Goose Point/Point Platte Marsh Creation (PO-33)

Interior ponding and, to a lesser extent, shoreline erosion are the major causes of wetland loss in the project area. Loss rates were highest during the period from 1956 to
1978. Those high loss rates were associated with hydrologic alterations which allowed salt water to penetrate the fresher marshes. During the transition to a more brackish plant community, large ponds were formed. A narrow strip of land separates those ponds from Lake Pontchartrain. Although the shoreline erosion rates are relatively low, the shoreline is already breached in several areas, and marsh loss in the interior ponds is expected to increase if the shoreline fails.

The goal of this project is to re-create marsh habitat in the open water behind the shoreline. This new marsh will maintain the lake-rim function along this section of the north shore of Lake Pontchartrain by preventing the formation of breaches into interior ponds. Sediment will be dredged from Lake Pontchartrain and contained in cells within the interior ponds to create approximately 417 acres of marsh. In addition, 149 acres of degraded marsh will be nourished with dredged material. Marsh will be created to widen the shoreline so that the ponds will not be breached during the course of normal shoreline retreat.

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The project is located on the north shore of Lake Pontchartrain between Fontainebleau State Park and Louisiana Highway 11 and within the Big Branch Marsh National Wildlife Refuge in St. Tammany Parish, Louisiana. The project area at Goose Point also includes a portion of the St. Tammany State Wildlife Refuge.

On February 12, 2009, a final inspection of the project site was conducted. All construction activities are complete. This project is on Priority Project List 13.

 

The Federal Sponsor is USFWS

The Local Sponsor is CPRA

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Boston Canal/Vermilion Bay Bank Protection (TV-09)

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Construction of the Gulf Intracoastal Waterway, Boston Canal, and oilfield canals has greatly increased tidal exchange between Vermilion Bay and the adjacent marshlands to the north, particularly near their confluence with Vermilion Bay. This tidal exchange, combined with the effects of wave action from the bay and boat wake from traffic on the canal, has contributed to significant shoreline erosion along the Vermilion Bay shoreline. This same set of problems has also caused shoreline erosion along Boston Canal, particularly near its confluence with Vermilion Bay.

Rock dikes configured as sediment traps were constructed along the shoreline at the mouth of Boston Canal to promote sediment deposition and protect the shoreline and adjacent wetlands from continued wave-induced erosion. Vegetation was planted along 14 miles of the Vermilion Bay shoreline to act as a wave buffer and decrease shoreline erosion rates.

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The project encompasses 466 acres of brackish marsh along approximately 16 miles of Vermilion Bay’s northern shoreline adjacent to Boston Canal. Running from the Oaks Canal to Mud Point, the project is located roughly 6 miles southeast of Intracoastal City, Louisiana, in Vermilion Parish.

Following the construction of the rock dikes, as much as 4.5 feet of sediment has  vertically accreted in the lee, or windsheltered regions, of the structures. The dikes and vegetative plantings have increased vegetation cover, resulting in 57
acres of land growth. The shoreline has been stabilized at the mouth of Boston
Canal.

The survivorship and vegetation cover percentage along the shoreline were more pronounced in areas where native vegetation did not exist. Survivorship and percent cover were least pronounced when marshhay cordgrass (Spartina patens) was planted in established stands of roseau cane (Phragmites australis). Overall survivorship of planted smooth cordgrass (Spartina alterniflora) was over 90% after 12 months. Current coverage is nearing 100%. The 2005 OM&M Report concluded the sediment build-up behind the dike on the east and west sides is continuing and vegetation has taken over the exposed mud flats. Elevation data show an increase in sedimentation behind the rock breakwater.

This project is on Priority Project List 2.

Federal Sponsor: NRCS

Local Sponsor: CPRA

Holly Beach Sand Management (CS-31)

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The Chenier Plain shoreline was created with sediment transported by the Mississippi River’s periodic westward oscillation. The swales that characterize the Chenier Plain were created by the deposition of these alluvial sediments, and these same sediments also served to extend the shoreline gulfward and create the area’s expansive mudflats.

