GIWW (Gulf Intracoastal Waterway) to Clovelly Hydrologic Restoration (BA-02)

The constructed rock breakwater located in Bay L’Ours will assist in reducing wave energies before they impact the shore and will also arouse the curiosity of local waterfowl such as these pelicans.

Location

The center of the project area is in Lafourche Parish, Louisiana, approximately 5 miles southeast of Cut Off. It is bordered to the north by a pipeline canal north of the Clovelly Canal, to the west by West Fork Bayou L’Ours, to the east by Little Lake, and to the south by oilfield canals. The project encompasses 14,948 acres of primarily intermediate (94%) and brackish (6%) marshes.

Problems

The wetlands in the project area are of great importance to the ecological future of the Barataria estuary and to the protection of adjacent developed areas. The area is losing approximately 450 acres per year due to channelization, shoreline erosion, and saltwater intrusion.

Restoration Strategy

The project features include three rock weirs and four canal plugs. There is also a plug with a flap-gated culvert and one with a variable crest weir. In addition, there is a weir with a barge bay in the Clovelly Canal, 5,000 feet of shoreline reestablishment along project-area canals, and 6,000 feet of lake-rim reestablishment at Bay L’Ours. Finally, the spoil and marsh banks along canals in the project area’s southern perimeter are being maintained.

 

Progress to Date

The project was divided into two contracts in order to expedite implementation. The first contract was to install most of the weir structures. The second contract was to install bank protection, one weir, and one plug. The construction of the project’s unit 1 was completed in November 1997. Unit 2 was completed in October 2000.The O&M plan was signed in 2002. This project is on Priority Project List 1.

This winch which is permanently attached to the variable crest, water control structure located right off Briton Canal, will help to configure the structure according to a pre-determined water management plan.

The project is on Priority Project List (PPL) 1.

The Federal Sponsor is Natural Resources Conservation Service.

The Local Sponsor is CPRA.

Approved Date: 1991
Project Area: 14,948 acres
Approved Funds: $12.7 M
Total Est. Cost: $12.8 M
Net Benefit After 20 Years: 175 acres
Status: Completed October 2000
Project Type: Demonstration: Hydrologic Restoration

Freshwater Bayou Bank Stabilization (ME-13)

By placing riprap in front of the existing shoreline, further wetland loss will be decreased dramatically. It is anticipated that open water areas behind the rock structure will accumulate sediments and eventually become vegetated.

Location

This project is located along the west bank of Freshwater Bayou Canal near Little Vermilion Bay, 4 miles southwest of Intracoastal City, Louisiana, in Vermilion Parish. It
extends north from North Prong and Belle Isle Bayou to Sixmile Canal.

Problems

Increased tidal action, saltwater intrusion, and boat wakes have accelerated erosion long the banks of the Freshwater Bayou Canal. The spoil banks have completely eroded in some areas. The remaining spoil banks along the southern reach of the project area separate Freshwater Bayou Canal from several interior marsh ponds. If the banks breach, shoreline erosion will accelerate interior marsh loss.

Restoration Strategy

The objective of this project was to prevent further wetland loss through the reduction of bank erosion and subsequent tidal scour of shoreline marshes. Approximately 23,193 linear feet of freestanding rock dike were constructed in shallow water along the west bank of Freshwater Bayou Canal (from its confluence with Sixmile Canal on the northern end and North Prong to the south).

Progress to Date

The local cost share for this project was provided by Acadian Gas Company. Construction began in March 1998 and was completed in May 1998. The monitoring plan was approved in February 1997. To date, monitoring has consisted of documenting the pre-construction shoreline position relative to the rock dike and a land-to-water analysis of the preconstruction aerial photography that was taken in January 1997. This project is on Priority Project List 5.

The project is on Priority Project List (PPL) 5.

The Federal Sponsor is National Resources Conservation Service

The Local Sponsor is CPRA.

