Basin: Bottom Sediments and Related Environmental Resources
1992 BASICS OF THE BASIN ABSTRACTS
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Basics of the Basin abstracts
Anderson, A. C., Tulane University School of Public Health and Tropical Medicine, New
Recreational Impact of Fecal Loading on Lake Pontchartrain Basin Streams.
There have been several epidemiological studies addressing the health implications of
exposure to pathogens in recreational waters. These data, including the study done at Lake
Pontchartrain, are reviewed. Based on these studies, EPA recommended new bacteriological
criteria for recreational water quality: 126 E. coli / 100 ml. fresh water or 33
enterococci / 100 ml. fresh water. Levels of these indicators and sources of contamination
are discussed using the Tangipahoa River as a model for fecal loading of Pontchartrain
Basin streams. The impact of fecal contamination on other basin streams is also discussed.
The status of adoption of the new criteria organisms as bacteriological standards for
recreational water is reviewed. The steps being taken to improve recreational water
quality in the Pontchartrain Basin are outlined.
Binet, G., St. Charles Parish, Hahnville, LA, and Ensminger, A. B., Wetlands and
Wildlife Management Co., Inc., Belle Chasse, LA
Habitat Degradation of the LaBranche Wetlands and an Approach to its
Considered the most productive wetlands within the Lake Pontchartrain Basin, the
LaBranche Wetlands south of Lake Pontchartrain consists of over 14,000 acres of brackish
to fresh marsh and forested swamp. Before natural and man-made processes produced massive
degradation and habitat changes of the LaBranche Wetlands, the entire area was a
freshwater swamp and marsh complex. Between 1970 and 1980, one-fourth of the LaBranche
Wetlands habitat was lost due to saltwater intrusion, natural subsidence, channelization,
and shoreline erosion. Major contributing factors to LaBranche's decline has been the
dredging of access channels for the construction of I-10, the construction of the
Mississippi River Gulf Outlet that periodically brings saltwater into Lake Pontchartrain
from the Gulf of Mexico, shoreline retreat of over 15' per year due to Lake Pontchartrain
wave action, and of course natural sediment depletion and marsh subsidence.
In 1984, a comprehensive marsh management plan was developed for the 12,460 acres of
LaBranche Wetlands owned and managed by the St. Charles Land Syndicate. The area under
management is generally bounded by Lake Pontchartrain, the Jefferson/St. Charles Parish
line, US Highway 61, and Bayou LaBranche. In February 1987, the Louisiana Department of
Natural Resources/Coastal Management Division issued a coastal use permit for the plan,
and a Section 404 Permit was received from the US Army Corps of Engineers in May 1988.
Since that time, the LaBranche area north of the Illinois Central Railroad (just south of
I-10) has been passively managed as a brackish to intermediate marsh, while the wetlands
south of the Illinois Central Railroad have been actively managed as a fresh marsh and
swamp complex. Structural modifications that plug or regulate water flow through man-made
canals has greatly improved LaBranche's habitat for both fisheries and waterfowl
production, has halted saltwater intrusion in the area, and has increased the land to
water ratio within the entire complex. Steps have also been taken to diversify marsh
plants by implementing an annual re-vegetation program aimed at introducing non-native and
more salt tolerant plant species to the area.
The LaBranche Wetlands is an excellent example of an environmental public/private
partnership. Over $2 million worth of marsh management techniques have been implemented in
LaBranche since the inception of the plan, utilizing funds in the form of grants,
mitigation, donations, and landowner and Parish participation. The landowner and the
Parish realizes the major habitat role LaBranche plays to the Lake Pontchartrain Basin,
and has assumed an active role in preserving and enhancing its valuable habitat.
Boebel, R. W., Consultant, New Orleans, LA., and Crawford, Frank C., Crawford &
Associates, Inc., New Orleans, LA
The Lake Borgne and Lake Pontchartrain Commercial Seafood Production from 1970
to 1989, Volumes and Variations
Landings data compiled by the National Marine Fisheries Service, U.S. Department of
Commerce, show that the volume of seafood harvested and sold commercially from lake Borgne
and Lake Pontchartrain significantly increased in the Twenty (20) year span, 1970-1989.
The year 1989 is the last year that this federal agency recorded fishery data from theses
two (2) state lakes.
Six (6) types of seafood (three (3) fish and three (3) shellfish), comprising more than
99% of the total harvest, show an increase in total poundage and total exvessel value from
2,075,100 pounds and $492,777 for year 1970 to 8,946,150 pounds, and $6,103,237 for year
1989. The species included are Drum (black) sea trout (spotted, white), sheepshead
(Atlantic), blue crab (hard, soft, peeler), shrimp (brown,white), and oyster. All species
increased over the period studied except oyster. Black drum, sheepshead, and blue crab
showed the most dramatic expansions of catch.
Substantial volume variations are present for some species within this time span.
Causal factors may include economic changes, shifting demographies, and regulatory forces.
The introduction of Mississippi River freshwater and silt into these brackish water lakes
probably caused some fluctuations. Other physical changes in the environment were
occurring. Nevertheless, in 1989 Lake Borgne and Lake Pontchartrain were not hostile to
these members of the biota. Marine life was alive, well, and harvested in large volumes by
the commercial fishing industry.
Brown, Murray L., Minerals management Service, New Orleans LA
A Public Domain Software Program for Charting Environmental Attributes in Lake
Although a number of excellent proprietary geographic information systems (GIS) are in
use by environmental resource agencies/groups in southeastern Louisiana, there remains a
need for an easy-to-use, well documented, public-domain software program that allows
general users to prepare and share basic charts of environmental attributes using simple
ASCII files. The SEAPLOT software program, originally written for use by oceanographers
around the globe, has been expanded to include the Lake Pontchartrain Basin on its
regional selection menu. Although the available coastline file is still rather crude,
instructions are provided to allow the user to import higher resolution files, if locally
SEAPLOT is a menu-driven, interactive code written in GWBASIC (available on most DOS
personal computers). Using a specific data format described in the available manual, the
user can create, plot, and combine files that depict locational information. To a lesser
degree, certain oceanographic parameters can be represented graphically, because the
program is provided as source code, the user can easily extend this aspect of SEAPLOT to
include water quality parameters. Locational information that can be plotted includes
boundaries, points, polygons, as well as associated labels and titles. SEAPLOT is being
used in oceanographic research to plot ocean station locations, the tracks of drifting
buoys, water current and wind vectors, survey areas, stranded marine mammal sites, oil
spill dimensions, instrument sites, shipwreck locations, and satellite analyses of ocean
fronts. A utility routine in SEAPLOT allows the user to add information to existing files
using an on-screen cursor. There is also a routine to sort data files according to
recommended file-naming conventions.
SEAPLOT Version 1.3 (which includes Lake Pontchartrain), with the draft manual and a
sampler of different data files, can be obtained by sending one high-density, formatted, 5
1/4 inch floppy diskette to the author at 1201 Elmwood Park Boulevard, New Orleans,
Louisiana 70123-2394, U.S.A.
Burns, J. W., Urban Waste Management and Research Center (UWMRC), M. A. Poirrier,
Biological Sciences \ UWMRC and K. Preston, Geography \ UWMRC, University of New Orleans,
New Orleans, LA
The Occurrence of Potamogeton Perfoliatus L. (clasping pondweed), a Rare
Submerged Aquatic Vascular Plant in Lake Pontchartrain
Submersed plants of both freshwater and marine origin comprise important communities
within estuaries, but their ecology in estuarine habitats is poorly understood.
Potamogeton perfoliatus L. (Clasping Pondweed) is a submersed aquatic vascular plant which
is listed as a sensitive species in the coastal zone of Louisiana and is considered
extremely rare. Louisiana collections of P. perfoliatus are limited and restricted to Lake
Pontchartrain and its surrounding marshes.
Potamogeton perfoliatus was first recorded for Lake Pontchartrain by Riddell in 1838
near the Tchefuncta River Lighthouse. Clair A. Brown also collected a specimen from the
beach at Mandeville in 1945. Although Suttkus, Darnell and Darnell; Perret et al.;
Chabreck; Turner, Darnell and Bond conducted studies which noted the submerged vegetation
of Lake Pontchartrain in 1953-1954, 1971, 1972 and 1980 respectively, P. perfoliatus was
not reported in the lake for the following 28 years. Montz reported P. perfoliatus to be
abundant both before and after the 1973 opening of the Bonne Carré Spillway, at Pointe
aux Herbes in the southeastern sector of the lake. A 1978 icthyological survey by Thompson
and Verret, which noted submerged aquatic vegetation at specific stations located around
the perimeter of Lake Pontchartrain, did not list P. perfoliatus as a species encountered.
