Water-quality of the Yazoo River During the 2011 Mississippi River Flood

Author(s): Woods, M.; Rose, C.; Coupe, R.

The Mississippi River was above flood stage at Vicksburg, Mississippi, for much of spring 2011. Water samples were collected during this period on a weekly basis from the Yazoo River near Vicksburg, Mississippi, and analyzed for nutrients, sediment, and pesticides as part of a U. S. Geological Survey study to assess water quality of the Mississippi River Basin. High water affected the water quality of the lower Yazoo River, as the Mississippi River stage rose and fell during the flood. Water-quality changes correspond not only to stagnant or reversed flows and accumulation and backwater effects, but also to different sources of water to the Yazoo River before, during, and after the flood. Before the spring 2011 flooding of the Mississippi River, the Yazoo River water came from two sources: the Delta and the Bluff Hills. Along the upper Yazoo River, flood-control structures at Steele Bayou and Little Sunflower Diversion Canal outlets were closed to prevent flooding in the Delta from the Mississippi River; during this time, the Yazoo River source is primarily from the Bluff Hills. During the flood, when the Mississippi River stage was higher than the Yazoo River stage, the Yazoo River flow was impeded and reversed, and mixing of the Mississippi River into the Yazoo River occurred. The Mississippi River was a major source of water to the Yazoo River near Vicksburg during flooding. For much of the 2011 growing season, the control structures along the Yazoo River were closed, thus causing sediment and nutrients to accumulate behind the flood control structures. As the Mississippi River receded following the flood, the flow control structures were reopened, flushing the stagnant and sediment-laden backwater into the Yazoo River, allowing the streams of the Delta to return to normal flow. Following the flood, the Yazoo River water source was primarily from the Delta. The changes in water-quality on the Yazoo River during the 2011 Mississippi River flood can be attributed to the different water sources caused by the flood.

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Technical Sessions

1 Best Management Practices #1
2 Delta Water Assessment
3 Flood Assessment & Mgmt.
4 Wetlands
5 Watershed Mgmt. #1
6 Non-Point Source Assessment
7 Modeling
8 Water Quality
9 Best Mgt. Practices #2
10 Delta Water Conservation
11 Sedimentation
12 Storm Water
13 Watershed Mgt. #2
14 Public Water Systems
15 Surface Water Assessment & Evaluation

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