Lake Pontchartrain Basin:  Bottom Sediments and Related Environmental Resources


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Armingeon, N. A., Lake Pontchartrain Basin Foundation, New Orleans, LA:

The Bonnet Carré Freshwater Diversion Reanalysis: Science vs. Pork Barrel Politics

In 1973, a private citizen in Mississippi funded a study through the Business School at the University of Southern Mississippi to examine the effects of freshwater diversions on the fisheries of Coastal Mississippi. Through political maneuvering, the small study grew into one of the nation's last, large civil works projects, the Bonnet Carré Freshwater Diversion. The proposed project would divert billions of gallons of Mississippi River water into Lake Pontchartrain to reduce salinities in a target area over 70 mile away at a cost to the taxpayer of over $200 million.

The project has been opposed by various groups since its inception, including commercial fishermen, the Louisiana Department of Natural Resources, all the parishes in the Pontchartrain Basin, and numerous environmental organizations. Despite the opposition, the project moved forward.

Due to building public opposition, Congressman Bob Livingston directed the Environmental Protection Agency to undertake a complete reanalysis of the merits of the proposed project and its impacts to the ecological health of Lake Pontchartrain. In December, 1993, a technical team was assembled to conduct an objective review of the project. The group included scientists, regulatory agencies representatives, representatives of citizens groups and commercial fishermen.

The reanalysis process initiated numerous studies which produced new data regarding the proposed diversion of the river water into Lake Pontchartrain. The reanalysis included an experimental opening of the Bonnet Carré spillway during May, 1994 which provided additional water quality data.

Based upon the reanalysis findings, the technical committee recommended the U.S. Army Corps reduce the size of the original diversion by 70 percent. The Corps was also directed to design a structure that would reduce nutrient loads in river water to meet water quality standards in the Lake. In addition, the Corps was asked to investigate the placement of a sill or other modifications the Inner Harbor Navigation Canal to curtail saltwater intrusion into Lake from the Mississippi River Gulf Outlet (MRGO).

The New Orleans District enlisted the aid of the Corp's Tidal Hydraulics Group to study the intrusion problem. The group concluded: 1) the primary cause of increased salinity in Mississippi Sound and Lake Pontchartrain was the MRGO and, 2) saltwater intrusion problems should be addressed at their source, the MRGO.

The District contracted with a private engineering firm to evaluate the overland flow design option. The study indicated that to construct a project to meet the technical team's recommendations the cost of the project would increase by 54 percent, from $81 million to $125 million.

The reanalysis is scheduled to end mid-May, 1996. The final results of the reanalysis process will be presented at the conference.  

Autin, Whitney J., Institute for Environmental Studies, Louisiana State University, Baton Rouge, LA 70803, and Mossa, Joann, Department of Geography, 3141 Turlington Hall, University of Florida, Gainesville, FL 32611:

Environmental Systems Approach to Flood Basin Management: The Amite River's Link to the Pontchartrain Basin

The Amite River Basin drains part of southeastern Louisiana and southwestern Mississippi and empties into the Pontchartrain Basin, a link in the hydrologic cycle that has existed for the past ca. 5000 years. This evolutionary relationship influences many of the present functions that sustain modern environments in the lower Amite and upper Pontchartrain basins. Human landscape changes in the twentieth century have been imprinted upon the setting created by this millennia-scale natural evolution.

Human modification of the Amite River Basin has been intensive, producing one of the most disturbed drainage basins in the northern Gulf of Mexico region. Land use alterations include the conversion of natural forest habitats to managed pine forests and agricultural land, urban/suburban growth of the Baton Rouge metropolitan area, significant stream channelization, and intensive flood plain mining for sand and gravel resources. It has been suggested that stream channelization and flood plain mining have directly aggravated downstream flooding and increased stream turbidity. These activities have induced a hydrologic and sedimentologic response that is only partly understood and not well quantified. It is likely that the system's physical response is triggering related ecological responses to terrestrial and aquatic habitats in both the Amite River and Pontchartrain basins.

However, the key public issue in the Amite River is the lower basin's flood hazard and the related inhibition of continued land development and suburban growth. Repeated large floods since 1977 and a record peak event in 1983 resulted in hundreds of millions of dollars in property damages and a public outcry for flood protection. The primary flood hazard alternatives proposed to date are an upper basin reservoir to store flood water, a diversion channel to redirect flood flow to the Mississippi River, and trunk and tributary channel modifications designed to accept larger flows below bankfull stages. Flood plain management and hazard mitigation strategies have received significantly less attention, in spite of the inability of engineering project proposals to pass the scrutiny of environmental impact and cost/benefit analysis. Also, the public has expressed a lack of willingness to pay the costs associated with expensive engineering projects.

Environmental rehabilitation of the Amite River Basin may have benefits beyond the restoration of the surface hydrologic and sedimentologic balances necessary for self-sustaining terrestrial and aquatic ecosystems. Mine reclamation of flood plain lands and reconstruction of meandering channel patterns to a pre-disturbance state could help to balance flood hydrology and sediment transport and increase the quantity and quality of flood plain habitat. Watershed retention in upland tributaries could significantly trim the peakedness of the flood hydrograph and increase the quantity and diversity of permanent aquatic habitat.

The potential benefits of environmental rehabilitation in the Amite River, when blended with logical flood plain management, includes significant reductions in flood hazard, improvement in downstream water quality, and increases in ecological resources. Such an approach is likely to be cost-effective, resolve significant public environmental management conflicts, and help the Amite River provide a self-sustaining, beneficial link to the ecological system of the Pontchartrain Basin.

Banbury, M.M., University of New Orleans, New Orleans, LA; Lyons, S.E., Holy Cross School, New Orleans, LA; Flanagan, S., Elaine P. Nunez Community College, Chalmette, LA; and Maygarden, D., Audubon Institute, Office of Environmental Policy, New Orleans, LA:

Project C.E.E.D.: Coastal Education for Economic Development

Global warming, ozone depletion, hazardous waste disposal, nuclear holocaust, coastal erosion, habitat loss---all of these potential environmental disasters dominate human concern, but the question is always asked: "What can I, alone, do to help the environment?" Humans tend to see global environmental issues as something they can't control, yet they want to do something. It is incumbent upon educational institutions to address that need, and it is best answered by (1) educating people about ecosystems and how they work, and (2) getting then involved, even tangentially, with decision-making and solutions. Project C.E.E.D., developed to meet those goals, was a joint venture of the University of New Orleans (Department of Special Education and the Urban Waste Management & Research Center) and the Society for Environmental Education.

Project C.E.E.D. produced curriculum supplementary materials designed to introduce children to the basic concepts of wetlands education through a non-traditional approach. In Welcome to the Wetlands: An Activity Book for Teachers, the authors have successfully combined important ecological information with a mix of challenging, fun, teaching activities. Wetland Blues is a video designed to engage and entertain young people while giving them enough information about the value of wetlands to instill in them appreciation for this important environmental issue. It is accompanied by Wetland Blues: A Video Guidebook for Teachers, written for further student development of the problem-solving, decision-making skills necessary for contemporary environmental issues. The final product of Project C.E.E.D. is a series of seven monographs, each of which explores a different facet of wetlands or wetlands-related problems. Each activity book incorporates background information on the issue at hand, then involves children in designing a product that makes environmental learning fun and dynamic: making buttons, designing T-shirts, writing poetry, taking social action, etc.

Project C.E.E.D. materials have been distributed widely at teacher workshops across the nation and have been extremely successful.

Barnidge, Brent, Lake Pontchartrain Basin Foundation, Metairie, LA:

Valuation of Lake Pontchartrain's Northshore Seagrasses

Seagrasses are naturally occurring subtidal vegetation which exists along the shallow coastline of Lake Pontchartrain. They contribute to important biological and physical processes and form an intricate biological linkage with surrounding wetlands systems. In addition, they provide for commercially and recreationally important species as a food source, shelter and habitat.

For years their ecological significance has been documented; however, an economic valuation -- to the detriment of the seagrasses -- has never been made. Legal nonrecognition has continued to allow policy makers to erroneously assume that seagrasses possess little or no economic value. In an effort to preserve the integrity of Lake Pontchartrain's surrounding marshlands, the Green Point/Goose Point Restoration Plan proposes revetment construction which will threaten the existence of the healthiest grassbed community in the lake. While wetland protection is certainly a top concern in this state, the manner in which it is being approached will prove to be a costly and inefficient one.

Using information on the their contribution to finfish and shellfish production in the lake and surrounding waters, a monetary value per acre of the grassbeds can be determined; but, while we wait for a flawless value to be determined, the seagrasses could be lost forever. A reasonable, justifiable value range can allow decision makers the opportunity to use their limited funding in a safer and more cost-efficient manner. As a valuable renewable resource, the remaining northshore grassbeds make a substantial contribution to the local ecology and long-term economic stability of the region and warrant our protection.

Bianchi, T.S., and M. Argyrou, Dept. of EEO Biology, Tulane University, New Orleans, LA:

Spatial and Temporal Variability of Dissolved and Particulate Organic Carbon (DOC AND POC) in the Lake Pontchartrain Estuary: The Use of Chemical Biomarkers

The Lake Pontchartrain estuary is a shallow-turbid estuary located on the northern Gulf coast. While Lake Pontchartrain is one of the largest estuaries along the Gulf of Mexico and is situated adjacent to the city of New Orleans, very little is known about the carbon and nutrient dynamics of this system. In 1995-96 we made bi-monthly samplings of the water column and sediments at nine stations that covered the full expanse of the estuary. Total POC ranged from 0.2 to 0.5 mg/L while DOC ranged from 5 to 10 mg/L, and reached its highest concentration in January 1996. The percentage of DOC represented by high molecular weight DOC (HMW DOC or colloidal material), defined here as <0.2 µm to > 3kD, was greatest (ca. 10%) at stations where freshwater inflow was high as well as wetland inputs. Pore-water concentrations of DOC averaged ca. 25 mg/L indicating that there was a net flux of DOC from sediments to the water column. Stations with the highest concentrations of pore-water DOC (i.e. 350 to 410 mg/L) typically had high densities of the bivalve Rangia cuneata. Lignin-phenols (biomarkers of terrestrial plant sources) indicated that Lake Pontchartrain had higher sedimentary concentrations near regions where wetland inputs were high (i.e., Manchac Pass and the Tangipahoa River). Moreover, terrestrial inputs to these sediments were generally higher when compared to other estuaries along the northern Gulf coast. Concentrations of PO4-3 and NH4+ were moderately high ranging from 1 to 2 mM and 3 to 12 mM, respectively. However, total NO2- and NO3- concentrations were particularly low throughout most of the year with the highest concentrations occurring in January 1996 (10 mM ); with NH4+ representing the dominant form of inorganic N it is likely that sedimentary sources of N (via resuspension are important in this shallow-turbid system. Despite these inputs of N, phytoplankton appeared to be light limited - as indicated by the generally low chlorophyll-a concentrations (3 to 6 mg/L) and high concentrations of suspended particulate matter (SPM) ( 3 to 24 mg/L). Concentrations of the carotenoids fucoxanthin and zeaxanthin (measured by HPLC), indicated that diatoms and cyanobacteria were the dominant forms of phytoplankton in the estuary.

Boshart,W. M., Department of Biological Sciences, Southeastern Louisiana University, Hammond, LA:

Management Strategies for Maximizing Growth and Survival of Baldcypress (Taxodium distichum (L.) Rich.) in Southeast Louisiana

Two study sites were used to compare different strategies for maximizing growth and survival of baldcypress. The first site is located in the vicinity of the Turtle Cove Environmental Research Station in the Manchac Wildlife Management Area. Historically, this area was dominated by baldcypress (Taxodium distichum) swamp. The area was commercially logged from the mid 1800s through approximately 1950. During this period, commercial interest was limited solely to timber harvest with no regard for long term ecological effects to these wetlands, nor were sustainable timber practices followed. Pullboat logging techniques severely altered the landscape and thus the hydrologic regime of the area. It is believed hat the natural regeneration of baldcypress has failed due to factors attributed to this altered hydrologic regime and compounded by the effects of herbivory.

In contrast is the second study site, located on the southeast bank of the Amite River in Clio, LA. Riparian baldcypress forests were alternately clear-cut and select-cut during 1993. No heavy equipment was used in the area during the timber harvesting process, therefore minimum damage appears to have occurred to the region. The Clio site is almost continuously flooded, with the depth of the water varying due to precipitation, wind, and tidal effects.

Two separate hypotheses were tested concerning baldcypress growth and survival in both study sites; direct comparisons were subsequently made between the sites. Hypotheses tested were management from competing vegetation, and quantity and type of limiting nutrients (nitrogen-phosphorus-potassium). Both were tested with respect to differing age classes of baldcypress seedlings (twelve month, twenty-four month and thirty-six month).

Britsch, L.D., U.S. Army Corps of Engineers, New Orleans, LA; and Dunbar, J.B., Waterways Experiment Station, Vicksburg, MS:

New Coastal Land Loss Maps for Louisiana

Land loss mapping and rate curve development for 62 quadrangles in the Louisiana Coastal Plain shows that land loss rates and trends vary significantly throughout coastal Louisiana. Land loss rates for each quadrangle were defined for 4 time periods: 1930's to 1956-58, 1956-58 to 1974, 1974 to 1983, and 1983 to 1990. Differences in land loss rates among the individual quadrangles are a function of the geologic and hydrologic setting and the factors which contribute to land loss such as subsidence, storm induced erosion, channelization of streams and rivers, and canal dredging. Of the 62 quadrangles mapped, 9 quadrangles are losing more than 1 percent of their land area each year, and 12 quadrangles are losing between 0.5 and 1.0 percent per year during the 1983 to 1990 period.

On a regional scale, the land loss rate for the entire Louisiana Coastal Plain has decreased from an average yearly rate of 41.83 square miles in the 1956-58 to 1974 period to 25.34 square miles during the 1983 to 1990 period. The percentage of land being lost is also decreasing from 0.51 percent per year in the 1956-58 to 1974 period to 0.35 percent per year during the 1983 to 1990 period. The regional land loss rate will probably continue to decrease slowly until a background rate is reached.

In February 1996, the U.S. Army Corps of Engineers-New Orleans District published a map series summarizing this database in Technical Report GL-90-2 Land Loss in Coastal Louisiana (7 maps).

Burns, J. W., St. John's River Water Management District, FL; M. P. Poirrier, Dept. of Biological Sciences, Univ. of New Orleans, New Orleans, LA; and K. P. Preston, Dept. of Geography, Univ. of New Orleans, LA:

Submersed Aquatic Vegetation as Indicators of Water Quality in the Lake Pontchartrain Estuary

In response to the continued decline of submersed aquatic vegetation (SAV) in the Lake Pontchartrain estuary, SAV were experimentally transplanted in Lake Pontchartrain near Fontainebleau State Park, Bayou Lacombe, and Pointe aux Herbes. SAV transplants were used to determine if water quality conditions were conducive to SAV survival and if transplanting was a viable technique for restoring submersed plants to areas where they had declined in response to natural disturbance.