During the summer of 1985, a survey of aquatic vegetation in the lake by Mayer did not
find P. perfoliatus. Efforts to relocate P. perfoliatus in 1988 by Lester were
unsuccessful during an ecological inventory of the sensitive plants and animals for the
coastal zone of Louisiana. Brantley and Platt recorded a 7 m x 17 m submerged bed of P.
perfoliatus 1500 m west of Bayou Lacombe in June 1990. Additional smaller beds, which
yielded fruiting specimens, were located in the same area in August 1990.
Recent surveys beginning August 1991 to the present have located submerged beds of P.
perfoliatus on both the north and south shores of Lake Pontchartrain. South shore beds
have been located at Pointe aux Herbes (39 m x 26 m) and at the confluence of Irish Bayou
with Lake Pontchartrain on the west side of the Pointe aux Herbes peninsula (50 m x 50 m;
15 m x 12 m; 20 m x 15 m). North shore beds were located between Goose Point and the
confluence of Bayou Lacombe with Lake Pontchartrain (15 m x 20 m; 10 m x 15 m),
approximately 4.0 km east of Bayou Lacombe near Point Platte (150 m x 120 m) and off the
swimming beach at Big Point (several individuals). Attempts to relocate P. perfoliatus at
Big Point during December 1991 were unsuccessful. Submersed beds of P. perfoliatus
reported by Brantley and Platt were also relocated near Bayou Lacombe.
Factors affecting the distribution of P. perfoliatus in Lake Pontchartrain are not
known. Some areas have been repopulated after an absence of 18 years, and growth is
occurring in previously unreported sectors of the lake. Its status in Lake Pontchartrain
is currently being monitored and examined for factors which affect its distribution.
Calix, A. G.; Seeger, E.; Velado, L.; Rucker, J.; TGS Technology, Inc., U.S. Fish and
Wildlife Service, National Wetlands Research Center, Slidell, La, and Handley, L. R., U.S.
Fish and Wildlife Service, National Wetlands Research Center, Slidell, LA
Shoreline Changes of Lake Pontchartrain 1955-1990
Lake Pontchartrain plays an important role in the wetland ecosystems of Louisiana. Over
the past few decades the lake has been directly affected by the urban development of New
Orleans and surrounding areas. Shell dredging, saltwater intrusion, shoreline development,
and pollution are some of the factors contributing to the lake's problems. Recently,
efforts have been made to restore the lake to an ecologically sound and economically
viable habitat for Louisiana. The purpose of this study is to cartographically demonstrate
the changes in the shoreline of Lake Pontchartrain using historical maps and recent aerial
Caraher, M. F., W. M. Dahl, and D. H. Easley, University of New Orleans, New Orleans,
Comparison of Single-Well and Two-Well Tracer Tests for Acquiring Velocity and
Effective Porosity Estimates in the Pine Island Aquifer, New Orleans, LA
The Pine Island aquifer is a barrier spit sequence located primarily in the northern
portion of Orleans parish, Louisiana. this aquifer is approximately 25 feet thick in the
study area located on the western edge of the University of New Orleans Lakefront campus.
Estimated transmissivities are approximately 3700 gal/day ft and storativity estimates are
approximately 0.00036. Average linear velocities are approximately 0.2 feet per day. The
aquifer consists of a fine-grained sand with shell fragments underlain by finer grained
bay sediments and overlain by silt and clay fill pumped from Lake Pontchartrain. This
aquifer provides an ideal site for comparison of tracer tests. A small well field, which
consists of four fully-penetrating wells, have been installed into the Pine Island
Aquifer. Both single-and dual-well tracer tests may be used to determine estimates of
average linear velocity and effective porosity. These tests may be complicated by minimal
gradient that results in low ground-water velocities, such as occur in the Pine Island
Aquifer. Low velocities require extended breakthrough monitoring, which may be expensive
if shorter well spacing is impractical.
The intent of this project is to provide an inexpensive, simple, and relatively rapid
method of estimating velocity and effective porosity in aquifers commonly found south of
Lake Pontchartrain. Our study utilizes the single-well drift and pump-back technique
described in Hall et al. 91991) and standard dual-wellpumping tracer tests. The
single-well drift and pump-back method allows the estimation of both average linear
velocity and effective porosity simultaneously. The dual-well test will be performed as a
comparison with the single-well test, using the same portion of the aquifer. The results
are then evaluated to determine their reliability and overall utility.
Conatser, W. E., New Orleans, LA
Petroleum Industry Activity in the Lake Pontchartrain Basin
The petroleum industry has had a commercially successful and environmentally compatible
history in the waters of the Lake Pontchartrain Basin for over 53 years. Gulf Oil Co.
completed the first well in Lake Pontchartrain on July 17, 1938. Since that time 266 wells
have been drilled in the waters of Lake Maurepas, Lake Pontchartrain, Lake St. Catherine
and Lake Borgne. These wells have penetrated more than 2,762,000' of strata for an average
depth of 10,383' per well. The deepest well to date was drilled to a depth of 25,600' by
Placid Oil Co. on their State Lease 5407 in Lake Borgne. The deepest well to date in Lake
Pontchartrain is the Union Of California - State Lease 6753 #2 which reached a total depth
The petroleum industry has completed 86 (32.3%) of the wells drilled as commercial or
possibly commercial. The first commercial well was drilled by Atlantic Oil and Refining at
Big Point Field near the north shore of Lake Pontchartrain in September of 1946. Since
that first completion the wells in the waters of the Lake Pontchartrain Basin have
produced 10,017,352 barrels liquid hydrocarbons and 116,204,782 MCF natural gas.
It is not possible to predict the future production of oil and gas from the lakes of
the study area but the potential is considered significant. Currently oil and gas is
produced from strata ranging in age from Middle Miocene through the Upper Cretaceous. Trap
types vary from elongate anticlines, to fault closures, to stratigraphic traps.
Prospective areas remain to be drilled in the study area. New exploration techniques and
recovery advancements could present possibilities for future petroleum production far
exceeding those already produced.
Condrey, Richard, Coastal Fisheries Institute and Department of Oceanography and
Coastal Sciences, Louisiana State University, Baton Rouge, LA
Historical Ecology of Lake Pontchartrain-Borgne Basin: 1699-1950
Once Iberville passed the buffalo plains and cypress swamps which were to become New
Orleans (because the area had a fine path which led to Bayou St. John and then Lake
Pontchartrain), he began looking for the right fork of the Mississippi. Failing to find it
(since he was on it and failed to recognize Bayou Lafourche as its left fork), he took a
small bayou chocked with huge log jams (Bayou Iberville, now Bayou Manchac) through Lake
Come on a voyage of discovery as we relook at this system through the writings and
illustrations of the early explorers and visitors. From Iberville and Collot, through
Audubon, and Lafcadio Hearn and Rebecca Harding Davis, watch the massive ecological
changes brought by European settlement. Ponder what the system was as you consider what it
Davis, D. W., Louisiana Geological Survey, P.O. Box G - University Station, Baton
Rouge, Louisiana 70893
New Orleans--North America's Premier Below Sea Level City
In the current popular and scientific literature one reads with repeated frequency
articles related to the greenhouse effect on sea level rise. As the world turns up its
global thermostat, melting the polar ice caps and enlarging the world's seas through
thermal expansion, coastal cities will be at risk. With nearly two-thirds of the planet's
population and more than 40 of its largest metropolitan centers within the coastal
lowlands, even a small upward movement in the earth's seas is significant. A change in
temperature of as much as 4o C has been predicted by 2030, that could elevate sea level
enough to flood New Orleans and other coastal municipalities. From its inception, New
Orleans was isolated from the mainland by cypress/tupelo swamps, marshes, and Lake
Pontchartrain. It was an "island city" delineated by water courses. When
surveyed in 1720 every block was defined by shallow ditches. From its beginning these
small channels established New Orleans' dependence on a drainage network.
Levee construction began as early as 1718. By 1720 all inhabitants were instructed to
enclose their land in "palisades" or forfeit their property. Ten years later an
embankment 1.6 km long protected the "Vieux Carre." Levees, therefore, are an
old and integral part of the urban landscape. New Orleans is part of an environmental
setting that requires an extensive levee and pump system to manage the region's excess
The "Vieux Carre" is the older section of the "Crescent City" and
is built on abandoned or modern natural levees. At 4.5 m above sea level, these features
are the region's high ground. They furnished the earliest inhabitants with a relatively
dry, firm foundation for residential and commercial construction. Draining the surrounding
wetland was a major undertaking. When the water was removed the soils shrank and settled
and eventually subsided below sea level. Even so, relatively rapid urbanization required
additional space. The only property available were the swamps and marshes that framed the
initial natural levee site. What was delineated as "uninhabitable wasteland" was
slowly reclaimed as the region's incorporated limits increased.
Much of the New Orleans' metropolitan complex has subsided to the point where in order
to drain properly pumps siphon excess rainfall up into Lake Pontchartrain. Human-induced
negative land surfaces are producing, in many instances, below sea-level citizens.
