Estuary Issues

Management Conference members have identified seven priority problems in the estuary that are contributing to the decline in certain animal populations, contamination of both fish and shellfish, land loss, habitat modification, and contamination of sediment in the marshes. Each of the priority problems, in some way, impacts the next, making the resolution of each of the problems that much more pressing and complex.

In general, the overall health of the Barataria and Terrebonne basins show signs of years of abuse and neglect. The following discussion provides a snapshot of the problems that must be overcome to prevent further degradation of the habitats, ecosystems, and cultural heritage that are so unique to the system.

Use the menu bar to the right to learn more about the Seven Priority Problems.

Hydrologic Modification

Hydrologic ModificationHydrologic modification is considered the “linchpin” problem of the basins, indicating that all other problems revolve around, and are often affected by it. When we build levees, dredge canals, or cut through natural ridges, the natural flow of water is changed. In some cases, such changes accelerate erosion. In other cases, it can result in changed salinity of water bodies. As a result, fresh marsh can be changed to a more “salt tolerant” type. In more extreme cases, marsh can be converted to open water.

Sediment Reduction

Reduced Sediment ResorucesYet another critical problem is sediment reduction. Louisiana marshes need a source of sediment to survive. Historically, the Mississippi River provided the sediment. Now, however, levees confine the sediment to the river thus bypassing the marshes, ultimately depositing it on the continental shelf in the Gulf. Our coastal marshes constantly undergo a natural process called “subsidence” which results in the land slowly sinking. In the past, the rate of sediment building equaled or surpassed the rate of sinking and the level of the marsh remained above the level of the sea.

Habitat Loss

Habitat LossWhat is known about the rate of habitat conversion, and ultimately land loss in the coastal areas of the Barataria and Terrebonne basins, is that it is alarmingly high. Studies through 1978 showed that over 11,500 acres of land a year were being lost as it slowly converted to open water due to subsidence or other factors. The rate in 1990 was estimated at almost 13,500 acres per year. Scientists have calculated that over 294,000 acres of marsh converted to open water between 1956 and 1978.


When too many nutrients, such as phosphorus and nitrogen, are in the water, a condition known as eutrophication occurs. The process begins with an accelerated growth of algae with the end result being that oxygen in the water is depleted as plant matter decays, killing fish and shellfish.


Pathogens are disease-producing organisms such as bacteria and viruses. The sources of these organisms are human waste, pasture runoff, and waste products of marsh animals such as nutria and birds.

Toxic Substances

ToxicsWater, animal tissue, and sediment testing have identified a variety of toxic substances in the basins. Some of the substances are known cancer-causing agents while others affect reproduction. When some animals consume contaminated food, the toxic concentration is magnified. Human consumption of highly contaminated seafood poses health risks. Toxics found throughout the system come from point sources, such as industry, and non-point sources, such as urban runoff.

Changes in Living ResourcesChanges in Living Resources

Approximately 735 species of birds, finfish, shellfish, reptiles, amphibians, and mammals spend all or part of their life cycle in the estuary. Several of the species are either categorized as threatened or endangered. Many factors contribute to declines in animal populations.



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