New Orleans Landbridge Shoreline Stabilization & Marsh Creation (PO-169)

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Since 1956, approximately 110 acres of marsh has been lost along
the east shore of Lake Pontchartrain between Hospital Road and
the Greens Ditch. One of the greatest influences of marsh loss in
the area can be attributed to tropical storm impacts. Wetland losses
were accelerated by winds and storm surge caused by Hurricane
Katrina, which converted approximately 70 acres of interior marsh
to open water. Stabilizing the shoreline and protecting the
remaining marsh would protect natural coastal resources dependent
on this important estuarine lake, communities that thrive on those
resources, the Fort Pike State Historical Site, and infrastructure
including U.S. Highway 90. USGS land change analysis
determined a loss rate of -0.35% per year for the 1984 -2011
period of analysis. Subsidence in this unit is relatively low and is
estimated at 0-1foot/century (Coast 2050).

Lake Pontchartrain supports a large number of wintering
waterfowl. Various gulls, terns, herons, egrets, and rails can be
found using habitats associated with Lake Pontchartrain, which has
been designated as an Important Bird Area by the American Bird
Conservancy. Restoring these marshes will protect the Orleans
Landbridge and will help to protect fish and wildlife trust resources
dependent on these marsh habitats, particularly at-risk species and
species of conservation concern such as the black rail, reddish
egret, brown pelican, mottled duck, seaside sparrow, king rail, and
the Louisiana eyed silkmoth.

Borrow material will be dredged from areas within Lakes St.
Catherine and Pontchartrain to create 169 acres and nourish 102
acres of brackish marsh. Containment dikes will be constructed
around four marsh creation areas to retain sediment during
pumping. The lake shorelines will be enhanced with an earthen
berm to add additional protection from wind induced wave fetch.
Containment dikes that are not functioning as shoreline
enhancement will be degraded and/or gapped. Vegetative plantings are
proposed including five rows along the crown and two rows
along the front slope of the shoreline protection berm, as well as
within the marsh platform area.

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The project is located in Region 1, Pontchartrain Basin,
Orleans Parish, flanking U.S. Highway 90 along the east shore of
Lake Pontchartrain and areas surrounding Lake St. Catherine.

This project was approved for Phase I Engineering and Design in
January 2015.

This project is on Priority Project List (PPL) 24.

The New Orleans Landbridge Shoreline Stabilization & Marsh Creation sponsors include:

 

 

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Bayou Dupont Sediment Delivery – Marsh Creation and Terracing

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Wetlands in the Barataria Basin were historically nourished
by the fresh water, sediment and nutrients delivered by
the Mississippi River and its many distributary channels.
These sediment and nutrient inputs ceased following the
creation of levees along the lower river for flood control and
navigation. In addition, the construction of numerous oil and
gas canals along with subsurface oil and gas withdrawal has
exacerbated wetland loss in the area. From 1932 to 1990, the
Barataria Basin lost over 245,000 acres of marsh. From 1978
to 1990, the area experienced the highest rate of wetland loss
in coastal Louisiana.

The primary goal of this project is to create and nourish
approximately 144 acres of emergent intermediate marsh
using sediment from the Mississippi River, and constructing
9,679 linear feet of terraces. The proposed project includes
dredging sediment from the Mississippi River for marsh
creation by pumping the sediment via pipeline into an area of
open water and broken marsh. The proximity of the project
to the Mississippi River provides a prime opportunity to
utilize this renewable river sediment resource. The strategy
includes utilizing the access route and infrastructure
previously put into place for the BA-39 project. This project
will complement existing restoration projects in the area.

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CWPPRA Region 2, Barataria Basin, Jefferson and
Plaquemines Parishes. The general project area is about 10
miles south of Belle Chasse, LA and is west of LA Hwy
23 and north of the Myrtle Grove Marina. The project
is immediately adjacent to the completed CWPPRA
Mississippi River Sediment Delivery System – Bayou
Dupont (BA-39) project.

The project was approved for engineering and design at the
January 24, 2013 Task Force meeting. The E&D was
completed in the fall of 2014 and sponsors requested phase
2 funding at the January 22, 2015 Task Force meeting,
however, there was insufficient money available to fund
the entire project. In order to take advantage of the existing
mobilization of the Long Distance Sediment Pipeline
(LDSP) Project, the sponsors proposed to reduce the scope
of the project to fit within the available CWPPRA funding.
The Task Force approved the reduced scope Phase 2 funding
request at the May 14, 2015, Task Force meeting. The asbuilt
project features include 144 acres of marsh creation and
9,679 linear feet of terracing.

