Gavins Point Dam

Gavins Point Dam
Aerial view of Gavins Point Dam power plant and spillway, on the Missouri River impounding Lewis and Clark Lake.
Location of Gavins Point Dam in the Midwestern United States.
Gavins Point Dam (the US)
Country United States
Location Nebraska and
South Dakota
near Yankton, South Dakota
Coordinates 42°50′58″N 97°28′55″W / 42.849382°N 97.482018°W / 42.849382; -97.482018Coordinates: 42°50′58″N 97°28′55″W / 42.849382°N 97.482018°W / 42.849382; -97.482018
Status Operational
Construction began 1952 (1952)
Opening date 1957 (1957)
Construction cost $51 million
Owner(s) U.S. Army Corps of Engineers
Dam and spillways
Type of dam Embankment, rolled-earth and chalk-fill
Impounds Missouri River
Height 74 ft (23 m)
Length 8,700 ft (2,652 m)
Width (crest) 35 ft (11 m)
Width (base) 850 ft (259 m)
Dam volume 7,000,000 cu yd (5,351,884 m3)
Reservoir
Creates Lewis and Clark Lake
Total capacity 492,000 acre⋅ft (606,873,064 m3)
Catchment area 279,480 sq mi (723,850 km2)
Surface area 31,400 acres (12,700 ha)
Maximum length 25 mi (40 km)
Maximum water depth 45 ft (14 m)
Normal elevation 1,210 feet msl
Power Station
Operator(s) U.S. Army Corps of Engineers
Commission date 1957
Turbines 3 x 44 MW
Installed capacity 132 MW
Annual generation 727 million KWh[1]
Website
U.S. Army Corps of Engineers, Gavins Point Project

Gavins Point Dam is a large embankment rolled-earth and chalk-fill dam on the Missouri River, located in the U.S. States of Nebraska and South Dakota in the Upper Midwest Region of the United States. The dam was constructed from 1952 to 1957 by the United States Army Corps of Engineers. The dam creates the 31,400 acre (12,700 ha) Lewis and Clark Lake. The dam is located approximately 4 miles west of Yankton, South Dakota in both Cedar County, Nebraska and Yankton County, South Dakota.

History

Tom Brokaw greeting the 20,000th visitor to the dam in 1958. Brokaw was once a tour guide at the dam.

Gavins Point Dam was constructed as a part of the Pick–Sloan Missouri Basin Program, authorized by the Flood Control Act of 1944 by Congress. The dam operations work in conjunction with the other Pick-Sloan Program Dams to assist with conservation, control, and use of water resources in the Missouri River Basin. The intended beneficial uses of these water resources include flood control, aids to navigation, irrigation, supplemental water supply, power generation, municipal and industrial water supplies, stream-pollution abatement, Sediment control, preservation and enhancement of fish and wildlife, and creation of recreation opportunities. Gavins Point is the most downstream dam on the Missouri River at river mile 811.1. The next dam upstream is Fort Randall Dam.

The dam releasing a record 150,000 cubic feet per second (4,200 m3/s) of water on June 14, 2011 as a result of the 2011 Missouri River Floods. The release was more than twice the previous record set in 1997.[2]

During the 2011 Missouri River Flood, the dam released a record water flow of 160,200 cfs, the previous record was 70,000 cfs in 1997. During the 2011 flood, the dam was damaged by debris and a significant portion of rocks were dislodged from its upstream side. The U.S. Army Corps of Engineers soon began repairs to the dam and its spillway gates. Pressure sensors were also installed in concrete portion of the dam.[3][4]

Hydroelectric Power Generation

The dam has a hydroelectric power plant with three generators, each having a nameplate capacity of 44,099 kW, for a total of 132.297 MW.[5] The hydroelectric power plant provides enough electricity to supply 68,000 homes. Power generated is sold through the Western Area Power Administration.

Reservoir

See main article: Lewis and Clark Lake

Aerial photo of Gavins Point Dam and Lewis and Clark Lake, looking north.

Gavins Point Dam creates Lewis and Clark Lake, a popular regional tourist destination for water-based recreational opportunities including boating and fishing, along with camping, hiking, and hunting opportunities managed by the State of South Dakota, State of Nebraska, and the U.S. Army Corps of Engineers (USACE). Public tours of the power plant are offered weekends between Memorial Day weekend and Labor Day weekend by USACE Park Rangers. The nearby Lewis and Clark Visitor Center on the Nebraska-side of the dam is open daily and tells the story of dam construction, along with local history, wildlife and the Lewis and Clark Expedition. The Gavins Point National Fish Hatchery is located just downstream of the dam on the South Dakota side.

Lewis and Clark Lake is significantly impacted by sedimentation and siltation issues, diminishing the overall water surface area, water storage capacity, and recreational opportunities. Sediment carried by the Missouri River and Niobrara River is slowed and trapped within the reservoir due to the dam impounding and thus stopping the natural river flow. Studies show approximately 5.1 tons of sediment are deposited in the lake each year, which contributes to the lake's increasing size of delta area on the western portions of the lake. Approximately 60% of the sediment comes from the Nebraska Sandhills via the Niobrara River. As of 2016, approximately 30% of the lake's overall surface area has diminished due to sedimentation deposits, and some figures project by 2045 approximately 50% of the lake will be diminished due to sedimentation deposits. Presently, there is no plan or solution to remove or slow the progression of the siltation within the lake.[6]

See also

References

  1. ↑ "Summary of Engineering Data – Missouri River Main Stem System" (PDF). Missouri River Division. U.S. Army Corps of Engineers. August 2010. Retrieved 2012-08-17.
  2. ↑ http://www.columbiamissourian.com/stories/2011/06/01/record-precipitation-reservoir-releases-cause-missouri-river-flooding/%5Bpermanent+dead+link%5D
  3. ↑ "Crews repair Gavins Point Dam from 2011 flooding". Black Hills Pioneer. 19 September 2013. Retrieved 19 September 2013.
  4. ↑ "Gavins Point Dam". Geographic Names Information System. United States Geological Survey. Retrieved 2006-05-10.
  5. ↑ "Gavins Point Dam & Powerplant". United States Army Corps of Engineers. 2008-10-24. Archived from the original on 2011-06-01. Retrieved 2009-01-27.
  6. ↑ http://msaconline.com/

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