Archive for Diversions


Study on sedimentation will help planners develop effective river diversions

December 4, 2012 | Posted by Delta Dispatches in 2011 Mississippi River Flood, 2012 Coastal Master Plan, Diversions, Reports, Science

By Alisha A. Renfro, Ph.D., Staff Scientist, National Wildlife Federation

This year, drought conditions throughout most of the country have left the Mississippi River flowing at a near all-time low. This is a stark comparison to 2011, when heavy rains and a large snowmelt in the spring sent record levels of water and sediment flowing down the river. At the Old River Control Structure north of Baton Rouge, the flow of the river is split, with 70 percent continuing down the Mississippi to the Bird’s Foot delta, and the remaining 30 percent flowing down the Atchafalaya River. During the 2011 flood, the flood protection levees and the opening of the Morganza and Bonnet Carré spillways successfully shunted water safely past the high population centers in the region. However, this event was a missed opportunity to capitalize on the influx of fresh water and sediment and to reconnect the river with sediment-starved wetlands of Louisiana.

In a recent study published in Nature Geoscience, research led by Federico Falcini, Ph.D. examined the link between the historic 2011 river flood and sediment accumulation in nearby wetlands. Their analysis suggested that the natural dynamics of the coastal system coupled with man-made alterations to the river system influenced the amount of sediment deposited in the wetlands. This work shows that under river flood conditions, diverting the flow of the river into shallow basins adjacent to the river could contribute significantly to sediment deposition in the wetlands and therefore contribute to wetland growth.

Mississippi River sediment plumes, as viewed from space (May 17, 2011). Credit: NASA Modis imagery

In the study, the sediment plumes of the Mississippi and Atchafalaya Rivers were tracked using satellite imagery from the 2011 flood event to understand where the sediment went once it exited these rivers. The Mississippi’s sediment plume exited the river in focused jets of sediment-laden water due to the confinement of much of the river’s flow between artificial levees. This plume moved past the coastal current and into the deeper waters of the Gulf of Mexico, limiting the amount of sediment that could be deposited in the near-shore area and adjacent wetlands. In contrast, the Atchafalaya’s sediment plume exited the river and moved along a broad, near-shore area, mixing with waters from the Gulf of Mexico and creating conditions that were likely to favor sediment deposition.

A comparison of sediment accumulation during the 2011 flood in nearby marshes shows a trend that corresponds to the difference in behavior of the two river plumes. Sediment accumulation was highest at marsh sites near the Atchafalaya River, which supports the idea that its sediment plume spreading out over a large area in relatively shallow water, promoting increased sedimentation in the region. Sediment accumulation in wetlands near the mouth of the Mississippi River was substantial, but significantly lower than near the Atchafalaya. While the Mississippi River carried a larger sediment load during the 2011 flood event, much of the sediment was lost to the deeper waters of the gulf.

Louisiana’s 2012 Coastal Master Plan identifies several sediment diversions that are key to restoring the important coastal Louisiana landscape. The success of these diversions will depend on a variety of factors, including location and operation. However, this new research confirms that fine sediments introduced into shallow water can substantially contribute to sediment accumulation in wetlands. In order to restore the rapidly deteriorating wetlands of coastal Louisiana, it is critical to reintroduce the sediment that once built this productive region.

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What the BP criminal settlement means for Gulf Coast restoration

November 29, 2012 | Posted by Delta Dispatches in BP Oil Disaster, Clean Water Act, Diversions, RESTORE Act

By Whit Remer, Policy Analyst, Environmental Defense Fund

Just in time for the holidays, the U.S. Department of Justice (DOJ) delivered welcomed and unexpected good news for Gulf Coast restoration efforts. On November 15, DOJ announced they had reached a settlement with BP on all criminal charges related to the 2010 Deepwater Horizon oil spill. But what was expected to be a simple press conference outlining the details of the criminal plea agreement turned out to be a huge $2.4 billion win for Gulf Coast restoration.

For the last two years, the Department of Justice has been working to bring criminal and civil charges against BP for its involvement in the deadly rig explosion and nation’s largest environmental disaster. On the criminal side, DOJ claimed BP broke a number of securities violations and environmental laws.  Environmental laws often contain provisions that allow the government to pursue criminal charges when the party is suspected of acting negligently during the incident. Criminal charges can carry hefty fines, require probation and may lead to the imprisonment of company officials. BP plead guilty to all criminal charges brought by DOJ and agreed to pay $4 billion in fines.

