FLOOD CONTROL PROJECT FOR THE

JACKSON METROPOLITAN AREA

Flood Elevations
Benefits
Flood Frequency
Lake Map

This is a proposal intended to solve the flooding problems in the Jackson area in such a manner that the attractiveness and growth potential of the metropolitan area would also be enhanced. Flood levels would be permanently lowered in the Byram to Jackson area by providing a better flow course for the passage of water and by reducing the rate of flow in the river . The graph below shows the profile of the flood levels that occurred in the 1979 flood. On this graph a person can see the extra water that had been backed up into the area north of Jackson. The curve also shows what both the 1979 flood and the 100 year frequency flood are projected to be after the proposed lake has been constructed and the improved reservoir discharge plan has been implemented (The better flow course would enable the reservoir to develop an improved discharge plan).

A person whose home or business flooded during the 1979 flood can use the following chart to determine what level of protection his structure would derive from the implementation of this plan. If a person has an accurate water mark on his structure made by the 1979 flood, that person could determine whether the structure would receive water in another 1979 flood by measuring down to his slab level from this mark. Column 2 shows where the new 1979 flood level would be. A person whose structure would still receive water in a 1979 flood (a 200 year flood) may be protected from a 100 year flood. This could be determined by using column 3. The best way to determine the level of protection for any structure would be to survey the elevation of the structures slab and refer to column 1.

FLOOD ELEVATION

MAXIMUM BENEFITS THAT WILL RESULT FROM THE
FLOOD CONTROL LAKES ALONE WITH NO ADDITIONAL BENEFIT
FROM RESERVOIR REGULATION
Flood benefits at 1979 Flow Rate
350 Year Probability

MAXIMUM BENEFITS THAT CAN BE DERIVED BY SUBTRACTING AN
ADDITIONAL 1.25 FEET THAT WILL RESULT FROM IMPROVED
REGULATION OF THE RESERVOIR
Renefits derived from reservoir regulation will be discounted
according to the consistency with which reservoir inflow can
be predicted from rainfall as it is measured on the ground.
This discount value will be applied to the chart below when a
computer model for inflow projection has been completed.

The 1979 flood was rated as a 500 year event by the USGS in a 1982 study. The inclusion of another large flood in 1982 had the effect of reducing the rating of the 1979 flood to a 350 year frequency event.

All the structures that flooded in the 1979 flood should be protected from a 100 year flood by the new lake and the improved reservoir discharge procedure. Additionally, the plan would provide that surveying be conducted in order to determine what structures exist in the various flood prone areas that would not be protected from the 1979 flood (a 200 year flood). If any structures exist that need protection, auxiliary plans would be considered and if warranted, additional protection would be extended to these structures.

The improved flow course for the river would be created by removing the trees from the very lowest level of the river flood plain (the river bottomland). This level would then be lowered approximately five feet with dredges and/or trackhoes and earth moving equipment and then the entire eleven mile river course opposite Jackson would be made into a permanent lake. (See following map of lower level flood control lakes). A lake would be necessary to prevent the redistribution of sand and silt and to prevent the regrowth of trees in the river flow course.

It would be necessary to remove very large amounts of sand from beneath the numerous railroad and highway structures south of downtown Jackson. This is needed to provide the proper flow course thru this area of the river. The levees and bridges are presently blocking the river’s flow and backing water up into Jackson homes and businesses. In order to have some place to put this sand the Flowood levee would be moved to the east and the excavated material would then be put in the middle of the newly formed lake. This would create a 600 acre island opposite downtown Jackson. North of Lakeland the dredged material would be placed on the east side of the newly formed lake.

The following map shows how the dredged material could be turned into an asset. This would be accomplished by accessing the newly created land with bridges and by constructing interchanges, parkways and city streets over it and along the entire length of the three thousand acre lake. Many of the roads and bridges are needed at this time to alleviate the metropolitan areas traffic congestion. Both the traffic and flooding problems could be solved at once and at less cost than plans for previous flood control, roads and bridges. This is because the newly created land would offer no impediment to construction.

Any flood control plan, to be successful, must pass the give and take considerations of the many communities that it will have an effect upon. The Jackson area has four distinct areas that will be effected in different ways by any flood control plan. We hope that the features of this plan that might be objectionable to a given area can be overcome by the good features that it contributes to that area.

Reservoir people would expect that on two or three occasions each year the water’s level, over a period of a day and a half, will fall one foot then rise again to its original level. Once every 25 years they would be warned to untie moorings and move boats because the level will be taken down below 295 feet. On the positive side, they would enjoy an extra one half to one foot of water in their boat slips.

Some people in northeast Jackson who appreciate hiking in the existing river bottom areas and who want to preserve the wetlands that exist there would be compensated by knowing that two thousand of their neighbors will never have to worry about their homes and businesses flooding again.

A few people in downtown Jackson built metal buildings at very low elevations and will not be protected from another 1979 flood, but they will be compensated by having protection from a 100 year flood on structures that probably will not last 100 years.

People who own land and camps on the river south of Jackson would experience one or two river bottom floods that they would not have had otherwise but they would be compensated by the assurance that the reservoir would have the capacity to take one foot of elevation off of every major flood that could occur in the area. One foot off of the 1979 flood would have prevented much of the flooding that these people’s neighbors suffered in 1979.

Anyone reading this proposal is reminded that we intend to change it in any way possible to overcome their concerns. Please let us hear from you.