United States
Environmental Protection
Agency
Louisiana
Geological
Survey
April 1987
EPA-230-02-87-026
<&EftV Saving Louisiana's Coastal Wetlands
The Need For a Long-Term Plan of Action
Report of The Louisiana Wetland Protection Panel
-------
-------
Library of Congress Cataloging-in-Publication Data
Louisiana Wetland Protection Panel (1985: Grand Terre
Island, La.)
Saving Louisiana's coastal wetlands.
Held in Grand Terre Island, La., September 17-19, 1985.
Bibliography: p.
1. Wetland conservation—Louisiana—Congresses.
2. Wetland—Louisiana—Congresses. 3. Sea level—
Louisiana—Congresses. 4. Greenhouse effect,
Atmospheric—Congresses. I. Louisiana Geological
Survey. II. Unites States Environmental Protection
Agency. III. Title.
QH76.5.L8L68 1985 333.91'816'09763 87—5400
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SAVING LOUISIANA'S COASTAL WETLANDS
The Need for a Long-Term Plan of Action
Report of the Louisiana Wetland Protection Panel
Convened By
Louisiana Geological Survey
U.S. Environmental Protection Agency
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
SUMMARY
America's largest wetland community is losing its marshes and swamps to the Gulf of Mexico. The
wetlands of coastal Louisiana are being converted to open water at a rate of fifty square miles per year,
largely as a result of maintaining shipping lanes, the dredging of canals, flood control levees, and the
withdrawal of oil and gas. If current trends continue, an ecosystem that supports the nation's oldest
bilingual culture, 25 percent of the nation's fishing industry, and North America's largest fur-producing
area, will be mostly lost in the next century. This process could be further accelerated if sea level rises
one or more feet as a result of the projected global warming from the greenhouse effect.
Over the last twenty years, various solutions have been suggested to save Louisiana's coastal
wetlands. Proposals have included unharnessing the Mississippi River; breaching the levees to allow river
water to reach the wetlands; building giant levees along the entire coast; restoring the rapidly
disintegrating barrier islands; filling the many canals that have been dredged through the marsh; or
combinations of these alternatives. Thus far, however, most investigations have focused on specific
impacts and responses, not on a comprehensive solution. No one has systematically synthesized the
available information to determine what must be done to save 10, 25, or 50 percent of Louisiana's coastal
ecosystem, or developed a comprehensive tool for such an analysis.
Although additional scientific research will be necessary, sufficient information is available to assess
this question and commence the development of a plan for saving Louisiana's wetlands. The Louisiana
Wetland Protection Panel was convened by the Louisiana Geological Survey and the U.S. Environmental
Protection Agency to outline a study to evaluate strategies to substantially reduce wetland loss in coastal
Louisiana through the end of the next century, for use in developing a comprehensive wetland protection
plan.
This report provides an overview of the problem and outlines the analysis that must be synthesized to
develop a plan, describing the causes of wetland loss, possible options to protect wetlands, and ongoing
activities to address the problem, and laying out a study to evaluate comprehensive solutions to wetland
loss in Louisiana.
Many federal, state, local, and private organizations will eventually have to address the loss of
Louisiana's wetlands. We hope that this report accelerates the process by which these groups become part
of the solution to the problem of wetland loss in coastal Louisiana.
CONCLUSIONS
1. Wetland loss in Louisiana is a problem with national importance. The coastal wetlands of
Louisiana support a major fraction of the U.S. fishing, hunting, and trapping industries, and
indirectly, the poultry industry. Unlike wetland loss elsewhere which mostly results from private
actions, the coastal wetland loss in Louisiana results primarily from activities conducted or authorized
by government agencies.
2. Although natural processes are involved, human activities are responsible for the net loss of
wetlands. These activities include levees, channelization, canals, draining and filling of land, and
human modification of drainage patterns.
3. Wetland loss could be reduced by combinations of marsh restoration and management;
Mississippi river diversion of freshwater, nutrients, and sediment; barrier island and beach
stabilization; and modification of human activities.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
4. A comprehensive plan of action is needed. Such a plan should have a reasonable chance of
protecting a large fraction of Louisiana's wetlands through the next century. This document has
outlined twenty options to be evaluated in the formation of such a plan.
5. A number of institutional impediments must be overcome before a consensus can be obtained
on the design and implementation of a plan of action.
6. No single approach will adequately curtail wetland loss in Louisiana.
7. Initial formulation of an action plan should not await completion of additional scientific studies.
Nevertheless, development of the plan will define additional research needs.
8. Ongoing and approved remedial measures should go forward on schedule. The need for a
comprehensive plan of action does not imply that previously approved projects should be delayed.
9. If projections that the greenhouse effect will raise sea level one foot or more in the next fifty
years are accurate, the need for immediate action is much greater than previously thought. The
global warming has not so far been an important factor in causing wetland loss in Louisiana.
However, long-term plans should consider the rise in sea level that could occur in the next fifty to one
hundred years. The possibility that sea level may eventually rise one or more meters is not a reason to
give up on efforts to protect coastal wetlands. It is another reason to implement measures to restore
the delta's former ability to keep pace with subsidence and sea level rise through sedimentation and
other processes.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
LOUISIANA WETLAND PROTECTION PANEL
Barney Barrett
Louisiana Department of Wildlife and Fisheries
Baton Rouge, Louisiana
Robert Buisson
U.S. Army Corps of Engineers
New Orleans, Louisiana
David Chambers
Louisiana Geological Survey
Baton Rouge, Louisiana
Mark Chatry
Louisiana Department of Wildlife and Fisheries
Grand Isle, Louisiana
Adrian Combe
U.S. Army Corps of Engineers
New Orleans, Louisiana
David Fruge
U.S. Fish and Wildlife Service
Lafayette, Louisiana
Sherwood Gagliano
Coastal Environments, Inc.