Approved Date: 1996
Project Area: 1,724 acres
Approved Funds: $5.56 M
Total Est. Cost: $8.91 M
Net Benefit After 20 Years: 511 acres
Status: Completed June 1998
Project Type: Shoreline Protection

GIWW – Perry Ridge West Bank Stabilization (CS-30)

Settlement plates such as the one pictured here will be used to determine if settling of the structure has occurred. Technicians from NRCS’s Crowley Watershed Office are shown taking baseline elevations before more rock is deposited. Future elevation readings will be taken after the structure is completed.

Location

The project is located along the northern bank of the Gulf Intracoastal Waterway (GIWW) between Perry Ridge and the Sabine River in Calcasieu Parish, Louisiana.

Problems

This section of the GIWW was dredged to allow the use of doublewide barges, and,  consequently, has intensified the occurrence of wake erosion. In addition, the construction of the Calcasieu Ship Channel and the deepening of Sabine Pass have increased the salinity and water currents within the GIWW. These activities have caused the GIWW shoreline to breach, thus impacting the interior marsh of the project area.

Restoration Strategy

Proposed project components involve installation of 9,500 feet of rock riprap along the northern bank of the GIWW from Perry Ridge to its intersection with the Sabine River.
An additional 2,200 feet of rock riprap will be installed from the Sabine/GIWW intersection north along the Sabine River. This proposed work is referred to as “construction unit number 2.” Approximately 22,952 linear feet of terraces will
be constructed in the shallow, open water areas north of the GIWW to reduce fetch (distance a wave can travel) and allow recovery of the interior marshes. Terraces will be
vegetated with 9,400 trade-gallon-sized plantings of California bulrush. This proposed work is referred to as “construction unit number 3.”

Progress to Date

Project construction is complete. The monitoring plan is currently in development and should be finalized in the spring of 2002.

The project is on Priority Project List (PPL) 9.

The Federal Sponsor is Natural Resources Conservation Service.

The Local Sponsor is CPRA.

Approved Date: 2000
Project Area: 1,132 acres
Approved Funds: $2.19 M
Total Est. Cost: $2.20 M
Net Benefit After 20 Years: 83 acres
Status: Completed
Project Type: Shoreline Protection

Atchafalaya Sediment Delivery (AT-02)

A bucket dredge is shown removing sediment from a shoaled-in channel in order to help reestablish water and sediment flow within the Atchafalaya Delta.

Location

The project is located east of the lower Atchafalaya River navigation channel in the Atchafalaya River Delta, approximately 19 miles southwest of Morgan City, Louisiana, in St. Mary Parish.

Problems

Growth of the lower Atchafalaya Delta has been reduced as a result of maintenance of the Atchafalaya River navigation channel. Delta development in the shallow waters of Atchafalaya Bay is dependent on distributary flows and the diversion of sediments into over-bank areas through crevasse channels.

Because of the placement of material dredged from the navigation channel and sediment accumulation within the channels that decrease flow efficiency, the open crevasse channels are frequently short-lived. As riverflow through a crevasse channel is reduced, the amount of sediment that can be deposited in the delta is likewise reduced, resulting in decreased marsh development.

Restoration Strategy

The purpose of this project is to promote natural delta development by reopening two silted-in channels and using those dredged sediments to create new wetlands. Approximately 720,000 cubic yards of sediment were dredged from Natal Channel and Castille Pass in 1998. Over 12,000 feet of channel were reopened, and more than 280 acres of new habitat were created by the strategic placement of the dredged channels’ sediments. By reestablishing water and sediment flow into the eastern part of the Atchafalaya Delta, an additional 1,200 acres of new habitat are expected to be naturally created over the life of the project.

Progress to Date

Construction was completed in 1998. A pre- versus post-construction habitat analysis using aerial photography indicated that, while there was an increase in land of 78.4 acres, the majority of the habitat created was represented by forested wetland (50.1 acres), while fresh marsh and upland barren habitats accounted for 14 acres gain each. Although many of the dominant plant species are present in both created and reference areas, the created areas contained different plant communities when compared to any time period in the development of a natural crevasse splay that served as a reference area for this project. Although the long-term effects on submerged aquatic vegetation (SAV) are unclear, habitat mapping indicated an increase in SAV habitat of 221.5 acres from 1997 to 1998, but this is very close to the increases that were reported in the project area pre-construction. Satellite imagery indicates that there have been significant increases in emergent acreage from 1998 to 2008.

