Calcasieu Ship Channel Salinity Control Measures

The Chenier Plain, located in Southwest Louisiana, is home to the Calcasieu-Sabine Basin. Flowing through the Calcasieu-Sabine Basin are the Neches and Sabine Rivers which feed Sabine Lake and the Calcasieu River which feeds Calcasieu Lake. Human modification of these rivers to accommodate shipping traffic has affected the flow and availability of freshwater in the basin. Since they were first dredged in the 1800s these shipping channels have expanded to over forty times their original dimensions as the earthen berms forming the channel banks eroded away. The deeper shipping channels now transport saltwater further into inland marshes where the eroded channel banks introduce salt water to surrounding wetlands. Another shipping channel, the Gulf Intracoastal Waterway, constructed in the early to mid-1900s, cut through the ridge that separated the two river basins, and connected the two shipping channels, allowing further saltwater access. Over time, this altered hydrology has turned the freshwater marshes into open water.

Land-loss in the Chenier Plain is primarily attributed to the changing hydrology of the region associated with manmade actions to dredge and deepen navigation and access canals. Controlling salinity intrusion along the Calcasieu Ship Channel has the potential to make the largest single reduction compared to managing hydrology using hundreds of water control structures across the region. While the channel is a critical asset for the entire region it also poses one of the greatest threats.

The Calcasieu Ship Channel Salinity Control Measures Project will include the construction of sill and wall structures, bank stabilization measures and salinity control gates. The ultimate goal of the project is to manage salinity levels to maintain fresh and intermediate marsh, while reducing bank and shoreline erosion. These structures will include areas for fish gaps and boat access. This project is currently in engineering and design and the current estimated cost of completing this project is $432 million. It is estimated to lose 1,458 acres of land in the short term (20 years) and is estimated to create 12,685 acres of land in the long term (50 years). This project is currently in Engineering and Design and will be funded using RESTORE funds.

Erosion of Calcasieu Ship Channel banks over time from 1978 (left) to 1998 (middle) to 2013(right). Source: left image CPRA, middle and right images Google Earth
Authorized dimensions of the Calcasieu Ship Channel from 1874 to 1968. These are only authorized dimensions. The actual size of the channel is much wider than this as the banks have slumped and eroded. Source: CPRA
Calcasieu Pass circa 1900. Source: CPRA
Current Calcasieu Pass opening, Source: Google Earth
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