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.

Phoenix Marsh Creation – East Increment (BS-42)

Degraded marsh in coastal Louisiana.

Location

The project is located in Region 2, Breton Basin, Plaquemines Parish.

Problems

Two major causes of wetland loss for this area are sediment deprivation and saltwater intrusion. Altered hydrology and oil/gas development have exacerbated this loss. Much of the fresh and intermediate marsh that once existed earlier in this century has either converted to more saline habitats or has become open water as a result of oil/gas canals, subsidence, and a lack of sediment deposition. The 1984 to 2019 USGS land change rate is -0.78% per year.

Restoration Strategy

The project goal is to restore 392 acres of marsh in the open water areas between Bayou la Croix and River aux Chênes through the placement of dredged material via hydraulic dredging. This project will work syngeristically with projects to the east by creating continuity with the Breton Landbridge Marsh Creation (West) Project (BS-38) and the Mid Breton Landbridge Marsh Creation and Terracing Project (BS-32). This proposed first increment would extend the reach of the Breton Landbridge and is part of an overall, long-range, restoration goal to create/nourish 1,000 to 2,000 acres of intermediate marsh across 5 miles of the Breton Sound Basin from River aux Chênes to the Mississippi River.

Sediment will be hydraulically dredged from the Mississippi River. The dredged riverine sediments will be pumped via pipeline into two semi-confined disposal areas. Where feasible, existing marsh will be used as containment instead of containment dikes.

Vegetative plantings are not proposed in the marsh creation areas, and containment dikes will be gapped no later than year three post construction.

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.

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.

North Delacroix Marsh Creation and Terracing (BS-41)

NOAA staff gather data to inform project design. 

Location

The project is located in Region 2, Breton Basin, St. Bernard Parish.

Problems

Hurricanes Katrina and Rita caused the majority of wetland loss in the project site. Wind erosion and saltwater intrusion have resulted in loss of marsh vegetation and wetland soils. Marsh loss has increased exposure of Delacroix to flooding from the east/ southeast. The 1984 to 2019 USGS loss rate is -1.4%/ year for the extended project boundary area.

Restoration Strategy

The project goal is to create and nourish approximately 389 acres of marsh and construct approximately 8,548 linear feet of terraces utilizing a layout to help protect the community of Delacroix.

Sediment would be hydraulically dredged from Lake Lery and placed into two confined disposal areas creating 322 acres of marsh and nourishing 67 acres of existing marsh. Two creation cells allow a channel for drainage. Approximately 8,548 ft of earthen terraces would be constructed. The terraces would be strategically placed east of the northern marsh creation cell and south of the southern cell. Dewatering of the marsh creation cells into areas adjacent to the terraces would take advantage of sediment laden water trapping the particulates to create additional marsh. Terraces would be planted with appropriate bare root plants 2.5 ft apart in one row per side and crown. Created marsh will not be planted.

Containment dikes will be gapped no later than three years after construction. Two additional areas of deteriorating marsh south and east of the proposed project will be investigated. Data acquisition for engineering and design would include an additional
349 acres to allow robustness for these additive or alternate features during Phase I.

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

This project is listed on Priority Project List 29.

The Federal Sponsor is NOAA NMFS.

The Local Sponsor is CPRA.

Delta Wide Crevasses (MR-09)

The Mississippi River Delta is one of the hallmark symbols of Louisiana’s rich natural heritage. Unfortunately, natural and man-made alterations to the Mississippi River have changed the hydrology of the river and impeded the natural wetland building processes in the delta. Levees constructed for navigation maintenance and flood control have reduced natural sedimentation and freshwater flow, causing deterioration of wetlands and saltwater intrusion. Crevasses are breaks in the levees that allow the river to deposit sediments into adjacent shallow bays. The wetlands formed from the deposition of these sediments are called crevasse splays. This restoration project mimics the natural process of crevasse formation that was responsible for building much of the Mississippi River Delta.

The project consists of maintaining presently existing crevasse splays, the construction of new crevasse splays and plugs, and future maintenance of selected crevasse splays in both the Pass a Loutre Wildlife Management Area and the Delta National Wildlife Refuge. The objective is to promote the formation of emergent freshwater and intermediate marsh.

The project is located in Plaquemines Parish, Louisiana, within the Pass a Loutre Wildlife Management Area (Louisiana Department of Wildlife and Fisheries) and the Delta National Wildlife Refuge (U.S. Fish and Wildlife Service).