Baton Rouge, Louisiana
Chip Groat
Louisiana Geological Survey
Baton Rouge, Louisiana
Oliver Houck
Tulane Law School
New Orleans, Louisiana
Ted LaRoe
U.S. Fish and Wildlife Service
Washington, D.C.
Irving A. Mendelssohn
Louisiana State University
Baton Rouge, Louisiana
Donald Moore
National Marine Fisheries Service
Galveston, Texas
Stanley Riggs
East Carolina University
Greenville, North Carolina
lens Sorensen
Brookline, Massachusetts
Robert Stewart
U.S. Fish and Wildlife Service
Slidell, Louisiana
lohnny Tarver
Louisiana Department of Wildlife and Fisheries
Baton Rouge, Louisiana
Paul Templet
Louisiana State University
Baton Rouge, Louisiana
Gordon Thayer
National Marine Fisheries Service
Beaufort, North Carolina
Norman Thomas
U.S. Environmental Protection Agency
Dallas, Texas
lames G. Titus
U.S.Environmental Protection Agency
Washington, D.C.
lohn Weber
U.S. Army Corps of Engineers
New Orleans, Louisiana
in
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
TABLE OF CONTENTS
Introduction
Causes of Wetland Loss
(1) Sediment Deficit
(2) Canals
(3) Reclamation
(4) Wave Erosion
(5) Subsidence
(6) Sea Level Rise
(7) Saltwater Intrusion
Measures for Curtailing Wetland Loss
Barrier Island Restoration
Wetland Restoration
Marsh Management
Canals and Land Use
Diversion
Authorized and Planned Projects for Curtailing Wetland Loss
Authorized Projects
Planned Projects
The Need to Move Forward
Towards a Strategic Plan: A Proposed Study
The Need To Examine the Big Picture
Phase I: Strategies for Achieving Particular Levels of Wetland Protection
Phase II: The Benefits of Wetland Protection
Conclusion
Bibliograghy
1
3
9
10
10
12
14
16
16
19
21
21
23
25
25
29
30
36
37
38
38
39
42
45
46
IV
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
CHAPTER 1
INTRODUCTION
America's largest wetland community is losing its marshes and swamps to the Gulf of Mexico.
Coastal Louisiana is being replaced by open water at a rate of fifty square miles per year, largely as a
result of federal navigation policy, the dredging of canals, flood control levees, and the withdrawal of oil
and gas. If current trends continue, an ecosystem that supports the nation's oldest bilingual culture, 25
percent of the nation's fishing industry, and North America's largest fur-producing area, will be destroyed
in the next century. This destruction could be further accelerated if sea level rises one or more feet as a
result of the projected global warming from the greenhouse effect.
Are these marshes and swamps worth saving? For how long? Who is responsible for seeing that a
decision is made? These are questions for policy makers, not a technical panel. Yet for them to make a
reasoned judgment, they will need to know how to solve the problem, what it will cost, and the likely
results for various measures.
Over the last twenty years, various solutions have been suggested to save Louisiana's coastal
wetlands. Proposals have included unharnessing the Mississippi River; breaching the levees to allow river
water to reach the wetlands; building giant levees along the entire coast; restoring the rapidly
disintegrating barrier islands; filling the many canals that have been dredged through the marsh; or using
combinations of these alternatives. Thus far, however, most investigations have focused on specific
impacts and responses, not on a comprehensive solution. No one has systematically synthesized the
available information to determine what must be done to save 10, 25, or 50 percent of Louisiana's coastal
ecosystem, nor has anyone developed a comprehensive tool for such an analysis.
Although additional scientific research will be necessary, sufficient information is available to assess
this question and begin to develop a plan for saving Louisiana's wetlands. The Louisiana Wetland
Protection Panel was convened by the Louisiana Geological Survey and the U.S. Environmental
Protection Agency, and met on Grand Terre Island September 17-19, 1985. The purpose of the panel was
to specify strategies likely to substantially reduce wetland loss in coastal Louisiana through the end of the
next century, for use in a subsequent effort to develop a comprehensive plan. Based on the available body
of scientific literature, the panel reached the following conclusions:
1. Wetland loss in Louisiana is a problem with national importance. The coastal wetlands of
Louisiana constitute 40 percent of all U.S. coastal wetlands, and support a major fraction of the U.S.
fishing, hunting, and trapping industries, and indirectly, the poultry industry. Unlike wetland loss
elsewhere which mostly results from private actions, the coastal wetland loss in Louisiana results
primarily from activities conducted or authorized by government agencies. Many of the options for
protecting wetlands cannot be implemented without the cooperation of the federal government.
2. Although natural processes are involved, human activities are responsible for the net loss of
wetlands. These activities include levees, channelization, canals, draining and filling of land, and
human modification of drainage patterns.
3. Wetland loss could be reduced by combinations of marsh restoration and management;
Mississippi river diversion of freshwater, nutrients, and sediment; barrier island and beach
stabilization; and regulation of human activities.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
4. A comprehensive plan of action is needed. Such a plan should have a reasonable chance of
protecting a large fraction of Louisiana's wetlands through the next century. This document has
outlined twenty options to be evaluated in the formation of such a plan.
