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LEVEES and FLOOD PROTECTION 22 6 David Rogers, Jaye Cable, William Nuttle RESTORATION and COMMUNITIES 24 7 Conner Bailey, Shirley Laska, Robert Gramling

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LEVEES and FLOOD PROTECTION 22 6 David Rogers, Jaye Cable, William Nuttle RESTORATION and COMMUNITIES 24 7 Conner Bailey, Shirley Laska, Robert Gramling The Science and Engineering Special Team is a network of eminent scientists and engineers convened by the National Audubon Society, the Environmental Defense Fund, and the National Wildlife Federation to provide objective and independent analysis pertaining to Mississippi River Delta restoration. SCIENCE & ENGINEERING SPECIAL TEAM • CHAIR: John Day, Ph.D. • Mary Kelly Department of Oceanography and Coastal Sciences Parula, LLC Louisiana State University • G. Paul Kemp, Ph.D. • Conner Bailey, Ph.D. National Audubon Society Department of Agricultural Economics & Rural Sociology Auburn University • Shirley Laska, Ph.D. Department of Sociology • David Batker, M.S. University of New Orleans Earth Economics • Sarah Mack, Ph.D. • Samuel Bentley, Ph.D. Tierra Resources, LLC Department of Geology & Geophysics Louisiana State University • James Morris, Ph.D. Department of Biological and Marine Sciences • Jaye Cable, Ph.D. University of South Carolina Department of Marine Sciences University of North Carolina, Chapel Hill • William Nuttle, Ph.D. Eco-hydrology.com • Robert Costanza, Ph.D. Department of Sustainability • Andy Nyman, Ph.D. Portland State University School of Renewable Natural Resources Louisiana State University Agricultural Center & • James Cowan, Ph.D. Louisiana State University Department of Oceanography & Coastal Studies Louisiana State University • David Rogers, Ph.D., P.E. Department of Geological Sciences & Engineering • Linda Deegan, Ph.D. Missouri University of Science & Technology The Ecosystems Center Woods Hole Marine Biological Laboratory • Gary Shaffer, Ph.D. Department of Biological Sciences • Angelina Freeman, Ph.D. Southeastern Louisiana University Environmental Defense Fund • Fred Sklar, Ph.D. • Liviu Giosan, Ph.D. Everglades Division Department of Geology and Geophysics South Florida Water Management District Woods Hole Oceanographic Institution • Clinton S. Willson, Ph.D., P.E. • Robert Gramling, Ph.D. Department of Civil and Environmental Engineering Department of Sociology Louisiana State University University of Louisiana, Lafayette TABLE OF CONTENTS INTRODUCTION 1 SEDIMENT AVAILABILITY 6 1 Samuel Bentley, Clinton S. Willson, Angelina Freeman USEFULNESS OF DIVERSIONS 8 2 Samuel Bentley, Angelina Freeman, Liviu Giosan, Clinton S. Willson, Jaye Cable THE EFFECT OF NUTRIENTS ON WETLAND VEGETATION 12 3 James Morris, Andy Nyman, Gary Shaffer THE RELATIONSHIP BETWEEN FISHERIES AND COASTAL RESTORATION 15 4 James Cowan, Linda Deegan NAVIGATION ISSUES 18 5 David Rogers, Paul Kemp LEVEES AND FLOOD PROTECTION 22 6 David Rogers, Jaye Cable, William Nuttle RESTORATION AND COMMUNITIES 24 7 Conner Bailey, Shirley Laska, Robert Gramling WHAT LOUISIANA STANDS TO LOSE 28 8 David Batker, Sarah Mack, Fred Sklar, Mary Kelly, Angelina Freeman, William Nuttle, Robert Costanza URGENCY OF RESTORING LOUISIANA’S COAST 31 9 David Batker, Sarah Mack, Fred Sklar, Mary Kelly, Angelina Freeman, William Nuttle, Robert Costanza COASTAL RESTORATION, CLIMATE CHANGE, AND ENERGY 34 10 John Day, Matthew Moerschbaecher ANSWERING 10 FUNDAMENTAL QUESTIONS ABOUT THE MISSISSIPPI RIVER DELTA INTRODUCTION The Mississippi River Delta is one of the largest and There is widespread recognition of the need to most productive coastal ecosystems in North America. restore the delta, but doing so will require innovative From energy, to fisheries, to navigation, the richness technology, billions of dollars, and a national of this ecosystem has sustained the U.S. economy for commitment. In the face of these challenges, many 300 years. In particular, the coastal wetlands have have asked whether it is even possible to restore the protected communities and critical national assets delta. Others have wondered whether doing so should from storm damage. However, this ecosystem is in be a national priority. With so many other needs grave danger. Unless we act soon, the delta and the throughout our country, the thinking goes, we need benefits it provides our country will disappear. compelling evidence of both feasibility and merit if we are to put the Mississippi River Delta at the top of The Mississippi River created the delta over the past the list. 7,500 years, depositing sediment from upstream and changing its course periodically to find a shorter route This document presents that evidence, based on to the Gulf of Mexico. But in the 19th and 20th centuries, a thorough examination of the primary questions levees and other artificial structures were built along people have raised about the future of the Mississippi the lower river for navigation and flood control. These