In this comprehensive, one-volume reference, Nature Conservancy scientist Bryan P. Piazza poses five key questions: —What is the Atchafalaya River Basin? —Why is it important? —How have its hydrology and natural habitats been managed? —What is its current state? —How do we ensure its survival? For more than five centuries, the Atchafalaya River Basin has captured the flow of the Mississippi River, becoming its main distributary as it reaches the Gulf of Mexico in south Louisiana. This dynamic environment, comprising almost a million acres of the lower Mississippi Alluvial Valley and Mississippi River Deltaic Plain, is perhaps best known for its expansive swamp environments dominated by baldcypress, water tupelo, and alligators. But the Atchafalaya River Basin contains a wide range of habitats and one of the highest levels of biodiversity on the North American continent. Piazza has compiled and synthesized the body of scientific knowledge for the Atchafalaya River Basin, documenting the ecological state of the basin and providing a baseline of understanding. His research provides a crucial resource for future planning. He evaluates some common themes that have emerged from the research and identifies important scientific questions that remain unexplored.

A comprehensive, state-of-the-art synthesis of biogeochemical dynamics and the impact of human alterations at major river-coastal interfaces for advanced students and researchers.

This book is a product of the joint JGOFS (Joint Global Ocean Flux Study)/LOICZ (Land–Ocean Interactions in the Coastal Zone) Continental Margins Task Team which was established to facilitate continental margins research in the two projects. It contains signi cant information on the physical, biogeochemical, and ecosystems of continental margins nationally and regionally and provides a very valuable synthesis of this information and the physical, biogeochemical and ecosystem processes which occur on continental margins. The publication of this book is timely as it provides a very strong foundation for the development of the joint IMBER (Integrated Marine Biogeochemistry and Ecosystems Research)/LOICZ Science Plan and Implemen- tion Strategy for biogeochemical and ecosystems research in the continental margins and the impacts of global change on these systems. This initiative will move forward integrated biogeochemical and ecosystems research in the continental margins. We thank all the contributors to this volume and especially Kon-Kee Liu who has dedicated a great deal of time to ensuring a high-quality book is published. IMBER Scienti c Steering Committee Julie Hall LOICZ Scienti c Steering Committee Jozef Pacyna v 1 Preface In general, interfaces between the Earth’s larger material reservoirs (i. e. , the land, atmosphere, ocean, and sediments) are important in the control of the biogeoche- cal dynamics and cycling of the major bio-essential elements, including carbon (C), nitrogen (N), phosphorus (P), sulfur (S), and silicon (Si), found in organic matter and the inorganic skeletons, shells, and tests of benthic and marine organisms.

Most water resources managers, scientists, and other experts would agree that nonpoint source pollution is a more pressing and challenging national water quality problem today than point source pollution. Nonpoint sources of pollutants include parking lots, farm fields, forests, or any source not from a discrete conveyance such as a pipe or canal. Of particular concern across the Mississippi River basin (MRB) are high levels of nutrient loadings--nitrogen and phosphorus--from both nonpoint and point sources that ultimately are discharged into the northern Gulf of Mexico (NGOM). Nutrients emanate from both point and nonpoint sources across the river basin, but the large majority of nutrient yields across the MRB are nonpoint in nature and are associated with agricultural activities, especially applications of nitrogen-based fertilizers and runoff from concentrated animal feeding operations. Improving Water Quality in the Mississippi River Basin and Northern Gulf of Mexico offers strategic advice and priorities for addressing MRB and NGOM water quality management and improvements. Although there is considerable uncertainty as to whether national water quality goals can be fully realized without some fundamental changes to the CWA, there is general agreement that significant progress can be made under existing statutory authority and budgetary processes. This book includes four sections identifying priority areas and offering recommendations to EPA and others regarding priority actions for Clean Water Act implementation across the Mississippi River basin. These sections are: USDA's Mississippi River Basin Healthy Watersheds Initiative; Numeric Water Quality Criteria for the northern Gulf of Mexico; A Basinwide Strategy for Nutrient Management and Water Quality; and, Stronger Leadership and Collaboration.

The Mississippi River is, in many ways, the nation's best known and most important river system. Mississippi River water quality is of paramount importance for sustaining the many uses of the river including drinking water, recreational and commercial activities, and support for the river's ecosystems and the environmental goods and services they provide. The Clean Water Act, passed by Congress in 1972, is the cornerstone of surface water quality protection in the United States, employing regulatory and nonregulatory measures designed to reduce direct pollutant discharges into waterways. The Clean Water Act has reduced much pollution in the Mississippi River from "point sources" such as industries and water treatment plants, but problems stemming from urban runoff, agriculture, and other "non-point sources" have proven more difficult to address. This book concludes that too little coordination among the 10 states along the river has left the Mississippi River an "orphan" from a water quality monitoring and assessment perspective. Stronger leadership from the U.S. Environmental Protection Agency (EPA) is needed to address these problems. Specifically, the EPA should establish a water quality data-sharing system for the length of the river, and work with the states to establish and achieve water quality standards. The Mississippi River corridor states also should be more proactive and cooperative in their water quality programs. For this effort, the EPA and the Mississippi River states should draw upon the lengthy experience of federal-interstate cooperation in managing water quality in the Chesapeake Bay.