NEWSLETTER FOR STAKEHOLDERS OF THE DAVIS POND DIVERSION
Vol. 1. April 27, 2005
1. Greetings from the researchers
First of all, we appreciate your participation in this project which has two major objectives:
1) investigating known and unknown concerns and conflicts among stakeholders including governments and local people, in operating the diversion structure, and
2) finding ways to reduce conflicts among stakeholders.
We believe that public and stakeholder opinions should be based on well-informed understanding and that their significant involvement in decision-making concerning the operation of the diversion facility is important.
Over the coming three months, we will provide scientific, historical, legal, and other socio-economic information to all of you through this bi-weekly newsletter. We also would like to know what you want to know and your opinions. Just let us know. Then we will pass out the needed information to all of you through this newsletter.
We hope this newsletter will be an active communication channel among all of you and other related stakeholders for well-informed decision- making concerning the Davis Pond diversion facility.
From this initial issue, you will get:
1) an overview of the Davis Pond diversion,
2) trends and causes of coastal land loss in the state, and
3) how the river diversion works. A detailed information of land loss for the Barataria basin is given in the appendix.
We’d like to appreciate your participation once again. Thank you.
Dr. John W. Day
Dr. Paul H. Templet
Dr. Jae-Young Ko
Ms. Emily Hyfield
Contact Information:
Jae-Young Ko Emily Hyfield
225-578-6505 225-578-2732
Coastal Ecology Institute, Louisiana State University, Baton Rouge, LA 70803
Fax: 225-578-6326
Website: http://www.lsu.edu/cei/research_projects/davis_pond_stakeholders.html
2. An Overview of the Davis Pond Diversion
The diversion structure diverts freshwater, along with dissolved nutrients and sediments from the Mississippi River into the Barataria basin. The objective of the project is to reduce salt water intrusion to achieve favorable salinity conditions in the area as a way to reduce land loss in the basin. Additionally, the diversion is expected to increase commercial and recreational fish and wildlife productivity, and increase plant growth for a healthier estuarine ecosystem. About 777,000 acres of marshes and bay areas will be benefited and 33,000 acres of wetlands will be preserved.
The diversion structure consists of four 14 foot square gated culverts, inflow and outflow channels, levees, and a rock weir. The maximum discharge is 10,650 cubic feet per second. The operation schedule is decided by the Secretary of Dept. of Natural Resources, based on the recommendation by The Davis Pond Advisory Committee. The advisory committee is composed of representatives from landowners, oyster fishers, shrimpers, and recreational fishers; parishes of Jefferson, Lafourche, Plaquemines, and St. Charles; the state government (Dept. of Natural Resources, Dept. of Environmental Quality, Dept. of Health & Hospitals, and Dept. of Wildlife & Fisheries); and the federal government (Natural Resources Conservation Service, Environmental Protection Agency, Barataria-Terrebonne National Estuary Program , National Marine Fisheries Services, US Army Corps of Engineers, and US Fish & Wildlife Service).
An extensive monitoring program is planned to investigate impacts of the diversion. About 10,084 acres of the basin area is being monitored.
Economically, average annual benefits are predicted to be $15,295,000, including $14,997,000 for fish and wildlife and $298,000 for recreation. The total cost was $105 million (75% from federal funding, 25% from State).
Source: http://lacoast.gov/programs/DavisPond/overview.html
Other relevant websites
http://lacoast.gov/programs/DavisPond
http://www.dnr.state.la.us/crm/coastres/coastres.asp
3. Explanation of the coastal land loss problem in Louisiana
Since the 1930s, there has been a dramatic loss of coastal wetlands in the Mississippi Delta, including the Barataria basin, with loss rates as high as 100 square-kilometers per year (or 25-35 square-miles per year), and a total area of about 3,900 square-kilometer (or 1,500 square-miles) has been lost.