Vallisneria americana was selected for transplanting due to prior transplanting success with this species by others in low salinity estuaries and because of its historical dominance in Lake Pontchartrain. Plants were harvested by hand near Bayou Lacombe (July 1994) and transplanted within 4 SAV enclosures at each site. Each enclosure measured 12 ft (l) x 12 ft (w) x 4 ft (ht) and was designed to baffle wave energy and to limit herbivory. Plants were anchored to the sediment by hand with metal staples so that roots and rhizomes were completely buried. Within each enclosure, plants were placed in four circular plots at densities of 50, 75, 100, and 125 shoots m-2 . Each plant density was represented at each of four positions located within each corner of the enclosures. Non destructive sampling techniques were used to determine transplant survival, species composition, foliar cover, plant density, blade length, and vegetative reproduction. Sediment grain size and water quality parameters specific to SAV survival (bottom water temperature, pH, free carbon dioxide, alkalinity, salinity, specific conductance, and Secchi disk transparency) were also determined.

Transplanting V. americana in Lake Pontchartrain was successful due to the following observations: (1) shoots survived transplanting without signs of physiological stress; (2) shoots produced flowers, fruit, and viable seeds; and (3) there was a significant increase in SAV foliar cover due to growth and the vegetative reproduction of new plants. Foliar cover, plant density, and blade length were greater at Fontainebleau during August 1994 sampling when compared to Bayou Lacombe and Fontainebleau. Mean Secchi disk transparency was also greater at Fontainebleau during the study. However, initial transplants and new shoots were lost at Fontainebleau following a blue-green algae bloom in Lake Pontchartrain during June 1995. SAV transplants were also lost at Pointe aux Herbes (November 1994) during extremely low water levels (ca. -3 ft.) that exposed transplants to desiccation. Although SAV foliar cover increased from 10% to >80% at Bayou Lacombe between August 1994 and November 1995, there was no significant change in foliar cover following the blue-green bloom.

The spatial and temporal separation of the May 1995 flood and the June 1995 opening of the Bonnet Carré Spillway, provided us the opportunity to differentiate the potential independent biological consequences between flood waters from north shore rivers and streams and nutrient rich water diverted from the Mississippi River. Distinct differences in water quality parameters (including pH, free carbon dioxide, and phenolphthalein alkalinity) were detected over the SAV transplants during these events. The pH ranged from 6.1 to 9.8 at Bayou Lacombe, 6.8 to 9.6 at Fontainebleau, and 6.7 to 8.3 at Pointe aux Herbes. This fluctuation in pH occurred between May 1995 and June 1995 following the May flood and June opening of the Bonnet Carr( Spillway. Although free carbon dioxide concentrations ranged from below detection limits to 26 ppm between May and June 1995, there was no significant difference in mean free carbon dioxide concentrations for all sites during the study period. Phenolphthalein alkalinity remained below detection limits at all sites except during June and July 1995 at Bayou Lacombe (2.0 + 0 ppm) and June 1995 at Fontainebleau (1.0 + 0 ppm). Mean salinity for the study period was significantly greater at Pointe aux Herbes (3.9 + 0.4 ppt) when compared to salinity at Bayou Lacombe (2.7 + 0.3 ppt) and Fontainebleau (2.1 + 0.3 ppt). Salinity ranged from 0.3 ppt to 6.8 ppt at Pointe aux Herbes (during July 1995), 0.1 ppt to 5.0 ppt at Bayou Lacombe, and 0.3 ppt to 5.7 ppt at Fontainebleau. Low salinity for the study period was recorded at all stations following the opening of the Bonnet Carré Spillway.

Ideal conditions for the occurrence of a blue-green algae bloom in Lake Pontchartrain were met during June 1995. Meteorological and water quality conditions prior to the algae bloom included: (1) max. air temperatures > 32 (C; (2) calm winds; (3) no precipitation for 29 days (3 June to 21 June 1995); (4) bottom water temperature > 30 (C in the littoral zone; (5) salinity < 1.0 ppt; and (6) increasing Secchi disk transparency. With the input of additional plant nutrients to Lake Pontchartrain following the May flood and the June opening of the Bonnet Carré Spillway, blue-green algae flourished in the estuary until the occurrence of Hurricane Erin. Surface bloom-forming algae in the estuary best fit the description of Anabaena circinalis (Kutz.) Rabenhorst; a blue-green belonging to the Division Cyanophyta. This species can be found in large rivers and ponds and is known to form "water blooms". Fish kills were associated with the algae bloom but were isolated to urban outfall canals and Bayou Saint John where decaying algae was trapped between two water control structures within the bayou.

Data from this study suggest that SAV are excellent indicators of water quality and can be transplanted successfully in Lake Pontchartrain if water quality conditions are conducive to growth and reproduction. The input of additional plant nutrients to Lake Pontchartrain, regardless of the source, may promote the increase of phytoplankton production and could cause further reduction of SAV. Physicochemical factors associated with Mississippi River water are not conducive to SAV survival in Lake Pontchartrain and directly contributed to the severity and duration of the blue-green algae bloom that occurred during June 1995.

Campo, F. M., Shaffer, G. P., and Llewellyn, D. W., Department of Biological Sciences, Southeastern Louisiana University, Hammond, LA:

In Situ Hurricane Simulations on Two Age Classes of Baldcypress (Taxodium distichum) (L.) (Rich) Seedlings

A tropical wave in August of 1994 created excellent conditions in the Manchac Wildlife Management Area, Louisiana, USA, for conducting hurricane simulations. Eighteen-month old and forty-two-month old baldcypress seedlings were subjected to a range of in situ salinity pulses (ambient 1-2 ppt, 5 ppt, and 10 ppt) for 10 days in the field. Specifically, a large cylinder, pushed into the soil, was deployed around each of the seedlings as containment vessels for the salt solutions. Basal diameters were measured before initializing the experiment and 9 months after the cylinders were removed. Photosynthetic measurements were taken 4 days into the experiment in an attempt to capture the seedling's initial response to the salinity treatments. Final photosynthetic measurements were taken 8 days after the cylinders had been removed (day 18). Overall, 42-month old seedlings were more tolerant to increases in salinity. However, photosynthetic rates across both age classes decreased linearly with increasing salinity. Eighteen-month old seedlings exhibited stable diameter growth across salinity treatments, whereas the older seedlings paradoxically increased in diameter in the 5 and 10 ppt treatments. Soil redox potentials were significantly higher for the 42-month old seedlings across all treatments. Among all units, there was not a single case of mortality. This field study provides direct evidence that baldcypress seedlings may be more salt tolerant than previous research has demonstrated.

Day, J. W., and Rybczyk, J., LSU, Baton Rouge, LA; A. J. Englande, Tulane University, New Orleans, LA; and Michael Dolese and Glenn Cooper, St. Bernard Water and Sewer Commission, Chalmette, LA:

Water Quality Improvement Using Coastal Wetlands in St. Bernard Parish

A study is currently being carried out to determine the potential effects of addition of storm water runoff and treated sewage effluent to the Poydras-Verret wetland in St. Bernard Parish. This 4800 ha wetland has received a combination of secondarily treated municipal sewage effluent and street runoff from the Gore pumping station for a number of years. In addition, the area is affected by Mississippi River water from the Violet siphon. Wetland vegetation in the area ranges from swamps with cypress and Iva frutescens, to fresh marshes, to saline marshes dominated by Spartina alterniflora. Cypress swamps formerly covered much of the area, but these were mostly killed by salt water intrusion from the Mississippi River Gulf Outlet. The waste water discharge has freshened part of the area and allowed the maintenance of the swamp and fresh marsh communities. The current study is designed to monitor the impact of the discharge on the wetland ecosystem as well as changes in water quality due to overland flow through the wetland. The study includes aspects of hydrology, soils, chemistry, vegetation, and animal populations. Preliminary results indicate that the ecosystem is benefiting from the freshwater inflow and that water quality is improved.

Day, J. W., R. R. Lane, G. Paul Kemp, Brian Perez, and Joe Suhayda, LSU, Baton Rouge, LA; Dennis Demcheck, USGS, Baton Rouge, LA:

Overland Flow of Mississippi River Water in Coastal Wetlands within and surrounding the Bonnet Carré Spillway

The Bonnet Carré freshwater diversion project will divert water from the Mississippi River into Lake Pontchartrain via the Bonnet Carré spillway. The original design of the project consists of a channel directly linking the two bodies of water. A reanalysis was initiated to address concerns about the affects of the Bonnet Carré freshwater diversion on water quality and fisheries in Lake Pontchartrain. The reanalysis included modeling of Lake Pontchartrain hydrology, possible affects on fisheries, diversion structure redesign, and the feasibility of overland flow through wetlands for nutrient and sediment reduction. During the reanalysis process a short term experimental diversion was performed. Overland flow in the Bonnet Carré spillway was minimal during the experimental diversion and a large volume of water was concentrated onto a small portion of wetlands. The general effect was negligible nutrient reduction and very high rates of accretion. The experimental diversion suggests that a greater wetland area than is available in the spillway may be required to sustainably process the proposed Bonnet Carré freshwater diversion. The amount of wetland area required, based upon naturally occurring loading rates of the Atchafalaya River basin, is available if wetlands within and adjacent to the spillway are utilized.

Day, J. W., R. R. Lane, LSU, Baton Rouge, LA;  Thibodeaux, B., Corps of Engineers, New Orleans District, New Orleans, LA:

Water Quality Analysis of the Caernarvon Freshwater Diversion Project

Since 1991 Mississippi River water has been diverted at Caernarvon into Breton Sound. Water quality was monitored at various locations in Breton Sound for four years prior to the diversion to the present. Analyses of these data indicate reductions of nitrate, phosphate and suspended sediments as diverted water passes through Breton Sound waters and wetlands. There is a slight increase in nitrite indicating denitrification is a pathway for nitrate reduction. The area is a source for ammonia indicating active remineralization. The loss of nitrate is much greater than the increase in ammonia indicating that the area is a strong net sink for inorganic nitrogen.

Dufrechou, Carlton, Lake Pontchartrain Basin Foundation, Metairie, LA:

Restoration of the Lake Pontchartrain Basin

The Lake Pontchartrain Basin Foundation (LPBF) is a private, non-profit organization dedicated to the restoration and preservation of the Pontchartrain Basin. Pontchartrain is a complex system of physical and biological elements. The Basin drains almost 5,000 square miles of land in 16 Louisiana parishes and 4 Mississippi counties. It is home to over 1.5 million people. The Basin forms one of the largest and most productive estuaries in the United States. Discharges from agricultural activities, businesses, and communities with inadequate sewage systems released into streams, bayous, or rivers in upper reaches of the Basin eventually flow into Lake Pontchartrain. Stormwater runoff from the highly urbanized south shore also drains into the Lake. Eroding wetlands in the lower part of the Basin have increased saltwater intrusion into the Lake.

Management of Lake Pontchartrain requires management of the entire Basin. Regulating the Basin's environmental resources are 98 separate agencies and governing bodies. The Lake Pontchartrain Basin Foundation through its Comprehensive Management Plan (CMP) coordinates the overall restoration. The CMP attempts to balance and promote improvements to the Basin's water quality and habitats while recognizing the needs of the Basins Communities, businesses, and residents.

Flanagan, S. A., Nunez Community College, Chalmette, LA:

Wetland Education: The Community College Connection

Nunez Community College, situated in a fragile vanishing wetland area, provides educational opportunities for students in the surrounding area. From its beginning in 1992, Nunez has offered a comprehensive course in wetland ecology. Students participate in a variety of lectures and experiential activities designed to acquaint them with the diverse wetland area in which they live. Activities and instructional material rely on scientific data, incorporate multidisciplinary activities and encourage individualistic and creative participation by students. Models for instructional activities, student projects and class activities will be shared with interested educators.

Flowers, G.C. Department of Geology, Tulane University, New Orleans, LA 70118; Poirrier, M. A., Department of Biological Sciences, University of New Orleans, New Orleans, LA 70128; Suhayda, J. N., Department of Civil Engineering, Louisiana State University, Baton Rouge, LA 70803; Koplitz, L. V., Department of Chemistry, Loyola University, New Orleans, LA 70118; Clymire, J. W. and McPherson, G. L., Department of Chemistry, Tulane University, New Orleans, LA 70118:

Changes in the Water Quality of Bayou Trepagnier after Diversion of Industrial Discharge

On February 24, 1995, Shell Chemical Co., after receiving final regulatory approval from the Louisiana Department of Wildlife and Fisheries, diverted Norco Manufacturing Complex (NMC) effluent into the Mississippi River. Removal of the Shell discharge from Bayou Trepagnier was the source of considerable anxiety for local environmental organizations trying to restore the bayou. In particular, many were concerned that the reduction in flow at the headwaters would result in a stagnant waterbody with a high concentration of dissolved heavy metals. Environmental assessments completed on Shell's behalf indicated that water quality in the bayou probably would not be degraded by removing NMC effluent because it represented a minor part (2% of the discharge caused by tidal variation--the most important source of water level variation) of the total water budget. This conclusion was based, in part, on observations made in the bayou during a three-day shutdown of the discharge in August, 1994. In this experiment, water levels and water quality parameters were measured around the clock every four hours. We repeated this study in August, 1995 in order to begin characterizing seasonal variations in bayou water quality. Although the discharge was a minor component of the bayou's water budget, it significantly affected water chemistry.

