Coastal Louisiana wetlands are a product of Mississippi River delta building that has occurred over a period of 3,000–5,000 years. The building processes were very nearly balanced. In modern times man’s use of the area (flood control, navigation improvement, exploitation of petroleum and other minerals, road building, etc.) has seriously altered the natural balance. As a result, overbank flooding has been virtually eliminated and river flow is confined to channels discharging into the outer shelf area. Most transported sediment is now deposited in the deep Gulf of Mexico or along the continental shelf. Saltwater encroachment in the deltaic estuaries has been detrimental to fauna and flora. Even though considerable sediment deposition has resulted from the historic Atchafa River diversion and growth of subdeltas, comparative map studies indicate a net land loss rate of 16.5 sq mi/year during the last 25–30 years. Land loss is only one symptom of general environmental deterioration.

A dynamic management plan is necessary for better utilization of combined freshwater discharge-dissolved solid and transported sediment input of the Mississippi River. Controlled flow into estuaries will reduce salinity encroachment and supply needed nutrients. Large areas of new marshland and estuarine habitat can be built by controlled subdelta diversion. Studies of natural subdeltas indicate that these systems are amenable to environmental management; salinities and sediment deposition may be manipulated to enhance desired conditions.

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