This project is on Priority Project List 2.

The Federal Sponsor is National Marine Fisheries Service.

The Local Sponsor is CPRA.

Nutria Harvest for Wetland Restoration Demonstration (LA-03a)

Louisiana’s growing nutria population is detrimental to the state’s coastal marshes as the animals consume wetland plants that hold the soil together.

Location

This project was located throughout the coastal zone of Louisiana.

Problems

The nutria is a non-native, fur-bearing species in the rodent family that was introduced to enhance the Louisiana fur industry. Since the decline of the fur industry, nutria populations have increased tremendously along the coast. Because nutria voraciously consume marsh plants that help anchor wetlands, this non-native nutria population is now having a significant negative impact on coastal marsh health.

Restoration Strategy

The goals of this demonstration project were to determine if nutria meat for human consumption could be promoted and determine if a meat processing system promotional program could be developed. Meeting these goals would have facilitated nutria harvest through an increased meat demand. The project called for Coastal Wetlands Planning, Protection and Restoration Act funding matching that of participating meat-processing plants in order to compensate trappers for the nutria they harvest. The project also included monitoring selected coastal marsh areas by the Louisiana Department of Wildlife and Fisheries (LDWF) to assess both nutria damage and recovery resulting from this project.

Other components of the project included nutria meat recipe development and publication, along with an advertising and marketing strategy focused on increasing the public demand for nutria meat. The project was implemented by the LDWF with oversight by the Louisiana Department of Natural Resources and the U.S. Fish and Wildlife Service.

Progress to Date

This demonstration project was approved by the Louisiana Coastal Wetlands Conservation and Restoration Task Force in April 1997. Through this project, LDWF has coordinated with consultants to develop and implement various nutria meat marketing activities.

Marketing activities included LDWF staff activities and contracting with consultants to: (1) develop and evaluate local, national, and international nutria meat market potential for human consumption; (2) develop a nutria meat marketing plan, including a Nutria Marketing Strategic Report which proposed various ways to encourage the public to eat nutria; (3) participate in festivals and chef’s competitions; (4) distribute nutria meat to the public through sales at grocery stores, restaurants, and other retail outlets; (5) determine nutria meat processing costs, product price structure, and potential meat production volume; and (6) plan promotional and advertising activities based on the Nutria Marketing Strategic Report.

The LDWF 1999, 2000, and 2001 nutria coastal damage surveys and reports indicated continued nutria-related marsh damages in the Louisiana deltaic plain at a level of approximately 100,000 acres per year impacted. Because of the January 2002 Task Force approval of the larger Coastwide Nutria Control Program (LA-03b), the LDWF discontinued providing incentive payments to trappers and conducting nutria herbivory surveys under this demonstration project. Those two items will be funded under the larger project. However, funding for nutria meat processors enrolled in the program, as well as nutria meat marketing activities, continued until the project was completed in October 2003. This project is on Priority Project List 6.

The project is on Priority Project List (PPL) 6.

The Federal Sponsor is US Fish & Wildlife Service.

The Local Sponsor is CPRA.

Approved Date: 1997
Project Area: N/A
Approved Funds: $0.80 M
Total Est. Cost: $0.80 M
Net Benefit After 20 Years: N/A
Status: Completed
Project Type: Demonstration: Herbivory Control

East Catfish Lake Marsh Creation and Shoreline Protection (TE-157)

Aerial view of marsh creation project in Terrebonne Parish.

Location

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

Problems

Significant marsh loss has occurred east and south of Catfish Lake. Causes of marsh loss include the construction of numerous oil/gas canals, subsidence, and sediment deprivation. Between Catfish Lake and Golden Meadow Hurricane Protection Levee, very little marsh remains after the construction of an extensive network of oil/gas canals. Much of the remaining land in this area consists of spoil banks and isolated patches of marsh. From examination of aerial photography, the majority of this loss occurred during the 1960s and 1970s. Based on the hypertemporal analysis conducted by USGS for the extended project boundary, the land loss rate in the project area is -0.86% per year for the period 1984 to 2019. Shoreline erosion rates (1998-2017) range from 10 ft/yr along the eastern lake shoreline to 22ft/yr along the southern lake shoreline.