In addition, CPRA increased the marsh creation feature of
the project by utilizing contingency funding left over from
BA-43, thereby increasing the total marsh creation in the
area to an estimated 296 acres. Construction started in April
2016, and marsh creation was completed in November
2016. Terracing was completed in June 2017, and vegetative
plantings for the terraces are scheduled for the spring of
2018.

This project is on Priority Project List (PPL) 22.

The Bayou Dupont Sediment Delivery – Marsh Creation and Terracing sponsors include:

 

World Wetlands Day 2018

In some parts of the world, February 2nd is a time to make weather predictions, and, while some of that did happen in coastal Louisiana, students and informal educators also gathered to celebrate World Wetlands Day. Celebrated internationally each year since 1997, World Wetlands Day commemorates the 1971 adoption of the Ramsar Convention on Wetlands and tries to raise awareness about the importance of wetlands to people and the planet; this year’s theme was “Wetlands for a Sustainable Urban Future.”

More than 100 students and educators gathered at the Bayou Terrebonne Waterlife Museum in Houma, LA for activities hosted by the South Louisiana Wetlands Discovery Center. Coastal Wetlands Planning, Protection, and Restoration Act staff were in attendance to talk with students about the different types of wetlands we have in Louisiana. In addition to a scavenger hunt in the museum as they learned about the services that wetlands provide, students had the opportunity to get up close to wetland wildlife, learn about different wetland habitats, and think about how water moves through coastal and urban systems. Groups providing activities included Restore or Retreat, the Barataria-Terrebonne National Estuary Program, LSU Wildlife Hospital of LA, and the USDA Sugarcane Research Station. In addition to wildlife habitat, wetlands provide flood control, water purification, and sediment capture services, making them important for urban and rural communities.

West Fourchon Creation & Nourishment Marsh

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The primary causes of land loss in the project area are oil
and gas canals, subsidence, and sediment deprivation, which
have resulted in an estimated rate of -0.41% per year based
on hyper-temporal analysis conducted by USGS for the
extended project boundary for the years 1984 to 2012.
Bounded by Bayou Lafourche to the east and Timbalier Bay
to the west the project area is also subject to shoreline
erosion.

This project would create 302 acres of saline inter-tidal marsh
and nourish 312 acres of emergent marsh using material
dredged from the Gulf of Mexico, southwest of the project
area. Earthen containment dikes will be constructed along
the project boundary to contain the material. Vegetative
plantings are planned at a 50% density, with half planned at
TY1 and half planned at TY3 if necessary. Containment
dikes will be degraded or gapped by TY3 to allow access for
estuarine organisms. Funding will be set aside for the
creation of tidal creeks if needed. This project, along with
TE-23 West Belle Pass Headland Restoration and TE-52
West Belle Pass Barrier Headland Restoration, will help
stabilize the edge of the marshes and protect Port Fourchon
from the west. The initial construction elevation is +2.4 feet
NAVD 88; after settlement, marsh is expected to be +1.4
NAVD 88.

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

This project was approved for Phase I Engineering and
Design in January 2015.

This project is on Priority Project List (PPL) 24.

The West Fourchon Creation & Nourishment Marsh sponsors include:

 

Decomposing in the salt marsh

Throughout the year salt marshes exhibit cycles of birth, growth, and death. That may be most obvious when looking at the plants, but it also applies to animals, bacteria, and fungi, sometimes on longer and sometimes on shorter time scales. Since marshes are such productive ecosystems, what happens to all of that organic matter when something dies, be it a leaf, single-celled organism, or alligator? Detrivores are an important part of the marsh ecosystem, breaking down organic matter and cycling nutrients; in fact, in salt marshes, detrivores are the dominant consumers.

 

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Fiddler crabs separate decaying matter from sand and mud. Photo from NPS (https://www.nps.gov/foma/learn/nature/crustaceans.htm)

Most decaying plant matter in a salt marsh is consumed by bacteria and fungi, which are then food for larger creatures, but a host of species in the salt marsh are detrivores: snails, crabs, amphipods, nematodes, fish, and many others. Some of these, like fiddler crabs, feed by finding pieces of detritus on grains of sand and soil, while others specialize on a particular species’ remains. Gammarus palustris is an amphipod which consumes the dead leaves from salt marsh cordgrass (Spartina alterniflora). Zimmer et al. (2004) suggested a variety of detrivores were needed in any habitat type for efficient decomposition and that you couldn’t substitute one species for another- the different species contribute in different ways. Whether big or small, detrivores keep nutrients moving within the system and prevent dead organic matter from building up, and that helps salt marshes continue to be so productive.

