Whiskey Island Back Barrier Marsh Creation (TE-50)

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Gulfside and bayside erosion has resulted in the narrowing of Whiskey Island (and the entire Isles Dernieres chain) as the two shorelines migrate toward each other, resulting in a 68 percent decrease in average width for the Isles Dernieres. Within 100 years, the entire subaerial portion of the Isles Dernieres barrier island system is expected to disappear except for small land fragments associated with the western end of Whiskey Island and the eastern end of East Island. However, some estimates project the Isles Dernieres will disappear much earlier. Other predictions suggest that, without restoration, Whiskey Island could become a subaqueous sand shoal by 2019. Another CWPPRA restoration project, Whiskey Island Restoration (TE-27), which included placement of dredge material, vegetative planting, and sand fencing, was completed in 2000.

The goal of the TE-50 project is to increase the longevity of the previously restored and natural portions of the island by increasing the island’s width. Increasing the island’s width will help to retain sand volume and elevation. Approximately 319 acres of back barrier intertidal marsh habitat, 5,865 linear feet of tidal creeks, three 1-acre tidal ponds and 13,000 linear feet of protective sand dune were created by semiconfined disposal and placement of dredged material. The sediment was dredged from a sediment source in the Gulf of Mexico near the island. The area was planted with native marsh vegetation to colonize and protect the newly-placed marsh soil.

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Whiskey Island, one of five islands that make up the Isles Dernieres barrier island chain, is located 18 miles southwest of Cocodrie in Terrebonne Parish, Louisiana. The island is surrounded by Coupe Colin to the west, Whiskey Pass to the east, Lake Pelto, Caillou Boca, and Caillou Bay to the north, and the Gulf of Mexico to the south.

The CWPPRA Task Force approved funding for construction (phase 2) at the February 13, 2008 Task Force meeting. Construction began in March 2009 and initial construction was completed in November 2009.Vegetative plantings were installed at the project site in June of 2010 and October 2011.

This project is on Project Priority List 13.

Federal Sponsor: EPA

Local Sponsor: CPRA

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East Sabine Lake Hydrologic Restoration (CS-32)

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The lower salinity marshes are converting to shallow, open water due to elevated salinity events and subsidence. Navigation channels provide a direct route for salt water to infiltrate the marsh, disrupt the natural water circulation, and allow rapid runoff of fresh water. The larger Sabine-Neches Waterway and the Gulf Intracoastal Waterway (GIWW) have allowed saltwater intrusion into the project area’s fresh and intermediate marshes. Elevated tidal fluctuations in these channels have led to increased water flow, which has increased the conversion of marsh to open water. Area marsh loss is also caused by wave action along Sabine Lake and interior marsh shorelines and other natural causes (i.e., subsidence).

The project features include: a rock weir in Pines Ridge Bayou; three culverts with flap gates at Bridge Bayou; a 3,000 foot-long rock rip-rap breakwater along the Sabine Lake shoreline at Willow Bayou; a weir/plug at the opening at Starks South Canal Section 16 levee; and 232,000 linear feet of vegetated earthen terraces in the vicinity of Greens Lake.

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The project is located in the western portion of the Sabine National Wildlife Refuge from Pool 3 to the eastern shoreline of Sabine Lake in Cameron Parish, Louisiana.

Construction was completed in October 2010.

This project is on Priority Project List 10.

The Federal Sponsor is U.S. Fish and Wildlife Service

The Local Sponsor is CPRA

Coastal Permitting and Mitigation

With the United States midterm elections coming up, this week’s Wetland Wednesday focuses on the roles of government in coastal restoration, specifically permitting and mitigation. Of course, each coastal parish has their own government and representatives, and the State of Louisiana has dedicated offices for coastal restoration.

Anyone who wants to construct a restoration project in the coastal zone must go through the State of Louisiana Department of Natural Resources (DNR) to obtain the proper permitting, most commonly a Coastal Use Permit. [1] The DNR requires all who apply for a coastal use permit to prove that they have sufficiently addressed the need for environmental damage mitigation. CWPPRA-funded projects are permitted through this office because they have sufficient positive environmental impact. Our engineers and managers must prove that they have done the necessary surveys and sustainable development plans. Other coastal uses that require permitting include dock construction, dredging and infilling, and oil well capping and abandonment.

All permits are distributed with the intent of preserving net ecosystem integrity, meaning that if there is a large impact at the project location, damage mitigation measures are required. Recent legislation at the state level has been moving toward the idea of “Environmental Banking”, [2] which would allow developers to invest in the coastal zone, providing funds for restoration and earning credits that can be cashed in for mitigation needs. This process would get dollars on the ground in advance to help fund restoration. Since local damage is so common in development, environmental bank investors must invest in the bank that deals with the zone they will want to develop.

CWPPRA was enacted in 1990 to minimize coastal land loss. One of the most important goals of our projects is to provide a net benefit to the local environment. Legislation and permitting allow us to do this vital work, and we appreciate the efforts in Louisiana toward responsible coastal use. We hope everyone, both in government and the larger public, continues to view coastal land loss as a serious threat to the economy, ecosystems, and civilization.

