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c I g, LSU-T-72-005 c. 2 J'. /I/. P//t ', C.r; Of 2 ],//,I/ Z> ,!IiI, jt .l I, h,, r LI/ 'I'<l,' "' imi ary sess ents 'ii iron en t Imp t <:erSuperpo 1 li r I .I < i>.l< on e ou 5 stern 'astaf' t f,, ttI'I Are o L 'dna I umW~-sa cop -= '4'It< 1IIt.i! -II S F<>/'z<'z Sl<tbh.>; <'/r /I 1/'<l/t«'>/ ' AN L<i, <I, I C <'/ lr, ~ /A/ l ~ >// ' «'' 1 <It/ ' <»'/ l,t. 7;I 92'' ll/I' I t' //I'/I I T , // ld/ /..1 ' r//, t' , IIILrti//»It//.t' ~ II< ,Itt!' Zt IV t/.I' ,Y:" ' James H. ne l.t,">I >t>t , ,1/ II !w1>% ~. g ''> <I' " r :r . j/j, X '. 1K;LIT ' "P; 't > ig'I/l <7 ,. /, >Ilg.<'l.l,. I I l t 1> I c i.' i //,./t. r P I I "-;; 4 '/»I I rp I;, rr I ri' r' : r'r +' I ETLAND RPSOUR~ I,OU'I UNIVER<>ITY . gp,TON LSV-se-72-a5 /$t REPORT 2 Preliminary Assessment of the Environmental Impact of a Superport on the Southeastern Coastal Area of Louisiana LOUIS IANA SUPERPORT STUDIES Prepared by: Dr. James H. Stone Department of. Marine Sciences Center for Wetland Resources Louisiana State University Baton Rouge, Louisiana 70803 Prepared for: Dr. Hugh J. McLellan Mr. Steven D. Jellinek Associate Program Director Senior Staff Member Institutional Support Council for Environmental National Sea Grant Program and Quality National Oceanic and 722 Jackson Place, N. W. Atmospheric Administration Washington, D. C. 20006 Rockville, Maryland 20852 This work is a result of research sponsored by NOAAOffice of Sea Grant, Departmentof Commerce,under Grant 2-35231. The U,S. Government is authorized to produce and distribute reprints for governmentalpurposes notwithstanding any copyright notation that may appear hereon. I ii I . AB S TRACT Two offshore sites for a proposed Superport, off southeastern Louisiana, are evaluated for potential environmental impact on the coastal region. The most vulnerable areas along the coast are the estuaries. Oil drift projections indicate that the site more distant from shore would have less effect because a potential spill there would probably not reach the estuarine areas. Louisiana's estuaries are flanked by Levees and, on the Gulf side, usually by barrier islands. This configuration, coupled with a gentle slope, has produced a nutrient-rich environment that now supports over 4 million acres of estuarine marshlands--one of the world's most extensive coastal wetland areas. The climatic regime provides high solar insolation, abundant rainfall, and a wind system all of which interact with the physical setting in such a way that primary production supports the largest fishery in the United States. The principal fishery species are menhadenand shrimp, and they depend on the estuaries for a habitat and/or nursery area and for detrital food the product of marsh grass disintegration. Oil drift projections of hypothetical oil spills are based on a hydrodynamical numerical model using wind conditions, local tides, and bathymetry. At the closest site oil spills movedeither northwest toward Timbalier Bay or northeast toward Barataria Bay. Oil spills at the farther site did not impinge on the shorelines nor into the estuaries. Oil spills at both sites usually assumed an east-west orientation and moved somewhat faster than drift projections based solely on winds. Potential adverse effects resulting from an oil spill would be most severe in the estuaries. Oil could damage or kill extensive areas of marsh grass, thereby reducing or eliminating the most important food source for the major consumers, which are fishery species. This damage could be by direct contact with the top of th= plants, the root system, or the microbes which initiate the breakdown of grass into detritus. Most marsh fauna is located near the boundary between the grass and estuarine waters. Zf oil enters the estuaries, it is believed that it will concentrate in this boundary area and thereby possibly cause high mortalities of these forms and indirectly of the fishery species, inasmuch as detritus in the estuaries is used as a food source. The larval and juvenile stages of the fishery species use the tidal passes into and out of the estuaries as migratory routes, and if oil reached these areas mortalities could have severe effects on later fish harvests. Damage to the Gulf shoreline would probably be minimal unless the oil concentrated in the littoral currents, which are also us'ed as a migratory aid. The most severe effect off. hore would probably be damage to the spawning waters or grounds used by the fishery species. However, this damage would probably be low when compared with potential spill effects on est~aries because the size of the offshore shelf area and the large volume of water would tend to mitigate the damage. Regardless of the final location of the Superport, research should be initiated on the detailed hydrography and meteorology of the proposed site, the toxic effects of various crude oils on planktonic stages of fishery species, and the ef fects of oil on marsh grasses and microbes. vt, TABLE OF CONTENTS Page Ie