Archive for Diversions
By Estelle Robichaux, Restoration Project Analyst, Environmental Defense Fund and Gaby Garcia, Science Intern, Environmental Defense Fund
This post is part of a series on early restoration planning in Louisiana. Be sure to check out part one for a look back to 1973.
In 1988, the Coalition to Restoration Coastal Louisiana (CRCL) released a plan titled Coastal Louisiana: Here today and gone tomorrow? The plan, which was a joint effort by stakeholders and scientists, focuses on the Mississippi River Delta region and is framed as a citizens program for protecting Louisiana’s environment, economy and heritage.
The plan provides nearly 20 recommendations, including a restoration action program, suggestions for how to finance the program, as well as specific institutional and legislative recommendations designed to galvanize restoration.
Among the most notable elements is the assertion that sediment diversions would be the most beneficial method of wetland restoration and that several of them should be constructed along the Mississippi and Atchafalaya Rivers. This was also one of the first plans to advise against any new levee construction.
Many of the plan’s most significant propositions, those focused on restoration action, have yet to be realized, though the science behind sediment diversions is well developed and we continue to advocate for them as a sustainable restoration tool.
A bold but realistic plan of action
CRCL’s plan has two specific resource goals that are still strongly advocated for:
- To utilize freshwater and sediment diversions along the Mississippi River and Atchafalaya Rivers to sustain and restore coastal wetlands;
- To beneficially use dredged material from channel maintenance and existing spoil banks to backfill canals and nourish created wetlands and barrier islands
Restoring natural processes: Mississippi River water & sediment diversions
The Caernarvon and Davis Pond diversions were still being designed at the time this plan was published. Although there were expectations these structures would help control saltwater intrusion and reduce wetland loss, the plan underscores their limitations in active wetland restoration and land building. Despite the fact these diversions were designed for salinity and flood control, both areas have seen new land growth, though not at the scale or rate anticipated for sediment diversions.
The action program calls for the construction of a suite of freshwater and sediment diversions to restore hydrologic connections and halt wetland loss. The essence of many of these restoration ideas can be found in Louisiana’s 2012 Coastal Master Plan (CMP). Some of the restoration actions proposed in the 1988 plan include:
- One or two diversions from the Atchafalaya River into the Lake Verret Basin and Western Terrebonne marshes.
- 2012 CMP: Two diversions from the Atchafalaya will increase freshwater and sediment flows into Terrebonne marshes from Bayou Penchant westward, including our of our coalition’s 19 priority projects, Increase Atchafalaya Flow into Terrebonne Marshes.
- Restoration of Bayou Lafourche into a distributary of the Mississippi River, with a diversion into Timbalier Bay.
- 2012 CMP: Small-scale freshwater diversion from the river into Bayou Lafourche.
- Freshwater and sediment diversions, at Bayou Manchac and Blind River, to bring Mississippi River water into the degraded swamps south of Lake Maurepas.
- 2012 CMP: Two freshwater diversions, at Blind River and Hope Canal, and hydrologic restoration of the Amite River to restore freshwater inputs to Lake Maurepas, including one of our priority projects, West Maurepas Diversions.
- A large-scale sediment diversion of the Mississippi River below New Orleans into Barataria Basin and a navigation channel from the river into Breton Sound in the vicinity of Empire.
- 2012 CMP: Two sediment diversions into Barataria Basin in the vicinity of Diamond and Myrtle Grove, Lower and Mid-Barataria Sediment Diversions (also two of our coalition’s priority projects).
Beneficial use of dredged material
In addition to the focus on restoring natural processes by using freshwater and sediment diversions, the plan has another major component that concentrate on restoration actions that would provide short-term benefits as well as some regulatory changes. This component focuses on using dredged sediments, taken from the bottoms of canals or by removing spoil banks, for restoration efforts.