5. A number of institutional impediments must be overcome before a consensus can be obtained
on the design and implementation of a plan of action. Among the impediments are incentives for
private property owners for the development and implementation of restoration plans; incentives for
leaseholders and others affected by proposed remedial strategies; criteria and values assigned to
wetlands; the role of cost-benefit analysis; conflicts within and between agency missions; and
ownership of newly created lands.
6. No single approach will adequately curtail wetland loss in Louisiana.
7. Initial formulation of an action plan should not await completion of additional scientific studies.
Nevertheless, development of the plan will define additional research needs.
8. Ongoing and approved remedial measures should go forward on schedule. The need for a
comprehensive plan of action does not imply that previously approved projects should be delayed.
9. If projections that the greenhouse effect will raise sea level one foot or more in the next fifty
years are accurate, the need for immediate action is much greater than previously thought. The
global warming has not so far been an important factor in causing wetland loss in Louisiana.
However, long-term plans should consider the rise in sea level that could occur in the next fifty to one
hundred years. The possibility that sea level may eventually rise one or meters is not a reason to give
up on efforts to protect coastal wetlands. But it is another reason to implement measures to restore the
delta's former ability to keep pace with subsidence and sea level rise through other processes.
This report provides an overview of the problem and outlines the analysis that must be synthesized to
develop a plan. Chapter 2 describes the causes of wetland loss. Chapter 3 discusses a variety of possible
options to protect wetlands. Chapter 4 describes ongoing activities to address the problem. Chapter 5 lays
out a study to evaluate comprehensive solutions to wetland loss in Louisiana.
Many groups will eventually have to address the loss of Louisiana's wetlands, including the Federal
Emergency Management Agency's Flood Insurance Administration, the Fish and Wildlife Service, the
National Park Service, the National Oceanic and Atmospheric Administration, the Environmental
Protection Agency, the Army Corps of Engineers, the State of Louisiana, coastal parishes, the U.S.
Congress, the Louisiana Legislature, and the private sector. We hope that this report accelerates the
process by which these groups become part of the solution to the problem of wetland loss in coastal
Louisiana.
A number of the wetland restoration and management activities discussed in this report fall under
existing federal programs, such as those authorized under sections 401 and 404 of the clean Water Act,
Section 10 of the River and Harbor Act, and the Coastal Zone Management Act, as well as state
regulatory programs. In particular, the regulatory program established by Section 404 provides the major
avenue of federal involvement in material. This program was designed to ensure that discharges into
wetlands and other waters covered by the program do not result in unacceptable adverse impacts on
aquatic environments. Anyone who intends to discharge material into wetlands, even if the propose is to
protect wetlands from rising sea level, should contact EPA or the Army Corps Engineers to determine
whether a permit for the proposed activity is necessary.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
CHAPTER 2
CAUSES OF WETLAND LOSS
Over the last seven thousand years, the sediment washing down the Mississippi River created
Louisiana's coastal wetlands. The river deposited sediment along its main channel and distributaries to the
sea, creating land just above sea level that supported marsh and swamp vegetation. The delta building
processes gradually lengthened the main channel's route to the sea. Every thousand years or so, the river
switched to a shorter course, and built a new delta along this route (Coleman and Gagliano 1964; Frazier
1967). Figure 1 shows the delta "lobes" that have formed in the last seven thousand years; Figure 2
illustrates a generalized model of delta building and deterioration processes.
Once the river changed course, the wetlands along the old channel would gradually deteriorate and
revert partially back to open water. The deltaic sediments have always tended to compact and sink while
at the same time sea level has been slowly rising. Deprived of new sediment, the marshes would be
unable to maintain their elevation above the surface of the water. As a result, the vegetation would die,
and the marsh would deteriorate and "convert" to (be replaced by) open water. The change in river course
would also reduce the availability of freshwater supplied to the wetlands, which would allow saltwater
from the Gulf of Mexico to encroach inland, killing freshwater marshes and swamps, often converting
them to open water as well.
0
0
ALLUVIAL / ~r.
15 mi & PLAIN c"%
'^ / ? «3i
25 km «. /
'ar' MEXICO
© ®S
KEY
Shell Reef
Barrier Shoreline
Sand
DELTA COMPLEX
Maringouin
Teche
St. Bernard
Lafoyrche
Modern
Atehafalaya
AGE (YEARS BP)
7250-6200
57OO-3900
460CH80Q
3500-400
Active
Active
Figure 1. Sequence of Mississippi River delta lobe formation (modified from Frazier 1967).
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
,-,, ,., • ,s RESTRICTED
* -i^& '°* INTERDISTRIBUTARY
INTERDISTRIBUTARY
BIGHT
STAGE 1.
EROSIONAL HEADLAND
WITH FLANKING BARRIERS
ACTIVE DELTA
® MARGINAL
DELTAIC BASIN
OPEN
INTRA-DELTAIC
LAGOON
STAGE 2.
BARRIER ISLAND ARC
STAGE 3.
INNER SHELF SHOAL
DELTA PLAIN
ENVIRONMENTS
[__ j Distributary Levee
j__J Marsh
Beach Ridges
BARRIER
ENVIRONMENTS
nSubaerial Reworked
Deltaic Sands
r==l Subaqueous Reworked
L—J Deltaic Sands
L//JJ Recurved Spit
1 Tidal Inlet Channel
® @ Shell Reefs
Figure 2. Cycle of delta growth and decay (after Penland and Boyd 1961).