The first dredging cycle of construction was completed in 1999; three dredging cycles are scheduled in the future. The second cycle is scheduled for early summer 2004.

This project is listed on Priority Project List 6.

The Federal Sponsor is NOAA NMFS

The Local Sponsor is CPRA

Penchant Basin Natural Resources Plan, Increment 1 (TE-34)

Area problems include major hydrologic alterations, interior marsh erosion, subsidence, saltwater intrusion, herbivory, and hurricane damage.

This project will combine the long-term realignment of Penchant Basin hydrology with restoration and protection measures aimed at maintaining the physical integrity of the area during the transition toward greater riverine influence.

The project includes about 6,520 feet of foreshore rock dike (shoreline protection) along the southern bank of Bayou Chene at its intersection with Bayou Penchant and approximately 35 acres of marsh creation. Two freshwater introduction structures, consisting of a) 10-48” flap gates in Superior Canal and b) steel sheetpile weir with 10’ boat bay and six 5’ x 5’ flap gated openings at Brady Canal, will be constructed to improve freshwater conveyance from Bayou Penchant into the central Terrebonne marshes. On the north bank of Bayou Decade extending from Lake Decade to Turtle Bayou (12,000 ft) an earthen embankment will be maintained and from Voss Canal to Lost Lake (14,000 ft) an earthen embankment will be constructed to 4.0 feet NAVD88 with 6:1 side slopes and rock armoring on the south-face. Within the embankment, a sheetpile weir, with a 10 ft wide boat bay, will be constructed at each of two existing channels that intersect Bayou Decade.

The objectives of the project are to eliminate erosion and create approximately 35 acres of emergent marsh along the southern bank of Bayou Chene at its intersection with Bayou Penchant, convey Atchafalaya River water, sediment, and nutrients to lower Penchant Basin tidal marshes to offset subsidence and saltwater intrusion and maintain the integrity of a deteriorated reach of the north bank of Bayou Decade to minimize encroachment of open water marine influence.

The project is bounded on the north by the Gulf Intracoastal Waterway (GIWW), the east by a north/south line from Lake De Cade to the GIWW, the south by Lake Mechant and Lost Lake, and to the west by a north/south line from Lost Lake to Avoca Island in Terrebonne Parish, Louisiana.

The Louisiana Coastal Wetlands Conservation and Restoration Task Force approved this project on April 24, 1997. Priority Project List (PPL) 6 authorized funding of $7,051,550, while PPL 8 authorized an additional $7,051,550.

Planning, engineering and design of this project included extensive data collection, hydrodynamic modeling, and related investigations. This effort resulted in a change in scope to the project which was approved by the Task Force in April 2008. Construction was completed in August 2011.

This project is on Priority Project List 6.

 

The Federal Sponsor is USDA NRCS

The Local Sponsor is CPRA

Black Bayou Hydrologic Restoration (CS-27)

The purposes of the Black Bayou Hydrologic Restoration
project are to (1) restore coastal marsh habitat, and (2) slow
the conversion of wetlands to shallow, open water in the
project area. The project limits the amount of saltwater
intrusion into the surrounding marsh and canals from the
GIWW and reduces erosion caused by wave action from
nearby boats and tides.

A 22,600-foot rock dike was placed on the southern spoil
bank of the GIWW. A barge bay weir (70-foot bottom
width) was constructed in Black Bayou Cutoff Canal. Weirs
with boat bays (10-foot bottom widths) were constructed in
Burton Canal and Block’s Creek. A collapsed weir was
plugged and replaced by a fixed crest steel sheet-pile weir
with a state-of-the-art, self-regulating tidegate. Spoil
material from weir installation and the dredging of access
routes was deposited in nearby open water areas to the
height of marsh elevations. The $3 million construction
contract included installation of 55,000 marsh plants over the
next two planting seasons.

This project, sponsored by the National Marine Fisheries
Service and the Louisiana Department of Natural Resources,
is a 25,529 acre wetland located in Cameron and Calcasieu
Parishes, Louisiana. Bordered by the Gulf Intracoastal
Waterway (GIWW), Sabine Lake, Black Bayou, and Gum
Cove Ridge, the project area consists of tidally-influenced
intermediate and brackish marshes.

Construction is completed. Installation of vegetative
plantings were completed in April 2002. The monitoring
plan was finalized in March 2000, and monitoring has
begun.

This project is on Priority Project List 6.