It is recommended that all dredged material from channel maintenance work should be used for wetland creation and restoration. Sediment from spoil banks would be used to plug many of the abandoned canals along the coast, which would also provide hydrologic restoration of freshwater flow across the affected marshes.
Looking back, moving forward
As we review these early restoration plans, it becomes clear that using water and sediment from the Mississippi River to restore Louisiana’s coastal wetlands is not a new idea. Diversions have long been a key component in coastal restoration planning, though they are only one of the suite of tools we can use.
Restoration planning has spanned more than four decades in Louisiana, but it is only in the last two that consistent funding became available. Check out our next post for more on funded restoration programs in Louisiana.No Comments
By Steve Cochran, Director, Mississippi River Delta Restoration Program, Environmental Defense Fund
Ten years ago, just after Hurricane Katrina, I was asked to talk to Environmental Defense Fund’s board about the place where I grew up, the New Orleans area that had been hit so hard.
I remember two things about that discussion. One was my voice breaking unexpectedly (and embarrassingly) as we talked through pictures of the Katrina aftermath and came across places I intimately knew.
As an adult, I had developed a love/hate relationship with my home – loving the beauty, the people, the community and the culture, but frustrated by what I saw as the general tolerance of mediocrity and corrupt politics that limited its possibilities. That frustration had pushed the love down, and I had moved away. But there it was again. Sometimes you don’t know how much you care.
The second thing I remember was saying that the Katrina response was a deep test of our governments – local, state and national. As we know now, in that moment, it was a test they failed. But fast forward to July 2, 2015, the day a global settlement was announced in the Deepwater Horizon oil spill case. It was a day when governments rose to the occasion. The result was literally the largest environmental settlement in U.S. history.
The BP Settlement and Louisiana Coastal Restoration
Under the agreement, Louisiana will receive more than a third of the money – $6.8 billion of the $18.7 billion, and $5.8 billion of that is specifically targeted to restoration. The overall restoration total for Louisiana will likely be just under $8 billion, including early restoration dollars and criminal settlements.
These are significant resources at a critical time. Land loss across the coast of Louisiana, exacerbated by the spill, continues at a fearful rate. But we are making progress against that loss, and with the solid state commitment that now exists, and effective plans in place, these resources will allow us to battle back in earnest, with a clear-eyed view toward success.
In particular, the state plans to re-engage the enormous power of the Mississippi River and its sediment through a series of sediment diversions – using the natural land-building capacity of the river by reconnecting it to the delta it originally built. This science-based, innovative approach is the critical piece in our ability to provide solutions at a scale that can match the challenges in the Mississippi River Delta – now the largest restoration effort under way in the world.
Rebuilding Our Coast to Protect Our Communities
About a month after the spill, I was allowed to sit in on a tribal council of the indigenous United Houma Nation. As the oil continued to pour into the Gulf of Mexico, which it would do for another two months, I listened and watched as a man described, through a quiet voice and uncontrolled tears, how he had always looked to the waters of the Gulf and drawn confidence, knowing he could always provide for his family by accepting its gifts. But now all he could feel was fundamental fear.
Money can’t replace that kind of loss any more than it can bring back the 11 loved ones who lost their lives in the accident.
But we must do what we can – and in that context, the BP settlement is a tremendous step forward, because we can restore the Mississippi River Delta, so it can protect this area in the future.
Details matter, of course, and details remain to be decided as the Agreement in Principle is turned into a consent decree. We need to remain involved and vigilant. But it does seem clear that this agreement combines avoiding years of litigation with levels of funding that can truly make a difference.
With these resources, we can go to work to make sure that the largest environmental settlement in our nation’s history also becomes the most meaningful settlement in a place that, well, I love.
By Natalie Peyronnin, Director of Science Policy, Mississippi River Delta Restoration, Environmental Defense Fund
Twenty-seven leading wildlife and fisheries biologists and other wetlands professionals are urging Louisiana’s citizens to support the construction of sediment diversions to restore marshes vital for protecting Louisiana’s diminishing coast and the people and wildlife it supports.