One of the most obvious changes in the bayou from 1994 to 1995 is the significant decrease in temperature observed in the bayou headwaters. Based on the Wilcoxon nonparametric test for independent samples, the mean temperature profiles for 1994 and 1995 are different at the .05 level (two tailed test) for stations 5-35. For station numbers greater than 35 there is no statistical difference between the temperature profiles for the two years. In 1994, there was a salinity minimum in the vicinity of Stations 60-70 with salinity increasing both up and downstream. The 1995 profile, in contrast, shows a general decrease in salinity towards the headwaters. Salinity profiles are statistically the same for Stations 30-45, 55-60, and 130-160; salinity variation at a given station is less in 1995 than 1994. In 1994, the average pH was 7.63+ 0.24 (N=629) with the max and min being 8.8 and 6.66, respectively. After shutdown in 1995, the average pH was 6.7+0.14 (N=658) with the max and min being 7.55 and 5.91, respectively. Because the ranges for both data sets overlap only for stations near Lake Pontchartrain, there is little doubt that the differences observed before and after diversion of the discharge are statistically significant. The profile for 1994 clearly shows an increase in pH toward the outfall, whereas in 1995 there is very little variation in pH along the bayou. The average pH of bayou water in 1995 was approximately 1 standard pH unit less than average values for 1994, and variability at each station was less in 1995 than in 1994. In 1994, the average DO was 3.49+ 1.89 (N=620) with the max and min being 12.15 and 0.1, respectively. After shutdown in 1995, the average DO was 2.87+1.79 (N=658) with the max and min being 0.1 and 10.26, respectively. There is no statistical difference between stations 5-25, 35, 45-70, and 155 for the two years. In the upper reach of the bayou, the DO content is either statistically equal or greater for 1995. In 1994, only 3 samples were analyzed for hardness (120 ppm as CaCO3 at 4;110 ppm at 75; 95 ppm at 160). In 1995, the average hardness of bayou water was found to be 362+ 23 ppm (N=9). On the basis of chloride content, the average mass fraction of lake water in the bayou was 0.56+ 0.11 with the max and min being .75 and .38, respectively. In 1994, for the three bayou samples analyzed the average mass fraction was 0.14+ 0.01. In general, the water chemistry data suggests that the lake has a greater influence on the water chemistry of the bayou in the absence of the Shell discharge. A proviso to this conclusion is that tidal magnitude (whether astronomical or wind driven) largely determines the degree to which lake water enters the bayou.

The biota of Bayou Trepagnier is composed of freshwater and estuarine species which are tolerant of low salinity and low dissolved oxygen. The distribution and abundance of organisms has high seasonal and annual variation due to the presence of transient, estuarine species and movement of organisms in response to environmental change. A direct measurement of the response of organisms to the diversion of the discharge by routine monitoring was not attempted because past studies of the distribution of fish and benthic invertebrates did not indicate a discharge effect, and because the high, natural variation in the system makes bona fide changes in the system difficult to detect. It was assumed that any change which would result in more natural environmental conditions would be beneficial to the biota. The decrease in temperature, salinity, and pH in the headwaters after diversion returned it to conditions typically found in natural tidal streams. Therefore, the diversion should have had a positive effect on the biota.

Francis, J. C., and Poirrier, M. A., Department of Biological Sciences, University of New Orleans, New Orleans, LA:

Recent Trends in Water Clarity of Lake Pontchartrain

An apparent decrease in water clarity of Lake Pontchartrain has been an environmental concern for several years. The concern has been based in part on regression analyses of the available data on Secchi disk transparency in Lake Pontchartrain from 1953 to present time which indicate a statistically significant decrease in transparency with time.

Secchi disk transparency is influenced by both salinity and wind speed. A significant positive relationship exists between Secchi disk transparency and salinity; a significant negative relationship exists between transparency and wind speed. In addition, both variables realize pronounced annual seasonality. Salinity realizes its highest values in November and its lowest values in May. Wind speed, on the other hand, realizes its highest values in February and its lowest values in August. These seasonal effects are not equally represented in the available data set on Secchi disk transparency in Lake Pontchartrain. When the seasonal bias is removed from the data set, it no longer supports the conclusion of a statistically significant change in Secchi disk transparency from 1953 through 1993.

An unbiased data set of Secchi disk transparency in Lake Pontchartrain is available for the recent period 1986 through 1995. The data include transparency values from stations along the Causeway bridge taken at regular monthly intervals. The seasonal effects of salinity and wind speed are thus adequately represented. These data suggest that although significant differences in transparency may exist at different sites in the lake at different times of the year, there has not been a statistically significant change in transparency over the period 1986 through 1995.

Gammill, S.P., Louisiana Department of Natural Resources, Coastal Restoration Division, Baton Rouge, LA:

Overview of Coastal Restoration Projects in the Pontchartrain Basin   Authorized under the Coastal Wetlands Planning, Protection, and Restoration Act of 1990

The Coastal Wetlands Planning, Protection and Restoration Act of 1990 (CWPPRA) directed that a Task Force comprised of representatives from the USACE, USFWS, NMFS, NRCS, EPA and the State of Louisiana develop a comprehensive approach to coastal wetland restoration and preservation in Louisiana. The CWPPRA provides a maximum of $40 million, each year for ten years, for coastal wetland restoration, based on the state's ability to cost share. The cost share ratio is 25% state and 75% federal. Restoration plans were developed for nine major hydrologic basins in the state in 1993. The CWPPRA Pontchartrain Basin restoration strategy calls for extensive bank stabilization along the Mississippi River Gulf Outlet (MRGO), reducing salinities in the basin with the Bonnet Carré Diversion and numerous small scale diversions, and preservation of the two land bridges separating Lake Pontchartrain from Lake Borgne and Lake Maurepas. Since 1991, seven wetland restoration and protection projects in the basin have been authorized. Cumulatively, these projects are expected to create protect and enhance approximately 8,000 acres of coastal marsh at a cost of roughly $17 million with an average cost per benefited acre of marsh of approximately $2,200. To date, one project, the LaBranche Marsh Creation Project, has been constructed and the remaining six are currently in various stages of planning, design or construction. A variety of coastal restoration technologies are being utilized such as: 1) marsh creation using dedicated dredging in the LaBranche Wetlands; 2) freshwater diversion outfall management at Violet in the Central Wetlands; 3) hydrologic management of impoundments in the Bayou Sauvage Refuge and at Eden Isles and; 4) shoreline protection to protect perched marshes along the MRGO.

Gurney, David, Southeastern Louisiana University, Hammond, LA:

Fecal Coliform Levels in the Tangipahoa: The Present Situation

The Tangipahoa River was closed to swimming and boating in 1987 due to high fecal coliform levels in the water. This paper examines the existing records on fecal coliform levels in the Tangipahoa, along with data on flow rates, water stages, and precipitation, to identify patterns and trends in current fecal coliform readings.

Hastings, Robert W., Southeastern Louisiana University, Hammond, LA:

Overview of Programs of Turtle Cove Environmental Research Station

Turtle Cove Environmental Research Station is a field research and educational facility of Southeastern Louisiana University located in the Lake Pontchartrain estuarine ecosystem. Because of its location at the upper end of this major estuary, Turtle Cove is within one hour by boat of various wetland environments, along with their aquatic counterparts, ranging from fresh to saline, including bottomland hardwood forests, cypress swamps, and marshes. Moreover, each of these habitat types exists in pristine, degraded, and restored states. The facility complements other field stations in the state (and nation) that are more concerned with higher salinity marine waters or fresh waters. Major environments present near Turtle Cove include estuarine and riverine aquatic systems, estuarine/freshwater ecotone, cypress/tupelo swamps, brackish, fresh, and intermediate marshes, and bottomland hardwood forests.

Activities at Turtle Cove address four major prioritized goals: scholarly research, university teaching, teacher training, and public service. Major research areas include biogeochemistry, ecophysiology, estuarine ecology, hydrology, population biology, and restoration ecology. Major educational programs include courses in estuarine and wetlands ecology, teacher training workshops, summer programs in science literacy, summer workshops for high school students, and field trips for K-12 school groups.

The Turtle Cove facility occupies a three story wood frame building crafted of virgin cypress in 1908 as a private hunting and fishing lodge. The facility is located on the Manchac Wildlife Management Area in St. John the Baptist Parish, Louisiana, along the south shore of Pass Manchac two miles west of Lake Pontchartrain. It has been administered since 1981 by Southeastern Louisiana University under a lease agreement with the Louisiana Wildlife and Fisheries Commission. The main building contains a first floor research area, second floor living quarters with kitchen, bathrooms, and bedrooms to sleep about 15, and third floor conference/class room and office. Since Turtle Cove is accessible only by boat, several vessels, including 25' lake skiffs as well as canoes, are available for use by station visitors. Boat sheds are located at Turtle Cove and five miles west of the research station along Galva Canal (shared with the Louisiana Department of Wildlife and Fisheries), where boats are kept for transportation to the station. Transportation for large groups is provided by a 38' pontoon boat. Various nets and other field equipment, as well as holding tanks (with aeration and filtration) for aquatic organisms, are available. Compound and stereo microscopes and other research equipment are also available.

Plans are being developed for the construction of new facilities at Turtle Cove, including a new research and educational building, additional housing facilities for both students and researchers, and increased storage and maintenance space for boats. In keeping with SLU's image as a dynamic and rapidly growing institution of higher learning, Turtle Cove is also developing as an active research and educational facility. The overall goal is to make Turtle Cove a nationally recognized center for environmental education and research in low-salinity environments.

Hawes, Suzanne R., Corps of Engineers, New Orleans District:

Restoration of a Marsh in the La Branche Ponds - A Case Study

The La Branche wetlands on the south shore of Lake Pontchartrain in Louisiana were formed by the Mississippi River about 1,700 years ago. The "prairie tremblante" (flotant marsh) near the lake was an uncultivated part of the La Branche plantation. Between 1905 and 1910, an Illinois land developer bought over 8,000 acres of these wetlands. He dug canals, drained the land, and farmed truck crops. In September 1915, a hurricane with 140 mph winds along the coast, pushed large volumes of water into Lake Pontchartrain. The tidal surge broke the levees and flooded the farm.

In 1990, Congress passed the Coastal Wetlands Planning, Protection, and Restoration Act in an attempt to restore coastal Louisiana which is losing 25 square miles of marsh per year. A Task Force made up of five Federal agencies and the State of Louisiana plans and implements the restoration process. The Corps suggested creation of marsh in the La Branche ponds just north of I-10 and the project was approved in November 1991. Even though this effort was expensive in terms of cost per habitat unit, it was selected because the Task Force felt that it was a showcase project.

From 1991 to 1993 a cost sharing agreement was worked out between the Corps and the State of Louisiana, and design work and environmental compliance were completed. The planning was closely coordinated with the parish, landowners, and duck hunters. Biologists determined that the optimum marsh elevation was between + 0.75 and + 1.34 NGVD and recommended that area be 70 percent marsh and 30 percent ponds and bayous at the end of five years. The maximum elevation of the dredged material was set at + 4 feet NGVD. Preconstruction monitoring showed that the existing ponds contained abundant submerged aquatic vegetation dominated by water milfoil and coontail. A rim of dwarf spikerush surrounded the shallow ponds. The sediments of the ponds had a high water content and bulk densities ranging from 0.64 to 1.06 g/cc. Organic matter ranged from 8 to 27 percent and the soil salinity was 3.5 ppt.

Originally, the borrow site was directly in front of the Bonnet Carré Spillway where the hole would refill quickly. Further analysis showed that the material there was sand while the material in front of the marsh creation site was lighter and better suited for marsh creation. The nearer site also reduced the cost of the project due to a shorter pumping distance.

The contract was awarded to T. L. James and Co. Inc. of New Orleans for $2,489,000 on November 10, 1993. They started construction of containment dikes in December and pumping began on March 7, 1994. One month later, the area was filled. They used a much larger dredge than anticipated which lowered project costs but caused some problems with material spillage. Water exiting the area contained much more sediment than planned and began filling an adjacent canal. A closure at the southern end of the canal was breached and the excess sediment filled a deep hole in a canal and spilled in the nearby Big Marlborough pond. In July 1994, the new marsh was aerially seeded with 8,000 pounds of Japanese millet provided by the Natural Resources Conservation Service and St. Charles Parish. Within a week the millet sprouted and by September it was producing seeds.

The first postconstruction aerial photography was flown on December 19, 1994, and showed 350 acres of new vegetation, 131 acres of existing vegetation and 34 acres of open water. Over 20 species of emergent marsh plants were recorded. Approximately 20,000 waterfowl were reported to be using the site during the winter of 1994/5 and duck hunters did very well, especially during teal season. By the spring of 1995, a break had occurred in the containment levee on the southeast side allowing a few more natural ponds and bayous to be formed within the site. These attracted wading birds and allowed some fishery access. National Marine Fisheries Service requested that trenasses be dug to allow even more estuarine access. An interagency group made a field inspection and determined that ponding of rainwater was keeping the area a wetland. The group decided that trenasses would drain the area instead of adding water. The sediment which spilled out of the weir formed a valuable mudflat in the Big Marlborough area and south of I-10. These areas may colonize with plants during prolonged low water. However, they have caused problems for the local duck hunters who have trouble reaching their blinds. They first requested that a channel be dug through the created marsh, but this was denied. The Corps is pursuing the possibility of an access trenasse between the railroad and I-10.

Since project completion, the monitoring team has had problems accessing the site. In the spring of 1994, they were able to place only 6 staff gauges because of logistical problems. Readings were taken five times in 1994/5. The reading indicated that the gauges were not reliable and thus they will not be used in data analysis. In the spring of 1996, location markers will be placed and vegetation and sediment sampling will be initiated.

The pioneer plant in the spring of 1995 was a buttercup. By summer, millet seeds from the previous year were sprouting and other wetland plants such as three square and wiregrass colonized. On higher areas, shrubs came in. Later in the year, camphorweed was present in large numbers and dwarf spikerush covered the lowest areas. Alligators and nutria frequent the site as well as endangered species such as brown pelicans, peregrine falcons, and bald eagles.

Lessons learned from this project:

  • even with extensive sediment data, prediction of settled height is difficult;
  • monitoring needs to be aggressively pursued even if logistics are a problem;
  • close coordination with locals can occasionally lead to excessive expectations;
  • marsh can be successfully created from dredged material.

Hester, M. W., Department of Biological Sciences, Southeastern Louisiana University, Hammond, La., Mendelssohn, I. A., and McKee, K. L., Wetland Biogeochemistry Institute, Louisiana State University, Baton Rouge, LA:

Population Variation in Salt Tolerance in Panicum hemitomon: Morphological and Physiological Investigations

Plant material was collected from nineteen Louisiana populations of Panicum hemitomon (maidencane), a fresh marsh dominant. Each population was vegetatively propagated from a single stem under uniform, non-saline conditions in a greenhouse for six vegetative generations to ensure that each population was represented by a single genotype and to alleviate any pre-existing acclimation to field salinity differences. Five replicates of each population were potted in a commercial potting medium and plant morphometric measurements were obtained. Populations were screened for intraspecific variation in salt tolerance by subjecting them to a weekly, stepwise salinity increase of 2 ppt until 50% death of aboveground tissue was observed, which we defined as the lethal salinity level. Populations displayed highly significant differences (intraspecific variation) in lethal salinity level, which ranged from 7.6 ppt to 12.0 ppt. Plant morphometric variables also displayed highly significant population differences, with several plant size characteristics showing significant positive correlations with salt tolerance. Of these, leaf length and leaf area (of the two youngest expanded leaves per stem) were able to explain 43% and 46%, respectively, of the variation in lethal salinity level among populations. To further investigate factors potentially associated with population differences in salt tolerance, we subjected a subset of six populations ranging from highly salt tolerant to poorly salt tolerant to a sublethal salinity excursion of 4 ppt and measured plant photosynthetic response, biomass partitioning, and numerous physiological and biochemical responses after one week (early harvest) and after five weeks (late harvest). In the early harvest, highly salt-tolerant populations had significantly greater photosynthetic rates, midday leaf xylem pressures, aboveground, belowground, and total covariable-adjusted biomass than the poorly salt-tolerant populations. Also in the early harvest, highly salt-tolerant populations displayed significantly lower leaf tissue cation concentrations, percentage dead tissue, and leaf proline concentrations (a stress metabolite and compatible solute that accumulates to significant levels only after a threshold of salinity stress is exceeded) than the poorly salt-tolerant populations. By the late harvest, many of the physiological differences were no longer significant, with all populations displaying signs of cumulative salinity stress. Nonetheless, in the late harvest the highly salt-tolerant populations were able to maintain significantly greater biomass production with less tissue death than the poorly salt-tolerant populations. Greater salinity tolerance in the more highly salt-tolerant populations of Panicum hemitomon appears to be the combined result of morphology interacting with an initially superior physiological response to salinity stress events.