River Delta: What are the economic impacts of levees isolated the river from its delta, even as dams, maintaining the status quo? How will restoration affect dikes, and other changes on the Mississippi River communities, fisheries, and navigation? Will sea level and its tributaries diminished sediment supply by 50 rise and subsidence negate our efforts? This paper percent. When the life sustaining water and sediment systematically answers these and other questions. Our of the river no longer flowed over the delta, wetlands research reveals considerable consensus within and loss rapidly accelerated. A quarter of the deltaic across scientific disciplines about how the Mississippi landscape, over 1,800 square miles, have been lost River Delta functions and what actions must be taken in the past 100 years. Oil and gas canals, dredged to ensure long term sustainability. It is clear that to provide energy to U.S. markets, allowed salt water immediate action is warranted and is essential to the from the Gulf of Mexico to intrude into freshwater future stability of our nation’s economy. Yes, saving the areas, further stressing the ecosystem. A host of other delta will require bold thinking and focused action. But factors—invasive species, subsidence, and sea level the cost of doing nothing is far greater. rise, to name a few—add to the problem. If we do not turn the tide now, much of the ecological and economic value of the delta will be lost by the end of this century. 1 SAVING THE MISSISSIPPI RIVER DELTA 3. Will Diversions Introduce Nutrients That Harm Summaries of our research are presented below. Wetland Vegetation? Diversions will have impacts on vegetation, particularly on 1. Is There Enough Sediment to Restore the Delta? the distribution of some plant species. However, without The Mississippi River does not now, nor has it ever supplied diversions and other methods for introducing nutrient rich enough sediment to continuously sustain the entire delta fresh water into the ecosystems of coastal Louisiana, the coastline. There have always been areas that were building wetlands will degrade to open water. Thus, the effect of and areas that were eroding. In recent decades, we have nutrients is not large enough to offset the larger benefits of reduced river sediment supply by approximately half, which diversions for coastal Louisiana, particularly if diversions are further constrains our ability to build land. Nevertheless, the pulsed to allow a balance of salt and fresh water. available sediment supply is still huge and adequate to the challenge of sustaining targeted regions of coastal Louisiana, 4. Will Diversions Harm Fisheries? if we are able to use this valuable resource efficiently. Different species will react in varying ways to landscape changes. However, our analysis supports the claim that the 2. Are Diversions Useful Tools for Building Land? large scale sediment diversions being considered for the If properly designed and operated, sediment diversions can Mississippi River Delta have a good chance of supporting the build substantial land from river sediment. Historical patterns health of fisheries because they may allow the ecosystem to of land growth and loss also suggest that with continued reset to a more sustainable baseline. In any case, the status subsidence and sea level rise, sediment supply must be quo will prove disastrous for the Gulf fisheries and the many maintained in order to sustain the land that is formed. human communities that depend on them. 5. How Will Restoration Affect Navigation? Reconfiguring the river and revising the decades old Mississippi River and Tributaries Project is imperative. Doing so will secure the long term viability of Louisiana’s navigation industry and its key role in the nation’s economy. These needs dovetail with the state’s plans to use sediment diversions to address coastal land loss. 6. Can Levees Alone Provide Enough Flood Protection? By themselves, levees cannot provide the storm protection that will protect national assets and coastal residents. In fact, by damaging nearby wetlands or encouraging unwise development in protected areas that require pumps to stay dry, levees can actually increase exposure to flood risks. Levee systems should be only one of several lines of defense, including wetland buffers. Photo By: Yuki Kokubo, www.yukikokubo.com 7. Will Restoration Measures Displace Communities? Some communities will be affected by restoration measures that change water salinity and the locations of coastal resources. For most communities, however, lack of wetland restoration will make the coast more vulnerable to continued flooding as well as hazards such as the BP oil spill. Ultimately, these threats, and not restoration, will be what force people away from the coast. If restoration and mitigation projects are coordinated to create compatible outcomes, they will be positive activities for coastal communities. 2 Photo By: Yuki Kokubo,
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