Deepwater Horizon offshore drilling unit on fire (April 20, 2010). Source: U.S. Coast Guard

Criminal fines are separate from the civil fines the company will pay for violations under the Clean Water Act and Oil Pollution Act in a forthcoming settlement or trial. The RESTORE Act, passed by Congress in June of this year, will direct 80 percent of civil fines to Gulf Coast restoration. The RESTORE Act does not capture criminal fines, which generally flow to the U.S. Treasury, or natural resource damage money assessed under the Oil Pollution Act.

The agreement reached by DOJ and BP is unprecedented for two reasons. One, the criminal fines assessed by DOJ, and agreed to by BP, are the largest ever levied against a corporation. If the criminal fine is any indication of the seriousness to which DOJ is pursuing civil charges under the Clean Water Act, then those fines could reach the $21 billion mark that some analysts have predicted. Whatever the amount, 80 percent will be returned to the Gulf Coast for restoration under the RESTORE Act.

The second reason the agreement reached by DOJ is unprecedented is the fact that the agency allocated more than half of the fine money – $2.4 billion – for Gulf Coast environmental restoration. Neither the gulf states nor coastal restoration planners expected DOJ to unilaterally direct money to environmental restoration.

What’s even more exciting is that $1.2 billion of this money is reserved to advance sediment diversions and barrier island restoration projects in the rapidly-disappearing Mississippi River Delta. Sediment diversions reconnect the Mississippi River, which is full of vital freshwater, sediment, and nutrients, with adjacent dying wetlands that have been cut off from the river by manmade levees.

Dedicating this much money towards restoration of the Gulf Coast signals that the Administration recognizes the importance of the gulf to the nation, and perhaps more pointedly, the importance of the Mississippi River Delta to the gulf. With its recently passed 2012 Coastal Master Plan, Louisiana is well-situated to devote money from the BP oil spill to critical restoration projects in the delta. We applaud the Department of Justice for their recognition of this important issue and encourage them to pursue civil Clean Water Act and Oil Pollution Act penalties with the same vindication, so the Gulf Coast and Mississippi River Delta can be restored and revitalized.

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West Bay Diversion to Remain Open

October 15, 2012 | Posted by Delta Dispatches in Diversions, Restoration Projects

This was originally posted on the Coalition to Restore Coastal Louisiana's Coastal Currents blog.

The much-debated West Bay Diversion will remain open for at least the next 10 years. That’s the word from the CWPPRA Task Force, which reversed its own 2008 decision to close the sediment diversion at its meeting on Thursday, October 12, 2012.

The move keeps open one of the few land-building diversions off of the Mississippi River, allowing sediment in nearby wetlands to continue to accumulate. Researchers will also have the opportunity to continue studying the diversion, which has reportedly built more than 10 acres of land in 2011 alone.

Quoted by The Advocate’s Amy Wold on Thursday, Colonel Ed Fleming of the U.S. Army Corps of Engineers said new research suggests the diversion is providing more benefit to the surrounding wetlands than first thought. “It appears the diversion is working better than expected,” he said. “When the task force made the decision a few years ago to close this, we didn’t have all the information we have today.”

The original decision to close West Bay was based on a complicated funding scenario that concluded the diversion was not providing enough benefit to justify the expense of keeping it open.

In light of new evidence, the CWPPRA Task Force decided to allocate the money it would have spent closing the diversion to take the necessary steps to keep it open for 10 more years.

While the West Bay Diversion has been criticized over the years for flaws in its design and the expense of keeping it open, the decision to keep the diversion running is important. The 2012 Coastal Master Plan, passed by the Louisiana Legislature this summer, relies on the use of properly designed and operated sediment diversions to rebuild sections of our delta. The acres of land created by West Bay lend credence to the position that these diversions will work. The opportunity to study a working sediment diversion is valuable to researchers who have few other options for studying this restoration method in the field. If West Bay continues its recent track record of success, it will also help proponents of diversions convince policymakers, and the public, of the worthiness of sediment diversions within Louisiana’s coastal restoration strategy.