Regional governments have learned, nevertheless, to live with this and other environmental
dilemmas. Canals, pumps, and large-diameter drainage pipes assist in keeping the
neighborhoods relatively dry. With much of the urbanized area less than 3 m above mean sea
level, the margin of safety is exceedingly small. This is particularly true for those
sections of the levee-protected metropolitan region 2 m to 4 m below sea level. In as much
as arable land has always been in short supply, the only practical and realistic solution
was to reclaim the "uninhabitable" swamps and marshes. Soils associated with
these aquatic habitats are subaqueous in origin and high in organic detritus. When air
dried, these histosols lose nearly 85% of their mass. The end result is the surface
subsides, because of the loss of volume within the soil column.
The product of reclaiming these marginal tracts is that the New Orleans' metropolitan
region is sinking. With a projected rise in sea level of 1.2 mm/yr, coupled with a
constant battle with subsidence, the New Orleans metroplex faces a challenging future. In
addition, the metropolitan area is at risk from hurricanes. Under the right conditions, a
tropical depression moving across Lake Pontchartrain's southeastern quadrant would move
considerable water over the lakefront levees into the below-sea-level bowl that
distinguishes parts of Jefferson and Orleans parishes. For more than two and a half
centuries the "Crescent City" and its satellite communities have been at odds
with the elements. Despite these issues, the region has developed, prospered, and
flourished within this inhospitable environment, but the future must be considered
DeLaune, R.D and Pardue, J.H., Wetland Biogeochemistry Institute, Louisiana State
University, Baton Rouge, LA
Distribution of Heavy Metals in Bayou Trepagnier Bottom Sediment
The depositional pattern of metals was determined in bottom sediment of Bayou
Trepagnier (located in the La Branche Wetland bordering Lake Pontchartrain). The majority
of flow into the Bayou is from an industrial outfall. Eight cores were taken from Bayou
Trepagnier and one core from Mississippi Bayou ( a control site ) along a transect
extending to Lake Pontchartrain. Results indicated that Bayou Trepagnier sediment was
contaminated with chromium, lead, and zinc. Chromium levels of over 5,000 mg/kg of
sediment were measured in sediment profiles. Lead concentrations on the order of several
thousand mg/kg were observed in the lower sediment profile taken near the industrial
Zinc concentrations of greater then 1,000 mg/kg of sediment were recorded.
Concentrations of metal increased with depth in the profile. Metal concentrations were
normalized to Al in the sediments and compared to uncontaminated sites in Louisiana. Bayou
Trepagnier sediments were shown to be highly enriched with respect to Cr and Pb when
compared with other areas of the state. Sedimentation in recent years (determined from
137Cs dating) was burying or removing metals from the surface environment where
bioavailability is greatest.
Delaune, R.D. and Lindau, C.W.,Wetland Biogeochemistry Institute, Louisiana State
University, Baton Rouge, LA
Stable Nitrogen Isotopes Studies Fingerprint Surface Water Inorganic Nitrogen
Sources Entering the Pontchartrain Basin
Estuaries such as Lake Pontchartrain are generally nitrogen limiting. Nitrogen entering
the system can influence water quality of the lake. A recent study investigated the use of
natural abundance variations in 15N/14N ratios for identification and tracing surface
water inorganic N sources entering the Pontchartrain Basin.Surface water samples were
collected from selected streams with distance from a point source in the northern Basin
and analyzed for NH4+-N, NO3--N and associated 15N/14N (d15N%) concentrations. Ammonium-N
from domestic sewage sources entering the Basin was found to have distinct d15N ranges.
Domestic sewage discharge was traced for about 30 km downstream from discharge point using
15N/14N ratios. At the sewage point source NH4+-d15N values averaged +43% and increased
linearly to +162% with distance from the discharge. Surface water NO3--d15N values
generally ranged from +1 to +99% and no significant association was observed between d15N
values with distance from the domestic sewage point sources. The discrete NH4+-d15N
signatures of domestic sewage compared to downstream surface water. NH4+-d15N values
demonstrated that N isotopic ratios can be used as tracers for identifying the sources of
nitrogen entering the Pontchartrain Basin. Such sources include the nitrogen in dairy
manure entering the Tangipahoa river and septic and sewage being introduced into the Amite
and Tickfaw rivers. Expanded studies are currently being initiated to further quantify
nitrogen sources entering the basin.
Demans, Charles R. and Garrison, Charles R.
Water Quality Monitoring Activities of the U.S. Geological Survey in the Lake
Pontchartrain and Lake Maurepas Basins
The Louisiana District of the U.S. Geological Survey Water Resource Division has been
involved in monitoring the water quality of surface- and ground-water resources of the
Lake Pontchartrain and Lake Maurepas basins since 1927. Surface-water samples and
volumetric flow rate discharge measurements have been made at 210 sites in these two
basins. Surface water quality samples have been collected at 102 sites, accounting for
2,187 water samples to date. Bed samples have been collected at 28 of the above sites,
accounting for 30 samples. Water and bottom material have been analyzed for suspended
sediment, nutrients, bacteria, major ions, trace metals, and pesticides. Currently, there
are three active water-quality sites within the two basins. These data were collected as
part of cooperative programs with the Department of Transportation and Development, the
U.S. Army Corp of Engineers, and the U.S. Geological survey NASQAN program.
Ground water has been sampled at approximately 1,160 sites within the basins, accounting
for 3,823 samples. Ground water has been analyzed for primarily major ions and selective
nutrients, although synthetic organic compounds, trace metals, and bacteria have been run
at selective sites. Ground-water data have been collected as part of cooperative programs
with the Department of Transportation and Development, Jefferson Parish Department of
Water, and St. John the Baptist Parish Department of Water.
The U.S. Geological Survey also has completed several interpretive studies within the Lake
Pontchartrain and Lake Maurepas basins. Studies completed on ongoing include:
- Movement of bacteria in shallow ground water,
- Assessment of trace metals in coastal streams (Pear River, Tickfaw River),
- Hydrology of Fritchie marsh, coastal Louisiana,
- Ground-water resources of southern Tangipahoa Parish, and
- Several other general water-quality studies.
Devall, Margaret S. and Parresol, Bernard R. Souther Forest Experiment Station, 701 Loyola
Avenue, Rm. T-10210, New Orleans, LA 70113
Assessing the Effectiveness of Several Protective Measures Against Herbivory of
Cypress Taxodium Distichum Seedlings
Second growth cypress remains an important source of lumber and is important for its
ecological and aesthetic role, and for wetland preservation. Louisiana contains a larger
inventory of baldcypress than any other state, but subsidence and hydrological
modification are reducing natural regeneration. Planting programs have been instituted,
but nutria and swamp rabbits have become serious deterrents to the success of cypress
plantings in Louisiana. This study examines the effect of treatments offering possible
protection against herbivory by nutria and swamp rabbits, and assesses seedling growth
(height and root collar diameter) with various treatments. Treatments include application
of tanglefoot, a sticky resin; application of ropel, a rodent repellent; and the use of
plastic tree guards. Study sites are a marsh that was formerly a cypress swamp on the U.S.
Fish and Wildlife Service's Bayou Sauvage Wildlife Refuge and a marsh on Southeast
Louisiana University's Turtle Cove Research Station near Pass Manchac. The Study is in its
Dranguet, C. A., Southeastern Louisiana University, Hammond, LA., and
Heleniak, Roman J., Southeastern Louisiana University, Hammond, LA.
Man in the Basin: Habitation and Forest Exploitation in the Pontchartrain Basin
Man's entrance into the Pontchartrain Basin has been marked by a degradation of the
cypress swamp that at one time surrounded Lake Pontchartrain. The coming of the railroad
to the western shore of the Lake in 1854 opened the area to commercial exploitation.
through war, flood, and man's utilization of the Basin's resources, the gradual shrinking
of the forest was only inevitable.
The purchase of vast tracts of virgin cypress stands by commercial lumber interests in the
1880's sealed the eventual fate of the forest. A short one hundred years elapsed between
the introduction of modern transportation and logging techniques, the establishment of
communities, and the final destruction of the swamp habitat.
Duffy, K. C., Dept. Oceanography and Coastal Sciences, LSU, Baton Rouge,
LA., and Baltz, D. M., Coastal Fisheries Institute, LSU, Baton Rouge LA.
