East Catfish Lake Marsh Creation and Shoreline Protection (TE-157)

Aerial view of marsh creation project in Terrebonne Parish.

Location

The project is located in Region 3, Terrebonne Basin, Terrebonne Parish.

Problems

Significant marsh loss has occurred east and south of Catfish Lake. Causes of marsh loss include the construction of numerous oil/gas canals, subsidence, and sediment deprivation. Between Catfish Lake and Golden Meadow Hurricane Protection Levee, very little marsh remains after the construction of an extensive network of oil/gas canals. Much of the remaining land in this area consists of spoil banks and isolated patches of marsh. From examination of aerial photography, the majority of this loss occurred during the 1960s and 1970s. Based on the hypertemporal analysis conducted by USGS for the extended project boundary, the land loss rate in the project area is -0.86% per year for the period 1984 to 2019. Shoreline erosion rates (1998-2017) range from 10 ft/yr along the eastern lake shoreline to 22ft/yr along the southern lake shoreline.

Restoration Strategy

The primary goal of this project are; 1) restore marsh habitat in the open water areas east and south of Catfish Lake, and 2) restore and protect the eastern and southern Catfish Lake shoreline. The specific goals of this project are; 1) create 235 acres of marsh, 2) nourish 71 acres of marsh, 3) protect the marsh creation cells from shoreline erosion.

Service goals include restoration/protection of habitat for threatened and endangered species and other at-risk species. This project would restore habitat potentially utilized by the black rail, which is proposed for listing as a threatened species. The project could also benefit other species of concern including the saltmarsh topminnow and seaside sparrow.

Sediment from Catfish Lake will be hydraulically dredged and pumped via pipeline to create/nourish 306 acres of marsh. Dewatering and compaction of dredged sediments should produce elevations conducive to the establishment of emergent marsh and within the intertidal range. Containment dikes will be constructed around each marsh creation cell. Where practicable, material will be borrowed from perimeter oil/gas canals. Containment dikes will be gapped at the end of construction or by TY3. Approximately 2,566 linear feet of sheet pile wall will also be installed as a containment feature. Approximately 12,479 linear feet of shoreline protection (gabion mattresses) will be installed along the lakeside boundary of the marsh creation cells on the constructed containment dikes.

The project was approved for Phase I Engineering and Design in January 2020.

The project is on Priority Project List (PPL) 29.

The Federal Sponsor is US Fish & Wildlife Service.

The Local Sponsor is CPRA.

Bay Raccourci Marsh Creation and Ridge Restoration (TE-156)

Post project degraded marsh and open water.

Location

The project is located in Region 3, Terrebonne Basin, Terrebonne Parish.

Problems

High saline waters from Lake Mechant have directly contributed to the loss and/or conversion of much of the historically intermediate marshes to low salinity brackish marshes north of Lake Mechant. Subsidence, canal dredging and storm damage have also contributed significantly to the loss of marsh in the area. The zone of intermediate marsh (transition zone between fresh and brackish marshes) is located just north of Lake Merchant. High salinity water entering Bay Raccourci via Bayou Raccourci/Lake Mechant flows unimpeded into low salinity marshes surrounding Bayou Raccourci, effectively short circuiting the TE-44 Project. The 1984 to 2016 USGS loss rate is -0.32%/yr for the extended boundary area.

Restoration Strategy

The primary goals of this project are; 1) restore marsh habitat in the open water and degraded marsh areas via marsh creation and 2) restore forested ridge habitat along Bayou Decade.

The project would consist of the creation of 341 acres if marsh and 103 acres of marsh nourishment with sediments dredged from Lake Mechant and confined with earthen dikes. The proposed design is to place the dredged material to a fill height of +1.17 ft NAVD88. Dewatering and compaction of dredged sediment should produce elevations conducive to the establishment of emergent marsh and within the intertidal range. Containment dikes will be gapped at the end of construction.

The northern containment dike would be built to a height of +4.0 feet NAVD88 with a 10 feet wide crown and would also serve as a ridge. Material for the ridge would be bucket dredged from both Bayou de Cade and from within the marsh creation cell. The entire 16,350 linear feet (17 acres) of ridge would be planted with saplings and bare root seedlings on the crown and smooth cordgrass along the bayou side slopes.

The project would result in approximately 342 net acres over the 20-year project life.

The project was approved for Phase I Engineering and Design in January 2020.

The project is on Priority Project List (PPL) 29.

The Federal Sponsor is US Fish & Wildlife Service.

The Local Sponsor is CPRA.

Enhancement of Barrier Island Vegetation Demonstration (TE-53)

Barrier Islands provide critical habitat and are the first line of defense to not only day-to-day coastal erosion but also to the destructive forces of major storm events. There remains a critical need to develop cost-effective improvements to existing restoration methodologies that will enhance the successful establishment and spread of vegetation in these important restoration projects. Developing methodologies to enhance vegetation establishment and growth in barrier island restoration projects is important in this very stressful environment because healthy vegetative cover traps, binds, and stabilizes sand and sediment, thereby improving island integrity during storm and overwash events.

The purpose of this demonstration project was to test several technologies and/or products to enhance the cost-effective establishment and growth of key barrier island and salt marsh vegetation. Humic acid and broadcast fertilization regimes were applied. The humic acid amendment and broadcast fertilization regime techniques are intended to “jump start” and facilitate the rapid establishment and expansion of vegetation. Humic acid benefits were demonstrated in both intertidal and supratidal plantings, whereas broadcast fertilization benefits were only demonstrated in supratidal plantings.

Each product (humic acid and fertilizer) is commercially available and off-the-shelf. Enhancing the establishment of woody vegetation (black mangrove and groundsel bush) was achieved via high-density dispersal techniques of propagules and seeds, a cost-saving alternative to planting container-grown transplants. All treatment test sections and reference planting areas were visually inspected and sampled quarterly (plant and soil variables) and compared to the reference area in order to develop recommendations for future planting projects.

This project involved greenhouse studies and the testing of technologies at two previously planted CWPPRA project sites. The CWPPRA projects involved were New Cut Dune and Marsh Restoration (TE-37) and Whiskey Island Back Barrier Marsh Creation (TE-50). Both sites are located in Terrebonne Parish in the Isles Dernieres Barrier Island area.

 

The project has been completed.

This project is on Priority Project List 16.

The Federal Sponsor is EPA

The Local Sponsor is CPRA