Joseph, Jr. Randolph, Crowley, Louisiana, USDA-Natural Resources Conservation Service:

Water Quality Initiatives on Dairy Operations in the Florida Parishes of Louisiana

In 1987, the Louisiana Department of Environmental Quality and the Department of Health and Hospitals posted the Tangipahoa River and all of its tributaries against all primary and secondary water contract sports due to the high levels of the fecal coliform bacteria. The sources of the bacteria were traced back to inadequate sewage treatment plants in towns and villages, inadequate septic tanks in rural areas, dairy operations in the immediate area, and dairy operations and urban areas from the State of Mississippi.

Because of the high priority of this water quality problem, state and federal agencies focused their attention on the problem and implemented programs to address the sources. The agricultural industry including USDA and local soil and water conservation districts, focused on assisting dairy farmers in installing zero-discharge animal waste systems. Special cost-sharing programs such as the Special Water Quality Incentive Program of 1988, the Middle Tangipahoa Land Treatment Watershed, the Louisiana Department of Environmental Quality Special Cost-Sharing Program and the Lake Pontchartrain Basin Foundation Cost-Sharing Program, were implemented to supplement the annual cost-sharing programs for waste management systems.

The Natural Resources Conservation Service (NRCS), formally the Soil Conservation Service, provide oversight on insuring that all systems installed met quality standards established by governing agencies. As of February, 1996, according to figures gathered from the Louisiana Department of Health and Hospitals, Milking Division, approximately 501 dairies existed in the eight parish area. To date, approximately 220 dairy operations have installed waste management systems through NRCS. Once certified by NRCS, the dairy operation qualifies for cost sharing. The maximum cost-shared amount in most programs is $13,000.00. However, in the Middle Tangipahoa Treatment Watershed Program, a producer may qualify for a maximum cost-share of up to $100,000.00. The cost share rate of these programs may be 50/50 or 75/25; government to individual respectively.

Currently NRCS has approximately 100 dairy operations on schedule to install waste management systems within the next two years. This leaves approximately 181 dairy operations still in need of technical and financial assistance. Although test results do not show a proportional decline in the fecal coliform bacteria, lower averages and mediums have been recorded between 1988 and 1993.

Kendrick, D. Brian, Buchtel, James R., and Burkholder, David M., Louisiana Department of Natural Resources Coastal Restoration Division, Baton Rouge, LA:

Construction of a 7100'-long Segmented Geotextile Tube Breakwater along the North Shore of Lake Pontchartrain

In the late summer of 1996, the Louisiana Department of Natural Resources Coastal Restoration Division (LDNR/CRD) will begin construction of a segmented breakwater (State Project No. 4355NP4) along the Fontainebleau State Park shoreline for the LA Department of Culture Recreation and Tourism. The breakwater is being constructed in response to a shoreline rate of loss of approximately 10 feet per year. Funding for this project is being obtained from the state Mitigation Trust Fund and from private contributors.

The breakwater structure will be located in St. Tammany Parish and extend approximately 7100 feet from Bayou Castine and the City of Mandeville Harbor on the west to the Main Pavilion/Recreational Area of the park on the east. The primary objectives of the breakwater are to protect the shoreline along Lake Pontchartrain and to prevent further breaching of a narrow strip of land between the lake and marsh to the north. The breakwater will also prevent brackish water intrusion into the adjacent cypress marsh located within the State Park by providing soil accretion along the lake shoreline. The structure will also provide an area of low wave energy to support submerged aquatic vegetation such as water-celery (Vallisneria americana) and fish and marine species such as speckled trout (Cynoscion nebulosus) and blue crabs (Callinectes sapidus).

The project will consist of eighteen (18) segmented geotextile tube structures, 250-foot long, spaced approximately 100 feet apart, and two (2) continuous 250-foot long tubes adjacent to the east harbor jetty. The structures will be positioned approximately 300 to 500 feet from the existing shoreline. The gap distance between each structure is designed to allow for some accretion of sediment along the shoreline. A woven geotextile apron will underlie each structure to prevent erosion from undermining the tubes. Each tube will be approximately 25 feet in circumference (8' theoretical diameter) filled with imported sand or on-site dredged silty sand material. The fill material will be stabilized using a 5% Portland cement with added geotextile fibers to increase tensile strength to prevent the possible damage of the tubes due to severe storms or vandalism. The cement stabilized material will be pumped into the tubes with only a minimum release of material expected through the fabric. It is estimated that approximately 10,000 cubic yards of material will be required to fill the estimated 20 tubes.

The project has received permits from the Louisiana Department of Environmental Quality (Water Quality Certification), the LDNR (Coastal Use Permit) and the United States Army Corps of Engineers (Section 10/404 Permit). The entire 7100-foot project length is included under one permit; however, construction may be in phases due to limited funding. The breakwater foot print will cover approximately 1 to 1Ľ acres of state water bottoms over the project length. However, over 75 acres of state water bottoms and 7100 linear feet of shoreline will be protected from further erosion and degradation.

Kenwood, Clifford M., Lake Pontchartrain Basin Foundation, New Orleans, LA:

Using the Internet for Environmental Education and Advocacy

The Lake Pontchartrain Basin Foundation currently operates a world wide web site at The site serves three primary purposes: education, advocacy and development. [2008 Update: The site is now located at]

Visitors to the site are greeted by a live video image of Lake Pontchartrain. The site also features a satellite photo of the Pontchartrain Basin that is divided up into areas that visitors can "click" to access information on that geographical region. For example, if the area marked "Grassbeds" is clicked, an image of the lake's seagrasses appears along with text on the subject.

The site will also feature an advocacy page where net-surfers can e-mail elected officials on critical issues directly from the page. For example, if comments are being solicited on a permit, users can click a button to send an e-mail on the subject. Future plans include using the site as a repository for water quality data.

The site will be displayed "live" to show its functions. Design and maintenance of the site was donated by Pertuit Online Marketing Service, Inc. of Metairie.

Clifford Kenwood, Lake Pontchartrain Basin Foundation, Metairie, LA 70009-6965;   Frank T. Manheim U.S. Geological Survey, Woods Hole MA 02543, and  S. Jeffress Williams, U.S. Geological Survey, Reston, VA 22092:

An Upgraded Environmental and Geological Bibliography for Lake Pontchartrain

A bibliography relating to environmental science information on Lake Pontchartrain was compiled by the Lake Pontchartrain Basin Foundation (LPBF) for a research symposium in 1992. This bibliography, encompassing approximately 2000 titles, has been converted to a desktop computer spreadsheet / database format. The work was done in cooperation with USGS, which has begun further bibliographic research as a part of a broader cooperative study of the Lake Pontchartrain Basin (LPB).

The LPBF reference list is based in part on earlier bibliographies by Mary G. Curry (1984, with updates in 1986 and 1987), and by Rod E. Emmer in 1984-5. The references were mainly in brief, 6-field ASCII text format, including keywords. Many items refer to newspaper, government or survey reports that are not widely distributed but may have importance for full documentation of the LPB environment. The following provisional list summarizes included subjects: bibliography, biology, chemistry, contamination - pollution, economics, engineering, erosion, geology, history, hydrology and floods, overviews, municipal affairs, petroleum, planning, political and legal, and wetlands.

USGS staff will coordinate entering supplementary references in standard desktop bibliographic software format. This includes large National Technical Information Service (NTIS) documents from the U.S. Army Corps of Engineers and other federal agencies, Louisiana State agency documents, journals, dissertations and other sources. When completed, the two databases will be merged. Dr. Shea Penland, of the Louisiana State University Coastal Studies Institute will be involved in the work, and additional cooperators are welcomed.

Desktop bibliographic software permits comprehensive search capability and automatic output into common publication and database formats. Retrieval of needed titles and referencing for reports is faster and more accurate and consistent. The envisaged bibliography is designed to be available in widely accessible desktop spreadsheet or database software computer formats and to permit users to expand reference subsets with their own supplementary references and research notes.

Koplitz, Lynn Vogel; Nguyen, Anh, Department of Chemistry, Loyola University, New Orleans, LA 70118; and Flowers, George C., Department of Geology, Tulane University, New Orleans, LA 70118; and McPherson, Gary L.; Clymire, Joe; Dowling, Jeff; Ramirez, Suzie; Washington, Will, Department of Chemistry, Tulane University, New Orleans, LA 70118:

Sediment Contaminant Profiles in Bayou Trepagnier Before and After Diversion of Industrial Effluent

The Pb, Cr, Cu, and Zn contents of sediments and associated pore waters at 27 sites along Bayou Trepagnier were determined in June 1994 and again in June 1995 from grab samples. Sediment acid volatile sulfide (AVS) values, an indicator of the ability of sediments to scavenge dissolved heavy metals from the water column, were also measured both summers. Effluent from the Shell Norco Manufacturing Complex entered the bayou at its headwaters until late February of 1995 when it was diverted to the Mississippi River as required by the USEPA. Hypotheses offered herein to explain observations are based primarily on these two data sets for samples collected one year apart. These suggested explanations will be tested in part by analysis of data to be collected in a similar fashion this coming June 1996.

In general, concentrations of all four contaminants are relatively low near the former effluent outfall (site 0), increase to maximum values in the upstream third of the bayou (sites 20-60), then gradually fall to background levels near the confluence with Bayou LaBranche (site 160). (Note that each site marker indicates an additional 100 ft. downstream.) From '94 to '95 lead, copper and chromium values fell markedly in the upper third of the bayou (sites 0-50). The analytical concentration of Pb and Cu at site 0 decreased by about half while Cr went down to about one-fifth of its '94 value. Zinc sediment concentrations decreased most between sites 24 and 64, generally declining by about 20-25%. High lead values found at sites 16 (1540 ppm), 72 (995 ppm) and 88 (786 ppm) in '94 were far lower in '95 (all ~300-350 ppm). However, lead and chromium were appreciably higher (Pb up to 1500 ppm from 350 ppm, Cr up to 750 ppm from 250 ppm) downstream at site 104 in '95, and chromium increased markedly at sites 48 (up to 1220 ppm from 385 ppm) and 80 (up to 1350 ppm from 750 ppm).

These observations may indicate deposition of material downstream from an upstream area of suspension, or dissolution, either due to physical factors such as abruptly decreased flow allowing suspended material to drop out of the water column, or because of changes in water chemistry from mixing with tributary water causing insolubility and precipitation of certain metal phases. For sites 110-160, the last mile of the bayou closest to Lake Pontchartrain, all four contaminant distributions were essentially unchanged from '94 to '95, suggesting that any suspended or dissolved material did not migrate to or through this end of the bayou. If release events are occurring, they are probably short-lived and extend only a short distance since AVS is abundantly available to scavenge dissolved heavy metals. Monthly monitoring of bottom water does not show high levels of dissolved (filterable) metals.

Pore water and sediment concentrations for individual metals are not correlated except in the case of chromium (r2 = 0.605 for a linear least squares fit of pore water vs. sediment values, '95 data). Zinc and copper sediment values show strong correlations with themselves from '94 to '95 (94/95 Zn r2 = 0.874, Cu r2 = 0.717), while lead and chromium are not well correlated between years (Cr r2 = 0.300, Pb r2 = 0.081). These observations and the previous discussion indicate that multiple dominant modes of contaminant transport (e.g. suspended particulates, adsorbed, or dissolved species) are operating in the bayou.

Lead seems to be influenced extensively by inputs from the adjacent spoil banks. Elutriate tests performed with spoil bank samples show the highest release of lead from solid to filtered "dissolved" fraction (passes 0.45 m filter) at the spoil bank sites with the highest lead levels. Sediment samples for this study were collected near the western side of the bayou close to the site markers. For June 1994, the lead distribution pattern in the bottom sediments is similar to that of the spoil banks. However, the June 1995 samples do not display this pattern and more closely resemble the distribution shown by mid-channel samples collected in early 1994 and analyzed by EA Environmental Consulting for Shell. These facts imply a homogenization of lead over the channel cross section, probably due to suspension and redistribution by motor boats.

Preliminary MINTEQA2 model calculations show that truly dissolved phases are not responsible for the pore water metal concentrations since the calculated values are at least three orders of magnitude lower than those found by GFAAS analysis. However, the analyzed samples probably contain colloidal particles that pass through the 0.45 m filters and become dissolved by strong acid added later. This microcolloidal phase, which may also contain appreciable amounts of adsorbed heavy metal species, is a current focus of investigation. In addition, dissolved organic matter (DOM) may account for some of the dissolved metal load given the obviously high concentration of DOM indicated by the tea color of the water. Including generic DOM in the MINTEQA2 calculations had no effect on dissolved Cu2+ or Cu1+, but it raised the solubilities of Zn2+ and Cr3+ by about a factor of 10, and increased the total dissolved Pb2+ by about 200 times.

From 2/94 to 6/94, Pb increased from 400 ppm to 1000 ppm at a site in Engineer's Canal adjacent to a small cross channel connecting it to Bayou Trepagnier. Recent intense studies of Bayou Trepagnier by at least five different research groups have been accompanied by heightened motor boat activity in the bayou and canal. This activity may account for some, or most, of the observed redistribution of sediment contaminants.

List, Jeffrey H. and Signell, Richard P., U.S. Geological Survey, Woods Hole, MA:

Wave Modeling in Lake Pontchartrain

The currents associated with wind-generated waves are likely to be the primary cause of sediment resuspension in Lake Pontchartrain. Wave-induced resuspension enables transport by weak steady flows and may have a strong influence on the overall distribution of bottom sediment types in the basin. In order to better understand the distribution of bottom sediment types and to predict the transport and deposition of these sediments, we applied the wave prediction model HISWA (Hindcasting Shallow-Water Waves) to Lake Pontchartrain.