A number of factors have been linked to the land loss problem. First, levees along the Mississippi River have interrupted the annual flooding over deltaic marshes and eliminated inputs of freshwater, dissolved nutrients, and sediments. Second, natural water flows for maintaining and building lands have been disrupted by canal construction. Third, saltwater intrusion through changed water channel into fresh marsh zone has worsened. Fourth, heavy traffic in waterways have increased wave erosion along exposed shorelines. Fifth, dam building in the Upper Mississippi River basin have reduced suspended sediments in the Mississippi River. Sixth, sea level is accelerating due to global climate change. Finally, subsidence in the coastal zone was increased due, to oil and gas development.
Fig.1. A conceptual diagram of ecological impacts of oil and gas development in Louisiana wetlands (Source: Ko and Day 2004).
Source:
Boesch, D. F. et al. 1994. Scientific Assessment of Coastal Wetland Loss, Restoration and Management in Louisiana. Journal of Coastal Research. Special Issue No. 20.
Day, et al. 2000. Patterns and process of land loss in the Mississippi Delta: A spatial and temporal analysis of wetland habitat change. Estuaries 23:425-438.
Ko,
Jae-Young and John W. Day. 2004. Wetlands: Impacts of energy development in the
Mississippi Delta. Encyclopedia of Energy. Vol. 6: 397-408.
The detailed information of coastal land loss for specific areas of the Barataria basin is presented in Appendix A.
4. How the diversion works for coastal restoration
River diversion is a management approach aimed at restoring a more natural deltaic functioning by diverting river water in a controlled way to mimic the natural deltaic cycle. The ability to manage the flow rate through the diversion structure ensures flood protection and navigation. The design of the diversion structure includes culverts that run through the levee and a channel to guide the water to the marshes.
River water introduces sediments that contribute directly to vertical accretion, nutrients that stimulate vegetation productivity and organic soil formation, iron that detoxifies sulfide by precipitation, and freshwater to counter salinity intrusion.
One of the benefits of a diversion is that once the structure is built, it is relatively economical to operate because natural energies such as tides and winds control the distribution of water in the estuary.
The idea of diversions is not new and was proposed nearly a century ago by Viosca in 1927. When freshwater diversions were first planned in Louisiana over three decades ago, the primary goal was to reduce salinity to enhance oyster production in surrounding regions. More recently, diversions have increasingly been used as a way of delivering sediments and nutrients to wetlands, because completed and ongoing research indicates that diversions lead to increased marsh biomass growth, maintaining wetlands and creating new lands, and higher fishery yield.
Recently there is concern that nutrients in diverted water will lead to eutrophication and there is continuing research on the issue and ways to manage diversions to minimize the potential for water quality problems. We have found that in a properly operated diversion, the uptake of nutrients can be promoted.
One concern in designing restoration projects is cost. Oil is expensive now and may become more expensive in the future. Thus, energy intensive management methods may become increasingly expensive in the future. Because diversions use the energies of nature, they will be economical to operate in the future if energy and economic costs increase. After construction, they can be operated using relatively little energy, probably for the next century and longer. For example, the Bonnet Carré was constructed over 70 years ago; it is still functioning and is likely to do so for decades.
Energy intensive approaches, such as pumping sediments long distances to build wetlands, should be used now but they may not be affordable 40-50 years from now. New land created by pumping sediments will last for a shorter period than would have been because of sea level rise and higher salinities. Thus, diversions of river water should be planned in conjunction with pumping sediments to maintain the marshes.
Source:
Day, W.J., et al. 2005. Implications of global climatic change and energy cost and availability for the restoration of the Mississippi Delta. Ecological Engineering 24; 251-263.
Martin, J. F. 2002. Emergy valuation of diversion of river water to marshes in the Mississippi River delta. Ecological Engineering 18:265-286.
5. Your Inputs
We’d like to have your feedbacks on this initial newsletter. Let us know if there are specific questions or issues you would like to have addressed in future newsletters. You can contact us by phone, regular mail, or email.
We will do our best to get the information and pass it to all of you as a way to keep you well-informed on the Davis Pond Diversion as well as other issues in coastal wetlands protection in Louisiana.
Thanks.
Appendix A. Detailed information of land loss trends for the Barataria Basin.
( Source: Louisiana dept. of Natural Resources. 1999.
Coast 2050. Appendix D)