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The Next 50 Years: Implementation of Coastal Master Plan projects

August 22, 2012 | Posted by Delta Dispatches in 2012 Coastal Master Plan, BP Oil Disaster, Clean Water Act, Coastal Master Plan series, Community Resiliency, Diversions, Hurricanes, Natural Resource Damage Assessment (NRDA), Restoration Projects, RESTORE Act

By David Muth, Louisiana State Director, National Wildlife Federation

Now that Louisiana’s 2012 Coastal Master Plan is law, it is critical that the state’s Coastal Protection and Restoration Authority (CPRA) moves the process forward as quickly as possible. While the plan lays out a series of projects for over its fifty-year timeframe, the actual sequence of projects has not yet been completely planned. The sooner CPRA can finalize this project list and timeline, the sooner vital construction and restoration can begin.

Several things are necessary for creating that list of projects. First is to carry out continued modeling to measure how projects and suites of projects will interact with one another. One example is looking at how a mid-Barataria 50,000 cubic feet per second (cfs) sediment diversion will interact with marsh creation projects in the middle Barataria Basin and with a ring levee and community resiliency measures for the nearby town of Lafitte.

2012 Coastal Master Plan projects. Source: CPRA

Second is to work out how funding streams can be most effectively sequenced to begin building out the projects identified in the list. This is especially critical with Clean Water Act penalty funding to be distributed under the RESTORE Act and the separate Natural Resource Damage Assessment (NRDA) process. These funding sources, resulting from the BP Deepwater Horizon oil spill, could become available at almost any time over the next few years.

Third is to move quickly to implement nonstructural hurricane risk reduction measures. Nonstructural storm protection measures are those that build community resiliency by means other than “structural” methods such as levees, floodwalls and floodgates. They include raising structures and homes up out of danger, hardening infrastructure and assisting with voluntary relocation. Unfortunately, the suite of existing nonstructural programs is reactive: invoked after, but not before, a disaster. That has to be changed moving forward.

Another challenge concerns the Chenier Plain in southwest Louisiana. The key to long-term restoration in that area is to find ways to modify the hydrology of the area’s navigation system to prevent the continued influx of sea water into formerly freshwater marshes. Simple on paper, tricky in practice.

At an implementation level, two important capabilities need to be developed for the master plan to move forward. One is to demonstrate the feasibility of long-distance pipeline sediment delivery. Much of the Coastal Master Plan depends upon finding a viable way to move vast volumes of sediment many tens of miles through dredge pipes. We have a great deal of experience with relatively smaller scale projects for both marsh creation and barrier island restoration, but the master plan proposes projects that will be carried out on a much larger scale — moving material over much greater distances than ever before. While there seems to be no technical reason this cannot be done, actually doing it will be important for fine tuning the plan.

The Wax Lake Outlet on the lower Atchafalaya River: the newest land in North America.

Similarly, we need to test and demonstrate a sediment diversion somewhere other than at the mouth of the Mississippi River. The very existence of southeast Louisiana proves that such diversions build land. We have extensive experience cutting artificial distributaries near the mouth of the river and letting them build land – from Cubit’s Gap and a dozen other cuts on the Mississippi below Venice to the Wax Lake Outlet on the lower Atchafalaya River. We also know that crevasses through the man-made levee system prior to 1928 moved vast quantities of sediment into the upper estuaries. But we have never deliberately designed and constructed a controlled sediment diversion, and we will learn a great deal more than modeling can tell us by actually doing it.

All told, the to-do list for Coastal Master Plan implementation seems long, but with RESTORE Act and NRDA fines on the way, we will have the funding to jumpstart restoration. Combine this funding with the proper planning and prioritization, and coastal Louisiana will take several steps closer to a more sustainable future.

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Mississippi River’s newest distributary: Mardi Gras Pass gets a tour

August 17, 2012 | Posted by Delta Dispatches in 2012 Coastal Master Plan, Diversions, Mardi Gras Pass

At just five months old, Mardi Gras Pass is the newest distributary of the Mississippi River – a modern addition to an ancient system. Located about 50 miles south of New Orleans on the east bank of the river, the pass was discovered by Lake Pontchartrain Basin Foundation (LPBF) staff on Mardi Gras Day 2012. The natural flow of the Mississippi River had cut a continuous channel through the river’s bank and into the Bohemia Spillway, creating a new distributary and offering a small glimpse at what a natural delta system looks like.