Coastal Louisiana has always experienced natural wetland loss in the abandoned delta after the river
changed course. Until recently, however, the loss was always more than offset by creation of wetlands in
the new delta. Seven thousand years ago Louisiana's Gulf of Mexico shoreline was along a line
corresponding to the present locations of Slidell, Baton Rouge, Lafayette, and Lake Charles; today it is
fifty to one hundred miles south of that location.
In the last century, human activities have disrupted the natural delta-building cycle. Levees along the
Mississippi River built for flood protection prevent the river from overflowing its banks and conveying
freshwater and sediment to the wetlands during annual floods. Navigation channels and projects that
artificially maintain the river's banks speed the river's flow, preventing sediment from settling out. Many
distributaries have been closed. As a result, the sediment, freshwater, and nutrients carried by the
Mississippi River now wash out into the deep waters of the Gulf of Mexico, rather than spreading out to
nourish and build Louisiana's coastal wetlands.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
COASTAL LOUISIANA
WETLAND CHANGE RATES
OC
C/D
O
_l
Q
Z
55n
50-
40-
30-
20-
10-
LOUISIANA
COASTAL ZONE
16,700 Ml2
(43,250
/
1
KM2)
\
I
20.1
>
f
f
1913 .'' /
8 5 *
x'"-^
^-"'-""6-
>' ^^
^
7
55. 0»
/
t
50.1 •'
'' «45.0
/ / 1 985
/ / 39.4
35.7 / /1980
* /
1967/
/ /28.1
/ /
/' /
•'1946
-* H "~ O 1 \
MISSISSIPPI
DELTAIC PLAIN
11,500 Ml2
(29,800 KM2)
-140
-120
CM
-100 ^
^^
-80 W
O
i
- 60
OU Q
Z
-40 ^
-20
- n
1880 1900 1920 1940 1960 1980 2000 2020
MODIFIED FROM GAGLIANO (1984)
Figure 3. Rates of wetland loss in the Louisiana coastal zone
compared with loss in Mississippi Deltaic Plain.
Human activities have also prevented the Mississippi from changing its course to the Atchafalaya
River. Although this river does capture 30 percent of the Mississippi River's flow and is creating a small
delta at its mouth, without the upstream control structure built by the U.S. Army Corps of Engineers, the
majority of the river's flow would reach the Atchafalaya delta and a far larger amount of wetlands would
be created.
Canals dredged through the marsh have also contributed to the loss of wetlands in a number of ways.
In some parts of Louisiana, the direct losses from dredging the canals themselves are quite large. Waves
from boats traversing the canals further erode the marsh. The canals also provide a conduit for saltwater
to advance rapidly inland into cypress swamps and freshwater marshes that cannot tolerate saltwater,
particularly where the flow of freshwater from the river to the wetlands has been blocked. Finally, spoil
banks from dredging canals interrupt the flow of water and nutrients. Other activities also contribute to
wetland loss, including draining and filling for development, agriculture, sanitation, and navigation.
As a result of these human factors, the historic expansion of the Mississippi Delta has been reversed.
Coastal residents and some scientists first noticed marsh deterioration and shoreline erosion more than
fifty years ago (e.g., Russell 1936). However, the rate of land loss was not established until Gagliano and
van Beek (1970) estimated that Louisiana was losing 16.5 square miles per year. Wicker (1980) later
showed that the deltaic plain lost 39 square miles per year between 1955 and 1978. Gagliano et al. (1981)
concluded that the rate of wetland loss has been increasing geometrically over the last century. As Figure
3 shows, the rate of wetland loss in 1985 for the deltaic plain alone is 45 square miles per year. The
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
Chenier Plain in southwestern Louisiana is losing an additional 10 square miles per year (Gosselink et al.
1979), bringing the total land loss within the Louisiana coastal zone to approximately 55 square miles per
year (nearly 100 acres per day). Figure 4 illustrates average rates of wetland loss for various portions of
coastal Louisiana. Figure 5 illustrates the land loss that has taken place at the mouth of the Mississippi
River, where the rate of loss is among the highest.
LOSS
LEGEND
ac/mi2/yr
UNCHANGED1
I very severe (>4)
severe (2-4)
moderate (1-2)
L~~l low (0-1)
LOUISIANA COASTAL ZONE
LAND CHANGE RATES 1955 - 1978
ALL VALUES AVERAGED OVER THE GROSS LAND AREA WITHIN
EACH 7.5 MINI!TE TOPOGRAPHIC QIJ ADRAMJLE
MILES
0 25 50
GAIN
0
50
KILOMKTKRS
0 f Mexico
AFTER VAN BKKK AND MKYKR-ARKNUT. 1082
Figure 4. Land change rates in the Louisiana coastal zone, 1955 - 1978.
Recent studies by the U.S. National Academy of Sciences (Charney 1979; Smagorinsky 1982;
Nierenberg et al. 1983) and international meetings of atmospheric scientists (e.g., UNEP/WMO/ICSU
1985) suggest that the rate of wetland loss may further accelerate in the future. Increasing concentrations
of carbon dioxide and other gases are expected to cause a global warming that could raise sea level one
meter (three feet) or more in the next century (Revelle 1983; Hoffman et al. 1983 and 1986; Meier et al.