Works Cited:

Zimmer, M, Pennings, SC, Buck, TL and TH Carefoot. 2004. Salt marsh litter and detrivores: a closer look at redundancy. Estuaries 27: 753-769.

Fritchie Marsh Creation and Terracing

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A significant portion of the Fritchie Marsh was lost due to
Hurricane Katrina. Post storm shallow open water areas
dominate the landscape which limits the effectiveness of the
PO-06 CWPRRA project. Wetlands in the project vicinity
are being lost at the rate -1.09%/year based on USGS
data from 1985 to 2015. These marshes cannot recover
without replacement of lost sediment, which is critical if the
northshore marshes are to be sustained.

Project goals include restoring and nourishing marsh.
Specific goals of the project are: 1) create approximately 291
acres of marsh; 2) nourish approximately 49 acres of existing
marsh; and 3) construct about 36,610 feet of earthen terraces
or 26 emergent acres.

An alternative analysis was conducted leading to the
selection of features and configuration to compliment and
work synergistically with the existing PO-06 project and
planned mitigation and restoration projects in the Fritchie
Marsh. A robust engineering cost is included to evaluate
increasing the project size if costs allow or adjust the
layout, if needed during Phase 1. Approximately 2 million
cubic yards of material would be placed confined to restore
291 acres and nourish approximately 49 acres of brackish
marsh. Material would be dredged from a borrow site in
Lake Pontchartrain. The borrow site would be designed to
avoid and minimize impacts to aquatic habitat and existing
shorelines. Approximately 26 acres of earthen terraces would
be constructed within various locations totaling approximately
36,610 feet or 523 acres of terrace field. All containment
dikes would be gapped or degraded no later than three years
after construction to facilitate the development of tidal marsh
functions supportive of estuarine species. The terraces would
be planted as well as 50% of the created marsh acres to
expedite colonization and enhance stabilization.

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Region 1, Pontchartrain Basin, St. Tammany Parish, located
approximately three miles southeast of Slidell, Louisiana. A
substantial portion of the project is located on Big Branch
National Wildlife Refuge.

This project was approved for Phase I Engineering and
Design in January 2016.

This project is on Priority Project List (PPL) 25.

The Fritchie Marsh Creation and Terracing sponsors include:

 

Mangroves in Winter

The recent cold weather in Louisiana may have been the end of the road for some plants as temperatures dipped into the teens and stayed below freezing for full days. The hibiscus in your garden may have survived because you gave it extra insulation, but what about marsh plants? Louisiana salt marshes are home to black mangroves (Avicennia germinans), but this represents the very northernmost part of their range. Of the three mangrove species found in the continental United States [red (Rhizophora mangle), black, and white (Laguncularia racemosa)], black mangroves are the most cold-hardy, but they are still sensitive to winter weather- they generally cannot establish above 28° N and S latitude because winters are too cold (a sliver of the Birdsfoot Delta is below 29° N, so we really are at their limit).

The three mangrove species are also different in their tolerances for other environmental conditions: red mangroves establish in the intertidal zone, while black and white mangroves are found at higher elevations, and white mangroves can colonize areas with little to no soil. In Florida where all three species occur, mangrove zones can be defined from the water extending inland and up in elevation .

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Red mangroves are found in the intertidal zone, while black and white mangroves establish at higher elevations. Graphic from the Florida Museum of Natural History at the University of Florida (https://www.floridamuseum.ufl.edu/southflorida/habitats/mangroves/zonation/)

Black mangroves are an important component of Louisiana salt marshes, providing habitat to a variety of species. The complex root systems trap and collect sediment, limiting erosion and maintaining land. Juvenile invertebrates and fish find shelter among the roots, while seabird chicks, such as brown pelicans and roseate spoonbills, are protected from high water events and predators up in the branches.

CWPPRA projects that nourish barrier islands and create new marsh habitat help maintain black mangrove populations by providing new land for the plants to colonize; in turn, the mangroves help the new land persist in the face of wind and wave energy.