On August 1, Louisiana’s Governor’s Coastal Advisory Commission held their regular meeting in Davant in Plaquemines Parish. At the meeting, Dr. John Lopez, executive director and coastal sustainability program director for LPBF, presented on the status of Mardi Gras Pass to the commission. The presentation showcased how LPBF and its partners were taking every advantage to study and learn about the river’s natural ability to connect to the wetlands. In June, LPBF released a report on the dimensions of the new channel, and its staff continues to regularly monitor the pass’s progress. Both the report and Dr. Lopez’s presentation can be found at SaveOurLake.org.

Mardi Gras Pass’s flow has increased modestly since February, but the discharge is almost entirely dependent on the height of the Mississippi River water level. This summer, while the river has been exceptionally low, the flow rate has been less than 500 cubic feet per second. But when the river rises toward the end of the year, the flow could be ten times greater.

Governor’s Coastal Advisory Commission at Mardi Gras Pass. Commission Chairman King Milling is on the far left and LPBF’s Dr. John Lopez is at the bottom right. Photos courtesy of LPBF.

The Governor’s Commission also visited Bohemia Spillway and Mardi Gras Pass themselves. They were taken to a location where the newly-established Mardi Gras Pass has cut through a private road within the spillway, making it impassable. A local oil company has applied for a permit to repair the road, which could close off the flow from the river and block the pass. The state has expressed scientific interest in Mardi Gras Pass and recognizes it as a potential restoration opportunity. Therefore, the state has requested that the company evaluate alternatives to repairing the road which would allow the pass to still function.

The Commission also visited the actual location where Mardi Gras Pass has cut through the Mississippi River’s bank. Some Commission members had never seen the Mississippi River without an artificial river levee, and it was a moving experience to see the river in its natural condition and to see the meandering Mardi Gras Pass’s channel cutting through the river’s willow tree forested bank. Mardi Gras Pass is a real-life example of nature at work. As a natural distributary and natural diversion, Mardi Gras Pass represents a small precursor to what a more natural Mississippi River and delta could look like in a Coastal Master Plan future.

Additional resources:

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The RESTORE Act: Past, present and future

August 14, 2012 | Posted by Delta Dispatches in BP Oil Disaster, Clean Water Act, Congress, Diversions, Job Creation, Restoration Projects, RESTORE Act, Seafood, Senator Mary Landrieu

By Whit Remer, Policy Analyst, Environmental Defense Fund

It’s been an exciting year for Louisiana and the Mississippi River Delta Restoration Campaign.

In July 2011, nine gulf senators banded together and introduced the RESTORE Act – legislation that would ensure penalties paid by BP and others responsible for the gulf oil spill would be used to restore the gulf region’s environment and economy. In September, the Senate Environment and Public Works Committee approved the bill and in October, Representative Steve Scalise (R-LA) and 20 other gulf representatives introduced the House version of the bill. Supporters worked hard and waited patiently as the RESTORE Act continued winding its way through congressional hearings and historic votes until finally, on June 29, 2012, the RESTORE Act was included as part of the final transportation bill and days later signed into law by the President. It was an amazing journey from start to finish, and we want to take a moment to reflect on the past year and begin looking forward to how the RESTORE Act will unfold to become the single largest environmental restoration investment ever made by Congress.

Sen. Mary Landrieu introduces Rep. Steve Scalise, who led the RESTORE Act effort in the House, during a Capitol Hill event marking its passage. Photo courtesy of Sen. Landrieu.

The idea of spending penalty money from the oil spill on environmental and economic restoration in the gulf region is only fair. Diverse groups, including conservation organizations, the Secretary of the Navy, chambers of commerce from across the gulf region and even a special commission created by the President in response to the spill, all agreed it was the right thing to do. Heeding this call, Congress came together to design a bill to return the money where it belongs: to the Gulf Coast. In the Senate, the RESTORE Act received 76 votes – a remarkable display of bipartisanship which highlights the broad support had by the bill. Of course, it could not have happened without our campaign’s supporters, who used social media, letters to the editor and appeals to their congressional representatives to make the bill a top priority.

Looking forward, we are excited that the RESTORE Act has the potential to make the environment and economies of the Gulf Coast healthy again. The RESTORE Act includes a list of various eligible activities that states may use funds for, ranging from coastal restoration and shoreline protection to seafood and tourism promotion. All of these activities will provide new job opportunities for residents along the Gulf Coast and across the nation. As a recent Duke University report shows, the RESTORE Act is a win for the entire country.