Restoration Strategy

The primary goal of this project are; 1) restore marsh habitat in the open water areas east and south of Catfish Lake, and 2) restore and protect the eastern and southern Catfish Lake shoreline. The specific goals of this project are; 1) create 235 acres of marsh, 2) nourish 71 acres of marsh, 3) protect the marsh creation cells from shoreline erosion.

Service goals include restoration/protection of habitat for threatened and endangered species and other at-risk species. This project would restore habitat potentially utilized by the black rail, which is proposed for listing as a threatened species. The project could also benefit other species of concern including the saltmarsh topminnow and seaside sparrow.

Sediment from Catfish Lake will be hydraulically dredged and pumped via pipeline to create/nourish 306 acres of marsh. Dewatering and compaction of dredged sediments should produce elevations conducive to the establishment of emergent marsh and within the intertidal range. Containment dikes will be constructed around each marsh creation cell. Where practicable, material will be borrowed from perimeter oil/gas canals. Containment dikes will be gapped at the end of construction or by TY3. Approximately 2,566 linear feet of sheet pile wall will also be installed as a containment feature. Approximately 12,479 linear feet of shoreline protection (gabion mattresses) will be installed along the lakeside boundary of the marsh creation cells on the constructed containment dikes.

The project was approved for Phase I Engineering and Design in January 2020.

The project is on Priority Project List (PPL) 29.

The Federal Sponsor is US Fish & Wildlife Service.

The Local Sponsor is CPRA.

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

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.

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

Moving Land: Erosion and Sediments

Land loss and land gain are terms we throw around a lot at CWPPRA but what do they mean? Where does the old land go and where does the new land come from? To answer that, we need to understand that “land” is made of inorganic particles that we call sediment and various types of organic matter. Sand, clay, gravel, boulders, and silt are all types of sediment, and grain size is how we classify them. [1] For example, a boulder is larger than gravel, which is larger than a grain of sand, which is larger than a silt particle, etc. Sediment size influences how each grain experiences force and inertia, which leads to different rates of land loss and gain between sediments. Imagine holding a handful of sand in one hand and a handful of gravel in the other. Now imagine you blow as hard as you can on each one. More gravel would stay in your hand than sand. The same is true of sediment in water- smaller grains of sand can be picked up more easily by the forces acting on them than the gravel can.

Erosion detaches sediment from an original source, such as a cliff face or the middle of a valley. Over long periods of time, eroded particles get smaller and smaller, eventually degrading to sand or silt, depending on the mineral base. Once they get into a river or stream, their movement is connected to water flow. When water flows faster or stronger, it “suspends” and carries more sediment, while sediments in slower currents tend to settle out and “deposit” on the bottom of the lake, bayou, or swamp. Approximately 40% of the USA drains through the Mississippi River, and any suspended sediment in those waterways travels through Louisiana on its way to the Gulf of Mexico. [2]

Sediments move downstream differently depending on their size class.

Wetlands are defined by sediment type and other characteristics including salinity. In Louisiana, we have fresh water wetlands like swamps and bottomland hardwood forests, but also saline wetlands like salt and brackish marsh. Each of these wetlands types contains fine sediment particles, and they are all relatively new in the scope of geologic time. Because they are young, there are not many hard-packed substrates in Louisiana wetlands, but instead deeper layers of sediment that are compacting and subsiding. [3] Sediment replenishment is important to all the wetlands in Louisiana because new sediment is needed on top of compacting sediment to maintain elevations that support plant life and productive ecosystems. Unfortunately, sediments that should be replenishing the wetlands of Louisiana are not doing so. Instead, they are being transported out into the Gulf of Mexico or are trapped farther upstream behind dams. More information about this topic can be found in our post “The Mississippi River Deltaic Cycle”. Controlling the flow of the Mississippi river keeps sediments suspended for longer because water does not disperse or slow down as it naturally wants to. Without new sediment, marsh platforms lose structural integrity and they erode, leaving open water where marsh once was.

