Raccoon Island Shoreline Protection/Marsh Creation (TE-48)

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The Isles Dernieres barrier island chain is experiencing some of the highest erosion rates of any coastal region in the world. Raccoon Island is experiencing shoreline retreat both gulfward and bayward, threatening one of the most productive wading bird nesting areas and shorebird habitats along the gulf coast.

An existing demonstration project on the eastern end of the island, Raccoon Island Breakwaters Demonstration project (TE-29), has proven that segmented breakwaters can significantly reduce, and perhaps even reverse, shoreline erosion rates. The primary goal of this project is to protect the Raccoon Island rookery and seabird colonies from the encroaching shoreline by: 1) reducing the rate of shoreline erosion along the western, gulfward side and 2) extending the longevity of northern backbay areas by creating 60 acres of intertidal wetlands that will serve as bird habitat.

This project has been separated into two construction phases, Phase A and Phase B. Phase A includes the construction of eight additional segmented breakwaters gulfward of the island and immediately west of the existing breakwaters demonstration project and an eastern groin that will connect existing Breakwater No. 0 to the island. Phase B involves the construction of a retention dike along the northern shore to create a back bay enclosure that will be filled with sediments dredged from the bay and/or gulf, followed by vegetative plantings.

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The project is located in the Terrebonne Basin on the western-most island of the Isles Dernieres barrier island chain in Terrebonne Parish, Louisiana.

Rock breakwater construction for the prior demonstration phase of this project was completed on the east end of the island in June 1997. Sand deposits or “tombolos” have developed behind the breakwaters that protect and enhance the island. A less dramatic, however still positive effect, is expected to occur behind the 8 additional breakwaters being constructed to the west of the existing breakwaters.

Construction of Phase A was completed in September 2007 and Phase B in June 2013. All plantings are to be completed by the end of 2017.

This project is on Priority Project List 11.

The Federal Sponsor is USDA NRCS

The Local Sponsor is CPRA

Barataria Bay Waterway East Side Shoreline Protection (BA-26)

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The banks of the Dupre Cut have eroded considerably as a
result of vessel wakes. Large breaches in the banks
exposed the adjacent marsh to increased water exchange,
tidal energy, and saltwater intrusion.

The objective of this project was to rebuild and stabilize
the east bank of the Dupre Cut. A stronger bank would
reduce erosion and help reestablish wetlands by allowing
sediment accretion on the leeward side of the foreshore
rock dike.

The project plan involved the construction of over 3 miles
of foreshore rock dike along the east bank of the Dupre
Cut to protect adjacent marshes from shoreline erosion.
This rock dike extends above the surface of the water and
will protect the fragile marsh area from boat wakes
generated within the BBWW.

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The project is located in Jefferson Parish, Louisiana, on
the east bank of the Dupre Cut portion of the Barataria Bay
Waterway, north of the Lafitte Gas and Oil Field and south
of the subsided land reclamation effort known as “the
Pen.”

 

Construction was completed in June 2001. Baseline
monitoring information has been collected and will be
used to evaluate the project’s effectiveness. The O&M
Plan was signed in October 2002. This project is on
Priority Project List 6.

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.

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

Living Shorelines

According to NOAA, one of our managing agencies, a living shoreline is “A protected and stabilized shoreline that is made of natural materials such as plants, sand, or rock.” [1] In some situations, living shorelines are a better option than hardened shoreline protection because they have more movement of natural sediment, the ability to grow, and the obvious aesthetic value of a natural area.

‘Living shorelines’ can refer to multiple restoration techniques and coastal environments; for CWPPRA, a living shoreline can mean vegetative planting on a marsh creation cell or using a shoreline protection barrier that promotes oyster reef growth. Living restored shorelines help maintain the integrity of ecosystems, but they also provide benefits to recreation and potentially to commerce. One big push in restoration over the past few years has been artificial oyster reefs which provide wave attenuation, natural water filtration, and a harvestable population of oysters for the seafood industry. [2]

Illustration, Courtesy of NOAA [1]
Vegetated marsh provides similar benefits to artificial oyster reefs and is a tried-and-true restoration strategy. Many marsh creation projects will naturally revegetate thanks to seed banks in borrow sites but some need management to limit invasive species. In more vulnerable sites, CWPPRA actively plants native species like smooth cordgrass and California bulrush to give them an advantage against invasive populations.

CWPPRA understands that successful restoration projects, including shoreline protection, help keep ecosystems intact and productive. A changing coast means we need changing solutions, and we will strive to find better alternatives to maintain the natural environment.

[1] https://oceanservice.noaa.gov/facts/living-shoreline.html

[2] https://www.smithsonianmag.com/innovation/storms-get-bigger-oyster-reefs-can-help-protect-shorelines-180967774/

Featured image from https://oceanbites.org/oyster_reef_restoration/

 

Raccoon Island Shoreline Protection/ Marsh Creation (TE-48)

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The Isles Dernieres barrier island chain is experiencing some of the highest erosion rates of any coastal region in the world. Raccoon Island is experiencing shoreline retreat both gulfward and bayward, threatening one of the most productive wading bird nesting areas and shorebird habitats along the gulf coast.

An existing demonstration project on the eastern end of the island, Raccoon Island Breakwaters Demonstration project (TE-29), has proven that segmented breakwaters can significantly reduce, and perhaps even reverse, shoreline erosion rates. The primary goal of this project is to protect the Raccoon Island rookery and seabird colonies from the encroaching shoreline by: 1) reducing the rate of shoreline erosion along the western, gulfward side and 2) extending the longevity of northern backbay areas by creating 60 acres of intertidal wetlands that will serve as bird habitat. This project has been separated into two construction phases, Phase A and Phase B. Phase A includes the construction of eight additional segmented breakwaters gulfward of the island and immediately west of the existing breakwaters demonstration project and an eastern groin that will connect existing Breakwater No. 0 to the island. Phase B involves the construction of a retention dike along the northern shore to create a back bay enclosure that will be filled with sediments dredged from the bay and/or gulf, followed by vegetative plantings.

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The project is located in the Terrebonne Basin on the western-most island of the Isles Dernieres barrier island chain in Terrebonne Parish, Louisiana.

This project was selected for engineering and design funding at the January 2002 Breaux Act Task Force meeting. Construction funding for Phase A was approved in October 2004. Request for Phase B construction funding is anticipated to occur in January 2008.

This project is on Priority Project List 11.

The Sponsors include:

Federal Sponsor: NRCS

Local Sponsor: CPRA

Black Bayou Hydrologic Restoration (CS-27)

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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.

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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