Chronic erosion in this area is caused by a lack of sand and sediment caused by the channelization and regulation of the Mississippi and Atchafalaya rivers to the east. In addition, the Calcasieu and Mermentau rivers are not supplying coarse-grained sediment to the area, and the Cameron Jetties associated with the Calcasieu Ship Channel deflect the little material that does exist away from the project area.

The project’s goals are: (1) to protect approximately 8,000 acres of existing, low energy intermediate and brackish marsh wetlands north of the forested ridge and (2) to create and protect roughly 300 acres of beach dune and coastal chenier habitat from erosion and degradation.

The project also provides protection for the wooded chenier to the west, which has been purchased by the Baton Rouge Audubon Society. It is being maintained as a sanctuary because of its importance as habitat for Neotropical migratory birds.

The project plan consists of placing approximately 1.7 million cubic yards of high quality sand on the beach to reestablish a more historical shoreline, as well as improve the effectiveness of the existing segmented breakwater system.

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The project is located west of Calcasieu Pass along the Gulf of Mexico shoreline, extending between Holly Beach and Constance Beach in Cameron Parish, Louisiana.

This project was selected for Phase 2 (construction) funding at the August 2001 Louisiana Coastal Wetlands Conservation and Restoration Task Force meeting. Since that time, 1.75 million cubic yards of sand were added to the beach. Sand placement was completed in March 2003.

Project staff installed 102,000 linear feet of vegetative plantings at dune elevation on the Holly Beach dredge platform; 20,400 four-inch containers of bitter panicgrass (Panicum amarum) were planted. The installation of the plantings was completed in August 2003. Cameron Parish believes this project is what saved HWY 82 from being washed out during Hurricane Rita.

This project is on Priority Project List 11.

The Federal Sponsor is NRCS

The local sponsor is CPRA

Little Lake Shoreline Protection/Dedicated Dredging Near Round Lake (BA-37)

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The Little Lake mapping unit has high wetland loss caused by shoreline erosion, subsidence, and channel construction. The project is located in an area protecting approximately 3,000 acres of fragile interior marshes between the Little Lake shoreline and Bayou L’Ours Ridge. Project area wetlands are subject to high shoreline erosion rates (20 to 40 feet per year) and subsidence deteriorating interior marshes. Without construction, the project area marsh was expected to convert to mainly open water over the next 20 years.

The project’s goals were to:
1) prevent erosion along roughly 4 miles of Little Lake shoreline;
2) create 488 acres of intertidal wetlands along the Little Lake shoreline;
3) nourish and maintain 532 acres of intermediate marsh; and
4) reduce land loss rates by 50 percent over the 20-year life of the project.

The project consists of two major features, a shoreline protection structure and a marsh creation and nourishment area. The 25,976 ft foreshore rock dike was constructed by placing rocks on top of a geotextile foundation. The dike was constructed using three lifts and include gaps every 1,000 to 1,500 ft for fisheries access.

The marsh creation and nourishment phase of this project consisted of containment dikes, marsh creation in open water areas, and marsh nourishment over existing marsh. Approximately, 920 acres of marsh were created and nourished through placement of 3,165,121 cubic yards of sediment from Little Lake. The marsh creation area was planted with 17,000 Spartina alterniflora (smooth cordgrass) plugs.map.jpg

The project is located in the central Barataria Basin in Lafourche Parish, Louisiana. The project area is bounded by the East and West Forks of Bayou L’Ours and the southern shoreline of Little Lake from Plum Point westward to Breton Canal.

This project was selected for Phase I (engineering and design) funding at the January 2002 Task Force meeting and for Phase II (construction) funding in November 2003. Construction was completed in 2007.

The project is listed on Priority Project List 11.

South Lake De Cade Freshwater Introduction (TE-39)

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The project area is experiencing marsh deterioration due to subsidence, rapid tidal exchange, and human-induced hydrologic changes that result in increased salinities. Saltwater intrusion has caused a shift in marsh type and a conversion of over 30 percent of emergent vegetation to open water habitat. Shoreline erosion along the south embankment of Lake De Cade threatens to breach the hydrologic barrier between the lake and interior marshes.