1985). Such a rise would represent a major acceleration of the historical trend of 10 to 15 centimeters (4
to 6 inches) per century, and could eventually double or triple the rate of wetland loss. Figures 6a and 6b
illustrate projections of the state's shoreline for current sea level trends and a 55-centimeter rise by the
year 2033.
Many of the panel members initially recommended that this report place less emphasis on the issue of
accelerated sea level rise. Not because it is not a serious possibility, but because a one-meter rise could
have implications so profound as to cast doubt upon the wisdom of undertaking major efforts to protect
Louisiana's wetlands, and might thereby lead to a delay in several pending projects. Moreover, the
predictions of future sea level rise are still very uncertain. However, the panel concluded that the
possibility of an accelerated rise in sea level implies that these projects would be even more essential to
buy time, while a long-range strategy is formulated.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
WETLAND CHANGES IN THE MISSISSIPPI RIVER ACTIVE DELTA (1956-1978)
U.S. FISH A
NATIONAL WET
SLID
I-JP^I
NDWILDLIFE SERVICE
.AMDS RESEARCH CENTER
ELL, LOUISIANA
LEGEND
1956 1978 ACREAGE
HABITATTYPE ACREAGE ACREAGE CHANGE % CHANGE
R^H MARSH 182,838 89,381 -93,457 -51%
EH! FORESTEDWETLAND 7,894 3,233 -4,661 -59%
•• UPLAND 3,362 6,915 +3,553 +106%
DREDGE DEPOSIT 3,057 11,369 +8,313 +272%
25 0 25_50 75 100
MILES
Figure 5. Illustration of wetland loss at the mouth of the Mississippi river.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
BATON ROUGE
Gulf of Mexico
MORGAN CITY
THIBODAUX«
HOUMA
LOOP facility
N
0 50
miles
SOURCE
COASTAL ENVIRONMENTS, INCORPORATED
" f
^— T
COASTAL ZONE WETLANDS
PREDICTED LOUISIANA COASTLINE
IN 50 YEARS AT PRESENT
LAND LOSS RATES
Figure 6a. Louisiana shoreline in the Year 2030.
\ Baton Rowgi
Projccled Land Surface
Morgan C'Uy
Eugene Island •
Louisiana Geological Sui
Projected Future Coastline of Louisiana for the year 2033 A.IX
(EPA Sea Level Rise Scenario)
Figure 6b. Projected future coastline of Louisiana (after Ramsey and Moslow 1987) for the Year 2033
A.D. Given a rise in sea level of 54.9 cm as predicted in the high scenario (from Hoffman et al. 1983).
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
The remainder of this chapter discusses the factors causing land loss in more detail.
(1) Sediment Deficit
A major cause of wetland loss in Louisiana involves the reduction in sediment available to maintain
the wetlands above sea level. This reduction can be attributed to two causes: less sediment flowing down
the Mississippi River and confinement of the river in a manner that prevents sediment from reaching the
wetlands.
Recent studies by the U.S. Army Corps of Engineers (Keown et al. 1980) indicate that the suspended
sediment load of the Mississippi River has decreased substantially during the last 20 years, especially the
larger-grain-sized sediments (sands). Causes of these changes include: (1) the damming of Mississippi
River tributaries (especially upper Missouri River tributaries, sources of most of the coarse sediments);
(2) improved soil conservation practices (i.e., less topsoil erosion); (3) the mining of pointbar (river)
sands for construction and industrial usage; and (4) the dredging and land disposal of riverine sediments.
The net effect of this upstream sediment use is to reduce the amount available for deltaic sedimentation,
nourishment of barrier beaches, and transport into marshes by floods and tidal currents. The decrease in
grain sizes has also reduced the land-building potential.
Although the sediment washing down the river has decreased, there is some doubt regarding the
extent to which this reduction should be implicated as a source of wetland loss. The sediment loading that
prevailed during the first half of the twentieth century may have been unusually high, due to altered
farming practices and the dust bowl of the 1930s. However, there is little doubt that confinement of the
Mississippi River resulting from artificial levee construction along practically its entire length has played
an important role in the disintegration of Louisiana's wetlands. Levees and control structures restrict the
flow into distributary channels and crevasses. These human modifications have interfered with natural
delta building processes, such as overbank flooding and sedimentation, distributary and subdelta
development, and broader, long-term cycles of delta development and abandonment (Frazier 1967). As a
result, the sediment that does wash down the river is funneled offshore, instead of reaching the wetlands.
A significant proportion of Louisiana's land loss is directly attributed to the inability of the marsh to
maintain its elevation above sea level (Baumann and DeLaune 1982; DeLaune et al. 1978 and 1983; and
Hatton et al. 1983). Between 1954 and 1963, for example, subsidence rates were about 1.2 centimeters
(0.49 inches) per year. Streamside marshes have accreted approximately 1.32 centimeters (0.52 inches)
per year, while backmarsh accretion rates have been only approximately 0.72 centimeters (0.28 inches)
per year (DeLaune et al. 1978; DeLaune et al. 1983; Hatton et al. 1983). Thus, only streamside marshes
have been able to keep pace with subsidence and sea level rise. Away from streamside locations, where
tidally transported mineral sediments are deposited, the marshes are rapidly eroding because of this
sediment deficit.