Federal Sponsor: NOAA 

Local Sponsor: CPRA

Measuring Water Quality

Many wetlands of Louisiana receive their freshwater input from the Mississippi river, whose watershed drains approximately 40% of the United States’ waterways. [1] Pollutants get into the river from nonpoint sources, which are things like agricultural runoff, urban runoff from roads and sewage, or precipitation of atmospheric compounds, and thus they are spread into Louisiana’s wetlands.[2] Excessive pollutants deteriorate wetlands because they kill vital plants and animals in the ecosystem, which has feedback onto other species. Before interfering with anything in an ecosystem, we need to understand how the ecosystem functions.

Water quality plays a huge role in keeping wetlands healthy. The term “water quality” refers to several characteristics of a body of water, including salinity, nutrient concentration, turbidity, and dissolved oxygen [3]. These factors contribute to how well individuals can live and grow in the ecosystem associated with that body of water. For example, some plants and animals have a strong preference for either high or low salinity (See Salinity Stress Tolerance article), some prefer higher water levels (see Flooding and Hypoxia article), and some can live in many combinations of conditions.

Turbidity is a measure of how much suspended sediment is in the water column. Higher turbidity causes less light to penetrate to the deeper layers, so highly turbid waters often have less submerged aquatic vegetation. Turbidity can be measured with a Secchi disk or Secchi tube. Dissolved oxygen is important to aquatic plants because they still need to exchange oxygen to carry out their metabolic processes. Dissolved oxygen is measured by either luminescence sensors or electrode oxidation. [4] Many of the instruments that measure different aspects of water quality are combined into a Multiparameter Water Quality Sonde to get multiple measurements from the same sample of water. More information on specific procedures and equipment for measuring water quality can be found at https://www.fondriest.com/environmental-measurements/equipment/measuring-water-quality/.

Measuring water quality as a way of determining wetland health is important to many CWPPRA project locations. Measurements allow ecologists to determine any potential risks or threats from developing a project to the integrity of site’s established ecosystem. Fragile ecosystems can be drastically affected by constructing a project because the projects are likely to alter hydrology, salinity, and may introduce conditions that residents cannot survive. Forming a profile of water quality helps to predict the project’s positive and negative outcomes, and to predict the success and longevity of the project.

 

[1] https://www.nps.gov/miss/riverfacts.htm

[2] https://www.epa.gov/nps/basic-information-about-nonpoint-source-nps-pollution

[3] https://www.fondriest.com/environmental-measurements/parameters/water-quality/

[4] https://www.ysi.com/parameters/dissolved-oxygen

Featured image from https://phys.org/news/2017-01-technique-quickly-salt-marsh-vulnerability.html

Black Bayou Culverts Hydrological Restoration (CS-29)

The marsh within this area has been suffering from excessive water levels within the lakes subbasin that kills vegetation, prevents growth of desirable annual plant species, and contributes to shoreline erosion. Black Bayou offers a unique location in the basin where the water in the lakes subbasin and the outer, tidal waters are separated by only a narrow highway corridor.

Project components include installing ten 10 foot by 10 foot concrete box culverts in Black Bayou at the intersection of Louisiana Highway 384. The structure discharge will be in addition to the discharges provided by Calcasieu Locks, Schooner Bayou, and Catfish Point water control structures.

The project features are located in southern Calcasieu Parish, Louisiana. The majority of the project area is located east of Calcasieu Lake and includes areas north of the Gulf Intracoastal Waterway and west of Grand Lake in Cameron Parish, Louisiana.

Construction has been completed.

This project is on Priority Project List 9.

Federal Sponsor: NRCS

Local Sponsor: CPRA

Freshwater Wetlands

Did you know:

Freshwater habitats make up only 1% of the planet’s surface but are host to 1/3 of all known vertebrates and nearly 10% of all known animal species.

Usually located in close proximity to an intermediate marsh, freshwater marshes commonly occur adjacent to coastal bays. Freshwater marshes are of the most productive freshwater habitats and are essential to the survival of many wildlife populations ranging from important nursery needs to supporting large numbers of wintering waterfowl. Freshwater marshes have the greatest plant diversity and highest organic matter content of any marsh type. The heavy demand for freshwater has become outweighed by its availability due to salt water intrusion. The Coastal Wetlands Planning, Protection, and Restoration Act aims to restore the natural conditions of water quality by implementing hydrologic restoration projects to combat saltwater intrusion.

Source