Armingeon, N. A., Lake Pontchartrain Basin Foundation, New Orleans, La,
THE BONNET CARRE' 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' Carre 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 Carre' 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.
Brent Barnidge, 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 Carr( 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 Carre 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 Carr( 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 CARRE SPILLWAY.
The Bonnet Carre freshwater diversion project will divert water from the
Mississippi River into Lake Pontchartrain via the Bonnet Carre 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 Carre 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 Carre 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 Carre 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.,
B. Thibodeaux, 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.
RECENT TRENDS IN WATER CLARITY OF LAKE PONTCHARTRAIN
Francis, J. C., and Poirrier, M. A., Department of Biological Sciences, University
of New Orleans, New Orleans, LA.
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 Carre 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 Carre 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 1¼ 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.
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 Pontchartrian 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 DATA BASE 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 Dept. 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 indentify 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 accomodates 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 Carre Spillway during June and
July of 1995, and intense blooms of the blue-green algae and associated fish kills
occurred during July of 1995.
Sites in southern Lake Pontchartrain were sampled on November 19, 1995 to
determine the condition of bottom waters and the status of benthic invertebrate
populations. Salinity and dissolved oxygen measurements were made and benthic
invertebrates sampled at nine stations along two transects which ran from the
mouth of the Inner Harbor Navigation Canal west to the Lake Pontchartrain Causeway
at 2.5 and 5.0 miles from shore.
Although strong north winds which can mix south shore waters occurred before
sampling, salinity stratification and low bottom dissolved oxygen concentrations
were present. Past studies of benthic invertebrate populations in the same study
area found communities indicative of stressful conditions near the Inner Harbor
Navigation Canal and a transition to communities indicative of normal conditions
occurring with distance from the canal. In contrast, November 1995 samples
indicated stressful conditions at all sites on both transects. The number of
mollusks, including the clam Rangia cuneata and the snails Texadina sphinctosoma
and Probythinella louisianae was low at all sites. The benthic invertebrate
community was dominated by oligochaetes and polychaetes which are known to
tolerate stress. The presence of few mollusks and numerous annelids at all sites
indicates that adverse environmental conditions occurred throughout the study area.
Penland, S., Louisiana State University, Baton Rouge, LA;
Wayne, L., Louisiana State University, Baton Rouge, LA;
Britsch, D., U.S. Army Corps of Engineers, New Orleans, LA; and
Williams, S.J., U.S. Geological Survey, Reston, VA,
COASTAL LAND LOSS RATES, FORMS, AND PROCESSES IN THE PONTCHARTRAIN BASIN.
The Pontchartrain Basin in this coastal land loss study extended from Lake
Maurepas through Lake Pontchartrain to Lake Borgne and includes the areas north of
the MRGO navigation channel. Utilizing the USACE-NOD coastal land loss GIS
database, the authors used a subset of this information to quantify the rates,
forms, and processes of loss in the Pontchartrain Basin.
The rate of coastal land loss in the Pontchartrain Basin has averaged -1.97mi2yr-1
between the 1930's and 1990's. The rates of loss have accelerated from 1.43
mi2yr-1 in 1930's/1950's to -3.07 mi2yr-1 in 1950's/1970's. Since these time
periods, the rate of land loss has decreased from -1.97 mi2yr-1 in 1970's/1980's
to -1.41 mi2yr-1 in the 1980's/1990's. Coastal land loss occurs throughout the
basin, however, the eastern basin has greater loss than the western basin.
To further quantify coastal land loss, a geomorphic classification was developed
for GIS analysis. Coastal land loss has two basic forms, shoreline loss and
interior loss. Shoreline describes areas of loss that occur relative to existing
water bodies. Interior describes areas of loss that occur independent of existing
water bodies. The next level of the hierarchy addresses the water body type most
closely related to loss. For shoreline areas, this level depicts the type of
water body physically related to the loss. Four classes of shoreline loss were
established:
1) gulf - the outer shoreline facing the Gulf of Mexico,
2) bay - semi-enclosed water body with direct contact to the Gulf of
Mexico,
3) lake - enclosed or semi-enclosed water body with no direct contact to
the Gulf of Mexico, and
4) channel - linear water body that commonly connects other water bodies.
For interior areas, this level of the classification depicts the water body type
that is most similar new interior loss. Two interior classes were established:
1) pond - enclosed or semi-enclosed water body with minor connections to
the existing drainage network, and
2) channel - narrow, linear water body.
Once the forms of loss were delineated and mapped, a process classification was
developed to quantify cause. The first level of the classification hierarchy
addresses the basic processes of land loss. For purposes of this classification
scheme, the term land is defined as all subaerial materials including surface
vegetation, sediments, and organic soils. Three primary land loss processes were
identified:
1) erosion - mechanical removal and transport of land by water action,
2) submergence - increase of water level relative to ground surface
elevation, and
3) direct removal - physical removal of land by actions other than water.
A fourth category, undetermined, is included for those areas to which no
assignment can be made.
The second level of the process classification scheme identifies the primary
physical actions that are associated with each loss process. This level of the
classification includes both natural and cultural actions.
The action of erosion include:
1) scour - mechanical removal of land by water, and
2) transport - suspension and conveyance of land by water.
The actions of submergence include:
1) flooding - short-term increase in water level,
2) substrate collapse - reduction in substrate thickness, and
3) subsidence - reduction in land surface elevation.
The actions of direct removal include:
1) excavation - extraction and transport of land to another location, and
2) burning - oxidation of the organic component of land.
At the third level of the process classification scheme, issues of cause emerge.
This level identifies the natural and cultural catalysts to the physical actions.
Natural catalysts include phenomena such as wind, loss of vegetation, high water,
loading, and faulting. Cultural catalysts include human activities such as
dredging of navigation channels, building of impoundments, resource extraction,
excavation of ponds, and fires.
The fourth level of the process classification identities the factors known to
stimulate natural and cultural land loss catalysts. This is a diverse category of
information which includes natural and cultural events, activities, and structures.
Factors included at this level of the classification scheme include storms,
herbivory, sediment transport, recreation, agriculture, commerce, levees, and
engineered coastal preservation/restoration structures.
In the Pontchartrain Basin, natural erosion and submergence account for a small
percent of the coastal land loss problem. A greater percentage is related to
man's activities such as canals, highways, failed land reclamation, borrow pits,
and altered hydrology. This paper presents the results of the GIS land loss
analysis.
Poirrier, Michael A., Department of Biological Sciences, University of New Orleans
THE BIG STINK OF 1995: OBSERVATIONS ON ALGAL BLOOMS, FISH KILLS AND GRASSBED DECLINE.
Intense blue-green algal blooms fish kills, grassbed loss and dead zone expansion
occurred in Lake Pontchartrain during the summer of 1995. Unusual environmental
conditions were associated with the algal blooms, and related events. Runoff from
heavy rainfall in April and early May, and Mississippi River water which entered
through the Bonnet Carre 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 Carre 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.
Sabate', 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. The site 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., Louisiana State University, Baton Rouge, LA;
Zganjar, C., Louisiana State University, Baton Rouge, LA;
Westphal, K.A., Louisiana State University, Baton Rouge, LA;
Penland, S., Louisiana State University, Baton Rouge, LA;
Mathies, L., U.S. Army Corps of Engineers, New Orleans, LA;
Nord, B., U.S. Army Corps of Engineers, New Orleans, LA; 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 Carre' 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, Louisiana State University, Baton Rouge, LA;
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.