Different marsh types show considerable variability. Hatton et al. (1983) found that intermediate and
brackish marshes(0.1-1.0 percent salinity) exhibited the highest rates of conversion to open water. While
exhibiting higher conversion rates, freshwater marshes have often converted to more saline marsh rather
than open water.
The interference with distributary and subdelta formation processes has not only altered
sedimentation patterns but delta building mechanisms in general. By maintaining the course of the
Mississippi River within its present channel with various engineering controls, large-scale "delta-
switching" has been prevented. During the 20th century, an increasing proportion of Mississippi River
water has been flowing down the Atchafalaya River (a distributary of the Mississippi), which could
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
become the new main channel. To prevent this from happening, the Flood Control Act of 1954 directed
the U.S. Army Corps of Engineers to regulate Atchafalaya discharge to approximately 30 percent of total
Mississippi River discharge by constructing the Old River Control Structure near Simmesport, Louisiana
(Figure 7). The nearly completed Old River Auxiliary Structure will further reduce the possibility of a
natural diversion. In spite of flow restrictions, Atchafalaya River sedimentation has filled its inland
depressions in the Atchafalaya Basin and is now actively building a delta out into Atchafalaya Bay.
Although this delta is only about 10 square miles today, Wells et al. (1983) project that it will grow to 80
square miles by 2030. The active sedimentation there represents the only significant wetland creation in
Louisiana today.
Figure 7. Old River Control Structure near Simmesport, Louisiana.
(2) Canals
Canals currently comprise about 2.5 percent of the total coastal surface area in Louisiana (Craig et al.
1980; Turner et al. 1982), and the percentage has been accelerating through time. Historically, canals
have been dug for drainage and access. Today the greatest share of canalization is attributed to the oil and
gas industry (Figure 8). In 1984, 70 to 80 percent of the coastal management permits issued for canals
were for oil and gas activities. The primary reasons for the myriad of canals in the Louisiana coastal zone
include navigation, pipeline routes, and access to drilling sites.
Although dredging canals has only directly converted 2.5 percent of the wetlands to open water, their
impact is much greater. Spoil banks composed of the material dredged from the canals tend to smother
adjacent marshes, converting wetlands to uplands, often interrupting natural hydrologic processes, and
blocking the distribution of sediment. Canals oriented perpendicular to water flow tend to impound water
and reduce sediment availability, and ponding of water can drown a marsh. Canals parallel to water flow
tend to lessen freshwater retention time and allow greater inland penetration of saltwater. Turner et al.
(1982) estimate that as much as 90 percent of Louisiana's land loss can be attributed to canals.
(3) Reclamation
Reclamation of water or wetlands—via fill, dredge and fill, or drainage—is usually undertaken for
purposes of creating dry land that can be used for residential (see Figure 9), industrial, or agricultural
purposes. Consequently, the areas in which reclamation poses the greatest threats are near large urban
areas (notably New Orleans) and along the backswamps that fringe populated natural levees.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
At the turn of the century, many agricultural ventures took place in the Louisiana wetlands, later
resulting in the numerous rectangular water bodies that now dot the coastal landscape due to failed levees
and inundated fields. Urban and agricultural reclamation of backswamp wetlands continues to have
substantial impacts.
Figure 8. Canals dug in Louisiana's coastal marshes for oil and gas drilling and production operations.
Figure 9. Wetlands dredged and filled for residential development
along the north shore of Lake Pontchartrain.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
(4) Wave Erosion
A. Gulf Shoreline Erosion. Rates of shoreline erosion appear to have increased during the last several
decades, due to human activities (e.g., jetty construction, reef removal, sand mining), indirect human
impacts (e.g., reduction in available sediment, accelerated subsidence), sea level rise, and increased
frequency of hurricane landfall (Morgan & Morgan 1983; Penland and Boyd 1982; Penland and Suter
1984; Penland et al. 1985; van Beek and Meyer-Arendt 1982). Rates of shoreline erosion exceed ten
meters (thirty-three feet) per year, along much of the barrier coast, in both the deltaic plain and the
chenier plain. (See Figure 10.) These high rates threaten established development along the coast. (They
no longer threaten the base line from which the three-mile offshore state/federal boundary is measured,
which has been fixed by Congress.) The rapid disintegration of the barrier islands and beaches also
threatens Louisiana's first line of defense against incoming stormsurges. (See Figure 11.) If the beaches
and marshes disappear, cities such as New Orleans, Houma, and Morgan City will be subjected to higher
storm surges and direct wave attack during severe storms.
CRITICAL
MODERATE
LOW
Figure 10. Severity of Louisiana shoreline and barrier island erosion.
B. Lake/Bayshore Erosion. The physical process of waves interacting with the shoreline also occurs
within estuaries and is an important factor, especially along the shores of larger lakes or bays.
Unlike the Gulf shoreline where incoming waves have been generated at distant locations, wave
generation within the estuaries is localized and depends primarily upon prevailing winds and boat wakes.
Wind-generated wave energy is a function of wind speed, duration, fetch (distance across water body),
and depth. Theoretically, the highest bayshore erosion rates should occur in the largest bays, other factors
remaining equal. Bayshores facing prevailing winds (NW during winter, S-SE during summer) appear to
be the most vulnerable. One study of bayshore erosion, however, determined that factors varied from
location to location (Adams et al. 1978).