The Influence of the Introduced Eurasian Milfoil (Myriophyllum spicatum) and
Native Aquatic Vegetation on Fish Nursery Habitat in Lake Pontchartrain
Quantitative samples in monospecific stands of submerged aquatic vegetation (SAV) and bare
sands habitats have been collected on a monthly basis from three stations in the
northeastern area of the Lake Pontchartrain estuary since July, 1991. the samples of the
community associated with the SAV beds are being collected with a Wegener ring (1.2 m ),
in a microhabitat approach to describe the population response of fish, invertebrate, and
SAV species to environmental variables. These data are being used to evaluate the impact
of an introduced SAV species on the community structure of coastal fishes and
invertebrates in Lake Pontchartrain and its adjacent waters. Historically, the dominant
native SAV species were Vallisneria americana and Ruppia maritima; however, Myriophyllum
spicatum became established and abundant in the 1970's. In this study, we have seen
dynamic changes in the SAV species composition that may be seasonal or directional and
related to recent changes in lake water quality. Presently, 9 fish and 9 invertebrate
species have been identified. From the preliminary samples, the mean numbers per sample
(range) for fishes and
invertebrates, respectively, are 12.5 (0-39), and 235.7 (11-508). Species of commercial
and recreational interest include juvenile spotted seatrout and blue crab, and post-larval
Earl, C., Hicks, B., and Hull, F., U.S. Army Corps of Engineers, New Orleans, LA
Jefferson and Orleans Parishes, Louisiana, Urban Flood Control and Water
Quality Management Study
The new Orleans District Corps of Engineers is currently conducting a reconnaissance study
entitled, Jefferson and Orleans Parishes, Louisiana, Urban Flood Control and Water
Quality Management. The purpose of the study is to consider measures to alleviate
rainfall flooding in the parishes and to improve the water quality of stormwater
discharges into Lake Pontchartrain, Lake Borgne, and the Barataria Estuary.
Our goal for the water quality management plans under consideration is to reestablish the
designated use of the receiving waterbody, such as making it swimmable and fishable.
During the reconnaissance phase we rely heavily on existing data. We determined the
impacts of stormwater runoff using a preliminary screening procedure recommended by EPA.
Based on research of the best available technology, we will estimate the cost and
effectiveness of the
various water quality management plans.
The Reconnaissance Report will discuss a wide range of alternatives, such as source
controls, in-line treatment, and end-of-pipe treatment.
Ellis, L. E., Biological Sciences / Urban Waste Management and Research Center (UWMRC),
UNO; Francis, J. C., Biological Sciences / UWMRC, UNO; and Tracy D. K., Biological
Determination of Fecal and Total Coliform Levels in Lake Pontchartrain by
Polymerase Chain Reaction (PCR)
Fecal coliform and total coliform levels were monitored in Lake Pontchartrain over a
several month period using oligonucleotide primers for detection of the lacZ and uid DNA
sequences by PCR. Good correlation was realized between PCR detection and standard method
procedures. Refrigerated storage of water samples prior to PCR detection was evaluated.
Bacteria were detectable for 10 days but showed significant declines after 48 hours. High
fecal and total coliform levels in Lake Pontchartrain appear to be associated with high
turbidity of the water.
Emmer, R. E., College of Urbanand Public Affairs, University of New Orleans, New Orleans,
Shrinkage of the Pontchartrain Basin, The Need for a Cooperative Regional
The Pontchartrain basin in shrinking in our perception of its size, the remoteness of the
headwaters, the vastness of its waterbodies, the supply of natural resources, and the
rapidity of population growth and how soon their presence is felt by neighbors. Tradition
segments the basin into four regions: metropolitan New Orleans or the south shore; the
river parishes from St. Charles to Iberville Parish; the north shore of St. Tammany,
Washington, and Tangipahoa Parishes; and the distant headwaters, the Amite River watershed
including East Baton Rouge, Livingston, East Feliciana, and St. Helena parishes. these
regions have historically acted independently for several reasons. Culturally, they were
distinct, i.e., Anglo-Saxon vs. French vs. The City. Second, the regions were
separated by distance. Trips between regions as late as the 1940s were major excursions
because of the absence of all-weather roads and bridges over major waterbodies such as the
Rigolets, Pass Manchac, and the many rivers. Third, the economic foundation of each region
was different. Finally, popular beliefs and attitudes ranged from Laisse lse bons ton
rouler to strict biblical followings.
Communities were scattered clusters of homes and businesses along the Mississippi River;
isolated groupings of stores and residences at cross-roads or spaced along the bayous,
railroads, and highways. Because these enclaves were small they were insulated from their
neighbors and, thus, were little affected by or had little effect on the nearest villages,
much less Lakes Maurepas or Pontchartrain. The Pontchartrain minimal if any significant
adverse impacts extending beyond the boundaries of the community. Post World War II
growth, improved highways, the automobile, and industrial development have changed the
basin from overall rural to an emerging suburban/urban
system. Time and space are compressed and with an increasing population problems are
magnified. The basin has become one community whether it wants to be or not. I turn, our
common problems must be approached in new ways.
The Pontchartrain basin as one community faces many institutional and environmental
problems. Federal, state, and local laws and jurisdictions overlap and, in many instances,
conflict in mission and authority. In addition, the private landowner is concerned with
his/her right to use property in a way that benefits them. Water quality, wetland loss,
harvesting of renewable resources, and extraction of minerals are issues that confront
decision makers in the basin and can no longer be ignored. Planning offers the vehicle for
addressing these issues in a timely and systematic manner. Former Governor of California
Edmund G. Brown said, "planning is thinking ahead intelligently ..."
and an idea that has received wide acceptance. In fact, it is methodically avoided by many
parishes and municipalities. Such as negative attitude requires modification if the
institutional and environmental problems of the basin are to be solved in a timely
fashion. The Lake Pontchartrain Basin Foundation through a grant from the Environmental
Protection Agency is undertaking a basin planning process that will confront many of the
most difficult institutional and environmental problems in the basin. What evolves will be
a formal regional cooperative mechanism for formulating positive actions that result in a
healthier and safer place to live for the people in the basin.
Farabee, M.V., and R.C. Cashner, Department of Biological Sciences, University of New
Orleans, New Orleans, LA
Distribution of Fishes and Community Stability in Bayou Lacombe
Bayou Lacombe is a relatively small drainage system tributary to the northeastern section
of Lake Pontchartrain. Based on records from fish collections made since 1951, a total of
77 resident and migratory species have been documented for the system. Bayou Lacombe has
been the focus of four major ichthyofaunal surveys. The most extensive study was done by
Sobczak, in which 10 stations were sampled monthly from August, 1973 to August, 1975, and
the most recent survey included monthly samples at five sites from November, 1988 to
October, 1989. Numerical
dominants in the upper reaches of Bayou Lacombe include grass pickerel, chubsuckers, black
bullhead, bayou topminnow, mosquitofish, dollar sunfish, and warmouth. The middle of the
river has greater numbers of cyprinids, blackspotted topminnow, brook silverside, and
longear sunfish. The longitudinal pattern of distribution of fishes in Bayou Lacombe is
characterized by a rather abrupt change in the fauna between upper, middle, and lower
reaches, rather than addition of species.
Morisita's Index (Im) and Percent Similarity Index (PSI) indicate that the greatest
dissimilarities between fish assemblages occur between the lowermost stations and those
above tidal influence. Stations near the mouth of Bayou Lacombe are characterized by
euryhaline forms, such as bay anchovy, Gulf menhaden, inland silverside, sciaenids, and
gobies. Community similarities were calculated for five common stations between the
1973-75 and 1988-89 surveys. Relatively low values for Im and PSI may indicate less
stability and persistence of fish communities over time than reported for midwestern
streams. The most abundant species, the blacktail shiner, collected during the 1973-75
study was not represented in any of the 60 collections made during the 1988-89 survey.
Francis, J. C., Biological Sciences / Urban Waste Management and Research Center (UWMRC),
UNO; Wijesundera, V., UWMRC, UNO; Barbe, D. E., Civil Engineering / UWMRC, UNO; Mulino, M.
M., Steimle & Assoc., Inc., Metairie, La.; and Poirrier, M. A., Biological Sciences /
Historic Changes in Secchi Disk Transparency in Lake Pontchartrain
A major environmental concern about Lake Pontchartrain is an assumed long-term decrease in
water clarity. Available data on Secchi disk transparency in Lake Pontchartrain from 1953
through 1990 were examined to determine if changes in water clarity had occurred. Linear
regression analysis of Secchi disk transparency versus time indicated a statistically
significant (5% level) decrease in transparency with time.
The relationship between Secchi disk transparency and two environmental factors, salinity
and wind speed, were studied using regression analysis. The analysis revealed a
statistically significant, positive relationship between water clarity and salinity, and a
statistically significant, negative relationship between water clarity and wind speed.
Further analysis indicated that neither average annual salinity nor average annual wind
speed had realized a statistically significant change during the period from 1953 through
Secchi disk transparency data were adjusted for the effects of salinity, wind speed, and
both salinity and wind speed. The base for adjustment in each case was the long-term
average of the variable for
which adjustment was being made. Regression of Secchi disk transparency versus time, with
adjustment for salinity, revealed a statistically significant relationship, indicating
that adjusting the
data for the effect of salinity had not removed the long-term decrease in water clarity.