The RESTORE Act also sets up a Restoration Council comprised of various federal agencies and states affected by the spill to create an environmental restoration plan for the Mississippi River Delta and Gulf Coast. The plan has the potential to address major, and very expensive, challenges in the Mississippi River Delta. A top funding priority in the plan for Louisiana will be designing and constructing large-scale sediment diversions along the lower Mississippi River. Sediment diversions provide wetlands with essential supplies of fresh water and new silt which help rebuild land and protect the coast.

Over the next few months, the Mississippi River Delta Restoration Campaign will update readers on important RESTORE Act developments. We hope to provide you with useful information as the Restoration Council forms and begins the important process of creating a restoration plan for America’s Gulf Coast.

Stay tuned.

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The Next 50 Years: Climate change and the Coastal Master Plan: “Hope for the best but plan for the worst”

July 19, 2012 | Posted by Delta Dispatches in 2012 Coastal Master Plan, Coastal Master Plan series, Diversions, Hurricanes, Science

By Dr. Doug Meffert, Executive Director, Audubon Louisiana

Louisiana’s 2012 Coastal Master Plan takes a realistic and critical examination of the effects of climate change impacts on the future of coastal Louisiana, both in terms of prioritization of restoration projects as well as risk reduction. In its “less optimistic scenario,” the master plan estimates 0.45 meters of sea level rise over the next fifty years. This is in addition to between zero and 25 millimeters per year of land subsidence, with the fragile deltaic plain having the highest rates. The resultant combination of sea level rise and subsidence predicts that relative sea level rise will be more than one meter during the next century in some areas of the Mississippi River Delta. Additionally, this scenario anticipates a 20 percent increase in storm intensity and a 2.5 percent increase in storm frequency for Category 1 hurricanes and greater. As climate change brings more severe storms and rising seas to Louisiana’s coast, it is important to incorporate these predictions into the formulation of the Coastal Master Plan.

Predicted land change over the next 50 years. Source: Coastal Protection and Restoration Authority of Louisiana (CPRA).

This “less optimistic scenario” predicts a very different and more vulnerable coast than we had in the 20th century. The master plan uses this scenario for its predictions for future flooding from a 100-year event and for prioritization of restoration projects, since what is labeled as “less optimistic” in the report could just as accurately be labeled as “increasingly likely.” This scenario is consistent with the recent assessments by the Intergovernmental Panel for Climate Change (IPCC), the findings from the Durban Climate Change Conference in November 2011, and more recently, peer-reviewed articles (Blum and Roberts, 2012; Day et al., 2012). In fact, one of the master plan’s Science and Engineering Board members, Dr. Virginia Burkett, was a coauthor of the IPCC’s 2007 report, which garnered the 2007 Nobel  Peace Prize for the IPCC.

“Hope for the best but plan for the worst” is the adage adopted by the Coastal Master Plan, and I couldn’t agree more. As it is, there is not enough sediment in the Mississippi River to offset the predicted land loss from relative sea level rise and erosion if we do nothing. This means we need to act now for a future coast that supports the fisheries, birds and other ecological services upon which we depend. We need to plan for a future coast that still provides a natural storm surge buffer for our cities, towns and critical infrastructure. That future coast will just be different than what we’ve known in the past. And that future coast depends on implementing large-scale river diversions with no further delay. We finally have a realistic master plan based on the best science possible. Now, we just need to implement it.

 

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The Next 50 Years: Louisiana Coastal Area projects in the master plan

July 12, 2012 | Posted by Delta Dispatches in Coastal Master Plan series, Louisiana Coastal Area (LCA), Mid-Barataria Sediment Diversion, Mississippi River Gulf Outlet, Restoration Projects, Whites Ditch

This is the fourth post in our "The Next 50 Years" Coastal Master Plan series. Check back as we continue diving into the master plan and what it means for the people and environment of the Mississippi River Delta.