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
PRESENT CONDITIONS
DETERIORATING SHORELINE AND BARRIER ISLAND
Accelerated
Erosion
Storm
Breach
Pipeline
CAUSES:
• SUBSIDENCE-INDUCED SEA LEVEL RISE
• MAN'S IMPACTS: EFFECTS OF JETTIES,
SEAWALLS, CANALS, AND OTHER STRUCTURES
• REPEATED STORM IMPACTS
Figure 11. Existing conditions on many of Louisiana's deteriorating shorelines and barrier islands.
Figure 12. Rapid widening of canals occurs as a result of boat wake and tidal erosion
along the banks of major navigation channels.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
C. Canal/Bayou Erosion. Canals and natural waterways are widening as a result of bank erosion, but
the causal factors are man-made and thus much more recent and somewhat different from those in the
previous two cases. (See Figure 12.) Wind and fetch-related factors are less important, while boat wakes
and tidal hydraulic energy (i.e., the ebb and flow of the tides) are more important. Several studies have
documented canal widening from ship traffic (e.g., Howard et al. 1984; Johnson and Gosselink 1982;
Turner et al. 1982; Doiron and Whitehurst 1974), and an excellent schematic of bank erosion is presented
by Howard et al. (1984). Tidal hydraulic energy in Louisiana estuaries increases in response to subsidence
(i.e., increased tidal prism) and tidal inlet widening, both attributed to a combination of subsidence and
barrier island erosion. Although few hard data are available, it is likely that boat wake erosion in canals
and bayous is more destructive to adjacent marshes than tidal erosion.
(5) Subsidence
Because Louisiana's coastal zone is
extremely flat, even a slow rate of land
subsidence can result in large-scale
disappearance of marshlands if no
additional sediment is provided to the
system. (See Figures 13 and 14.) The
subsidence that occurs in Louisiana can
be divided into two general categories:
tectonic subsidence and
consolidation/compaction (modified
from Adams et al. 1976 and Mossa
1980).
Tectonic subsidence refers to the
large-scale downward geologic
displacement caused by sedimentary
loading and associated settlement
processes (Adams et al. 1976). This
type of subsidence is directly linked to
the Mississippi River system,which
built Louisiana's deltaic plain during
the last seven thousand years (Coleman
and Gagliano 1964; Boesch et al.
1983). Beneath the present active
delta,for example, as much as 1,000
feet of sediments have accumulated,
and land subsidence rates have been estimated at 1.5 to 3 meters (5 to 10 feet) per century (Russell 1936).
Away from the active delta, the rate of sedimentary loading and associated subsidence decreases.
Although present subsidence rates in the lower deltaic plain are estimated at approximately ten
millimeters per year (three feet per century) by Nummedal (1983), longer-term rates have been estimated
between 1 and 5 millimeters per year (4 to 22 inches per century) (Boesch et al. 1983).
The consolidation/compaction aspect of subsidence is attributed to a variety of causes including
overlying weight, subsurface withdrawal, and dewatering.
Figure 13. Marsh tract that has been able to keep pace
with subsidence.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
I*.* v*
Figure 14. More typical view of coastal wetlands that are not receiving enough new sediment
to offset the effects of subsidence and are disappearing below the water surface.
A. Overlying Weight. Examples include physical features, such as natural levees, man-made levees,
buildings, spoil mounds, and even marsh-buggy traffic. The net consequence of this overlying weight is
localized surface sinking as soils are compressed. In the case of natural levees, adjacent marsh soils are
also often compressed to the point where waterfilled "levee-flank depressions" result (Russell 1936).
Although soil compression from marsh buggies may be temporary, rebounding often does not occur, and
the ruts evolve into permanent water scars.
B. Subsurface Withdrawal. The withdrawal of oil, gas, and groundwater from subsurface sedimentary
strata results in subsidence, which can manifest itself in the form of localized surface subsidence (Martin
and Serdengecti 1984). Based on studies in Texas and California, it is generally agreed that withdrawal
from strata less than approximately 10,000 feet below the surface can cause the land surface to subside
(Boesch et al. 1983; van Beek and Meyer-Arendt 1982). Although Martin & Serdengecti (1984) estimate
that normally pressurized oil and gas reservoirs in Louisiana should have a maximum equilibrium
subsidence of only 2 centimeters (0.8 inches), the high localized land loss rates near major hydrocarbon
reservoirs (e.g., Hackberry Dome, Venice Dome, Garden Island Dome) led Adams et al. (1978) to suspect
higher compaction rates.
C. Dewatering. The water table is essentially at or near the surface in a wetland environment. When it
is lowered because of drainage activities, the dewatered upper soils are subjected to processes of
biochemical oxidation, soil shrinkage, and wind erosion (Mossa 1980). Although "natural" factors, such
as marsh burning, have been cited as causing soils to dry out and subside (Adams et al. 1976), it is
primarily human efforts related to urban expansion, agricultural drainage and reclamation, and flood
control that have led to widespread localized surface subsidence. In terms of land loss, the most severe
environmental impacts have resulted from the failed agricultural reclamation projects that proliferated in
the early decades of this century (Gagliano 1973). After these large areas of former wetlands subsided
because of dewatering associated with drainage, the subsequent failure of protection levees caused rapid
inundation of the entire tracts.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
(6) Sea Level Rise
Because of the difficulty of separating the effects of subsidence and sea level rise during any analysis
of relative changes between land and water levels, many researchers have packaged the two factors
together for convenience under headings such as "relative subsidence" or "relative sea level rise." Because
surface processes are a function of the net effect of the two causal factors, their separation is largely
academic.