[1] http://www.dnr.louisiana.gov/index.cfm?md=pagebuilder&tmp=home&pid=85&ngid=5

[2] http://www.jmbcompanies.com/Services/Mitigation/mitigation-banking-environmental

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

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

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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 Fountainebleu 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.

 

Federal Sponsor: USFWS

Local Sponsor: CPRA

Measuring Elevation Change

To provide the best possible care, doctors first must know what is going on with their patients. The same goes for ecologists and engineers with wetlands. Just like doctors can measure your growth and deduce what could help you get over a sickness, ecologists measure the “health” of ecosystems to try to keep them healthy.

Wetland habitats have many moving parts which makes them difficult to fully understand, but we can get a pretty good idea of whether they are growing or deteriorating and sometimes why. All CWPPRA projects require significant amounts of research to estimate the benefit of the project and minimize any damage that could come from disturbing already established wetlands. CWPPRA funds the Coastwide Reference Monitoring System (CRMS) program, which provides reliable coastal elevation data to scientists. Completed projects are monitored for wetland health factors including land accretion, productivity, and water quality to determine whether they are making a positive impact on coastal systems.

Elevation studies are necessary across our coast since we experience such high levels of sediment subsidence. Elevation can be measured in a variety of ways, such as geodetic leveling, Interferometric Synthetic Aperture Radar (inSAR), or satellite imaging. [1] Because of the lower precision, satellite imaging is not great for measuring elevation change for a specific point but is relatively reliable for larger changes over longer periods of time. Another common technique for measuring elevation change in wetland ecology is Rod Surface Elevation Tables with Marker Horizons (RSET-MH), which is implemented at all CRMS sites.

 

. Rod surface elevation table - marker horizon (RSET-MH) in both shallow and deep configurations. All installations associated with the current work will be deep. 
RSET-MH diagram with deep benchmark, shallow benchmark, marker horizon [2]
An RSET is attached to a deep benchmark that will resist erosion and accretion, somewhere between 20 and 25 meters below the surface of the marsh, where the hard-packed sediments lie. With a benchmark, scientists can measure the relative surface elevation . To measure the rate of sediment accretion between two time periods researchers deposit a layer of white clay on the soil’s surface, called a marker horizon. At a later date, researchers return to the site, collect a core sample, and measure the amount of sediment above the white clay to calculate an accretion rate. [3] RSET-MH is great for measuring one specific site for small and precise elevation changes, but is limited in area coverage. Luckily, through the Coastwide Reference Monitoring System, we are able to monitor elevation change and accretion rates at over 390 sites across the coast!

Measuring wetland health has many factors, not only elevation change. Check in next week for our next installment on wetland monitoring!

 

[1] https://www.epa.gov/wetlands/wetlands-monitoring-and-assessment

[2] https://www.researchgate.net/figure/Rod-surface-elevation-table-marker-horizon-RSET-MH-in-both-shallow-and-deep_fig2_281113921

[3] https://www.pwrc.usgs.gov/set/

Featured Image from https://oceanservice.noaa.gov/sentinelsites/chesapeake-bay/welcome.html

The CWPPRA Public Outreach Committee

The Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) is federal legislation enacted in 1990 to identify, prepare, and fund construction of coastal wetland restoration projects in Louisiana. As part of the CWPPRA program, there is also the CWPPRA public outreach committee.

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The CWPPRA outreach committee works with people of different ages, backgrounds, and interests from across the state and country. The committee works to develop an appreciation for the unique wetlands of Louisiana, and the role that CWPPRA has in protecting and restoring those resources. Although based in Lafayette, Louisiana at the USGS Wetland and Aquatic Research, outreach staff travel across Louisiana and beyond to talk with policy-makers, educators, fishermen and hunters, scientists, and community members.

Since a diverse group of stakeholders have an interest in protecting Louisiana’s coast, the outreach staff network with many groups and participate in a variety of activities including:

  • hosting a yearly Dedication Ceremony for recently completed projects;
  • developing educational materials like Henri Heron’s Activity Book and WaterMarks magazine;
  • exhibiting at national conferences like State of the Coast 2018 and Restore America’s Estuaries Summit 2016;
  • working with CWPPRA Task Force, Technical Committee, and Working Group members to communicate the importance of our projects to the public at local events like Terrebonne Parish Coastal Day;
  • maintaining the LUCC calendar for coastal events.

The CWPPRA Public Outreach Committee enjoys talking to people about our interest in coastal Louisiana, and these conversations aid in the progress of coastal wetland restoration. Given the complex nature and scale of land loss in Louisiana, it takes many people working together to help restore the coast. — CWPPRA Outreach educates the public about why coastal wetland restoration is important and how CWPPRA projects contribute to supporting these habitats and communities.

More information about the outreach materials available can be found at lacoast.gov.