By Alisha A. Renfro, Ph.D., Staff Scientist, National Wildlife Federation

To formulate Louisiana’s 2012 Coastal Master Plan, coastal authorities evaluated nearly 250 restoration projects that had been proposed in previous parish- and state-level restoration plans. This number was then narrowed down by setting a realistically achievable budget, modeling for future environmental conditions and understanding how the implementation of individual projects could help sustain or build land over the next 50 years. Projects included in the Louisiana Coastal Area (LCA) Comprehensive Study were among those considered for inclusion in the master plan, and many of these projects – or similar versions of them – were included in the 2012 Coastal Master Plan. By incorporating these projects in the long-term vision of restoration for coastal Louisiana, these projects will be better integrated with others in the master plan. Additionally, inclusion of these LCA projects shows the state’s commitment to their construction and implementation.

The LCA Program was authorized through the 2007 Water Resources Development Act and includes 15 near-term critical restoration projects. As part of the LCA Program, the state of Louisiana and the U.S. Army Corps of Engineers work together to plan and implement these 15 projects. To date, construction has not begun on any of these projects, and as they near the construction phase, the lack of federal funding in the immediate future threatens to delays them indefinitely. That is, until Congress passed the RESTORE Act in June. Signed into law just last week, the RESTORE Act will ensure that 80 percent of the Clean Water Act fines BP and other responsible parties will pay as a result of the 2010 gulf oil spill are dedicated to environmental restoration in the gulf states. In Louisiana, this money will be used to help fund the restoration projects outlined in the master plan.

Of the 15 LCA projects, nine were included in the 2012 Coastal Master Plan. But in many cases, the project selected and described in the master plan is a modified version of the original LCA project. This is a result of the analysis conducted in the planning process that indicated that modifications to the project would increase the land it built or maintained. However, it should be noted that the projects described in the master plan are still conceptual, as their exact size and location will be determined through further planning and design. Below is a list of the LCA projects and a brief description of the corresponding project included in the master plan.

The extensive analysis that went into formulating the master plan indicates that the capacity of several of the LCA sediment diversions may need to be scaled up in order to maximize the amount of land they can build and sustain. By including so many LCA projects in the plan, coastal authorities reaffirmed the importance of these critical projects to restoring the coastal Louisiana landscape. Moving away from smaller restoration projects toward larger ecosystem-scale projects will help restore the natural hydrology and mimic the processes that built the Mississippi River Delta, thus creating a more sustainable coastline for the people who call the region home.

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The Next 50 Years: Sediment diversions as a necessary restoration tool

June 19, 2012 | Posted by Delta Dispatches in 2012 Coastal Master Plan, Coastal Master Plan series, Diversions, Restoration Projects, Science

This is the second post in our "The Next 50 Years" Coastal Master Plan series. Check back as we continue diving into the master plan and what it means for the people and environment of the Mississippi River Delta.

By Alisha A. Renfro, Ph.D., Staff Scientist, National Wildlife Federation

Since 1932, coastal Louisiana has lost almost 1,900 square miles of land and if bold action is not taken, another 1,700 square miles could be lost by 2060. Louisiana’s 2012 Coastal Master Plan, passed last month by the state legislature, is a 50-year strategy that aims to realistically, but aggressively, use numerous restoration tools to ensure a sustainable and more resilient coast. The plan’s analysis indicates that sediment diversions, structures that allow Mississippi and Atchafalaya River water to be moved strategically into the surrounding wetlands, are critical projects for halting land loss and building a more sustainable coastline for the future of the Mississippi River Delta.

Symbol used for sediment diversions in the 2012 Coastal Master Plan. Sediment diversions use channels and/or structures to divert sediment and fresh water from the Mississippi and Atchafalaya Rivers into adjacent basins. Source: Coastal Restoration & Protection Authority (CPRA)

Ten projects identified as sediment diversions were judged as important restoration tools in the plan. Sediment diversions mimic some of the natural processes that once built the Mississippi River deltaic region. By operating these types of control structures when river discharge is high, the large amount of sediment, that is being moved along with the water, is captured and funneled into the nearby wetlands. The introduction of sediment would not only help restore areas that are today shallow open water, but it would also help prevent future wetland loss due to rising sea levels.

Sediment diversions can build new marsh by transporting sediment-laden water from the river into the nearby basin. The heavier sand sediment is deposited quickly and over time, and a marsh platform is built. Once vegetation begins to colonize the area, sediment deposition increases as silts and clays are trapped by plants, and a new marsh will emerge. Sediment diversions can also help sustain the newly-built and existing marsh as sea levels rise, by providing a source of sediment that can be deposited on the marsh surface. Ultimately, this can increase the elevation of the marsh surface, which helps prevent prolonged flooding of the marsh, even as sea levels rise. Sediment diversion critics have voiced concerns about the introduction of fresh water into these basins and have questioned whether diversions are essential to restoring Louisiana’s coast.