The HISWA model is uniquely suited for modeling waves in restricted basins like Lake Pontchartrain because it accounts for the local generation of waves by wind and it simulates shallow-water effects on waves including refraction, shoaling, bottom friction, and breaking. HISWA's ability to simulate waves in Lake Pontchartrain is evaluated through comparisons with field data collected at three sites within the basin in the spring and summer of 1995. Correlations between measured and predicted waves are generally high, especially for wind events lasting more than one day.

Several applications of HISWA to studies of the basin's sediment distribution are presented. For individual storm events, HISWA predictions are compared with satellite imagery showing the patterns of suspended sediment. This provides an assessment of the degree to which model results can be used for predicting the initiation of sediment resuspension in the basin.

In addition, HISWA simulations using a wide range of wind speeds and directions are weighted with statistics from long-term wind observations to give the regional "climate" of bottom orbital velocity (showing the spatial and temporal variability of wave-induced currents at the bottom). The degree to which this orbital velocity climate controls the distribution of sediments within the basin is evaluated through comparisons with maps of bottom sediment type.

Lopez, John A., Amoco, New Orleans, Louisiana:

Historical Oil and Gas Production in Lake Pontchartrain

Lake Pontchartrain is significantly less productive in oil and gas production compared to the rest of south Louisiana. This is probably due to its lack of geologic complexity and its unique geologic setting. Eight of nine fields in the Lake are clustered in the southwest corner in closest proximity to more typical South Louisiana geology. Only one or two small gas fields have been found in the Northern half of the Lake. Over 30 years of drilling, approximately 103 billion cubic feet of gas and 8.5 million barrels of oil have been produced from the Lake. Approximately 120 exploratory wells and 35 development wells have been drilled in Lake Pontchartrain. This has resulted in 46 producing wells in nine fields with an average field size of 16 billion cubic feet of gas. The largest field is Block 41 which has produced approximately 47 billion cubic feet of gas. This largest field in 348th in field size rank for South Louisiana oil and gas fields. As of 1995, 22 wells were active with total production of 9 million cubic feet of gas per day and a small amount of oil. Most exploratory wells have targeted the Miocene, but there are 10 deep wells in excess of 15,000 feet. There are also several active gas transmission lines, but no oil pipelines in the Lake. Oil and condensate produced in the lake has traditionally been transported by barge at approximately 10,000 barrels per load. On average, South Louisiana is expected to produce 1.3 million barrels Oil (barrels of oil equivalent) per square mile. Lake Pontchartrain has produced 46,000 barrels oil (barrel of oil equivalent) per mile. Lake Pontchartrain has production is less than 1/20th of normal oil and gas production in south Louisiana.

Why is Lake Pontchartrain 20 times less productive than the rest of South Louisiana? Lake Pontchartrain happens to overlie a geologic region which is in a transitional position between two major geologic provinces. The Lower Cretaceous margin and platform lie northward of the Lake and has low production. The typical south Louisiana salt dome and growth faulted Tertiary basin lies southward of the Lake and New Orleans. In between and underneath the Lake is the margin of the Tertiary basin. Salt domes -- so prolific elsewhere -- are not present beneath the Lake. Major growth faults are also absent and consequently significant rollover structures are absent. Lake Pontchartrain lacks the traditional key geologic features for major oil and gas production.

Although there have been environmental incidents from the oil and gas activities in the Lake, the total environmental impact from all these activities is minor or negligible. There was a minor oil spill of approximately 10 barrels of oil (420 gallons to the public) in 1992. In addition, in 1990 one operator was discharging produced water without a discharge permit. The latest incident was in 1993 when a 1 barrel spill was reported. Even with these more "significant" incidents no direct environmental damage has been documented. Other less significant incidents have occurred with apparently no observable impact. In spite of this record, there are still environmental risks associated with oil and gas activities within the lake. First, existing facilities have deteriorated and there is evidence that they have not been properly maintained. Second, traditional oil and condensate are barged out of the Lake. Barging oil is considered a relatively risky mode of transport by posing the risk of an oil spill. Third, drilling exploratory wells, especially deep, poses a risk of blowouts and spills. Simply because there has not been a truly significant incident in the past, it is unwarranted to say that there is absolutely no environmental risks now or in the future. In addition the Lake and its estuaries are relatively vulnerable due to the Lake's restricted interchange to other water bodies. How likely is a significant environmental incident ? . . . how great is the potential impact? These are legitimate questions which should be discussed openly. Such discussion should consider the unique environmental setting of the Lake and the practices of those who are permitted to operate in the Lake.

Lopez, John A., Amoco, New Orleans Louisiana:

Review and Update of Active Geologic Faulting in Lake Pontchartrain

Active geologic faults in Lake Pontchartrain have been previously described in 1991. These faults have apparent surface expression and strongly suggest that at least some of these faults are currently active faults. The en echelon fault system in the Lake are the southeastward continuation of the well documented and active Baton Rouge - Denham Springs faults system in the Baton Rouge area. Documentation of geologic faulting in Lake Pontchartrain has continued since they were first described in 1991. This includes: 1) GPS positioning of bridge offsets 2) acquisition of US Geological Survey high resolution seismic 3) more complete mapping of all the faults in Lake Pontchartrain 4) new quantification Railroad and bridge offset at fault traces.

1) GPS positioning confirms the coincidence of bridge offset and projection of subsurface faults to the lake surface. This also demonstrates a common strike orientation to both the surface and subsurface fault data.

2) The US Geological Survey high-resolution seismic data does show significant lateral changes at the projected position of the faults in eastern Lake Pontchartrain. These changes are interpreted as faults. However other interpretations may be plausible. The high resolution seismic positioned parallel to the Causeway does not show any lateral change at all. A fault is not seen on shallow seismic at the projected trace of the fault. near the northshore. Two possible explanations are: 1) the projection of the subsurface fault to the bridge offset is coincidental and the fault is not active , 2) the fault offset is too small to be detected by even the high resolution seismic.

3) In 1995 a regional subsurface map of Lake Pontchartrain was released in a report from the Louisiana Dept. of Conservation. This map used more complete seismic coverage than had been previously available and demonstrated two regional fault trends in Lake Pontchartrain. The map confirms the northwest-southeast trending faults which parallels the north shore. These faults match the previously mapped trend which is the probable extension of the Baton Rouge-Denham Springs fault trend. A second fault system trending east-west was also mapped in the southern half of Lake Pontchartrain. These faults are more sinuous and are a continuation of the typical east-west fault trend seen throughout south Louisiana. The east-west fault system converges with the northwest-southeast fault system in the southeast corner of Lake Pontchartrain.

4) Simple visual observation and crude surveying has been used to attempt to quantify the apparent bridge offset by the faulting. Recent observations suggests possibly higher rates of fault movement than previously suggested. In particular the Southern Railroad bridge has shown 2-3 inches offset at the southern fault position where the bridge was completely re-built in 1986 and 1987. The northern fault trace shows similar new offset of the Southern railroad bridge. This is 2-3 times higher than the previous rate of fault movement suggested in 1991 by monitoring and observation at that time. Most likely, fault movement is episodic and the lower rates may be longer term average. However it is possible that the fault movement is accelerating.

Lyons, S.E., Holy Cross School, New Orleans, LA:

Project F.U.R. (Fight Urban Runoff)

PROJECT F.U.R. (Fight Urban Runoff) is an ongoing environmental service project of students at Holy Cross School since 1990. PROJECT F.U.R. raises public awareness of a used oil recycling program that benefits the Lake Pontchartrain Basin and the nation through energy conservation and the reduction of hazardous waste. If used motor oil is not recycled and is discarded improperly, it can present a serious hazard to our environment. Parish recycling centers, service stations and quick-change oil franchises are serving as collection centers. The oil collected at these sites is reprocessed and prepared for future marketing. With the donation of a "Crusher l" used motor oil filter compactor, Project F.U.R. members are able to collect used motor oil filters and recycle them. Thus, the filter and the used oil inside are reclaimed and recycled, preventing them from posing a hazard to the Lake Pontchartrain Basin ecosystem.

Project F.U.R.'s speaker program focuses public attention on urban runoff and its effects on Lake Pontchartrain. Flyers and brochures explain what residents can do to help stem this toxic tide. Knowledge without action is sterile. Other civic action projects by PROJECT F.U.R. include the "STENCIL-A-CANAL" project. A network of high school students and teachers joins forces with civic organizations and local residents to stencil the logo, "Dump No Waste--Drains to Lake" on storm drain covers throughout the area. This serves to remind residents that hazardous materials dumped in storm drains have a negative impact on the Lake Pontchartrain ecosystem.

PROJECT F.U.R. conducts water quality testing in the Lake Pontchartrain Basin at several sites. Data is collected and evaluated for evidence of a decrease in runoff pollutants, allowing PROJECT F.U.R. students to fully participate in the scientific process. In addition, weekly water testing of the Industrial Canal is contributing to a comparative study of drainage canals in New Orleans, currently under study by the Lake Pontchartrain Basin Foundation.

"Wetlands Ecology: A Service-Learning Project" is the latest phase of Project F.U. R. Student team leaders have learned wetlands ecology firsthand by participating in field camps at selected wetlands sites and by participating in volunteer projects to restore wetlands. They have served as peer instructors to other students in environmental science classes on a series of field trips.

A healthy lake is a major recreational and economic asset to New Orleans and the surrounding parishes. Achieving that goal through public education and civic action is the intent of PROJECT F.U.R. The dimensions of the challenge are enormous, but with its effort supported by the Lake Pontchartrain Basin Foundation and the Louisiana Department of Environmental Quality, PROJECT F.U.R. has been very successful. While rendering significant service to the community, these students are experiencing the scientific, social, and political components of environmental issues.

For their efforts PROJECT F.U.R. has been the subject of magazine and television coverage and has won local, state, and national awards, including the President's Environmental Youth Award for EPA Region 6 and Youth Conservationists of the Year for the Louisiana Wildlife Federation.

Manheim, Frank T. U.S. Geological Survey, Woods Hole MA 02543, Charles W. Holmes, U.S. Geological Survey, Lakewood CO, 80225, and  S. Jeffress Williams, U.S. Geological Survey, Reston VA 22092:

A New Geochemical Database for Sediments from the Lake Pontchartrain Basin

As a part of a broad-based regional study of Lake Pontchartrain Basin (LPB) the U.S. Geological Survey is beginning compilation of a data base on chemical and other properties of bottom sediments. In addition to larger studies by university-based scientists, the U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, USGS, and Louisiana state agencies, we will attempt to include all other available published and unpublished material. We welcome cooperation in this effort and propose to make all data publicly available on CD-ROM upon conclusion of the study.

Uniform methodologies, such as are employed in the larger studies of the Lake Pontchartrain region by the Louisiana Department of Environmental Quality, and by Flowers and Isphording, help assure internal comparability of data. However, until recently, the advisability of compiling chemical data from heterogeneous historical sources has been questioned owing to differences in sampling and analytical methodology, degree of documentation, and quality. Studies of heterogeneous historical sediment data from Massachusetts Bay have shown that special batch screening techniques are able to identify anomalous values that result from systematic errors and other internal inconsistencies which exceed limits for natural variability determined by well-controlled methods. This experience and the advantages of extending spatial and temporal data at relatively low cost, and developing better guidelines for new data collection have encouraged planning of a more comprehensive data base.

To facilitate cooperation, we will make available to interested cooperators a detailed data dictionary. It accommodates most available chemical information on toxic components, both inorganic and organic, as well as major element data, sediment texture and other parameters. The data dictionary can be provided as a data entry template in floppy disk format. The format is compatible with most commercial database and spreadsheet software for desktop computers. We attempt to document data from original sources in sufficient detail to minimize the necessity of users re-accessing such sources except where data other than sediments is sought.

Materne, M.D., Natural Resources Conservation Service, Baton Rouge, LA, and Croughan, T.P. LA Agricultural Experiment Stations, Crowley, LA:

Biotechnology Developments in Plant Materials for Coastal Restoration

The effectiveness of using plants to control erosion in upland situations has long been recognized. Interest has more recently developed in applying this approach to erosion control along shorelines and in coastal wetlands. On both economic and environmental grounds, plants offer an attractive adjunct to the structural approaches to erosion control typically utilized in these environments. While physical structures predictably affect a relatively limited area, plants can spread to surrounding areas and beyond, both holding what remains while reclaiming lost ground. Vegetative planting and seeding have been shown to retard the conversion of marsh to open water, to reduce the erosion of lake shorelines, canal banks, dunes or other marsh-water interfaces, and to promote the re-establishment of emergent wetland vegetation. Plantings are often a low-cost marsh restoration and enhancement technique applicable in all coastal basins and across a wide range of habitat types, from freshwater swamps to saline marshes.

Despite the advantages that vegetation holds over many other physical approaches to coastal restoration, technical problems currently limit wider utilization of this biological approach to coastal wetland erosion control. To date, much of the vegetative restoration work has been centered around plant species such as Spartina alterniflora (smooth cordgrass) and Scirpus californicus (California bulrush). Both of these species establish quickly and spread vigorously by means of vegetative reproduction. Both have demonstrated unique erosion control qualities and sediment accretion in areas of high wave energies and in areas of high suspended sediment loads. Both species develop dense canopies, stem densities, and extensive root development. However, like most coastal wetland species, both are poor seed producers and hand transplanting is the prevailing method for establishing. Planting even small areas is costly, laborious, and has limited applications given the inaccessibility of much of Louisiana's coastal marshes.

Consequently, two areas that the Natural Resources Conservation Service's plant materials program is concentrating in are advancing biotechnology techniques for mass production and methods for large scale planting application. Systems currently being developed for field testing are 1) economically mass production of plant materials designed to accommodate remote and extended planting sites (encapsulated plantlets); 2) genetic improvement of plants to extend their utility, range, and performance in varied wetland restoration application (laboratory-cultured cell lines); and 3) mechanical methods for establishing extended planting sites (hydro-sodding).

Meffert, Douglas J., and Good, Bill Ph. D., Coastal Restoration Division, Louisiana Department of Natural Resources, Baton Rouge, LA 70804-9396:

Ecosystem Management in the Breton Sound Estuary

The Breton Sound Estuary in Louisiana, an area 280,287 square km in extent, annually loses an average of 408 square km of marsh. This system has suffered a series of major anthropogenic impacts including the completion of flood-control levees along the Mississippi River in the 1920's, the Mississippi River Gulf Outlet (a major navigation canal) in 1963, and a labyrinth of smaller canal for oil extraction primarily from 1950 through 1980. Thus, the estuary was decoupled from alluvial water sediment and nutrients; then extensively connected to marine processes. The most immediate impact of these actions was a landward shift in salinity. Secondary impacts included land loss, habitat degradation, loss of biodiversity, and an inland shift in oyster production. Various attempts to ameliorate the direct and indirect consequences of these hydrologic alterations include several freshwater diversion projects constructed by different entities for various management objectives. However, environmental administration of the area has been evolving in the direction of ecosystem-level management. The authors discuss the remaining hurdles that must be overcome in the final phase towards ecosystem management of this real-world case study. Both the scientific and policy-related challenges and opportunities associated with such a strategy will be discussed.