In full-page ads that will begin appearing in Louisiana media, including the state’s largest newspapers, this Sunday, May 3, the experts write:
“Louisiana urgently needs to restore a better balance between wetland building and wetland loss, between freshwater intrusion and saltwater intrusion, and between the river and the sea so that Louisiana’s wildlife, fish, culture, communities and economy will benefit for generations.”
These wildlife and fisheries biologists and wetlands experts who signed onto the letter have a connection to Louisiana’s coast and want to see it restored: “Like many of you, the signers of this letter know all too well what is at stake. We are wetland professionals who share a passion for Louisiana’s natural places and the extraordinary abundance of fish and wildlife it sustains…In addition to our professional work, we hunt, fish and spend much of our leisure time enjoying our state’s coastal wildlife and fisheries. We watch the wetlands convert to shallow water every day, every year. No one wants to save Louisiana’s coastal fish and wildlife more than we do.”
“We call on Louisiana to continue moving forward with the construction of large-scale wetland-building diversions,” the experts write. “We call on federal agencies to support Louisiana’s efforts by streamlining project implementation. We call on the citizens of Louisiana to insist that our leaders hold to the plan and move quickly.”
Despite the ability of sediment diversions to anchor and sustain the overall coastal restoration system for years to come, opposition exists in limited pockets. Last week, the St. Bernard Parish Council adopted a resolution opposing the use of state funding for four proposed sediment diversion projects, and some commercial fisherman say the diversions would push their saltwater fishing areas further from the coast. The scientists acknowledge this, noting, “Wetland-building diversions will not destroy fisheries but instead will immediately push them farther from some parts of the coast” and recommend objective policies to assist affected fisherman.
“We shouldn’t manage coastal wetlands only for our generation,” the scientists write in their letter, saying that the continuing loss of wetlands will rob future generations of jobs, Louisiana’s unique culture and wildlife habitat.
They also note that “places on our coast continue to thrive . . . where the river is allowed to work its magic.”
The paid advertisements will appear in the following publications in the coming weeks: The Advocate, The Plaquemines Gazette, The St. Bernard Voice, The Times-Picayune, The Houma Courier, Coastal Angler and Louisiana Sportsman.
You can read their letter in full below:No Comments
Straddling the border of Plaquemines and St. Bernard parishes in Southeastern Louisiana is the Caernarvon Freshwater Diversion built by the Army Corps of Engineers and operated since 1992 to balance water salinity by funneling river water into coastal marshes.
Lately, the diversion has had indirect effects that are raising eyebrows among scientists and those seeking to find solutions to address the crisis of Louisiana’s disappearing coast. The Caernarvon Freshwater Diversion is creating land at a rapid pace by delivering nutrient-rich river fresh water to bayous that have been starved of sediment and are eroding at an alarming rate.
In a new video, Coordinator of Lake Pontchartrain Basin Foundation’s Coastal Sustainability Program Dr. John Lopez outlines how approximately 1,000 acres of wetlands have been developed from the Caernarvon Diversion to create a new delta and within it a new bayou known as Bayou Bonjour. The new bayou is named in contrast to the book "Bayou Farewell," foretelling of the tragic loss of our wetlands and bayous. “Caernarvon was not designed or operated to build land,” Lopez notes, yet “Big Mar Pond has been filling up over the last twenty years due to sediment from Caernarvon.” How did this happen? Lopez explains how the diversion has provided an “ideal recipe for building a delta”: (river freshwater + sediments + nutrients = land growth).
Big Mar is located directly behind Braithwaite Park, a Plaquemines Parish community housed outside the federal levee system where devastation from Hurricanes Katrina, Rita, and Isaac occurred. Building land in Big Mar could provide a much-needed buffer for this community and an example for how to protect others like it. “As long as Caernarvon Diversion is flowing, this waterway and others like it will develop and this gives us hope in Louisiana that we can rebuild our coast,” says Lopez. In addition, recently planted cypress trees are thriving and will provide additional environmental and flood protection benefit as a new "line of defense."