Proposed project components include installing three control structures along the south rim of the lake and enlarging Lapeyrouse Canal to allow the controlled diversion of Atchafalaya River water, nutrients, and sediments south into project area marshes. Outfall management structures are planned in the marsh interior to provide better distribution of river water. In addition, approximately 1.6 miles of foreshore rock dike is planned to protect the critical areas of the south lake shoreline from breaching.

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The project is located in Terrebonne Parish, approximately 15 miles southwest of Houma, Louisiana.

After initial engineering investigation, the project was divided into two construction units. Construction unit one consisted of the shoreline protection only and was completed in July 2011. Construction unit two consisting of the freshwater introduction component was further investigated and due to uncertainty of benefits was not constructed, and therefore, the project is considered completed.

This project is on Priority Project List 9.

The Federal Sponsor is NRCS

The Local Sponsor is CPRA

Cameron Prairie National Wildlife Refuge Shoreline Protection (ME-09)

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The management levee between the GIWW and the
Cameron Prairie National Wildlife Refuge was in danger
of breaching as a result of erosion from boat traffic in the
GIWW. If breaching had occurred, wave energy from the
GIWW and salt water would have entered the organic,
freshwater wetlands.

A 13,200-foot rock breakwater was constructed 50 feet
from the northern bank of the GIWW to prevent waves
caused by boat traffic from overtopping and eroding the
remaining spoil bank.
The project’s effectiveness is being evaluated by shoreline
movement surveys and by comparing pre-construction and
post-construction aerial photographs for changes in marsh
loss rates.

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This project is located in Cameron Parish, Louisiana, on
the north shore of the Gulf Intracoastal Waterway
(GIWW), approximately 7 miles southeast of Sweet Lake
and to the east of Louisiana Highway 27 at its intersection
with the GIWW. It encompasses 640 acres of fresh marsh
and open water.

During 1993-97, while the project area had a 4.9% increase in
water coverage due to management for waterfowl, the
reference area remained unchanged.

The results of shoreline monitoring indicate that the project
has protected 13,200 feet of shoreline, along with 247 acres of
marsh north of the dike. This protection is expected to accrue
throughout the life of the project for a net restoration of at
least 23 acres. Monitoring has shown that the GIWW’s
northern shoreline advanced 9.8 feet per year in the project
area while retreating at a rate of 3.0 feet per year in the
reference area, indicating that low sediment availability does
not prohibit wetland creation behind rock dikes on navigation
channels.

To date, the project has exhibited success. It is expected that
the project area will continue to accrete new wetland area
between the spoil bank and the rock dike, further
safeguarding the adjacent wetland area from encroachment by
the GIWW.

This project is on Priority Project List 1.

 

The Federal Sponsor is USFWS

The Local Sponsor is CPRA

Little Vermilion Bay Sediment Trapping (TV-12)

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High winds and waves prevent GIWW sediments transported down the Freshwater and Schooner bayous from settling and forming the basis of vegetated marsh. This same wind and wave energy also increases shoreline erosion rates.

This project involved the construction of a series of vegetated terraces to diminish waves in Little Vermilion Bay, helping to increase sediment deposition and reduce the rate of shoreline erosion. A pattern of channels was dredged 100-feet wide and 6-feet deep to beneficially distribute sediment from the GIWW through the Freshwater and Schooner bayous. Dredged sediments were used to construct 23 earthen terraces with a combined length of 23,300 feet. After settling, the average height of the terraces was 3.5 feet above mean sea level.

The bases of the terraces were planted with 20,450 containers of smooth cordgrass (Spartina alterniflora).

The design allows commercial and recreational fisherman to access the project area, and it stimulates fishery production by creating new habitat and increasing shoreline length.

In 1998 alone (prior to the project’s completion) 40 acres of wetland habitat were created.

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This project is located in the northwestern corner of Little Vermilion Bay at its intersection with the Gulf Intracoastal Waterway (GIWW) in Vermilion Parish, Louisiana. The project area encompasses 964 acres.

Monitoring is underway and preliminary observations show that the terraces are growing in width, and bay depth between terraces is decreasing indicating marsh expansion in the project area.

This project is on Priority Project List 5.

The Federal Sponsor is NOAA NMFS

The Local Sponsor is CPRA