Sediment-Overlying Water Relationships Affecting Wintertime Dissolved Oxygen Conditions in the Big Eau Pleine Reservoir, Wisconsin

Effects of sediment disturbance and associated chemical oxygen demand on dissolved oxygen (DO) depletion were evaluated during the winters of 1989- 1990 in the Big Eau Pleine Reservoir. As part of this effort, historical DO data, sediment physical and chemical composition, net sedimentation rates, a...

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Bibliographic Details
Main Authors: James, William F, Gunnison, Douglas, Eakin, Harry L, Barko, John W
Format: Report
Language:English
Subjects:
ACCUMULATION
AMMONIUM
ANOXIA
BIG EAU PLEINE RESERVOIR(WISCONSIN)
Biochemistry
BOD
CARBON
CHEMICAL COMPOSITION
COD
DAMS
DENSITY
DEPLETION
DEPOSITION
DISPLACEMENT
DISSOLVED ORGANIC CARBON
DISSOLVED OXYGEN
ENTRAINMENT
FISH KILL
Hydrology, Limnology and Potamology
HYPOLIMNION
INTERSTITIAL
IRON
MANGANESE
MOISTURE
MOISTURE CONTENT
ORGANIZATIONS
OXYGEN
OXYGEN SAG
PHOSPHATE
PHOSPHATES
RATES
REGIONS
RESERVOIRS
RIVERS
SEDIMENT OXYGEN DEMAND
SEDIMENTATION
SEDIMENTS
SURFACES
TRANSPORT
WATER QUALITY
WINTER
WU32694
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Summary:Effects of sediment disturbance and associated chemical oxygen demand on dissolved oxygen (DO) depletion were evaluated during the winters of 1989- 1990 in the Big Eau Pleine Reservoir. As part of this effort, historical DO data, sediment physical and chemical composition, net sedimentation rates, and water quality characteristics were examined. DO depletion and anoxia in the winter develop rapidly in the headwaters in association with drawdown conditions and low inflows from the Big Eau Pleine River. DO depletion also occurs near the dam of the reservoir. Entrainment of anoxic water from the headwaters and its downstream movement during the winter are promoted by continued withdrawal from the reservoir. Three distinct zones of sedimentation (erosional, accumulation, and transport zones) were identified, based on the moisture content of the surficial sediment. Sediments in the erosional zone occupied 60 percent of the reservoir surface area and exhibited low moisture content, high sediment density, and low net sedimentation rates. Physical composition of erosional zone sediments varied greatly at different times of the year, indicating deposition, disturbance and/or resuspension, and removal of sediment. The erosional zone was within the region of average winter drawdown (1,128 ft MSL). This suggested that winter drawdown may be an important factor in sediment disturbance and longitudinal transport toward the dam. The accumulation zone was located in the basin near the dam and occupied only 2 percent of the reservoir surface area. Sediments in this zone exhibited a higher moisture content, lower sediment density, and higher net sedimentation rate, indicating sediment focusing.