However, regression of Secchi disk transparency versus time, with adjustment for wind
speed, indicated that there was no longer a statistically significant relationship between
Secchi disk transparency and time. Adjusting the data for the effect of wind speed had
removed the long-term decrease in water clarity. Also, regression of Secchi disk
transparency versus time, with adjustment for both salinity and wind speed, revealed no
statistically significant relationship, indicating that adjusting the data for the effects
of both salinity and wind speed had removed the long-term decrease in water clarity.
Analysis of variance of monthly salinity data from 1953 through 1990 revealed a
statistically significant monthly seasonality with the highest values occurring in
November and the lowest values occurring in May. Similarly, analysis of variance of
monthly wind speed data from 1953 through 1990 revealed a statistically significant
monthly seasonality with the highest values occurring in February and the lowest values
occurring in August. These seasonal effects are not equally represented in the available
data 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 to 1990.
Goyer, R.A., G. J. Lenhard, J. L. Chambers, LA Agricultural Experiment Station, LSU, Baton
Rouge, LA, and V. R. Van Sickle, U.S. Fish & Wildlife Service, National Wetlands
Research Center, Lafayette, LA
Herbivory in Baldcypress: A Threat to the Pontchartrain Basin
The future of the baldcypress is closely linked to its ability to withstand
environmental, biological and man-caused stresses. Currently, all three of these
categories of stress are impacting cypress in south
Louisiana and, particularly, threaten trees in and near the Ponchartrain Basin. Studies
underway by the authors are evaluating the impact of an herbivore - the fruit tree
leafroller (Lepidopter: Tortricidae) - on baldcypress. Further evaluations are being
conducted to ascertain the interaction(s) of herbivory with flooding caused by man made
and environmental changes (e.g., global warming and associated changes in hydrology).
Studies to date have revealed continued expansion of fruit tree leafroller populations
into the periphery of the Ponchartrain Basin. In areas having experienced repeated
defoliation of cypress, radial growth has shown marked reduction. Additionally, crown
deterioration, increased transparency and dieback have occurred along
with scattered tree mortality. The threat to baldcypress results from herbivory coupled
with changes in hydrology. Sapling and pole-sized cypress exhibiting high live-crown
ratios appear most heavily browsed. Transect evaluations presently underway are aimed at
evaluating severity of herbivory in relation to seasonal flooding regimes. Rates of
refoliation on both mature and young saplings are compared to further elucidate the
ability of cypress to respond to herbivore and flooding stresses.
Hardy, J. W., Southern Regional Climate Center, Department of Geography &
Anthropology, Louisiana State University, Baton Rouge, La, 70803
Fresh Water Input into Lake Pontchartrain
Fresh water input into Lake Pontchartrain will be determined for a wet year and dry year.
The amount of runoff generated by each drainage basin of Lake Pontchartrain will also be
examined. Fresh water input into Lake Pontchartrain will be found in part from measured
runoff at gaging stations along Highway 190. The Thornthwaite water budget model will be
used to estimate the surplus water, hence runoff, for the part of the Pontchartrain
drainage basin below the gaging stations. Actual evaporation and the change in soil
moisture storage will be subtracted from precipitation to give the surplus for the ungaged
uplands. The freshwater input into Lake Pontchartrain from the ungaged swamps, marshes,
and lakes will be found by subtracting potential evaporation from precipitation.
Hastings, Robert W., Turtle Cove environmental Research Station, Southeastern Louisiana
University, Hammond, LA
Surface Drift Movement of Larval Marine Fishes and Other Organisms through
Passes of the Upper Lake Pontchartrain Estuary
The fish fauna occurring in the oligohaline upper Lake Pontchartrain estuary consists of
about half freshwater species and half marine. Freshwater species are present throughout
the year whereas most marine species are seasonal in their occurrence, leaving the upper
estuary for the winter. A major occurrence, leaving the upper estuary for the winter. A
major influx of such species occurs in the spring as larvae and early juveniles. Surface
plankton net sampling has been conducted to monitor patterns of movement for several fish
species, such as bay anchovy (Anchoa mitchilli), gulf menhaden (Brevoortia patronus), gulf
pipefish (Syngnathus scovelli), naked goby (Gobiosoma bosci), and tidewater silverside
(Menidia beryllina), as well as several invertebrates such as blue crab (Callinectes
sapidus ). Samples have revealed significant seasonal, diel, and spatial patterns of
occurrence for several species common in the estuary. Thus they may exercise significant
control over their movements, even though they are small and appear to be poor swimmers.
Although open waters of the upper estuary are clearly used as nursery habitats for such
species, their use of enclosed marsh canals and bayous may be more limited. Studies are
continuing to address such movement (or lace of movement) of small planktonic organisms
into enclosed waters, and how diel variation in activity patterns affects their patterns
of occurrence in surface plankton samples.
Keim, B.D., Southern Regional Climate Center, Department of Geography and Anthropology,
Louisiana State University, Baton Rouge, Louisiana 70803.
Storm Frequencies and Storm Runoff into Lake Pontchartrain
The large number of recent heavy rainstorms in southeastern Louisiana has raised concerns
about changing frequencies and magnitudes of heavy rainfall in the area. A changing heavy
rainfall climatology over the Lake Pontchartrain Basin may have noteworthy impacts. Most
from New Orleans is discharged into the lake and is obviously important to the lake's
water quality. Furthermore, storm runoff from the rivers draining the Florida Parishes
transports agricultural wastes into the lake and influences lake salinity levels. This
paper examines the historical storm events in metropolitan New Orleans and the Florida
Parishes from the nineteenth century to the present. The seasonality and synoptic
situations of storm rainfall will also be examined.
Lawler, G. C., Delgado Community College, New Orleans La., and Hartzog, L., Army Corps of
Engineers, New Orleans, LA.
Baseline Pollutant Data on Water Column, Sediment, and Bivalve Tissue Samples
from the Inner Harbor Navigational Canal, Chef Menteur Pass, and the Rigolets
As part of the environmental impact statement supporting the Army Corps of Engineers'
Hurricane Barrier Protection Plan, pollutants in the water column, sediment, and bivalves
of the Inner Harbor Navigation Canal (IHNC), Chef Menteur Pass, and The Rigolets were
investigated. This investigation was carried out in tow phases. In phase I, methods were
developed, the three passes were screened for pollutants, and replicate samples were
analyzed to determine the number of samples required to achieve reasonable analytical
precision. Phase I culminated with the production of a sampling protocol, which included
various sampling options and tables relating numbers of samples to analytical precision.
Phase II, which was designed to detect seasonal fluctuations of
pollutants, was aborted with the Hurricane Barrier Protection Plan was abandoned. The
first samples were collected for analysis in May of 1980. The data generated from these
and subsequent analyses qualify as baseline data for these location and matrices because
the analyses were carried out under rigorous conditions of quality assurance and the
analytical techniques employed were state-of-the-art. The major analytical effort was
directed toward detecting and quantifying EPA
designated priority pollutants. In addition, organic fractions were routinely searched for
compounds of probable anthropogenic origin. Water samples were analyzed for asbestos,
heavy metals, base-neutral and acid extractable organics, organochlorie pesticides and
polychlorinated biphenyls, volatile organics, acrolein and acrylonitrile, total cyanides
and total recoverable phenolic. Sediment samples were analyzed for heavy metals, total
base-neutral extractable organics, individual
base-neutral extractable organics, organochlorine pesticides and polychlorinated
biphenyls, and volatile organics. Bivalve tissue samples from oysters (Crassostrea
virginica) and clams (Rangia cuneata) were analyzed for heavy metals, total base-neutral
extractable organics, individual base-neutral extractable organics, organochlorine
pesticides and polychlorinated biphenyls, and voltile organics. The results of these
analyses were compiled in seven data reports submitted to the Army Corps of Engineers in
association with the "Nutrient and Toxic Substance Chemistry of Chef Menteur Pass,
The Rigolets, and Inner Harbor Navigation Canal, Lake Pontchartrain, Louisiana"
program. The results of dissolved inorganic nutrient analyses conducted on the water
were included in the data reports.