This map of southeastern Louisiana shows the locations of the sediment diversion projects included in the 2012 Coastal Master Plan, represented by brown circled triangles like the one in the previous image. The brown stippled areas show the diversion impact areas. Credit: CPRA

To evaluate the necessity of the sediment diversion projects in the master plan, the authors conducted an experiment to analyze the amount of land that could be built only using other types of restoration tools. The results of this experiment indicated that by removing the sediment diversion projects from the plan, total land built would be reduced by 340 to 630 square miles over the 50 years. This indicates that sediment diversion projects are crucial projects in the plan and necessary for rebuilding the Mississippi River Delta.

A similar experiment was conducted to address questions about using a few larger sediment diversions versus multiple smaller diversions. The multiple small diversions not only affected the benefits that people get from the land, such as oysters, as much or more than larger diversions, but the smaller diversions also built significantly less land over the next 50 years.

The restoration projects selected in the 2012 Coastal Master Plan may potentially build or sustain up to 800 square miles of land over the next 50 years – land that otherwise would be lost. While sediment diversions are not the only types of restoration project identified as critical to the future of the Louisiana coastline, scientific assessment suggests they are absolutely necessary. Other types of projects, such as barrier island restoration and marsh creation, can build land quickly, but without tapping into the sustainable power, sediment and fresh water of the river, these projects cannot be maintained over the long term.

The land loss crisis in Louisiana requires aggressive action. Louisiana’s 2012 Coastal Master Plan shows us that the path forward for building a more sustainable and resilient coastline is by reconnecting the Mississippi River to the landscape it once built.

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NRDA Trustees should consider long-term sustainability of wetland creation projects

June 13, 2012 | Posted by Delta Dispatches in BP Oil Disaster, Diversions, Natural Resource Damage Assessment (NRDA), Restoration Projects

By Whit Remer, Policy Analyst, Environmental Defense Fund

In late April, the Deepwater Horizon Natural Resource Damage Assessment (NRDA) Trustees finalized the first phase of projects to address Gulf Coast environmental damage caused by the 2010 oil disaster. The trustees are a group of federal and state representatives charged with overseeing environmental restoration following the oil spill. The project document, known as the Deepwater Horizon Oil Spill Phase I Early Restoration Plan and Environmental Assessment (ERP/EA), comes on the heels of the draft version released in February for public comment.

The document includes a variety of projects across the gulf, including oyster restoration, wetland creation and improvements to public amenities. Rightfully, the trustees have considered a diverse suite of restoration options, and we encourage them to continue exploring the use of sediment diversions to achieve restoration goals in the Mississippi River Delta.

One of the most promising techniques for restoring, rebuilding and stabilizing wetlands in coastal Louisiana is the use of sediment diversions along the Mississippi River. Diversions replenish wetlands adjacent to the river with the fresh water, nutrients and sediments necessary to maintain healthy ecosystem functions. The State of Louisiana recently recognized the importance of such diversions in the 2012 Coastal Master Plan, which the State Legislature unanimously passed earlier this month. The master plan outlines a 50-year, $50 billion strategy to restore Louisiana’s coast and protect communities. Diversions are a critical component to achieving the long-term and comprehensive restoration envisioned by the plan.

The final Phase I ERP/EA includes the Lake Hermitage Marsh Creation project, a small-scale sediment pipeline project in Plaquemines Parish. The project will transport fresh water and sediment from the Mississippi River through a pipeline to wetlands adjacent to the river, and is expected to create over 100 new acres of marshland at a cost of $14 million. Pipeline projects have been effective in Louisiana in the past, but they do not provide the long-term sediment flow necessary to sustain the land-building functions needed to restore the coast.

The Lake Hermitage project serves as a good starting point for restoration in the Mississippi River Delta, but to achieve long-term restoration, wetlands need a constant source of sediment and nutrients that pipeline projects do not provide. Moving forward, we recommend NRDA Trustees consider actions that will promote the lasting sustainability of Louisiana’s coast. Without such actions, we may lose a unique opportunity to undertake comprehensive restoration.

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