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Mississippi and Louisiana Estuarine Areas. Freshwater Diversion to Lake Pontchartrain Basin and Mississippi Sound. Feasibility Study. Volume 1. Main Report.

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Final environmental impact statement,

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The study area has experienced land loss and saltwater intrusion due to natural processes such as subsidence and erosion, as well as mans developmental activities including leveeing, channelization, and petroleum exploration. The various natural processes and mans activities have altered overbank flooding and natural distributary flow which historically provided fresh water, sediments and nutrients to the estuarine areas. This has resulted in conversion of fresh, intermediate, and brackish marshes to more saline marsh types and has also caused the loss of substantial areas of wooded swamp. Saltwater intrusion and loss of wetlands have adversely affected the productivity of wildlife and fishery resources. Influx of the saline waters is particularly harmful to the American oyster, due to increased predation and disease. Thousands of acres formerly productive oyster reefs in the area lie largely unproductive due to excessive salinities. One way to amelioriate loss of wetland habitat and rate of saltwater intrusion is timely introduction of fresh water and associated sediments and nutrients into the study area. A total of 13 potential sites were evaluated for diversion of fresh water. Based on the results of this study, it has been recommended that fresh water from the Mississippi River be diverted into Lake Pontchartrain at a site adjacent to the Bonnet Carre Spillway. This site is located at river mile 128.5. Implementation of this plan would save approximately 4.186 acres of marsh and 6,355 acres of wooded swamp. Additionally, average annual oyster production in the study area would increase by about 7.5 million pounds.

Subject Categories:

  • Hydrology, Limnology and Potamology
  • Civil Engineering

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