Take a tour of Bayou Bonjour:
Want to learn more about the Caernarvon Diversion and other solutions for restoring the Mississippi River Delta? Visit mississippiriverdelta.org, like us on Facebook, and follow us on Twitter. You can also share the video with your network using the following tweet:
- Introducing Bayou Bonjour: Caernarvon Diversion has created an “ideal recipe for building a delta” #RestoreOurCoast http://youtu.be/5TExITZM2Wg
By Philip Russo, Outreach Coordinator, Restore the Mississippi River Delta Coalition
Land along a river has long been coveted for its agricultural productivity, but few rivers can compete with the mighty Mississippi.
With a drainage basin stretching across 31 U.S. states and parts of Canada, it is no surprise that the Mississippi River carries a lot of sediment. Historically, the river would deposit this sediment near its mouth in what is now southeast Louisiana, creating new land. But since leveeing of the river, the majority of this sediment is lost out the mouth of the river and into the deep waters of the Gulf of Mexico.
Near the mouth of the Mississippi, the final 85-mile stretch of the Mississippi River in Plaquemines Parish is home to prodigious citrus farming land. And with cool temperatures and clear skies, the weather of early December was ripe for the 68th Annual Plaquemines Parish Orange Festival.
Nestled between the Mississippi River levee and historic Fort Jackson, the focus of the festival is all things citrus. In Louisiana, that means copious displays of red navels, tangelos, ruby red grapefruits, sweet oranges, satsumas, kumquats and more.
While we attended and blogged about our trip down to the Orange Festival last year, this was the first year we actively engaged the crowds about protecting and restoring our coast – and we got to do so while debuting our tabletop river delta model! Watch this short video of the diversion model in action.
There are some sections of Plaquemines Parish where the distance between the Mississippi River levee and the Barataria Bay levee is only a few hundred yards, so Plaquemines residents are familiar with and usually eager to talk about their coast. But having a model demonstrating the process which built the very land everyone is standing adds another dimension to conversations about restoring barrier islands, ridges and marsh.
This year’s Orange Festival celebrated yet another successful harvest, but the celebration – originally organized in 1947 to promote Plaquemines’ citrus crop – has known its setbacks, most significantly due to Hurricanes Betsy, Camille and Katrina. If we are going to ensure the success of future harvests, we need to restore our multiple lines of defense against storm surge and maintain our protective coastal wetlands with strategically located and operated diversions along the river.No Comments
By Theryn Henkel, Ph.D., Lake Pontchartrain Basin Foundation
The Coastal Sustainability Program at the Lake Pontchartrain Basin Foundation (LPBF) recently released an article titled “Examination of Deltaic Processes of Mississippi River Outlets–Caernarvon Delta and Bohemia Spillway in Southeastern Louisiana” in the Gulf Coastal Association of Geological Societies Journal. The article details work that LPBF has done investigating the development of the Caernarvon Delta and operation of the Bohemia Spillway, both located in Plaquemines Parish, La.
Natural land-building deltaic processes of the Mississippi River Delta have been severely limited by artificial river levees, which prevent water and sediment from flowing over the banks during spring floods. To counteract the effects of severing the connection between the river and the delta, focus has been placed on reconnecting the river to the surrounding wetlands by the creation of artificial outlets, also called diversions.
The Caernarvon Freshwater Diversion was designed to deliver up to 8,000 cubic feet per second (cfs) of water from the Mississippi River. For reference, a flow rate of 8,000 cfs could fill up an Olympic-size swimming pool in 11 seconds or the Superdome in 4.5 hours. The Mississippi River also contains sediment that is carried along with the fresh water through the Caernarvon Diversion into the adjacent wetlands or open water, where it can nourish the wetlands and/or build land.
