Today marks the 140th straight day of flooding

Today, Saturday, July 6th, 2019. is the 140th continuous day the Mississippi River at Vicksburg has been above flood stage.

A traditional map of the backwater area.

The Mississippi River flood and the Yazoo Backwater flood are related but separate events. Knowing the history of the Mississippi flood is important when it comes to understanding the Backwater flood.

For reference, the Yazoo Backwater (aka the South Delta) comprises approximately 4,093 square miles of alluvial valley in the lower Yazoo Basin. It encompasses the area south of the line between Hollandale and Belzoni, east of the Mainline Mississippi River Levee and west of the Yazoo River Levee.

The Mississippi begins to flood

In September 2018, Hurricane Florence came ashore at the border between North and South Carolina. As the storm continued inland and over the Appalachian Mountains, it dumped a tremendous amount of water in the Ohio Valley. That caused the Mississippi River to rise. Over the next three months, historic amounts of rain in Pennsylvania and other parts of the Ohio Valley continued to add to the river’s rise.

A chart showing the Mississippi River’s rise from September of 2018 to the end of February 2019.

On Jan. 12, 2019, the Mississippi at the Vicksburg gauge went above flood stage at 43.2 feet. It dropped back below flood stage on the 24th, but on Feb. 17 it went above 43 feet again, and it is still above flood stage today. The spring thaws and unprecedented amounts of rain in the upper Mississippi Valley added to the river’s volume as it flowed southward.

The Yazoo Backwater flood

At the same time, the state of Mississippi experienced huge amounts of rainfall, causing the Yazoo River, which flows into the Mississippi River north of Vicksburg, to rise as well.

The gates at the Steele Bayou structure were constructed to prevent the Yazoo River from inundating the Backwater.

When both the Mississippi and Yazoo rivers are on the rise, the U.S. Army Corps of Engineers close the gates at Steele Bayou to prevent the Yazoo from flooding the Backwater. With the gates closed, however, rainwater accumulating in the area had nowhere to go after the ground was saturated.

Originally, the Corps designed pumps to siphon the water from the Backwater when both the Yazoo River and water in the Backwater were high. The Environmental Protection Agency vetoed completing the pumps in 2008.

As a result, for several months starting in September 2018, the Yazoo Backwater held rainwater behind the closed Steele Bayou gates, causing a massive flood. At its peak, 550,000 acres, including over 225,000 acres of cropland, were under water.

The impact on the residents and wildlife has been catastrophic.

Satellite photos tell the story on the land

The Yazoo Backwater area on June 30, 2018.

Dramatic satellite photos from LandLook, a project of the U.S. Geological Survey, show the flooding in the Backwater area over time. The photos show how water filled the Backwater basin, which was created over decades to channel the water to Steele Bayou.

On June 30th, 2018, a satellite picture of the Backwater area shows the South Delta full of green fields.

Six months later, on January 24, 2019, another photo shows the Backwater already inundated.

Backwater flood area on January 24, 2019

A third photo, from June 1, 2019, shows how far the flooding had progressed.

Backwater flood area on June 1, 2019

The current projection is that the Mississippi River will drop below flood stage in about three weeks. That forecast has been fluid for several months now. Each time we have additional rain, it negatively impacts the river’s slow drop.

While the river is dropping, the gates at Steele Bayou can be opened to drain the Backwater at a more rapid rate than evaporation allows in the humid Mississippi summer. The gates are currently open.

The gates at Muddy Bayou control the level of water in Eagle Lake. They are also open and slowly draining the lake.

Backwater flood area composite of all the above satellite photos.

The lake and the surrounding area will be impacted for many years to come with no guarantee it will ever return to its pre-flood appearance.

This story was inspired and created based on social media posts by Victoria Darden, Nancy Coleman and James Coleman.

Corrections: This story was corrected to indicate the size of the Yazoo basin. It is 4,093 square miles, not 1,550. Also, the information about opening the gates when the risk of overtopping them is present was incorrect and deleted.