Flooding

Flash Flooding

Clarion Ledger, 1/14/2020

 Flash flooding is caused by heavy or excessive rainfall occurring over a short period of time, leading to torrents of water running through streets, neighborhoods, and storm drains.  Flash flooding is very dangerous because it combines the destructive power of a flood with incredible speed.

Flash flooding occurs when heavy rainfall exceeds the ability of the ground to absorb it. Urban areas are especially prone to flash flooding because their impervious surfaces like large parking lots, streets and buildings do not allow water to infiltrate the ground, causing the water to run off to the low spots very quickly.   In addition to causing a flood hazard, excessive stormwater runoff carries trash, debris and pollutants to our waterways, reducing water quality.   

​How you can help reduce Stormwater Runoff:
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1. Aim your downspouts onto the grass, away from foundations and paved surfaces. For roofs without gutters, plant grass, spread mulch, or use rocks under the drip line to prevent soil erosion and increase the ground's capacity to absorb water.
2. Keep your driveway and street clear of leaves, trash and other debris. 
3. Do not blow grass clippings or leaves into the street. This debris will clog the storm drains and lead to stormwater overflow and increase flash flooding problems. 
4. Install rain barrels on your gutters. A rain barrel can quickly store up to 55 gallons of stormwater for later use. 
5. Use native plants to build Rain Gardens that will soak up and filter water in place. 

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City of Jackson Flash Flooding: click to view more about neighborhood and tributary flooding in the City of Jackson

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River Flooding

Drone video captures the bloated Pearl River. (Source: WLBT) February 16, 2020

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In 1964, in an effort to rein in the Pearl River at Jackson, the Army Corps of Engineers began construction on a 1.5 mile levee on the Jackson side of the river, a 10.3 mile levee on the Rankin side, along with 5 miles of river straightening and channelization. At that time, the Jackson Daily News reported that the project would: "....mark the end of devastating (sic) floods which almost annually have inundated thousands of acres, forced hundreds from their home, and threatened to destroy major industries vital to the economy of both Rankin and Hinds counties." President of the Levee Board stated in the Clarion Ledger that, "(T)his project will make many many acres of valuable land secure for home, business and industrial use" and the USACE projected that, "(T)here is no reason why the project should not give indefinite protection from flooding in the area". 

1964 Levee system, Jackson, MS

What followed was a frenzy of public and private development in the flood plains of Hinds and Rankin county, with Jackson zoning its entire flood plain for residential, commercial and industrial uses. New highways, bridges, shopping centers, a new water treatment plant, the Coliseum, fairgrounds, electrical substations and homes were all built in the newly "protected" and secure flood plain. ​

1979 Easter Flood, Entergy archives

Less than a decade later, in April 1979, the City of Jackson and surrounding counties were hit with the flood of record, devastating communities and causing an estimated $500-$700 million in damages.  Thousands of homes and businesses in the Jackson area were inundated in the flood stage that  lasted from 10 to 14 days in some areas.   After the Easter flood, Congress authorized the Army Corps of Engineers to develop a comprehensive flood control plan for the Jackson metropolitan area.  

Since 1979, numerous Pearl River flood control plans have been introduced.  Originally, flood control plans, such as the Shoccoe Dry Dam Plan authorized by Congress in 1986, and the Comprehensive Levee Plan proposed by the Army Corps of Engineers in 1996,  focused solely on flood control.  Later, flood control plans attempted to leverage economic development opportunities along with flood control, starting with the Two Lakes Plan in 1996, the LeFleur Lakes Plan, the Lower Lake Plan and the  current One Lake Project. ​

City of Jackson Pearl River Flood Stages:

Minor: 28 feet  
Moderate: 33' 
Major: 36' (Flooding begins to impact homes in NE Jackson when the river reaches 36.2')

1979 "flood of record": 43.28'
1983, 2003: major flood stage
​February 2020: 36.8' (third highest flood on record)

During the Feb 2020 major flood event, proactive and deft management of the Ross Barnett Spillway by the Pearl River Valley Water Supply District and its state/federal partners allowed the Pearl River to crest lower than originally forecast.  Still, significant damage occurred in the City of Jackson and in downriver communities.  The federal disaster declaration for the February 10-18 flood event covered 14 counties: Attala, Carroll, Claiborne, Clay, Copiah, Grenada, Hinds, Holmes, Issaquena, Leflore, Marion, Sharkey, Warren and Yazoo. These counties sustained significant damage to public buildings, private homes, highways and roads.  

Jackson and surrounding counties need an updated flood mitigation solution, including a moratorium on any continued construction in flood-prone areas. 

In 2001, Rankin-Hinds Pearl River Flood and Drainage Control District (also known as the Levee Board) accepted the role of "local sponsor", taking over responsibility for planning and executing flood control projects in the Jackson area.  In February 2020, the Levee Board sent their "One Lake" Feasibility Study/Environmental Impact Statement (FS/EIS) to the Army Corps of Engineers (USACE) for review.  This plan calls for widening, deepening and straightening an additional 10 miles of the river.  USACE will review the FS/EIS for Policy and Legal compliance, and if all policy and legal guidelines are met, the FS/EIS will be sent to Federal and State Agencies for review. At that time the FS/EIS will be published for a public comment period.  ​USACE will prepare final recommendations and conditions based on State/Federal/Public and USACE review and then the Assistant Secretary of the Army (Civil Works) will make the final determination to accept or reject the "One Lake" plan.