Lopez, John A., Amoco Production Co., New Orleans LA
Potential Significance of Active Faults in Lake Pontchartrain
Examination of conventional seismic data collected in Lake Pontchartrain leads to the
compelling conclusion that the eastward extension of the Baton Rouge-Denham Springs faults
system is within Lake Pontchartrain and not as previously mapped on the northshore of the
Pleistocene/Holocene contact previously mapped as faults on the north shore is probably a
depositional contact. The faults within the lake are presently active as is the Baton
Rouge/Denham Springs fault system. Evidence for recent movement on the faults within the
lake is strongly
suggested by offset of the bridges which cross the lake. Offset varies from 2 to 6.5
inches depending on the age of the bridge. Movement on the fault is approximately 1 inch
per decade (.25 cm / year). Less detailed mapping suggests the fault system extends into
Chandeleur Sound. Thus the Baton Rouge-Denham Springs fault system is a regional basement
fault system extending 120 miles from Baton Rouge to Chandeleur Sound. One of the probable
effects of this fault system is to trigger small earthquakes, such as the 1987 Irish Bayou
earthquake. Other historic earthquakes located 5 to 20 miles south of the fault trace may
have also been related to the fault system. Past activity suggests that an earthquake
hazard is minimal. Other consequences or significant questions in relation to the active
1) The current high rate of movement on the faults is probably higher than in the geologic
past. So why does movement on the faults appear to have accelerated in the Holocene?
2) The coincidence of the regional fault system within Lakes Maurepas, Borgne, and
Pontchartrain suggests a genetic relationship. Do prior models for the formation of Lake
Pontchartrain need to re-evaluated?
3) At least two significant studies of ground water aquifers in Lake Pontchartrain
indicate that some of the faults do seal some of the aquifers. Since the faults are a
series of discontinuous faults the hydraulic connection of fresh and saline aquifers is
complex and probably intimately related to
faulting in the lake.
4) The high rate of fault movement conflicts with the interpreted top of the Prairie
Terrace accepted by most workers. Is the second weathered surface and not the first
weathered surface in the lake truly the top of Prairie Terrace?
Some of these questions may be academic and others may have more civic significance, but
all of these and others can be addressed with further basic research. Much can be gained
by research efforts by greater exchange of data and ideas between professionals which
generally operate in different institutional or commercial spheres.
Otvos, E. G., Gulf Coast Research Laboratory, Ocean Springs, MS
Lake Pontchartrain Basin Evolution; Late Pleistocene-Holocene Geological
The Pleistocene sedimentary cycle that preceded Holocene evolution of the lake system,
climaxed 128-122 ka B.P.during the Sangamonian Interglacial. It produced the muddy-sandy,
microfossil-rich, marine-to-estuarine Biloxi Formation, c. 13.5 m thick under
Fontainebleau State Park and south Hancock County, MS, and overlain by the thin regressive
alluvial Prairie unit. The oxidized, seaward-sloping Prairie coastwise surface, cut by
approximately E-W-trending faults,
forms the northern border of the Lake. A buried segment of the Gulfport barrier complex,
the Gulfwide Sangamonian high shoreline indicator, occurs at nearby Port Bienville, MS.
The previously reported presence of another Pleistocene segment beneath the Lake, c. 10 km
from the north lake shore, is not yet proven. (Earlier, this 3-5 m thick sand body,
appearing as channel-filling beneath the muddy lake deposits in the Causeway
foundation-drillholes, has been described as the "Miltons
Island Beach Trend", Saucier's assumed earlier Holocene lake shoreline.) Stream
channels became deeply incised in the general area and clusters of wind-blown dunes formed
along river floodplains in the Florida Parishes during subsequent marine lowstands of the
Wisconsinan glacial interval. By c. 4.5 ka B.P., Holocene transgression filled most of the
"Pontchartrain Embayment" with higher salinity but still brackish waters.
Westward-directed littoral drift from Pearl River delta shores 5.0-3.7 ka constructed a
chain of sandy underwater shoals, probably also including small barrier islands in front
of the embayment. These barrier sand bodies are 6-12 m thick. Occasionally, they extend
near, even slightly above the land surface (Pine and Oak "Islands" in New
Sediment and microfossil data marked steady eastward growth of the Mississippi delta
toward the shoals. A delta spur separated Lake Maurepas from Pontchartrain. By 4.0 ka, the
Morrison Rd. Pit area (at Frenchmans Wharf Apartments, on Interstate Highway 10, New
Orleans East), was covered by subdelta clays and sandy muds (Otvos, 1978). Recently
obtained radiocarbon dates (Dr. F. Stapor, Jr.) indicate that shore processes continued 4
km to the east at Bullard Rd. until c. 3.5 ka. As late as 3100-2900 yr B. P. barriers of
the separate South Hancock-Sauvage trend were active shore zones in easternmost Orleans
Intensive regional delta growth (St. Bernard and other subdeltas in present Orleans-St.
Bernard Parishes) subsequently buried the two barrier trends under the extensive
marshlands. Pontchartrain's waters freshened as a wide belt of delta land gradually cut
off the bay from the Gulf. Lake beaches and numerous Indian midden mounds date from this
period. Cessation of delta growth and continuing subsidence soon increased shore erosion.
Improved connection with the Gulf, most recently through the man-made Gulf Outlet Channel,
slightly increased salinities. Intensive commercial clam shell-dredging in recent decades
(Otvos and Sikora, 1990) liquefied central lake sediments and profoundly impacted bottom
biota, including the Rangia bivalve fauna. Lake tidal gage data indicate minor subsidence
probably along faults. Tectonic and eustatic changes, sediment compaction and marsh
degradation -related to natural and man-induced causes- will remain critical factors in
future basin development.
Perret, William S., L. Brandt Savoie, John F. Burdon and Karl A. Mapes, Louisiana
Department of Wildlife and Fisheries.
The Fisheries of the Pontchartrain Basin
The Lake Pontchartrain Lacustrine Basin is bordered by 8 parishes and drains 8 additional
parishes of Southeast Louisiana and numerous counties of southwest Mississippi.
Preliminary data indicate that in 1990, -*-% (-*- pounds) of Louisiana's commercial
fishery landings were within the basin. Historical records indicate that the Basin has
contributed significantly to the states fishery production. Landings include species
caught from freshwaters to adjacent continental shelf waters of the Gulf of Mexico.
In 1990 a significant number od commercial and recreational fishermen resided within
the Basin. Freshwater recreational fishermen from the Basin accounted for 22% (108,107)
while saltwater anglers accounted for 42% (88,331) of the states licensed resident
population. Commercial licenses sold within the Basin accounted for 31% (32,612) of the
Utilization of the Basin's fishery resources by recreational and commercial groups have
continued to increase during the last three decades but overall fishery production has not
kept pace. While
landings may have increased in some cases, the addition of more user's has resulted in a
decreased catch per effort.
The Basin's fishery has been significantly impacted by wetland and estuarine habitat loss
or modification due to such activities as leveeing, reclamation, subsidence, sea level
rise, erosion, toxins and eutrophication. Salinity modifications often accompany habitat
modifications and may significantly impact the distribution of fishery species. Point and
non-point source discharges of pollutants have impacted the quality of the harvest waters
of many species, especially the American oyster. Introduction of species or pathogens not
endemic to the Basin may also pose a threat to the fisheries.
Its diverse habitats and resources portray a region that is providing adequate fishery
production, despite its problems. However, it evident that there are many significant
economic and social changes occurring with more on the horizon. Sustaining or enhancing
the fishery resources of the Basin has no single solution. conservation, implementing
comprehensive wetland management plans, implementing comprehensive inventories of habitat
types, and strengthening the environmental consciousness of all who live, work and play in
the Basin will help.
*Landing data is forthcoming for NMFS.
Powers, S.P., Poirrier, M.A., and Yund, P.O., Department of Biological Sciences and the
Urban Waste Management and Research Center, University of New Orleans, New Orleans,
The Effects of New Orleans Urban Runoff on the Benthic Community of Southern
Between the summer of 1991 and the winter of 1992 we conducted a study of the benthic
community of southern Lake Pontchartrain to assess the impact of New Orleans urban runoff
on Lake Pontchartrain. A sampling grid, which extended North from the shoreline eight
kilometers and 5 kilometers East to West, was established in southern Lake Pontchartrain
adjacent to three outfall canals in Jefferson Parish (Parish line, Duncan, and Elmwood
canals). Two macrofauna and two meiofauna samples were taken from sets of sites within the
sampling grid between June 1991 and February 1992. Differences in species diversity,
abundance, dominance, and trophic structure among sites were analyzed to assess the effect
of the outfall canals on the benthic community.
Results from our study indicate that there is a pronounced effect on the communities
immediately adjacent to the outfall canals (0m-400m(?)). These sites were characterized by
low species diversity
values, reduced numbers of mollusks (particularly juveniles), and increased abundance of
nematodes, oligochaetes, and capitellid polychaetes on all sampling dates. A transient
effect was also seen in the meiofauna community following a period of high rainfall. This
short term effect extended much further than the chronic effect (2.40 km) and was probably
a result of the large input of freshwater into the lake. We also compared the effects of
three different canals, which differed in
discharge capacity and levels of toxins, on the associated benthic communities. A
comparison with previous benthos surveys allowed us to evaluate the effect of sewage
diversion into the Mississippi River, initiated in 1989.
