan Act, which sought to
control the floods on the Missouri River and provide electrical
power as a side benefit.
While being the smallest of the 6 major dams, the Gavins Point dam
is still very impressive at 8,700 feet long and 74 feet high, with
a typical waterfall of 45 feet. The power plan can generate 120-megawatts
of power, enough to supply the power needs of 65,000 people. From
this point and north to eastern Montana, the river is very much like
a stairway with each dam being a tall step. Water flows down these
steps, generating electricity on each step. As a result, water that
flows through the powerhouse at Gavin's Point dam may have generated
power 6 different times so far.
The Gavin's Point Dam is a major center for recreation for the upper
plains area. There are fishing and boating opportunities, a visitor
center that offers power house tours, and a well developed campground.
History remembers news anchor Tom Brokaw who was a tour guide at the Gavin's
Point Dam in 1958.
The photo above is a close-up view of the dam power house. The power house
was finished in 1957, two years after the dam was completed. It features
3 generating units, each of which can produce 44-megawatts.
The photo below is a view of the main dam control structure. The
spillway is 664 feet across, and features 14 Tainter gates that are
40 feet by 30 feet. When this photo was taken, the gates were all
closed, which meant that any water flowing out of the dam was going
through the powerplant.
The photo above is a view of the dam embankment, the fishing deck, and
the Lewis & Clark Lake. The lake is 25 miles long, runs as deep as
45 feet, and has 90 miles of shoreline.
The photo below is a close-up view of the electrical substation that
handles the power being generated in the power house.
The photo above is the start of a crossing of the dam from the Nebraska
side to the South Dakota side. We start by driving up a hill around the
back side of the power substation. There is a one-lane section behind
the power house, so a set of stop lights handles the task of alternating
the direction of traffic flow. What is odd about this light is that it
goes green before all the cars are clear from the road behind the power
plant. The reason is that the road is still 2-way, and they accounted
for that in the light timing. The photo below shows the one-lane
section of road behind the power plant.
In the photo above, we continue traveling past the power plant. The
large metal structure is a traveling crane that is used to adjust the
opening of the gates that allow water into the power house inlet.
The photo below is a view traveling across the spillway. The spillway
is very narrow, so it is also part of the one-way travel section.
The photo above is a view of the spillway from downstream. Notice that
the gates are all closed, and no water is flowing through the spillway.
Every so often, an especially large wave would hit one of the gates,
causing it to vibrate, and a small trickle of water would seep out of
the bottom of the gate. That manages to keep the concrete wet below
the gates.
The photo below is the main Missouri River channel looking downriver.
This is a very popular fishing spot. The parking lot for the fishing
deck was full, and there are a number of boats in the river.
The photo above is a view down the length of the dam embankment from
below the dam. The photo below is a view looking towards the dam as
we approach the ramp that leads to the top of the dam. The embankment
is 74 feet tall. It is mowed on a regular basis so workers can more
easily identify seepage before it threatens the integrity of the
structure.
These two photos are views from the road that crosses the crest of
the dam embankment. The photo above shows the dam just after the
spillway, while the photo below shows the dam as we near the end
of the crossing. The dam is a total of 8,700 feet across.
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Photo and text by John A. Weeks III, Copyright © 2008, all rights reserved.
For further information, contact:
john@johnweeks.com