ABSTRACT ~ a ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ iii I I ~ INTRODUCT ION ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ o ~ ~ ~ ~ A. Obg ectives ~ ~ ~ B. Study Area and Conditions ~ ~ 15 1 C. Data Sources and Acknowledgements ~ ~ ~ III. SELECTED ENVIRONMENTAL INVENTORY OF STUDY AREA Geological and Geographic Setting ~ ' ~ 1. Delta Formation ~ ~ ~ 2. Active Delta: Mississippi River ~ ~ ~ 7 78 3. Barrier Islands 4. Estuarine Areas ~ ~ ~ 9 5. Shoreline Features r 10 6. Offshore Area ~ ~ ~ 10 B. Characterization of Sediments and Wate rs ~ ~ ~ 11 l. Selected Estuarine Areas 11 2. Offshore Areas ~ ~ ~ 14 C. Climates ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 14 l. Average Conditions 4 14 2. Summer Conditions ~ ~ ~ 18 3. Fall Conditions ~ ~ ~ 18 4. Winter Conditions ~ ~ ~ 19 5. Spring Conditions ~ ~ ~ 20 D. Hydrographic Background ~ ~ ~ 21 1. General Description 21 2. Surface Circulation along Western Continental Shelf ~ ~ 22 3. Littoral Currents 23 4. High-Salinity Cells off Delta of Mississippi River 24 5. Modification of Shelf Hydrography b Mississippi River ~ ~ 25 6. Effects of a Hurricane on Hydrograp ~ ~ 25 7. Gross Circulation of Berataria Bay ~ ~ 26 8. Water Temperatures and Salinities ~ ~ 27 9. Sea Level and Tidal Effects ~ ~ 28 10. Wave Character is ties 28 Biological Units ~ ~ 30 l. Important Physical Parameters ~ ~ 31 2. Plant Communities ~ ~ ~ ~ ~ ~ ~ 31 3. Primary Production ~ ~ ~ ~ ~ ~ ~ ~ ~ 34 4. Harsh Consumer Species ~ ~ ~ ~ ~ ~ ~ 36 5. Fishery Species ~ ~ ~ ~ t ~ ~ ~ 39 6. Miscellaneous Species ~ ~ 46 vii Page 7. Offshore Communities 47 8. General Overview of Biological Units 48 F. Selected Cultural Aspects 51 l. Archaeological Sites 51 2. People and Some of Their Activities 52 G. Observed Effects from Previous Oil Spills and Studies in Louisiana 53 l. The Chevron and Shell Spills 53 2. Other Studies on the Impact of Oil on Louisiana Estuaries and Coastal Waters 59 IV. DRIFT PREDICTIONS FOR OIL SPILLS 64 A. Surface Circulation Based on Hansen's Model 64 1. Description of Hansen's Model. 64 2. Surface Circulation in Study Area Based on Hansen ' s Model . 65 R. Casualty Oil Spills 67 1. Study Conditions 67 2. Northeast Winds 68 3. East Winds 69 4. Southeast Winds 71 5. South blinds. 73 6. Summary of Oil Drift Studies 74 C. Chronic Oil Spills 75 V. PREDICTED EFFECTS OF OIL SPILLS 76 A. Estuarine Ef tects ~ ~ 76 1, Marsh Grass. 76 2. Microbial Populations ~ ~ 77 3. Other Primary Producers 77 4. Marsh Edge-Water Interface 78 5. Nutrient Cycle 78 6. Fishery Species ~ ~ 79 B. Shoreline Effects 79 C. Offshore Effects ~ - 80 D. Summary. 81 VI . RECOMMENDATIONS 83 VII, REFERENCES 85 VIII. FIGURESAND TABLES+ 9 figures and 110 tables! *Detailed listings are given on pages directly following. LIST OF FIGURES FigureMap showing geographic context of studyarea in 95 Louisiana. 2. Hydrologic catchment units and of fshore fishing 96 grids. 3. Chronology of deltas of Mississippi River deltaic 97 plain. Sequencesof development of deltaic faci s 5. Mudlumpareas in Mississippi River delta 99 6. Submarine topography of Mississippi River delta 7. Subaqueous profiles of seven river deltas. 101 8. Environmental management areas of coastal Louisiana, 102 9. Influence of subsidence on delta deterioration 103 10. Bathymetry of offshore region in study area. 104 11. X-ray diffraction for clay minerals from Barataria 105 Bay, Louisiana 12. Location map of sampled areas in Barataria Bay, 106 Louisiana. 13, Organic-C and total-U of sediments from Barataria 107 Bay, Louisiana 14. Soil organic matter in coastal Louisiana 108 15. Sulfides and total P content in sediments from Barataria Bay, Louisiana 109 16. Dissolved carbonates in waters of Barataria Bay, 110 Louisiana. 17. inorganic nitrogen, nitrate, and nitrite nitrogen in waters of Barataria Bay, Louisiana. 18. Total phosphates in waters of Barataria Bay, 112 Louisiana Figure Page l9. Gross lithology of sediments along shelf northwest Gulf ~ ~ ~ ~ ~ ~ 1 13 20. Surface phosphates and chlorophyll around Mississippi River delta....... ~..... - .. ~ 114 21. Annual insolation along coastal Louisiana....... 115 22. Cyclone occurrences along Gulf and Atlantic coas ts e ~ ~ e ~ ~ ~ ~ ~ o t ~ ~ 116 23. Cyclone probabilities along Gulf and Atlantic coasts ~ ~ ~ ~ ~ ~ o r ~ ~ ~ ~ ~ ~ ~ 117 24. Generalized surface circulation along coastal Louisiana 121 25. Mississippi River discharge and rainfall along coastal Louisiana 122 26. Current vectors at South Pass af Mississippi River 123 27. Distribution of suspended sediments at South Pass of Mississippi River 124 28. Results of oceanographic survey along coastal Louisiana before Hurricane Betsy 125 29. Results of oceanographic survey along Louisiana coast after Hurricane Betsy. 126 30. Results of oceanographic survey along Louisiana coast before and after Hurricane Betsy 127 31. Hydrologic catchment units of Barataria and Caminada Bays, Louisiana 128 32. Circulation pattern at ebb tide for Barataria and Caminada Bays, Louisiana 129 33.