Preston, K.P., Geography/Urban Waste Management and Research Center (UWMRC), Poirrier,
M.A. and Burns, J.W. Biological Sciences/UWMRC, University of New Orleans, New Orleans, LA
Community Structure and Distribution of Submerged Aquatic Vegetation in Lake
Submerged aquatic vegetation (SAV) generally occurs along the shallow, less exposed
shoreline areas in the Lake Pontchartrain Basin and provides a number of important
ecological functions. Submerged grassbeds help stabilize sediments, reduce shoreline
erosion, assimilate pollutants, and release oxygen. Moreover, they provide a protected
habitat for larval and juvenile stages of many estuarine organisms and a food source for
waterfowl, fish, invertebrates, and other aquatic species. Over the past 40 years several
studies have noted a decrease in grassbed coverage and a decrease in depth of grassbed
growth. Areal coverage of SAV in Lake Pontchartrain has decreased by 50% between 1973 and
1983. While previous studies provide general qualitative information about the status of
grassbeds in Lake Pontchartrain, they provide little quantitative information concerning
community structure and diversity and seasonal variation in growth and distribution.
Moreover, they fail to take into account the patchy nature of grassbed distribution when
estimating areal coverage thus likely overestimating the actual coverage of SAV beds in
In this study species composition, community structure, and diversity relations were
determined for five grassbed sites in Lake Pontchartrain. Foliar cover of all SAV species
was measured along five
randomly placed transects in each site during the summer of 1991. The measurements were
repeated during the winter of 1992 along a random subset of transects at each site. The
seasonal variation in SAV distribution and the degree of deciduousness among the dominant
species could thus be ascertained. Foliar cover for each species was stratified by depth
interval and substrate type along each transect in order to identify the influence of
these physical variables on SAV growth. In
addition, the degree of patchiness within grassbeds was used to modify estimates of
grassbed coverage in Lake Pontchartrain.
Rheams, Anne B. Louisiana Department of Environmental Quality, Baton Rouge, LA
Lake Pontchartrain Basin: Urban Nonpoint Source Pollution Problems and
Recent water quality monitoring studies in urban areas have shown that the highest
pollutant loadings and concentrations usually occur during rainfall events in the first
0-1 inch of rain, commonly referred to as the "first flush." In urbanizing an
area, impervious surface-area such as streets, parking lots, and rooftops is increased.
These smooth, impenetrable surfaces allow little or no detention or infiltration of
stormwater. As precipitation falls on urban areas, it picks up contaminants from the air,
littered and dirtied streets and sidewalks; petroleum residues from automobiles, exhaust
products, heavy metals and tar residuals from the roads; chemicals applied for
fertilization, weed and insect control; and, sediments from construction sites. The
dumping of chemicals such as used motor oil and antifreeze into storm sewers is another
source of urban nonpoint source (NPS) pollution.
Lake Pontchartrain is severly impacted by urban runoff and has been targeted as a priority
watershed within the Department of Environmental Quality's (DEQ) Urban NPS Program.
According to the state's 1990 Water Quality Inventory (305(b) Report) and the 1991 NPS
Assessment Report, Lake Pontchartrain ranks second in the state in total water quality
management subsegments impaired and/or threatened by urban runoff. This information is
based on evaluative data from the DEQ regional offices and specific water quality
monitoring stations in the basin.
In addition to the need for physical, corrective measures such as best management
practices (BMPs) to prevent and reduce urban NPS pollution, source control through public
education regarding NPS problems and solutions is critical to urban NPS pollutant
abatement. DEQ's urban NPS public education and involvement strategy includes the
dissemination of educational materials such as brochures, posters, fact sheets, and bumper
stickers. DEQ's Storm Drain Stenciling Program has been initiated in both Jefferson and
Orleans Parishes in an effort to alert basin residents of the connection between storm
drains and the water quality of the lake. The purpose of the stencil program's message is
to serve as a deterrent to people who dump pollutants such as used motor oil down storm
sewers, not knowing that the sewers drain directly into the lake instead of a wastewater
treatment facility. Other educational and technical assistance activities include an urban
NPS video, a model ordinance report, establishment of WATERWATCH groups, and a lawn care
DEQ's Urban NPS Program includes a task for the implementation of urban BMPs and the
evaluation of their effectiveness in improving water quality. DEQ is accepting proposals
for BMP projects in priority watersheds such as Lake Pontchartrain.
While the Urban NPS Program's strategy for implementation is non-regulatory, many of the
problems related to pollution from urban runoff will be addressed through EPA's stormwater
regulations. Both Orleans and Jefferson Parishes, bordering the south shore of the lake,
are in the process of applying for stormwater permits.
Rohli, R.V., Southern Regional Climate Center, Department of Geography &
Anthropology, Louisiana State University, Baton Rouge, LA
Deviations Between Modeled and Measured Runoff in the Lake Pontchartrain Basin
A Thornthwaite monthly water-budget model is used to estimate monthly surface runoff into
the Lake Pontchartrain Basin from the Comite, Amite, Tickfaw, Natalbany, Tangipahoa, and
Tchefuncte Rivers for the last fifty years. The modeled outputs for each drainage basin
are compared to measured monthly runoff data obtained from the U.S. Geological Survey for
the same time periods. Statistical tests are implemented to identify those basins where
seasonal and annual ratios of modeled to measured runoff differ significantly from each
other. Hypotheses about the differences are developed, and model adjustments are
recommended for better estimation of runoff from ungaged areas of the Pontchartrain Basin.
Sabaté, R.W., The San'Doil Co., New Orleans; Dewailly, E.L., Lumitox Gulf, New Orleans;
Stiffey, A.V., University of New Orleans
Algal Bioluminescence in Toxicity Testing
Environmental quality commonly is determined by bioassays, which measure the response
(primarily death rate) of living organisms to the presence of toxins. Subject organisms
range from indigenous populations to selected species with demonstrated standard
responses, predominantly minnows and shrimp. Cumbersome culture facilities and laboratory
techniques, which translate to time and expense, together with the desire for on-site
testing, has led to experimentation with monocellular
species. These offer the added statistical advantage of larger numbers (thousands or
hundreds vs tens) of individuals in a sample aliquot.
Lumitox (R) is a new, compact, fast (hours vs days) patented bioassay that uses the marine
bioluminescent dinoflagellate alga Pyrocystis lunula. When agitated, P. lunula generates a
brilliant flash of light. In the presence of varying concentrations of toxins, this light
- as measured by a patented photometer - is quenched in a predictable manner. The
procedure is very sensitive to small changes in toxic concentrations both at high and low
levels, is repeatable with low variation, and is effective in turbid or colored media.
The U.S. Navy inventor of Lumitox (R) has demonstrated its testing efficacy with many
substances, including pesticides, defoliants, marine antifouling paint, waterbottom
samples, and oil-well drilling fluids, the latter confirmed by Louisiana State University.
In conjunction with University of New Orleans, Lumitox (R) will engage in environmental
testing and develop a portable testing unit.
Smith, Sue K., Louisiana State University, Baton Rouge, LA
North-Shore Sources of Suspended Sediment in the Surface Runoff to Lake
The Lake Pontchartrain Basin in southeast Louisiana comprises Lakes Pontchartrain and
Maurepas, along with the surrounding land area. The major north-shore streams that
contribute fresh water into the basin are the Amite, Tickfaw, Tangipahoa, and Tchefuncte
river systems, along with their tributaries. These streams head in southern Mississippi
and flow southward across a series of down-stepping terraces through a region that is used
mostly for agriculture and forestry. Hydrologic
data are available for approximately 50 years for these streams. The data show some
variations in stage, discharge, and water quality. Suspended sediment data show distinct
differences between the seasons of the year and between the different rivers. During this
time period, some of the streams have also shown some changes in their planform
dimensions. The nature of these variations and changes are discussed, and some possible
explanations are offered.
Thiyagarajah, A., and Ledet, M. J., college of Pharmacy, Xavier University of Louisiana,
7325 Palmetto Street, New Orleans, LA
Histopathological Assessment of Two Species of Fish from the Bayou Trepagnier
Bayou Trepagnier is located in the Lake Pontchartrain Basin, in St. Charles Parish of
Louisiana. Bayou Trepagnier receives treated wastewater and storm water from an oil
refinery and manufacturing complex. According to the Water Pollution Control Division of
the Louisiana Department of Environmental quality reports, benzene, toluene, ethylbenzene,
dichlorobenzene and chloroform were detected in fish and crabs collected from the lower
stations on Bayou Trepagnier. Benzene is classified by USEPA as a known human carcinogen.