To answer the original question; for CWPPRA land loss is the process of sediment and marsh sinking or eroding into open water along Louisiana’s coastline and reducing the land available. Land gain describes the process of sediment depositing to form new platforms and it is much less common along our coast, but CWPPRA and their Partners in Restoration are working to restore the integrity of coastal wetlands by moving and capturing sediment, planting stabilizing species on terraces, and creating marsh in critical areas. Combating land loss is a multi-disciplinary effort, and we have a long fight ahead.

 

Featured image: http://amazonwaters.org/waters/river-types/whitewater-rivers/

Embedded image: http://blog.sustainability.colostate.edu/?q=schook

[1] https://www.tulane.edu/~sanelson/eens1110/sedrx.htm

[2] https://www.nps.gov/miss/riverfacts.htm

[3] https://www.sciencedirect.com/science/article/pii/S027277140600312X

The Mississippi River Deltaic Cycle

Water flows downhill naturally and, over time, will make a river change from one path to another. As sediment moved and elevations changed over the last 7 millennia, the Mississippi River has emptied into several historic delta complexes: Maringouin, Teche, St. Bernard, Lafourche, Plaquemines-Balize, and Atchafalaya. Each of the deltas built up part of Louisiana’s coast to what we see today, but now that natural process has been interrupted [1]. After the great Mississippi flood of 1927 that caused $1 billion worth of damages (almost $1 trillion in today’s dollars), the US Army Corps of Engineers built the world’s longest levee system under the Flood Control Act of 1928. The Levee system was constructed to reduce flood damages and allow for more control of the Mississippi [2].

Image 1: Historic Deltas of the Mississippi River

An unforeseen and unfavorable side effect to taming the river was that all the water is kept moving too quickly to deposit sediment, and now sediment is lost to the Gulf of Mexico rather than deposited into our coastal wetlands [3]. Our Louisiana coastline is dependent on new sediment to nourish wetland ecosystems. Without sediment delivery, there is no material for natural land gain or replenishment, which will continue to contribute to our retreating coastline. The solution is not as simple as removing the levee system, however, since so much of Louisiana is populated now, and removing the levees containing the Mississippi would displace millions of residents from their homes. Instead, CWPPRA and our partners in restoration use man-made systems to create marsh, nourish wetlands, and maintain hydrologic connectivity so that we can protect and restore Louisiana’s coast.

 

 

[1] https://en.wikipedia.org/wiki/Mississippi_River_Delta

[2] https://en.wikipedia.org/wiki/Great_Mississippi_Flood_of_1927

[3] http://mississippiriverdelta.org/our-coastal-crisis/wasted-sediment/

Image 1 from https://www.nationalgeographic.org/photo/miss-delta-formation/

Featured image from https://phys.org/news/2015-04-future-mississippi-delta.html

Learning about Wetlands and Dining on Invasive Species

On November 18th, residents and visitors in St. Bernard Parish were treated to live music, cooking demonstrations, and the chance to sample wild boar recipes prepared by teams vying for bragging rights. Hosted by the Coastal Division of St. Bernard Parish, the first Cook-Off for the Coast was held at Docville Farm in Violet, Louisiana with proceeds benefiting the St. Bernard Wetlands Foundation. In addition to evaluating the food of the six competing teams, visitors watched local celebrity chefs prepare everything from gumbo to snapping turtle and talked with a range of coastal organizations about the importance of protecting southeast Louisiana’s coastal wetlands.

Sinead Borchert and Mirka Zapletal from the Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA) Outreach Office were in attendance with information about restoration projects in St. Bernard Parish, activity books, posters from the #ProtectOurCoast series, and recent issues of WaterMarks magazine. They also invited children and adults alike to match Louisiana wildlife with the correct wetland habitat. St. Bernard’s coast is vulnerable to storms, subsidence, erosion, and invasive species, putting wildlife habitat and coastal communities at risk. CWPPRA projects work to support Louisiana’s coastal wetlands and the people and wildlife that depend on these habitats.