Melancon, George E., Louisiana Department of Wildlife and Fisheries, Ferriday, LA.; Chabreck, Robert H., School of Forestry, Wildlife, and Fisheries, Louisiana State University Agricultural Center, Baton Rouge, LA. 70803:

Wintering Lesser Scaup on Lake Pontchartrain and their Relationship to Mollusk Abundance

Lake Pontchartrain is an important wintering area of Lesser Scaup (Aythya affinis) in southeastern Louisiana. This study was conducted to evaluate current Lesser Scaup use of the lake and the relationship between Lesser Scaup concentrations on the lake and the abundance of mollusks. Biweekly surveys were made on the lake from October 1994 through March 1995. Lesser Scaup were first observed on 21 October 1994. Peak winter populations were present on 23 January 1995. Lesser Scaup were not observed on Lake Pontchartrain after March 8,1995.

Aerial surveys were conducted in December, January, and February to estimate Lesser Scaup numbers on the lake and concentration levels in different areas of the lake. Peak winter populations were estimated to be 250,762 birds on 17 January 1995. Bottom samples were collected in areas of Lake Pontchartrain where scaup abundance was classified as high, medium, low, and absent, and mollusks present were recorded by species, size, and abundance. Areas with high Lesser Scaup densities contained a greater volume of Rangia cuneata in the <1 cm size class than the areas of low Lesser Scaup densities. Bottom samples in areas with an absence of Lesser Scaup had greater volume of Rangia cuneata in the 1-3 cm size class.

A strong positive relationship occurred between distance from the shore and Lesser Scaup densities. No relationship was found between distance from the shore and volume of Rangia cuneata in any of the three size classes. Lesser Scaup apparently are unable to use the medium or larger-sized Rangia cuneata as a food source and thus concentrate in areas of Lake Pontchartrain were there are greater amounts of the smaller Rangia cuneata.

Miller, M.S., Department of Biological Sciences, Southeastern Louisiana University, Hammond LA:

A Critical Evaluation of the Wetlands Value Assessment

The Wetland Value Assessment (WVA) is a quantitative habitat-based assessment methodology developed for the use in prioritizing project proposals submitted for funding under the Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA) of 1990 (Mitchell, et. al. 1990). The WVA uses only existing or readily obtainable data. The WVA ranking procedure quantifies the feasibility and quality of proposed wetland restoration projects and is measured in Average Annual Habitat Units (AAHU's). The WVA, developed by an Environmental Work Group assembled under the Planning and Evaluation Subcommittee of the CWPPRA Technical Committee, is a modification of the Habitat Evaluation Procedures (HEP) developed by the U.S. Fish and Wildlife Service (U.S. Fish and Wildlife Service 1980) (Mitchell, et. al. 1990). HEP is used throughout the country by various Federal and State agencies in evaluating the impact of development projects on fish and wildlife resources. The WVA operates under the assumption that optimal conditions for fish and wildlife habitat can be characterized, and that existing or predicted conditions can be compared to that optimum to provide an index of habitat quality (Mitchell, et. al. 1990). There are six variables that have been chosen to characterize four wetland types, and these variables range in value from 0.1-1. A variable with a value of 0.1 would be considered to be of the lowest habitat value possible, while a variable with a value of 1 would be the representative of the best possible habitat value. The six variables used in the WVA include: V1-- The percentage of wetland area covered by emergent vegetation ( ( 10% canopy cover ), V2-- Percent of open water area dominated ( > 50% canopy cover ) by aquatic vegetation, V3--Marsh edge and interspersion, V4--Percent of open water area ( 1.5 feet deep, in relation to marsh surface, V5--Mean high salinity during the growing season (March through November), V6--Aquatic organism access. When these variables are ranked in a specific WVA, they are then run through the current formula and a single Habitat Suitability Index (HSI) is the result. The HSI is then transformed into it's relative number of AAHU's and weighed against other project AAHU's. The projects with the highest rankings for the year are then considered for funding in accordance with CWPPRA.

Two different Wetland Value Assessment (WVA) models were analyzed using the statistical package SYSTAT. The first model is the current WVA used by the State of LA to determine the value of a wetland area. The second is a simpler, arithmetic formula. After completing a Pearson Correlation Matrix for the data set it was found that the current formula was very highly correlated (0.98) with the derived formula, indicating that the formulas outputs were very similar. It was also discovered that V1 (emergent Marsh) was highly correlated with both models, suggesting that it was the driving force behind the models.

Multiple regressions were performed, with high degrees of predictive abilities for both models. The driving force behind the regressions was also V1, with V3, V4, and V5 only contributing little to the current model. When the same regression was done on the arithmetic model all variables took on a more even importance (except V1, which was still the most important). After eliminating certain variables from the models, regressions were run again. These runs gave lessened predictive abilities for both models (except when only V5 was removed). This suggests that all variables contribute some importance except variable 5.

Loading of variables onto certain "factors" was the next step in the analysis. Variables 1 and 3 loaded on a factor which could be considered the emergent marsh factor. Variables 5 and 6 loaded on a factor which could be designated salinity. Variables 2 and 4 loaded on the aquatic vegetation factor. Both model outcomes (HSI) loaded heavily on to factor 1 (the marsh factor), which is precisely what CWPPRA was designed to protect and restore.

Pedalino, Francesca A. and Poirrier, Michael A., Department of Biological Sciences, University of New Orleans:

The Status of Benthic Invertebrate Populations in Southern Lake Pontchartrain

A non-mixing, bottom layer of more saline water occurs in southern Lake Pontchartrain due to saltwater intrusion through the Inner Harbor Navigation Canal. Organic material from urban runoff and algal growth accumulates in this bottom layer and reduces dissolved oxygen concentrations which causes stress on benthic organisms. Areas of the bottom which lack large invertebrates have been termed "Dead Zones". Conditions in Lake Pontchartrain during the summer of 1995 were favorable for the development of saline bottom waters with a high concentration of organic material. Heavy rainfall in April and early May of 1995 introduced plant nutrients and organic material. After this rainfall and associated flooding, a period of over twenty days without rainfall occurred. This dry period allowed the movement of saline bottom water into the estuary. Nutrient rich Mississippi River water entered Lake Pontchartrain through the Bonnet Carré Spillway during June and July of 1995, and intense blooms of the blue-green algae and associated fish kills occurred during July of 1995.

Sites in southern Lake Pontchartrain were sampled on November 19, 1995 to determine the condition of bottom waters and the status of benthic invertebrate populations. Salinity and dissolved oxygen measurements were made and benthic invertebrates sampled at nine stations along two transects which ran from the mouth of the Inner Harbor Navigation Canal west to the Lake Pontchartrain Causeway at 2.5 and 5.0 miles from shore.

Although strong north winds which can mix south shore waters occurred before sampling, salinity stratification and low bottom dissolved oxygen concentrations were present. Past studies of benthic invertebrate populations in the same study area found communities indicative of stressful conditions near the Inner Harbor Navigation Canal and a transition to communities indicative of normal conditions occurring with distance from the canal. In contrast, November 1995 samples indicated stressful conditions at all sites on both transects. The number of mollusks, including the clam Rangia cuneata and the snails Texadina sphinctosoma and Probythinella louisianae was low at all sites. The benthic invertebrate community was dominated by oligochaetes and polychaetes which are known to tolerate stress. The presence of few mollusks and numerous annelids at all sites indicates that adverse environmental conditions occurred throughout the study area.

Penland, S., Louisiana State University, Baton Rouge, LA; Wayne, L., Louisiana State University, Baton Rouge, LA; Britsch, D., U.S. Army Corps of Engineers, New Orleans, LA; and Williams, S.J., U.S. Geological Survey, Reston, VA:

Coastal Land Loss Rates, Forms, and Processes in the Pontchartrain Basin

The Pontchartrain Basin in this coastal land loss study extended from Lake Maurepas through Lake Pontchartrain to Lake Borgne and includes the areas north of the MRGO navigation channel. Utilizing the USACE-NOD coastal land loss GIS database, the authors used a subset of this information to quantify the rates, forms, and processes of loss in the Pontchartrain Basin.

The rate of coastal land loss in the Pontchartrain Basin has averaged -1.97mi2yr-1 between the 1930's and 1990's. The rates of loss have accelerated from 1.43 mi2yr-1 in 1930's/1950's to -3.07 mi2yr-1 in 1950's/1970's. Since these time periods, the rate of land loss has decreased from -1.97 mi2yr-1 in 1970's/1980's to -1.41 mi2yr-1 in the 1980's/1990's. Coastal land loss occurs throughout the basin, however, the eastern basin has greater loss than the western basin.

To further quantify coastal land loss, a geomorphic classification was developed for GIS analysis. Coastal land loss has two basic forms, shoreline loss and interior loss. Shoreline describes areas of loss that occur relative to existing water bodies. Interior describes areas of loss that occur independent of existing water bodies. The next level of the hierarchy addresses the water body type most closely related to loss. For shoreline areas, this level depicts the type of water body physically related to the loss. Four classes of shoreline loss were established:

  1. gulf - the outer shoreline facing the Gulf of Mexico,
  2. bay - semi-enclosed water body with direct contact to the Gulf of Mexico,
  3. lake - enclosed or semi-enclosed water body with no direct contact to the Gulf of Mexico, and
  4. channel - linear water body that commonly connects other water bodies.

For interior areas, this level of the classification depicts the water body type that is most similar new interior loss. Two interior classes were established:

  1. pond - enclosed or semi-enclosed water body with minor connections to the existing drainage network, and
  2. channel - narrow, linear water body.

Once the forms of loss were delineated and mapped, a process classification was developed to quantify cause. The first level of the classification hierarchy addresses the basic processes of land loss. For purposes of this classification scheme, the term land is defined as all subaerial materials including surface vegetation, sediments, and organic soils. Three primary land loss processes were identified:

  1. erosion - mechanical removal and transport of land by water action,
  2. submergence - increase of water level relative to ground surface elevation, and
  3. direct removal - physical removal of land by actions other than water.

A fourth category, undetermined, is included for those areas to which no assignment can be made.

The second level of the process classification scheme identifies the primary physical actions that are associated with each loss process. This level of the classification includes both natural and cultural actions. The action of erosion include:

  1. scour - mechanical removal of land by water, and
  2. transport - suspension and conveyance of land by water.

The actions of submergence include:

  1. flooding - short-term increase in water level,
  2. substrate collapse - reduction in substrate thickness, and
  3. subsidence - reduction in land surface elevation.

The actions of direct removal include:

  1. excavation - extraction and transport of land to another location, and
  2. burning - oxidation of the organic component of land.

At the third level of the process classification scheme, issues of cause emerge. This level identifies the natural and cultural catalysts to the physical actions. Natural catalysts include phenomena such as wind, loss of vegetation, high water, loading, and faulting. Cultural catalysts include human activities such as dredging of navigation channels, building of impoundments, resource extraction, excavation of ponds, and fires.

The fourth level of the process classification identities the factors known to stimulate natural and cultural land loss catalysts. This is a diverse category of information which includes natural and cultural events, activities, and structures. Factors included at this level of the classification scheme include storms, herbivory, sediment transport, recreation, agriculture, commerce, levees, and engineered coastal preservation/restoration structures.

In the Pontchartrain Basin, natural erosion and submergence account for a small percent of the coastal land loss problem. A greater percentage is related to man's activities such as canals, highways, failed land reclamation, borrow pits, and altered hydrology. This paper presents the results of the GIS land loss analysis.

Poirrier, Michael A., Department of Biological Sciences, University of New Orleans:

The Big Stink of 1995: Observations on Algal Blooms, Fish Kills and Grassbed Decline

Intense blue-green algal blooms fish kills, grassbed loss and dead zone expansion occurred in Lake Pontchartrain during the summer of 1995. Unusual environmental conditions were associated with the algal blooms, and related events. Runoff from heavy rainfall in April and early May, and Mississippi River water which entered through the Bonnet Carré Spillway in June and July lowered salinity and introduced plant nutrients. In addition, the weather during the summer of 1995 was hotter and dryer than normal.

Blooms of the blue-green alga, Anabaena occurred from late June through mid July 1995. Algal distribution and density were difficult to quantify because algae accumulated near the surface and moved with wind. At times it was present throughout the estuary, and at other times it was concentrated on the north or south shore depending upon wind direction. Thick accumulations of algae near the shore and in embayments resembled concentrated pea soup.

Fish kills occurred in Bayou St. John and the West End Marinas during July. They were caused by the accumulation of decaying blue-green algae in areas where fish could not move away. A Myriophyllum grassbed which was located near the mouth of Bayou St. John died due to overgrowth by filamentous algae and shading by Anabaena. The decaying vegetation contributed to the bayou fish kill. Shading by Anabaena, the growth of epiphytes and changes in water chemistry adversely affect Vallisneria grassbeds in other areas.

The blue-green algal blooms and associated events are indicative of high levels of plant nutrients. Runoff from record rainfall in May and the flow of Mississippi River water through the Bonnet Carré Spillway during mid-summer were sources of nutrients. The hot, static weather with little rainfall during June was probably another major contributor to the bloom. Algae and nutrients were not flushed out of the estuary by freshwater discharge, or wind generated water level changes, but were retained in clear, warm, low-salinity water for an unusually long period. Water exchange associated with tropical storm Erin in early August flushed out the algae, increased salinity and abruptly ended this eutrophic episode.

Preslan, J.E., Adams, S., Bollinger, J., George, W.J. and Anderson, M.B. Tulane University Medical School, 1430 Tulane Ave., New Orleans, LA 70112:

General Water Quality and Sediment Conditions in the LaBranche Wetlands Assessed Using In Situ Testing and Sediment Core Evaluations

Bayou Trepagnier, located within the LaBranche wetlands, is a waterway adjacent to the Shell Oil Manufacturing Complex in Norco, Louisiana which has sediments that have been contaminated with petroleum residues since the mid 1950's. Recent studies conducted by our laboratory have identified the presence of polyaromatic hydrocarbons and elevated levels of lead and chromium as significant contaminants in the sediments. Between February 1994 and December 1995, nitrate, nitrite, ammonia, phosphate and silicate levels in the water column have been monitored periodically. Nutrient and metal fluxes as well as oxygen profiles were assessed at a heavily contaminated site (Marker 105) in Bayou Trepagnier and at a control site in Bayou Traverse during March, 1994 and September, 1995. The studies were conducted using 6 foot long pipes driven into the floor of the Bayou to isolate a segment of the sediment and the overlying water column. Changes in water quality were observed under conditions of reduced water flow and reduced exchange of oxygen with the air. The differences observed between the two time periods and between the two sampling sites may reflect differences in seasonal conditions, site contamination, and the change in the pattern of discharge from manufacturing plant activities into the Bayou. Density, organic content, and oxygen demand of the sediments from various locations within the wetlands were also measured. Supported by D.O.E.