The purpose of this preliminary study is to assess the fish health histologically. We
selected mollies (Poecilia latipinna) and sheepshead minnows (Cyprinodon yariegatus) as
test organisms because these species are very sensitive to carcinogens. Fish were caught
by beach seine twice in November, 1991. Fish were examined grossly, and then processed for
histological assessment. Preliminary observations indicate that the majority of the
lesions are present in the cartilage, muscle, liver, and pancreas. Liver lesions range
from fatty change to precancerous lesions. The preneoplastic lesions include basophilic
cell foci, vacuolated cell foci, clear cell foci, and spongiosis hepatis. Other lesions
include, fatty change in the exocrine pancreas, fat necrosis, vasculitis, protozoan and
metazoan parasites in various tissues, and inflammatory lesions. These lesions will be
described and discussed.
Thompson, Bruce A., Coastal Fisheries Institute, Louisiana State University, Baton
Rouge, Louisiana 70803-7503
A Review of Fish Studies on Lake Pontchartrain
Many questions have been asked over the years about the fish assemblages of Lake
Pontchartrain. The members of this 130 species assemblage play important roles in both the
ecology and economics of the region. Over the past 40 years there have been four major,
studies of the fishes of Lake Pontchartrain; two in the 50's, and two in the 70's. The
last fish survey was done during 1978, 14 years ago! The relative abundance of many common
fish species in the lake has changed little between 1953 and 1978 and no change in the
community proportion of marine, estuarine or freshwater fishes was found. The lake serves
a major function as nursery and feeding grounds for large numbers of juvenile fishes.
Certain environmental changes may be impacting the lake's ability to continue to function
as a major nursery. The salinity regime of the lake, controlled primarily by riverflow,
seems to control which fish species will be dominant. Overall, the fish assemblage appears
to have a "healthy" indication of seasonal change and a lack of
overdominance as found in more disturbed estuarine systems.
Thomson, A., University of New Orleans, New Orleans, La., and LeBlanc, R.J., Sr., Rufe
LeBlanc School of Clastic Sediments, Houston, TX
Geological History of Lake Pontchartrain
The Lake Pontchartrain Basin of southeastern Louisiana lies between the Late Pleistocene
Prairie Terrace to the north and the Late Holocene Mississippi Deltaic Plain Complex to
the south, a distance of about 28 miles. The western margin of the Basin is near the
present Mississippi River southeast of Baton Rouge, and the eastern margin of the Basin is
near the western end of the Mississippi Sound. Thus, the width of the Basin is about 90
Lake Pontchartrain is the largest lake within the Basin. It has an areal extent of about
700 square miles and lies to the east of Lake Maurepas and the west of Lake Borgne. The
areal extent of these three lakes comprises more than half of the Basin.
Considerable research on the geology of the Pontchartrain Basin was conducted over a
period of over 40 yrs (1935-1977) by several Louisiana State University Geology professors
and their graduate students and former students, with funds provided by the Corps of
several oil companies. None of this research has produced any evidence that the area
encompassed by Lake Pontchartrain was once an extensive deltaic plain.
Research results indicate the origin of the Pontchartrain Basin was different from the
origin of Lake Pontchartrain within the Basin. Sub-regional tectonic processes (faulting
and subsidence) were mainly responsible for the development of the Basin. In contrast,
Lake Pontchartrain originated as a result of sedimentation processes. After the last rise
in sea level reached its present stand about 5000 years ago an arm or embayment of the
Gulf of Mexico extended inland as far north as the latitude of Mandeville, La. Later the
western portion of the embayment was isolated from the Gulf by arms of the Cocodrie and
St. Bernard Deltas of the Mississippi River, producing Lakes Maurepas and Pontchartrain.
Thus, in spite of subsidence and some down-faulting within the embayment, the Mississippi
River overwhelmed the region with sediments, and Lake Pontchartrain remains isolated from
the Gulf, with the exception of the narrow Rigolets outlet into Lake Borgne. After the St.
Bernard Delta was abandoned, the trunk course of the present Mississippi River contributed
little sediment to the lake.
In conclusion, it is highly probable that faulting within the Pontchartrain Basin (south
of the Pleistocene Terrace) has played a minor role in the origin and development of the
lake, but there is
overwhelming evidence that Lake Pontchartrain was created as a result of Mississippi River
diversion and sedimentation.
Turbeville, J.H.Jr., Conoco Inc., New Orleans, LA
The Geology and Geohydrology of an Area Representative of Near Surface Aquifer
Systems on the Mississippi River Flood Plain in South Louisiana
The Mississippi River Flood Plain is approximately 100 miles wide, extending from Lake
Pontchartrain to Lafayette, and traversing the entire state of Louisiana from north to
south. The near surface aquifer system created on the floodplain coincides with both the
most heavily industrialized and environmentally sensitive areas in the state. This
includes the great majority of Lake Pontchartrain and wetland areas.
The study area is located outside of Luling, Louisiana, between the cities of New Orleans
and Baton Rouge. It is 1/2 mile south of the Mississippi River and 10 miles southwest of
Lake Pontchartrain. Located on an industrial park, the area encompasses two separate
sources of known dichloroethane contamination (a dense non-aqueous phase liquid or DNAPL),
the Ethylene Maleic Anhydrite (EMA) and Deep Well Pond sites. There were 23 wells used in
the study that penetrate four stratigraphic layers. Layers I and III are considered to be
aquitards, layers II and IV are aquifer sands. The aquifer system interval ranges from 2'
to 40' measured from ground surface.
Stratigraphic correlations of the aquifer system were completed by constructing a series
of cross-sections (10) across the area. A total of 7 geologic maps were then generated on
the base, top and thickness of each aquifer unit. A hydraulic gradient map was
constructed, and coupled with hydraulic conductivities (from slug tests), average linear
velocities of groundwater were calculated.
The penetrated stratigraphy is from Holocene to Recent in age and consists of 4 units.
Layers I and III are organic rich clays deposited as part of the natural levee system.
Layers II and IV are silt to
coarse grained sands in fining upward sequences deposited as overbank or swale fill that
vary in proximity and source direction from the Mississippi (or paleo Mississippi) River.
Maximum vertical relief is created on the flood plain from the natural levee systems,
which vertically accrete until the river overruns the levee and eventually abandons the
Both layers II and IV are partially confined aquifers that are moderately heterogeneous
with respect to hydraulic conductivity. Hydraulic conductivity values are relatively low
and range from .1 to 3
ft/day, increasing to the south and in the basal portions of layers II and IV. Groundwater
flow direction averages southwest, with a hydraulic gradient averaging .0036. The
Mississippi River is thought to be a head boundary that fluctuates with the rivers stage.
Groundwater velocity is relatively slow with a calculated range from .001 ft/day to .04
ft/day, increasing to the south of the study area. This is considerably slower than what
is observed in areas of known contamination in the EMA and Deep Well Pond areas.
Contaminant dispersion (spreading out) appears to be a significant factor based upon
contaminant plume delineation from soil vapor analysis relative to known source area.
There is potential for DNAPL contamination to follow the structural base of layers II and
IV, thereby retarding or accelerating migration velocity, depending on its directional
relationship to groundwater flow. Sharp basal contacts created from fining up sequences in
both layers enhance this effect.
Vega, A. J., Southern Regional Climate Center, Department of Geography &
Anthropology, Louisiana State University, Baton Rouge, LA, 70803
Long-term Climatic Variability of Modeled and Measured Runoff within the Lake
This study examines long term climatic variability of modeled and measured runoff within
the Lake Pontchartrain Basin. Runoff estimates will be determined using a Thornthwaite
water-budget model for the Comite, Amite, Tickfaw, Natalbany, Tangipahoa and Tchefuncte
Rivers. Time series analysis will be employed to determine yearly, seasonal and monthly
climatic trends in association with individual water years (October to September).
Long-term trends will be accessed for each of
the drainage basins and collectively to determine patterns of climate variability (i.e.
wet or dry months, seasons, years). This analysis will determine associations between the
frequency of extreme temporal precipitation events and global circulation variability.
Wee, James L., Booth, Dennis J. and Bossier, Michael A., Department of Biological
Sciences, Loyola University, New Orleans, Louisiana
Synurophycean Algae from the Lake Pontchartrain region: A Preliminary Survey
from the Southern Atlantic Coastal Plain of North America
Forty-three taxa of Synurophyceae were identified by means of transmission electron
microscopy from 10 samples collected in southeastern Louisiana, USA, on the southern
portion of the Atlantic
Coastal Plain Province of North America. Mallomonas prora and Synura australiensis are
reported for the first time from North America. Samples were collected during a one month
time period when water temperatures ranged from 15.5-24.5 C. Sample pH values ranged from
4.42-7.21. Notable scale morphology variation was described for some taxa. The flora
included three warm water taxa but was dominated by temperate and cosmopolitan taxa.
Comparisons with related studies from New World, subtropical regions in Florida, USA, and Argentina, were made, and significant
North American range expansions were noted. The large number of aquatic habitats, 7-8
consecutive months at temperatures (6-20 C) best suited for development of synurophyte
populations, and proximity to major bird migrations routes are postulated as explanations for the large
number of reported species.
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