If costs can be reduced and benefits increased, priority for implementing this strategy will increase.The fourth critical problem is that several marshes in the basin are vulnerable to rapid loss if adequate protection is not provided soon. Construction of the MRGO, which breaches the natural barrier of the Bayou La Loutre ridge and the Borgne land bridge, allowed saline waters to push farther into the basin.
Based on current loss rates, approximately 1,250 acres of marsh will continue to be lost each year without restorative action (Dunbar et al.
However, these mean increases are less than the overall variability in salinity.
Construction of the MRGO, which breaches the natural barrier of the Bayou La Loutre ridge and the Pontchartrain/Borgne land bridge, allowed saline waters to push farther into the basin.
The middle basin would be a lake surrounded by shallow ponds where marshes once existed.
1. The primary causes of wetland loss in the basin are the interrelated effects of human activities and the estuarine processes that began to predominate many hundreds of years ago, as the delta was abandoned.The three large lakes, Maurepas, Pontchartrain, and Borgne cover 55 percent of the basin.
Construction of the artificial barrier islands prevents the loss of an additional 33 percent of the lower basin. The long-term portion of the plan, necessary to achieve a no net loss of wetlands, consists of additional freshwater diversions, sediment import, and the creation of barrier islands.The basin contains 483,390 acres of wetlands, consisting of nearly 38,500 acres of fresh marsh, 28,600 acres of intermediate marsh, 116,800 acres of brackish marsh, 83,900 acres of saline marsh, and 215,600 acres of cypress swamp. This does not include the possible loss of the upper basin swamps.
1994) . Please look at the time stamp on the story to see when it was last updated. The The Inner Harbor Navigation Canal (IHNC) and the MRGO provide a direct link between Lake Pontchartrain and the … If no action is taken, 69,400 acres of swamp, 32 percent of the basin's existing swamp, would be converted to marsh or open water by 2040. “That allows the sun to penetrate to the bottom. Construction of a rock dike on the north bank of the MRGO and the beneficial use of all the material dredged for the MRGO would stop erosion, addressing the second critical problem, and create large amounts of marsh. Fewer fish and shellfish would be available for commercial or recreational fishermen. During the same time, 17 percent of the Maurepas Land Bridge marshes disappeared due to subsidence and spikes in lake salinity.
Long-term sediment import projects are essential in achieving no net loss in the lower basin.
Although expensive, it is defined as critical and retained in the selected plan for possible implementation in the long term.
This loss amounts to approximately 25,000 acres during the next 20 years.
Vast marshes for wintering ducks would no longer exist. The table provides the classification (e.g., critical, supportive, demonstration), estimated benefits and costs, and status of these projects.
The Bayou Chevee and Bayou La Branche projects beneficially use dredged material to create marsh. That butt could end up in a baby shark’s mouth.“There aren’t a lot of deep spots,” Trail said. The channel's north bank continues to eroding at a rate of 15 feet per year. A complete listing of all the projects proposed for the Pontchartrain Basin can be found in Appendix A, Table 8.
The diversion at the Bonnet Carr Spillway and bank protection with marsh creation along the MRGO are critical projects.All of the approved CWPPRA projects in the Pontchartrain Basin contribute to the restoration objectives previously listed.
Clearly, additional long-term efforts are needed to preserve these eroding marshes.