LPBF collects data on the turbidity, or cloudiness, of the water diverted through the diversion. Through established equations, the cloudiness of the water can be related to sediment load or the amount of sediment carried in the water. From this, it was calculated that the total amount of sediment carried into the wetlands and open waters areas from 2009 to 2012 was 264,000 cubic yards, or a volume equal to 81 swimming pools. Due to other considerations, the diversion is not always operated when the sediment load in the river is high and therefore does not maximize potential sediment capture. Despite this variability in operation of the diversion – and the fact that the Caernarvon Diversion was built to minimize sediment capture, as it was built solely for salinity control, not land building – there actually has been enough sediment diverted by the Caernarvon Diversion to build a new delta. Total wetland growth of the delta in the open water area receiving diverted water from 1998 to 2011 was 600 acres. This new wetland area is lush and thriving with a variety of plant species (trees and herbaceous) growing, and alligators, birds and insects abound.
The Bohemia Spillway is an 11-mile stretch along the east side of Mississippi River south of New Orleans where the federal protection levees were removed. It was created in 1926 by the removal of existing artificial river levees, thereby allowing river water to flow over the banks and into the adjacent wetlands when the river was high. This overflowing process is how the river would have operated historically.
In 2011, the Mississippi River watershed experienced an historic flood which provided an ideal opportunity to investigate and study how the spillway operates. When the river overflows its banks, if brings fresh water, nutrients and sediment to the wetlands. This cannot happen when the connection is cut off by levees. The severing of the connection of the river to the wetlands is one of the contributing factors to the high rates of land loss rates experienced by southeast Louisiana.
Current land loss rates in the Bohemia Spillway are negligible, perhaps due to receiving inputs of fresh water, nutrients and sediment during high river events since 1926. We have not observed delta formation in the Bohemia Spillway, as we did at the Caernarvon Diversion, but we have observed the infilling of defunct navigation and oil and gas canals as they slowly convert back to land.
In many parts of Louisiana’s coast, man-made canals often contribute to increased land loss. Poorly maintained canals erode and become wider, and salt water is conveyed through the canals into adjacent fresh marshes, killing plants and converting land to open water. Therefore, seeing canals infilling and low rates of land loss in the Bohemia Spillway indicates that the restoration of somewhat normal processes, by reconnecting the river to the wetlands since 1926, has had a positive effect on the area.
For both Bohemia Spillway and the Caernarvon Diversion, there are clearly benefits to sustaining or increasing wetland areas. However, the two outlets also provide a contrast in the future possibilities. Precisely replicating the Bohemia Spillway by levee removal is generally not feasible because of the ongoing need for protection from river floods. However, a controlled diversion built and operated to more efficiently capture and deliver sediment in ways that emulate more natural processes, such as in the Bohemia Spillway, may hold great promise for coastal restoration, rather than the obsolete design and operational goals of a diversion such as Caernarvon.No Comments
By Erin Greeson (National Audubon Society) and Alisha Renfro (National Wildlife Federation)
While there is no question that large-scale action is urgently needed to add address Louisiana’s land loss crisis, some questions surround the scientific solutions necessary to address this challenge. As the state of Louisiana advances its Coastal Master Plan and the comprehensive set of restoration projects within it, experts have opened discussion to scientists and interested members of the public to provide information, share science and encourage dialogue.
This week in New Orleans, the Expert Panel on Diversion Planning and Implementation had their second meeting, which offered an opportunity to reconvene for updates and discussion on sediment diversions – one of the key tools in Louisiana’s coastal restoration toolbox. In addition to addressing environmental concerns, the panel addressed social and economic questions about river diversions and the communities they will impact.
