Lake Hermitage Marsh Creation (BA-42)

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The project is within the West Pointe a la Hache Mapping Unit which lost 38 percent of its marsh from 1932 to 1990. By the year 2050, 28 percent of the 1990 marsh acreage is expected to be lost. That loss is expected to occur even with operation of the West Pointe a la Hache Siphon (State project BA-04). Significant marsh loss has occurred south and east of Lake Hermitage and along the eastern lake shoreline. Deterioration of the lake rim has exposed interior marshes to the wave energy of Lake Hermitage and increased tidal exchange. Based on USGS land-water data from 1985 and 2006, the project area has an annual loss rate of -1.64%.

The original project features included dredging in the Mississippi River and pumping sediments via pipeline to create 549 acres of marsh. Additionally, 6,300 feet of shoreline restoration using river material and 7,300 linear feet of terraces were included. Fortunately, a favorable bid on the construction contract allowed for project expansion and the marsh creation feature was increased to encompass a total of 795 acres.

Funding from the Louisiana Oil Spill Coordinator’s Office, the Louisiana Department of Natural Resources – Office of Coastal Management, and Deepwater Horizon Early Restoration allowed construction of an additional 215 acres of marsh. Terraces were removed from the CWPPRA project to provide an area for marsh creation with Deepwater Horizon Early Restoration funding.

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The project area is located in the Barataria Basin, south and east of Lake Hermitage in Plaquemines Parish, Louisiana near the community of West Pointe a la Hache.

The Louisiana Coastal Wetlands Conservation and Restoration Task Force approved funding for engineering and design in February 2006 and approved construction funding in January 2009. Construction began in February 2012 and was completed in June 2015.

This project is on Priority Project List 15.

The Federal Sponsor is USFWS

The Local Sponsor CPRA

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

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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.

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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

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

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

Louisiana’s Live Oak Cheniers

With coastal needs continuing to grow, we can learn from nature’s history for ways to strengthen our coastlines. While we often think about how barrier islands protect the coast from storms, coastal cheniers and forests across Louisiana are also essential in providing that protection. These coastal forests are often found on shell ridges known as cheniers.

French for “place of oaks”, cheniers act as storm barriers, prevent saltwater intrusion, and provide wildlife habitat for migratory birds and butterflies [1,3]. Cheniers along  Louisiana’s coast extend from Cameron Parish in the west to Iberia Parish” [1]. Due to their higher relief, or height above sea level, a large majority of these areas were cleared for human development uses such as highways, agriculture, and oil and gas [2]. Louisiana originally hosted 100,000 to 500,000 acres of chenier, but today only 2,000 to 10,000 acres remain [1].

While these numbers can be discouraging, local and state efforts are in place to conserve live-oak (Quercus virginiana) cheniers and coastal forests.

Louisiana is fortunate to have programs and organizations like this to conserve the coast and its natural abundance. These practices along with landowner, volunteer and citizen engagement are essential to coastal restoration. You may visit CWPPRA’s website lacoast.gov to learn how you can help Louisiana’s coastal wetlands!

Do your part to conserve our environment and help Louisiana’s coast!

Source:
[1] Louisiana Comprehensive Wildlife Conservation Strategy. Date Accessed October 30, 2018. Available:http://www.wlf.louisiana.gov/sites/default/files/pdf/document/32867-coastal-live-oak-hackberry-forest/coastal_live_oak-hackberry_forest.pdf
[2] Army Corps of Engineers. Southwest Coastal Louisiana Final Integrated Draft and Feasibility Report and Environmental Impact Statement. Date Accessed October 30, 2018. Available:http://www.mvn.usace.army.mil/Portals/56/docs/PD/Projects/SWCoastal/11%20Appendix%20A%20Env%20Report.pdf
[3] Baton Rouge Audubon Society. Accessed on 10/31/2018. Available:http://www.braudubon.org/peveto-woods-sanctuary.php