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Water Quality Conditions Monitored at the Corps' Gavins Point Project in Nebraska/South Dakota during the 3-Year Period 2008 through 2010

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Special rept.

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The U.S. Army Corps of Engineers Corps Gavins Point Project consists of Gavins Point Dam and Gavins Point Reservoir i.e., Lewis and Clark Lake. Gavins Point Dam is located on the Missouri River at River Mile RM 811 along the NebraskaSouth Dakota border, near the town of Yankton, South Dakota. The reservoir and dam are authorized for the uses of flood control, recreation, fish and wildlife, hydroelectric power production, water supply, water quality, navigation, and irrigation. Lewis and Clark Lake is an important recreational resource to both the States of Nebraska and South Dakota. Water quality monitoring was conducted at the Gavins Point Project by the Omaha District District over the 3-year period of 2008 through 2010. The water quality monitoring conducted included 1 continuing long-term, fixed-station monitoring in Lewis and Clark Lake at a near-dam deepwater location and of the Gavins Point Dam tailwaters 2 monthly sampling and continuous monitoring i.e., hourly of water quality conditions in the powerplant of water discharged through Gavins Point Dam 3 intensive water quality surveys in 2008, 2009, and 2010 4 bacteria monitoring and 5 a special study in 2008. The results of this monitoring were used to assess the existing water quality conditions at the Gavins Point Project. Water quality conditions in Lewis and Clark Lake vary temporally, longitudinally from the dam to the reservoir s upstream reaches, and vertically from the reservoir s surface to the bottom. During periods of calm weather in the summer, Lewis and Clark Lake develops a slight thermal stratification. When this slight stratification occurs, a thermocline is present at about 8 meters depth. This indicates the reservoir is probably polymixic. The thermal stratification breaks down under windier conditions, given the shallow depth of the reservoir i.e., 14 meters, and the reservoir mixes throughout its water column.

Subject Categories:

  • Hydrology, Limnology and Potamology
  • Water Pollution and Control

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