Calcasieu / Sabine Basin
The basin contains about
312,500 acres of wetlands, consisting of 32,800 acres of fresh marsh, 112,000
acres of intermediate marsh, 158,200 of brackish marsh, and 9,500 acres of
saline marsh. A total of 122,000 acres have been lost since 1932,
28 percent of the marsh that existed in 1932.
Marshes within the Sabine Basin began forming about 3,500 years ago. Whenever the Mississippi River established a westerly course, large quantities of reworked riverine sediment were deposited along the gulf shore, resulting in southerly growth of the shoreline. When the Mississippi River shifted to an easterly course, the sediment supply decreased and erosive forces were greater than sediment deposition due to littoral drift. As a result, the shoreline converted to a more typical beach-like nature and gradually retreated. The repetitive occurrence of these pulses of sediment due to change in the Mississippi Rivers course helped to build the systems of cheniers (oak ridges) in the basin.
The progradation process served to establish an undulating land form along the gulf coast. The areas between the cheniers were collecting points for water and, over time, built up by decomposition and regeneration of plant materials to form low salinity marshes. These interior marsh areas would occasionally receive pulses of mineral sediment input due to storm tides.
Calcasieu and Sabine lakes are the major water bodies within the basin. Freshwater inflow to the basin occurs primarily through these lakes via the Calcasieu and Sabine rivers. Marshes within the basin historically drained into these two large lakes. This process was altered by the construction of channels to enhance navigation and mineral extraction activities. Navigation channels now dominate the hydrology of the basin. The Calcasieu Ship Channel is maintained at 40 feet deep by 400 feet wide and extends from the Gulf of Mexico to Lake Charles, Louisiana. The GIWW is maintained at 12 feet deep by 125 feet wide. The reach of the GIWW between the Sabine River and the Calcasieu Ship Channel was dredged to a depth of 30 feet in 1927. The Sabine-Neches Waterway, between the Gulf of Mexico and Port Arthur, Texas, is 40 feet deep by 400 feet wide.
The hydrology of the marshes between Sabine and Calcasieu lakes has also been altered by numerous relatively small access canals. The GIWW and this network of canals have established a hydrologic connections between the Sabine and Calcasieu Estuaries. Additionally, a number of bayous which once drained adjacent marshes into either of the estuaries have been connected to one another. Consequently, marshes between Sabine and Calcasieu Lakes have become a large interlinked system with water draining and circulating to the northern, eastern, and western portions of the basin.
The water circulation patterns allow for higher salinity water to enter the interior marshes (saltwater intrusion). The basin soils, which are 87 percent organic and support lower salinity marsh vegetation, are infiltrated by the more saline waters. This leads to increased stress and loss of the plant communities, and eventually erosion and sediment transport out of the inner marsh areas.
Subsidence and sea level rise are natural processes that contribute to wetland deterioration and loss. Under pristine conditions, natural marsh building and maintenance processes are effective in maintaining coastal marshes despite subsidence and sea level rise; however, human alterations have disrupted the hydrologic processes which contributed to wetland building and maintenance, while subsidence and sea level rise continues. In the Sabine Basin, subsidence and sea level rise result in an average water level rise of 0.25 inches per year. Although natural wetland building processes no longer occur, natural marsh maintenance processes can be fairly effective at keeping wetland loss rates low.
Erosion is a problem along the shores of Calcasieu and Sabine lakes and the banks of the GIWW. Erosion related breaching of the lakes shores threatens adjacent marshes because of the vulnerability of their typically weaker soils to increased water exchange and saltwater intrusion. Along the Gulf of Mexico, shoreline retreat is causing the loss of back-beach marshes and is threatening to alter the hydrology of interior marshes. Flood control projects on the Mississippi and Atchafalaya rivers, and construction of jetties on the Mermentau River, Calcasieu Ship Channel, and at Sabine Pass, have altered long shore sediment transport and sediment availability.
In summary, wetland loss within the basin is largely the result of extensive hydrologic alterations to wetland building and maintenance processes. Recent observations regarding marsh recovery indicate that in some areas, reducing salinities may protect and restore wetlands.
Basin-Wide Land Loss Map for Calcasieu Basin.  |
Basin-Wide Habitats Maps for Calcasieu Basin.
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(Time lapsed animation of basin from 1956 to 1993.)
CWPPRA Restoration Sites for the Calcasieu / Sabine Basin.
| PPL | Number | Agency | Project Name |
| 1 | CS-17 | USFWS | Cameron Creole Plugs |
| 10 | CS-32 | USFWS | East Sabine Lake Hydrologic Restoration |
| 3 | CS-23 | USFWS | Replace Sabine Refuge Water Control Structures at Headquarters Canal, West Cove Canal, and Hog Island Gully |
| 1 | CS-18 | USFWS | Sabine National Wildlife Refuge Erosion Protection |
| 9 | CS-30 | NRCS | GIWW - Perry Ridge West Bank Stabilization |
| 2 | CS-21 | NRCS | Highway 384 Hydrologic Restoration |
| 11 | CS-31 | NRCS | Holly Beach Sand Management |
| 4 | CS-24 | NRCS | Perry Ridge Shore Protection |
| 4 | CS-25 | NRCS | Plowed Terraces Demonstration |
| 18 | CS-49 | NRCS | Cameron-Creole Freshwater Introduction |
| 3 | CS-04a | NRCS | Cameron-Creole Maintenance |
| 9 | CS-29 | NRCS | Black Bayou Culverts Hydrologic Restoration |
| 2 | CS-09 | NRCS | Brown Lake Hydrologic Restoration |
| 5 | CS-11b | NRCS | Sweet Lake/Willow Lake Hydrologic Restoration |
| 1 | CS-19 | NRCS | West Hackberry Vegetative Planting Demonstration |
| 2 | CS-20 | NRCS | East Mud Lake Marsh Management |
| 6 | CS-27 | NMFS | Black Bayou Hydrologic Restoration |
| 4 | CS-26 | EPA | Compost Demonstration (Deauthorized) |
| 2 | CS-22 | COE | Clear Marais Bank Protection |
| 8 | CS-28-1 | COE | Sabine Refuge Marsh Creation Cycle 1 |
| 8 | CS-28-3 | COE | Sabine Refuge Marsh Creation Cycle 3 |
| 8 | CS-28-2 | COE | Sabine Refuge Marsh Creation, Cycle 2 |
| 8 | CS-28-4 | COE | Sabine Refuge Marsh Creation, Cycle 4 |
| 8 | CS-28-5 | COE | Sabine Refuge Marsh Creation, Cycle 5 |
24 projects listed
PPL stands for "Priority Project List"