Sabaté, R.W., Stiffey, A.V., and Dewailly, E.L., Lumitox Gulf L.C., New Orleans, LA:

Testing Toxicity of Lake Pontchartrain Waters with a Bioluminescent Organism

Water samples taken in the Spring of 1994 from nine stations near the southeastern shore of Lake Pontchartrain for Lake Pontchartrain Basin Foundation by the New Orleans Power Squadron were shared with a private toxicity testing laboratory. These samples were tested by the Foundation only for coliform bacteria. They were tested on a contemporary basis by the laboratory for acute total toxicity with a microscopic, naturally bioluminescent marine dinoflagellate alga, Pyrocystis lunula. When exposed in the dark to stress, such as stirring, this organism emits a strong, pale-green light, or bioluminescence (the sailor's "phosphorescence"). Light values are measured, one minute per sample replicate (usually five), by a hand-held, portable toxicity tester. Laboratory incubation time is four hours; range-finder tests in the field take only one hour. The presence of toxicants measurably reduces the amount of light emitted, as compared to a non-toxic control. This relative light reduction, in percentage terms, is called "bioluminescence inhibition," or BI. Variation among negative controls and replicate test samples - and among positive controls (sodium lauryl sulphate) from day to day - typically is less than 10%. The test organism is very sensitive to strong toxins. For example, concentrations in ppt of some household pesticides and herbicides cause total light extinction. Empirically, BI<10 is regarded as non-toxic, BI>50 gives rise to concern, and 10<BI<50 is a range of low to mild toxicity. EPA permits discharging oil-well drilling fluids with BI<63 directly into the sea. Maximum BI observed in the Lake samples was 45, mildly toxic. The easternmost samples, off Lincoln Beach, consistently were the least toxic: BI = 10 to 23. Some BI values correlate with coliform counts, while most seem completely independent. There being no scientific basis for the test organism to be sensitive directly to coliform bacteria, it must be sensitive to contaminants carried into the Lake from some sources along with the bacteria. Repeat testing of the same samples eleven days later generated a significantly lower BI for eight of the nine stations (average 27% lower overall), suggesting natural remediation. This implies that Lake Pontchartrain will cleanse itself quickly of contaminants if their sources are eliminated.

Shaffer, G., Greene, M., Llewellyn, D., Myers, R., and Forder, D., Department of Biological Sciences, Southeastern Louisiana University, Hammond, LA:

Swamp Restoration in Louisiana: Amelioration of Multiple Stressors - Is it worth the Cost?

In the early 1900s, old-growth baldcypress (Taxodium distichum) was completely logged out of most of Louisiana's swamps. Natural regeneration of swamp was limited and many areas converted to marsh or open water. This effort was conducted to isolate the major factors prohibiting cypress regeneration. Specifically, hundreds of baldcypress seedlings were planted in several factorial treatment arrangements that included nutrient augmentation (fertilized vs. unfertilized), management of entangling vegetation (managed vs. unmanaged), herbivore protection (Tubex tree shelters, PVC sleeves, Tanglefoot), elevation (raised vs. not raised), substrate type (natural, topsoil, sand), silvicultural practices (clear cut, select cut, uncut), and salinity inundations (0 ppt, 5 ppt, 10 ppt). Nutrient augmentation nearly doubled growth in an estuarine location, but decreased growth in a riparian location. Seedlings that were managed grew nearly two times greater in diameter than unmanaged seedlings. However, seedlings that were unmanaged grew nearly two times greater in height than managed seedlings. Relatively inexpensive, recyclable, PVC sleeves were more effective at prohibiting herbivory than Tubex Tree Shelters; unprotected seedlings experienced 100% mortality. Initial restoration efforts should be concentrated in raised areas, such as natural levees. Successful coppicing, of cypress but not tupelo (Nyssa aquatica), is occurring in clear- and select-cut areas. Cypress can tolerate in situ salinity pulses of up to 10 ppt. In all, these studies indicate that biotic factors are primarily responsible for the lack of cypress regeneration in Louisiana, not the prevalent, but largely untested, hypothesis of salt water intrusion. Moreover, it is likely that, with a combination of management techniques, it is possible to restore swamp habitat in this area. Though labor intensive in the short run (i.e., first few years), once established these trees may survive for many centuries.

Signell, R.P., U.S. Geological Survey, Woods Hole, MA, List, J.H., USGS, Woods Hole, MA and Stumpf, R.P., USGS, St. Petersburg, FL:

Modeling Storm-Driven Circulation in Lake Pontchartrain

The U.S. Geological Survey is conducting a study of storm-driven sediment resuspension and transport in Lake Pontchartrain. Central to understanding the transport of sediment during storm events is determining the lake circulation patterns due to remote and local forcing. Chuang and Swenson (Journal of Geophysical Research, 1981) and Swenson and Chuang (Estuary, Coastal and Shelf Science, 1983) showed that non-tidal water-level variations in Lake Borgne dominate the flux of water through Rigolets and Chef Menteur passes and thus play a large role in flushing of the lake. In addition to remote forcing, circulation is driven by the winds over the lake. Some aspects of the depth-averaged circulation response to local wind were described in a modeling study by Hamilton et al (Journal of the Waterway, Port, Coastal and Ocean Division, ASCE, 1982). This study showed that transport in shallow water around the periphery of the lake was downwind, whereas transport in the deeper central region of the lake was upwind.

We use a three-dimensional numerical model to understand the relative contributions of remotely-driven and locally-driven currents on the circulation in Lake Pontchartrain. Results of the modeling effort indicate that remote forcing dominates the circulation near the passes in the eastern end of the lake, while local forcing dominates water movement in the western end. Locally-driven circulation responds to the magnitude of the wind, while the remotely-driven circulation responds to changes in Lake Borgne (often related to changes in the alongshore component of wind). During typical storms with winds from the north-northeast or the south-southeast, currents along the south coast near New Orleans generally transport material westward, while material in the central region moves against the wind. When periods of sustained winds are followed by a drop in coastal sea level, a large amount of suspended sediment can be flushed from the Lake. Remote sensing images of turbidity are used to document the distribution of suspended sediments during strong wind events.

Soudamini Mishra , Flowers, G. C., and Kohl, B., Geology Department, Tulane University, New Orleans, La., 70118:

Benthic Foraminifera and Heavy Metals in the Lake Pontchartrain

Lake Pontchartrain is the largest brackish water body in Louisiana. The lake's ecosystem is threatened by urban runoff from the New Orleans metropolitan area and agricultural runoff from surrounding parishes. Benthic organisms are a good indicator of pollution because they have low motility, as well as high sensitivity to changes in water quality caused by pollution. This study focuses on the use of benthic foraminifera in Lake Pontchartrain to monitor the impact of heavy metal pollution on benthic communities. Bottom sediments were collected from stations in the vicinity of outfall canals along the south shore of Lake Pontchartrain. A split of each sample was used to determine the heavy metal content using ICPAES and particle size distribution using the sieve/hydrometer method. Benthic foraminifera were concentrated from the other split by wet sieving. Foraminifera samples were dissolved and analyzed for As, Al, Cr, Cu, Pb, Zn, Ba, Mn, Fe, Ni, and Co contents. As, Pb, Ba, and Co levels were found to be elevated in bottom sediments taken in the vicinity of outfall canals. These metal concentrations are higher than average values for the lake taken as a whole and average shale values. Average lake sediment values for As were not available for comparison. Benthic foraminifera found in the lake sediments are dominated by agglutinated varieties; a total of 10 species of foraminifera were found in bottom sediment samples. The assemblage consists of (in order of abundance) Ammobaculites subcatelanulatus, Ammoscalaria? dilatatus, Ammobaculites exiguus, Ammotium directus, Miliammina fusca, Ammonia beccarii, Arenoparella mexicana, Ammoastuta inepta, Elphidium gunteri salsum and Ammontium salsum. Comparison of the concentration of Cu, Cr, Pb, and Zn in foraminifera tests and sediments suggests that Cu and Zn may be preferentially absorbed in foraminiferal tests relative to Pb and Cr. Cr in foraminifera tests is a little higher than in the sediment, whereas the concentration of Pb is approximately equal to the sediment concentration. It is not known whether or not this conclusion holds in general given the relatively small area where samples were collected.

Steiner, S.J. and Grymes, J.M., III, LSU Southern Regional Climate Center, Baton Rouge, LA:

Lake Pontchartrain's Meteorological Monitoring Network

Considerable energy and resources have been and will be invested into various environmental assessments of the Lake Pontchartrain Basin. In many cases, these research endeavors require meteorological and climatological information to adequately describe the entire environmental characteristics of the nation's fifth largest natural lake (excluding the Great Lakes). In past years, the availability of detailed, representative long-term weather/climate data has been restricted to observations taken at New Orleans International (Moisant) and Lakefront Airports. Unfortunately, as many researchers are well-aware, these two sites fall short of providing a complete picture of the variability of the basin's meteorological characteristics.

Unbeknownst to most of us, the National Weather Service has maintained a series of four data-collection stations around Lake Pontchartrain for more than fifteen years. These automated platforms were installed to provide NWS personnel with supplemental real-time information regarding meteorological and hydrological conditions impacting the lake, particularly during unusual or severe weather. Currently, stations are located near the Rigolets at Fort Pike ('East Lake'), at the foot of the Causeway ('North Shore'), near Frenier ('West Lake') and along the Causeway near the center of the lake ('Mid Lake').

As the network was created for real-time assessment, little consideration was given to its potential for research services and support. Thus, no provisions were established by the NWS for the long-term archival of these data. Recognizing these data as a unique resource for regional assessment of meteorological, climatological and hydrological characteristics of the Pontchartrain Basin, LSU's Southern Regional Climate Center (SRCC) implemented a data collection and storage scheme based on data delivered via INTERNET feeds. The SRCC's Pontchartrain archive of hourly data currently extends from January 1993 to the present, with a valid-report frequency of approximately 90% for the variables reported by the platforms.

Variables recorded on an hourly basis by all four automated stations include air and water temperatures, lake level (relative water level), precipitation, and wind speed and direction. In addition, the 'North Shore' site reports dewpoint temperature and visibility. The regional monitoring of meteorological characteristics can be further augmented by the inclusion of hourly observations from the manned weather offices Lakefront Airport as well as data from nearby Moisant Airport and the NWS Regional Forecast Office in Slidell. Middle- and upper-atmospheric data are also recorded twice each day at Slidell's NWS site.

Already the SRCC has used these data to provide support services and climatological interpretations of basin characteristics for the US Army Corps of Engineers and the USGS. The purpose for this presentation is to notify other environmental researchers that the SRCC serves as a resource for their respective studies as well. More importantly, our goal is to extend beyond the limitations of a data-provision center and to assist the Pontchartrain research community by providing climatological expertise for the evaluation of the basin.

Steller, Diana Lee, Reptile Defense Network, Baton Rouge, LA:

Restoring an Urban Estuary with Christmas Trees and Flowers: Making a Home Fit for the Birds

Coastal and shoreline erosion are reducing the viability of our estuarine heritage. The seaward shoreline relentlessly retreats while interior marshes deteriorate and emergent vegetation gives way to open water. The project area is located in the eastern portion of the Mississippi Deltaic Plain. Only 16 miles east of the New Orleans Central Business District, the 20,000+ acre area borders Lakes Pontchartrain and Borgne and contains fresh, intermediate, and brackish marshes, bottomland hardwoods, barrier island live oak hammocks, and submersed aquatics. Home to over 50,000 waterfowl annually, the area contains a national register property, 19 archeological sites, a bald eagle nest, four state-ranked plants and animals including american alligator, three state-ranked natural communities, wading bird rookeries, and abundant fisheries resources. The story of the Bayou Sauvage Refuge is similar to that of many areas throughout the Pontchartrain Basin, Louisiana and the entire Gulf Coast. Over half of the refuge has been impounded and impacted by hurricane protection levees, three major roads including an Interstate and two state highways, one oil and gas pipeline canal, two railroads and one major waterway (GIWW) leaving a little over half of the area free access to Lake Pontchartrain. In addition to these man-induced changes, subsidence rates average one foot per century and shoreline erosion rates have been estimated at 4.8 - 11 ft/yr on Lake Borgne and 10.2 to 37 ft/yr along Lake Pontchartrain (CEI 1984). Thus, natural processes combined with human intervention have led to the loss of 117 ac/yr between 1956 and 1988 (USFWS 1994). Large interior ponds developed within and outside of the impounded/managed areas. Over the last three decades coastal and shoreline erosion processes have breached stable shorelines and caused massive deterioration of interior marshes. The resources at risk are the wetland marsh and submersed aquatic grassbed habitats and the recreation, fishery, waterfowl and wildlife they support. This project, funded by the Gulf of Mexico Program, uses wave-damping fences built in a checkerboard pattern and natural occurring emergent and aquatic plantings to reduce fetch and wave action, encourage sedimentation, build habitat, and protect adjacent shorelines. The techniques involved are new and are combined in a unique way to maximize their success in this environment.

The overall objective of the project is to reduce coastal erosion and increase marsh and grassbed habitats. Subsidiary objectives are to reduce fetch, dampen waves and seiche, stabilize sediment, encourage sediment accretion, increase submersed aquatic and emergent vegetation growth, and increase the land to open water ration. Specific objectives include building 3,000 ft of wave-damping fence structures in an open checkerboard pattern in shallow open water ponds to reduce fetch, damp waves and encourage local sediment accretion, stabilizing fragile bordering shorelines and marshes surrounding the open water ponds by reducing fetch and wave action, documenting sediment accretion and shoreline movement by monthly monitoring of sediment elevation relative to fixed posts and shoreline markers, and planting 5,000 submersed aquatics and emergent plants adjacent to wave-damping fences (e.g. Vallisneria americana (celery grass), Najas guadalupensis (southern naiad), Iris giganticaerulea (large blue iris), Crinum americanum (swamp lily), and Scirpus californicus (giant bulrush). A subsidiary objective is to expand public awareness of resource problems and solutions by volunteer participation in construction and planting of the project.

The first study area is an impounded fresh to intermediate pond and a brackish estuarine pond. Both have experienced drastic increases in their pond areas and reduction in their vegetated areas. Thesite 1 interior pond is about a foot deep, over a mile wide and adjacent to a pipeline canal. The large fetch to depth ration causes high wave action and constant resuspension of the fine organic bottom sediments. Breaches in the pipeline canal cause water flow into the canal and overall loss of sediment from the pond into the deeper (8 ft) canal. Unstable sediment conditions and high turbidity are factors in the lack of any submersed aquatics in the pond. The project criss-crosses areas in the pond near canal breaches with a checkerboard pattern of treated wood Christmas tree fences. Standing water vegetation has been planted adjacent to and within the completed fences. Similar wave-damping fences built in the area have been shown to reduce wave action. The criss-cross design of earthen levees has been shown to be very effective in reducing fetch and wave action.

