| Lake Pontchartrain
Basin: Bottom Sediments and Related Environmental Resources |
1996 BASICS OF THE BASIN ABSTRACTS
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Basics of the Basin abstracts
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
http://www.brecht.com/saveourlake/. The site serves three primary purposes: education,
advocacy and development. [2008 Update: The site is now located at http://www.saveourlake.org/]
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:
- gulf - the outer shoreline facing the Gulf of Mexico,
- bay - semi-enclosed water body with direct contact to the Gulf of Mexico,
- lake - enclosed or semi-enclosed water body with no direct contact to the Gulf of
Mexico, and
- 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:
- pond - enclosed or semi-enclosed water body with minor connections to the existing
drainage network, and
- 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:
- erosion - mechanical removal and transport of land by water action,
- submergence - increase of water level relative to ground surface elevation, and
- 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:
- scour - mechanical removal of land by water, and
- transport - suspension and conveyance of land by water.
The actions of submergence include:
- flooding - short-term increase in water level,
- substrate collapse - reduction in substrate thickness, and
- subsidence - reduction in land surface elevation.
The actions of direct removal include:
- excavation - extraction and transport of land to another location, and
- 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.
TABLE 1
Change in Total Acres of each Habitat in the MRGO - Jetty Study Area between 1985 and 1995
| HABITAT |
1985* |
1995* |
AREA CHANGE |
| |
|
|
|
| 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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