At the start of the meeting, Mr. King Milling, Chair of the Governor’s Advisory Commission on Coastal Protection, Restoration and Conservation, delivered a powerful reminder of Louisiana’s disappearing coast:
“Demise of this delta would be an environmental impact of international proportions: disaster for economy, culture, communities – all the things we do and live for in the delta. If we don’t proceed urgently, we will lose the delta. Nothing will stop this damage if we don’t proceed in an orderly fashion with large-scale, comprehensive solutions. This is not a time for debate. Our role is to address the issue of remarkable deterioration, and the state’s diversion committee will be addressing issues and conflicts. Its position is to focus on the larger picture of how we can preserve as much as we can, and how can we create a system that will protect as much as we can.”
The first day of the meeting was open to the public, and the agenda reflected many of the areas of focus that require follow-up from the panel’s first meeting. Presentations from the Army Corps of Engineers, The Water Institute of the Gulf and Biedenharn Group focused on the Hydrodynamic Study, which is collecting data in the river and using models to represent conditions in the river as it is today, predicting what the river will be like in the future without diversion projects and how the construction and operation of diversion projects change the river compared to the future without the diversions. They also briefly discussed the Mississippi River Delta Management Study, expected to begin soon, which will focus on the basin-side effects of diversions and evaluate combinations of diversion projects that maximize the number of acres of wetlands built or sustained over time.
Presentations from David Lindquist from the state’s Coastal Protection and Restoration Authority (CPRA) summarized the current state of knowledge on fisheries and wildlife response to existing freshwater diversions. Craig Colten, Ph.D. from the Water Institute of the Gulf highlighted the importance of considering the influences of restoration projects on communities.
A presentation from Micaela Coner and Bob Beduhn narrowed the discussion down to the engineering and design considerations of a single project – the Mid-Barataria Diversion. Ms. Coner, CPRA, discussed the Mid-Barataria sediment diversion project within the context of the 109 Coastal Master Plan projects. Speaking to the plan’s theme of reconnecting the river with its estuaries, she described sediment diversions as the best opportunity to build, maintain and sustain land.
Dr. Robert Twilley, Louisiana State University, described how the river once built natural resource wealth: “Natural resource economies and the flooding of the river once coexisted. The wealth of fisheries, and the wealth of the river building wetlands, once coexisted. Today, there’s a conflict. Historically, the river built land during big flood events. Nature had this figured out. We’re forcing a conflict. There is a resolution to this.”
During the closing portion of the meeting, attendees had opportunities to provide comments to the Expert Panel. Mississippi River Delta Restoration Coalition leaders were among the conversation.
David Muth of the National Wildlife Federation urged the panel to consider the historical context of the river in addressing site-specific questions about diversions: “We have glimpses from historical record about how productive this system once was. But for the past 300 years, we have been choking off that system.”
John Lopez of the Lake Pontchartrain Basin Foundation described the coastal land loss crisis in powerful terms and underscored for a sense of urgency: “This house is on fire. Lives are at risk. We have a great scientific challenge, but we don’t have time to delay.”
More background on the Expert Panel:
During its first meeting in January, the Expert Panel was asked to focus on the topics of uncertainty – underlying natural variability and limitations in knowledge – they perceived surrounding the design and operation of major freshwater and sediment diversions. A report summarizing their findings and recommendations from that first meeting was released in February.
In this report the panel focused on identifying six areas that should be answered or considered as sediment diversions move further from idea into planning, engineering and design:
- Data collection is important for understanding the system as it is today and for evaluating performance of individual diversion projects.
- A controlled sediment diversion does not currently exist, but some information needed to understand the time scales and extent of land building that could be expected from a controlled sediment diversion can be gleaned from natural crevasses.
- The response of plant, fish and wildlife communities to the operation of sediment diversions should be incorporated into modeling of different scenarios, both capacity and operation, of a diversion.
- The potential social and economic influences of a diversion project need to be considered to minimize any potential negative impacts that can be foreseen.
- Planning and design of diversion projects need to be explored under present day and possible future conditions (e.g. sea level rise, changes in precipitation) to maximize project success in the very near and long-term future.
- Communications between planners and stakeholders to discuss the realities and limitations of any predictions is essential for project success.