The second study area is an estuarine pond about a 1/2 mile wide and only a few inches deep. It is bordered by a fragile marsh covered island on the lakefront. This marsh has breached and currently high waters from Lake Pontchartrain are further deteriorating the interior pond. Wave-damping fences in a criss-cross pattern have been built surrounding the remaining bordering marsh and across the ponds in order to bolster and expand the shoreline as well as to reduce fetch and wave action in the pond. Submersed aquatics will be planted in the open water, as well as marshhay cordgrass in the intertidal zone. Both of these sites will be monitored monthly after construction and planting of the project. Parameters to be monitored include percent survival, percent over and average height of plantings, sediment accretion, and shoreline retreat or advance.

Tao, Q., Zganjar, C., Westphal, K.A., and Penland, S., Louisiana State University, Baton Rouge, LA;  Mathies, L., Nord, B., and Gunn, R., U.S. Army Corps of Engineers, New Orleans, LA:

The Beneficial Use of Dredged Material at the Mississippi River Gulf Outlet - Jetties Between 1985 and 1995

The Mississippi River Gulf Outlet (MRGO) navigation channel is located in southeast Louisiana. The U.S. Army Corps of Engineers-New Orleans District (USACE-NOD) periodically dredges this navigation channel and beneficially uses this material to create, enhance, and restore the surrounding coastal wetlands. The USACE-NOD in cooperation with Louisiana State University-Coastal Studies Institute documents the creation and enhancement of new coastal land using dredge material along the MRGO through the Beneficial Use Monitoring Program (BUMP).

The total area of the MRGO study area in 1985 was 2603.58 acres. Natural processes accounted for 2283.65 acres or 88 percent of the total area. Man-made processes related to beneficial use of dredge material accounted for 319.93 acres or 12 percent of the total area. The total area of the MRGO study area in 1995 was 2473.87 acres. Natural processes accounted for 2056.73 acres or 83 percent of the total area. Man-made processes related to the beneficial use of dredge material accounted for 417.14 acres or 17 percent of the total area (Table 1). The MRGO study area decreased by -129.71 acres between 1985 and 1995. Natural processes were responsible for -226.92 acres of decrease and the beneficial use of dredge material was responsible for -97.21 acres of increase.

Natural processes are responsible for eroding salt marsh. Beneficial use of dredged material appears to be effective in creating shrub/scrub, bare land, and salt marsh. The field surveys indicate the correct stacking heights are optimal for creating salt marsh and to a lesser extent shrub/scrub. The optimal elevation for marsh creation appears to be less than +2 feet MSL. At the MRGO - Jetty study area, the beneficial use of dredged material created 122.51 acres of new habitat between 1985 and 1995. This total includes: 54.99 acres of salt marsh, 33.64 acres of shrub/scrub, 19.04 acres of bare land, and 14.84 acres of beach. Within the MRGO - Jetty study area, the beneficial use of dredged material reduced the amount of coastal land loss by 67 percent.

Change in Total Acres of each Habitat in the MRGO - Jetty Study Area between 1985 and 1995

Natural Salt Marsh 2092.10 1830.26 -261.84
Natural Upland 123.57 173.90 +50.33
Natural Shrub/Scrub 0 16.66 +16.66
Natural Bare Land 37.54 5.47 -32.07
Natural Beach 30.44 30.44 0
Total Natural Habitats 2283.65 2056.73 -226.92
Man-made Salt Marsh 190.64 245.63 +54.99
Man-made Upland 32.48 7.18 -25.30
Man-made Shrub/Scrub 65.91 99.55 +33.64
Man-made Bare Land 30.90 49.94 +19.04
Man-made Beach 0 14.84 +14.84
Total Man-made Habitats 319.93 417.14 97.21
HABITAT TOTAL 2603.58 2473.87 -129.71

  * in acres

Thompson, Bruce A., Allen, Yvonne C., Coastal Fisheries Institute, Louisiana State University, Baton Rouge, La., and Glas, Patricia S., Environmental Protection Agency, Environmental Research Laboratory, Gulf Breeze, FL:

The Potential Impact and Distribution of Zebra Mussel, Dreissena polymorpha, in the Lake Pontchartrain System from Introduction via the Bonnet Carré Spillway

It is well known that the introduction of an exotic species into an ecosystem, whether intentional or accidental, can be very disruptive. Unfortunately, we have a long history of introductions, both plant and animal, into Louisiana's aquatic environment. Recently Louisiana has experienced an additional infestation, the zebra mussel, one of the most damaging exotic species present in the aquatic systems of North America. Following its introduction into the Great Lakes and based on European studies, some scientists believed that the warm southern United States water temperatures would be lethal enough to the zebra mussels that permanent populations would not become established. Unfortunately, this has proven to be incorrect and this species has spread southward in the Mississippi River to the delta near the Gulf of Mexico. We have documented records from several dozen localities from the Mississippi River in Louisiana, and projections are being made about the potential for the zebra mussel to spread outside the Mississippi River. It has been recorded in the Atchafalaya River and the potential exists for spreading via pumping stations and floodway gates. Periodic openings of the Bonnet Carré Spillway gates during times of high waters presents a pathway for the zebra mussel to spread eastward into the Lake Pontchartrain ecosystem. In the spring of 1994 and again in 1996 we have been monitoring densities and temporal patterns of zebra mussel larvae (veligers) to document the potential for their introduction outside the Mississippi River. In 1994 high Mississippi River levels led the U.S. Army Corps of Engineers to do a test opening of a few Bonnet Carré Spillway gates and we documented that zebra mussel veligers were drawn from the Mississippi River into the floodway environment. Flood gates were opened to maintain only about 8000 cfs, but the six mile connection between the Mississippi River and Lake Pontchartrain remained open for ten days. For comparison, the Spillway was open for 75 days in 1973 and 35 days in 1983. While the gates were open in 1994, zebra mussel veligers densities outside the spillway increased from 0.2 to 19.3 veligers/L, and densities within the floodway increased from 0.2 to 7.3 veligers/L. There is therefore a clear conduit for introduction through the floodway. So far, there is no evidence that this introduction resulted in zebra mussels becoming established in Lake Pontchartrain. However, as has been the case in most interconnected waterways, the eventual establishment of zebra mussels is not if, but when.

Previous studies have described the physical and biological character of the Lake Pontchartrain system. Average maximum water temperatures are between 30O and 31OC. Studies have indicated that zebra mussels can be maintained indefinitely in the lab at 30OC, but that temperatures above this value are ultimately lethal. Zebra mussels are primarily freshwater, but have been found in salinities as high as 12ppt. It appears as though zebra mussels will be able to tolerate salinities in Lake Pontchartrain (often less than 5ppt), especially the west side, provided that any increases in salinity are gradual.

Changes at the ecosystem level will be more difficult to predict. Dreissena will encounter a wider variety of other more closely related mollusks in Lake Pontchartrain than in other, less saline systems. There are also a substantial number of predators in the lake. Examination of stomachs of blue catfish from the Mississippi River shows this species to be a major predator of zebra mussels. Predators may reduce zebra mussel densities in accessible areas. They will not, however, reduce densities in inaccessible areas, and the potential impacts here may be substantial and costly.

Turner, R.E., Coastal Ecology Institute, Louisiana State University, Baton Rouge, LA:

Water Quality, Diversions and Cost

The 1995 river diversion into Lake Pontchartrain apparently caused an extensive algal bloom -- something that should be anticipated to be in common to other similarly-sized river diversions into Louisiana estuaries. Louisiana wetlands may be the sink for nutrients to compensate for these diversions. How water moves within and through wetlands determines several aspects of the nutrient exchanges with the overlying water. If the residence time is short, then there is less time for nutrient uptake and release. The recent experimental release of Mississippi River water through the Bonnet Carré spillway resulted in virtually no changes in dissolved nitrogen and phosphorus as water moved from the diversion site to Lake Pontchartrain, probably because the times, unless deoxygenation occurs (anerobic conditions greatly favor ammonia and phosphate release, for example). Further, the higher the loading rate, the lower the efficiency of removal in overland flow systems, at least. Finally, waterflow through (or under) a wetland has a higher removal rate of some nitrogen and phosphorus forms than waterflow over a wetland. Swamps appear to take up some nitrogen and phosphorus forms, whereas wetlands with emergent macrophytes release these nutrients. An exception is the brackish and saline marshes of western Terrebonne parish that appear to release phosphate, whereas the same marsh type in Barataria Bay is absorbs phosphate.

The application of results from a few measurements to broad management principles generally applicable to river diversions should be done cautiously if only because the scaling up from small experimental study areas to something the size (and expense) of a river diversion has not done before in Louisiana. This is not to say that river diversions should not be attempted or not attempted. Observations on the effects of the planned diversion at Davis Pond will shed light on the net transport rates and effects on phytoplankton in the downstream water bodies.

Williams, S.J., U.S. Geological Survey, Reston, VA;  Penland and Connor, P., Louisiana State University, Baton Rouge, LA; Britsch, D., U.S. Army Corps of Engineers, New Orleans, LA; Holmes, C., U.S. Geological Survey, Denver, CO.; Kindinger, J., U.S. Geological Survey, St. Petersburg, FL; and Lopez, J.A., Amoco, New Orleans, LA:

Holocene Geologic Framework and Development of the Pontchartrain Basin

The Pontchartrain Basin is the largest marginal deltaic basin in North America measuring about 200 km along dip and 75 km along strike. This basin is bounded by incised Pleistocene terraces with small bayhead deltas to the north, the Mississippi River delta plain to the south/southwest, and the relict Pine Island barrier shoreline trend to the south/ southeast. Over the last 150 years the urban growth of New Orleans and the northshore communities and the exploitation of natural resources have severely altered the environmental quality of the Pontchartrain Basin. In 1994, the USGS began a multidisiplinary study of the geology, geomorphology, coastal processes, and environmental quality of the Pontchartrain Basin for use by Federal, state and local officials in coastal management and restoration planning. This paper builds on pre-existing geological information integrated with new high resolution seismic, vibracore, and geochemical data.

The radiocarbon database for the Pontchartrain Basin chronicles a complex history of sea level withdrawal, rise, and stillstand followed by barrier shoreline development and deltaic enclosure. During the Late Wisconsin low stand, the Pontchartrain region was dissected by a series of entrenched river valleys. Sea level rose during deglaciation, submerging this landscape and depositing a blanket of transgressive nearshore deposits. At sea level stillstand + 4000 years ago, the Gulf of Mexico shoreline was eroding into the Pleistocene terraces and the formation of a barrier shoreline trend was initiated. Termed the Pine Island barrier trend, the combination of sandy sediments moving west along the mainland shoreline of Mississippi and those transported to the coast by the Pearl River supplied the material to build the large recurved spit and barrier island complex. Backbarrier deposits and extensive shell reefs infilled this open estuary. About + 3000 years ago the St. Bernard delta complex built out of the incised Mississippi River valley to the southeast enclosing the Pontchartrain Basin to the south and eventually including the Pine Island barrier shoreline trend. During this time, the Basin began to fill with prodelta, delta front, and crevasse deposits. Cypress swamp and fresh marshes formed in the upper basin and intermediate to saline marshes formed in the lower Basin. During this time up to the present, active growth faults have also influenced basin geometry and geomorphology, particularly along the northshore. This paper reports on the results of recent seismic, vibracore, and geochemical surveys in the basin, particularly its late Quaternary stratigraphy and sediment pollution history.

Woods, M. K., Zoology and Physiology, Baltz, D. M., Arrivillaga, A., and Duffy, K. C., Oceanography and Coastal Sciences, CCEER, Louisiana State University, Baton Rouge, LA:

An Analysis of Vallisneria americana Leaf Characteristics Near Bayou Lacombe, Lake Pontchartrain

Wild celery, Vallisneria americana, was studied in Lake Pontchartrain near Bayou Lacombe, in the summer of 1995. Our purpose was to survey the health and growth of Vallisneria by looking at the variables of seagrass leaf width and length, leaf projection rate, and longevity. Vallisneria was collected with a core sampler (10.2 cm diameter) in three zones. Zones were between 15 and 130 cm deep, and approximately 25, 75, and 110 m from the shore with muddy and sandy substrates. For each shoot, every leaf's width and length was measured. To determine growth rates of Vallisneria leaves, reference points on living plants were established in situ by a using a rectangular horizontal plexiglass plane with two round holes. The plane was supported by semi-permanent reinforcing bar legs. The grass blades were pulled through the holes and marked by puncturing the leaves with a 21-gauge needle at the level plane. After an interval of 6-14 days, the grass blades were remarked using the same method and then harvested. Distance between successive marks was used to estimate individual leaf growth. Individual shoots, or vertical rhizomes, are attached to a horizontal rhizome. Leaves of shoots grow in a rosette pattern and are numbered from youngest to oldest in relation to position with the youngest at the center. We were unable to detect significant differences in the number of leaves per shoot; however, a slightly higher number of leaves was observed in the mid-zone rosettes and numbers in the near and off-shore zones were similar. Mean leaf lengths (+ 1 SE) were significantly different (F-ratio = 62.9, df = 2 & 582, P < 0.0001) among zones: shortest (14.1 cm + 0.54) in the near-shore zone, intermediate (22.9 cm + 0.67) in the mid-zone, and longest (30.7 cm + 1.68) in the off-shore zone. Mean leaf widths were also significantly different (F-ratio = 62.9, df = 2 & 582, P < 0.0001): narrowest (0.40 cm + 0.008) in the off-shore zone, intermediate (0.44 cm + 0.007) in the near-shore zone, and widest (0.56 cm + 0.007) in the mid-zone. Leaf area was lower near shore (6.2 cm2 + 0.28); however, differences between leaf area of the mid- (13.4 cm2 + 0.47) and off-shore zones (13.0 cm2 + 0.85) were not significant (F-ratio = 50.0, df = 2 & 581, P < 0.0001). Leaf growth rates differed significantly (F-ratio = 24.8, df = 11 & 422, P < 0.0001) with age class. The highest growth rates were in relatively young leaves (e.g., 1.4 cm/day + 0.1). The older age classes had sharply reduced growth rates that approached zero growth in oldest classes (e.g., 1.54, 0.37, 0.33, 0.38, and 0.12 cm/day for age classes, 0, 2, 4, 6, and 8, respectively). Thus, it appears that the habitat characteristics provided by Vallisneria americana to fishes and macroinvertebrates differed substantially with depth, substrate, and distance from shore near the mouth of Bayou Lacombe in Lake Pontchartrain.


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