interpretation of old aerial photographs indicate that freshwater from Bayou LaBranche buffered 

 brackish tidal surge in the northwestern edge of the study area; vegetation which is characteristic 

 of fresh to intermediate marshes resulted. This would explain why this marsh was so vulnerable 

 to saltwater intrusion after dredging of the Interstate Highway 10 canal in the mid-1960's. 

 Conversely, marsh vegetation in areas further east was predominately brackish plants and much less 

 damage resulted from the construction of Interstate Highway 10. 



Other natural and artificial events compounded the problems in these wetlands. The Mississippi 

 River Gulf Outlet Project which was completed in 1963 increased salinity levels in Lake 

 Pontchartrain threefold (Montz 1973). This project also increased daily tidal ranges, thereby 

 accelerating erosion. Hurricanes Betsy (1965) and Camille (1969) flooded the marsh and swamp 

 with 0.61 to 1.83 m of saline water. Oil and gas activities induced brackish water into the cypress 

 swamps resulting in a reduction of stand density and quality of trees. Since 1953, 1,190 ha of the 

 1,868 ha fresh marsh have become open water. 



Shoreline erosion along Lake Pontchartrain is jeopardizing the brackish ponds and remaining 

 marsh vegetation. A 914-m section of shoreline extending from the Pipeline Canal west ranges 

 in width from 1.5 m to 30.5 m. Shoreline retreat in this area has been over 7.6 m per year since 

 1971. The shoreline protecting the area east of the pipeline has experienced slower erosion rates 

 of 5.18 m per year because the abandoned U.S. Highway 51 buffered most of the wave energy for 

 many years. However, most of the highway bed has now eroded away, and shoreline retreat will 

 likely accelerate. 



In response to all of these problems, planting of smooth cordgrass was initiated. Smooth 

 cordgrass is fairly fast growing, reproduces by seeds and tillers, has shown success in shoreline 

 stabilization, is very salt tolerant, and responds well to tidal fluctuations. No evidence of smooth 

 cordgrass was documented in the study area after initial evaluation of 43 sites. The nearest natural 

 occurrence of this plant is approximately 45 km away in the extreme eastern portion of Orleans 

 Parish and along the north shoreline of Lake Pontchartrain in St Tammany Parish. Structural 

 methods have also been initiated in the area to aid in shoreline erosion control and water 

 stabilization. 



METHODS 



Twelve plantings of smooth cordgrass were made on 2 May 1984, on Lake Pontchartrain in St 

 Charles Parish (Table 1). Plant materials were vegetative sprouts grown in styroblock tubes at the 

 Soil Conservation Service Coffeeville Plant Materials Center. The plants were from accession No. 

 MS-5121. Each row had about 40 plants. Plants were about 25.40 cm tall and had a good root 

 mat to the 10.16-cm depth of the tube. 



Planting sites 1 through 8 were along a cut in the lake bank and are protected from direct wave 

 action. An old bulkhead is about 30.5 m out in the lake from this site. Soils at this site are 

 organic overlaid with sand (in some cases up to 7.6 cm deep). 



Sites 9 through 1 1 were planted along the edge of a shallow, open water area. This area is away 

 from the lake shoreline, and the soils are organic. Planting site 12 was made on the lake shore 

 directly opposite sites 9 through 11. 



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