Based on various studies of tidalgauges throughout the world, commonly accepted rates of present
eustatic (global) sea levelriserange from 1.0 to 1.5 millimeters per year (4 to 6 inches per century)
(Gornitz et al. 1982; Barnett 1984). Tidal gauges along the coast of Louisiana indicate that the rate of
relative sea level rise is 9 to 13 millimeters per year (3 to 4 feet per century) (Baumann and DeLaune
1982; Ramsey et al. 1985). Thus, global sea level rise accounts for about 10-15 percent of relative sea
level rise along the Louisiana coast.
Recent developments suggest that sea level could become more important in the future. Three panels
of the U.S. National Academy of Sciences, and international conferences of climatologists and
oceanographers have concluded that increasing concentrations of carbon dioxide, methane,
chlorofluorocarbons, nitrous oxide, and other gases will warm the planet several degrees in the next
century (Charney et al. 1979; Smagorinsky et al. 1982; Nierenberg et al. 1983; UNEP/WMO/ICSU 1985).
Such a warming could cause sea level to rise by expanding ocean water, melting mountain glaciers, and
eventually causing polar glaciers to melt or slide into the oceans.
In 1983, two independent reports published estimates of future sea level rise. The National Academy
of Sciences Climate Research Board estimated a 70-cm rise by 2080, assuming that the possible
disintegration of Antarctic glaciers does not begin by that date (Revelle 1983). The Environmental
Protection Agency developed a variety of scenarios to incorporate uncertainties regarding future
emissions on "greenhouse gases", the resulting impact on climate, oceanic heat absorption, and the
response of glaciers to the warming, and estimated that a global rise in sea level of 26 to 39 centimeters
by 2025 and 91 to 137 centimeters by 2075 is most likely (Hoffman et al. 1983). A 1985 report by the
National Academy of Sciences Polar Research Board for the first time provided models of the response of
specific ice fields to the projected global warming. Meier (1984) and Bindschadler (1985) estimated that
alpine and Greenland glaciers, respectively, could raise the sea 10 to 30 centimeters by 2100. Thomas
(1985) estimated that the contribution of Antarctica by 2100 is most likely to be about 30 cm, but that a
contribution of 1 to 2 meters is possible. The panel did not revise Revelle's estimate of thermal expansion.
Hoffman et al. (1986) revised their earlier projections in light of this new information, estimating the rise
by 2025 to be between 10 and 21 centimeters, and 36 to 191 centimeters by 2075.
Table 1 summarizes available estimates of global sea level rise and relative sea level rise along the
coast of Louisiana implied by current subsidence. Current trends would result in a 90-centimeter (3-foot)
relative rise by 2085; the most conservative scenario of future sea level rise implies that such a rise will
take place by 2060; but a 90-cm rise by 2040 cannot be ruled out. The current rate of relative sea level
rise (1 cm/year) could double by 2030 and perhaps triple by the end of the next century.
(7) Saltwater Intrusion
Saltwater intrusion is technically not an active process but a passive response to the aforementioned
processes. Canals and the reduction of freshwater supplied to the wetlands caused by levees and
channelization have been the primary causes of increased salinity levels in the wetlands. Land subsidence,
sea level rise, and barrier island erosion also cause saltwater ntrusion. The inland encroachment of higher
salinities, evidenced especially by the changing distribution of oyster-growing areas (Van Sickle et al.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
1976) is held responsible for a number of environmental impacts. For example, the optimal oyster-
growing areas in each basin are shifting inland closer to sources of freshwater but also closer to sources of
urban runoff, which may have high concentrations of contaminants. Although the more saline marsh types
may be less valuable to furbearing animals and birds, they can be more important as estuarine nursery
grounds. Some of the most severe impacts of saltwater intrusion include the destruction of cypress forests
(Figure 15) and floating fresh marsh (flotant), neither of which can survive in brackish or saline water.
Although fresh and brackish marshes are often replaced by brackish and salt marshes, respectively,
cypress swamps frequently convert to open water instead of being replaced by more saline vegetation.
Table 1
Estimates of Future Worldwide Sea Level Rise
(centimeters above 1980 level)
Global Sea Level Rise
Current Trends
Revelle (1983)
Meier etal. (1985)
Hoffman etal. (1983)
Low
mid-low
mid-high
High
Hoffman etal. (1986)
Low
High
2000
2.4
2025
5.4
13.2
17.1
3.5
5.5
13
26
39
55
10
21
Louisiana Relative Sea Level Rise**
(Wordwide sea level rise plus sibsidence)
Current Trends 22
Revelle (1983)
Meier etal. (1985)
Hoffman etal. (1983)
Low 25
mid-low 29
mid-high 33
High 37
Hoffman etal. (1986)
Low 24
High 26
50
58
71
84
100
50
61
2050
23
53
79
117
20
55
78
93
123
149
187
90
125
2075
11
38
91
137
212
36
191
106
133
186
232
307
111
286
2080
12
70
44
258
2100
14
50-200*
56
144
217
368
57
358
112
170
144
358
134
170-320
176
264
337
488
177
478
* Assuming Revelle's model for thermal expansion, which implies 40 cm by 2100.
** Assuming subsidence of 1 cm per year.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
Figure 15. Destruction of a former cypress swamp by saltwater intrusion.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
CHAPTER 3
MEASURES FOR CURTAILING WETLAND LOSS
The possible options for curtailing wetland loss are numerous. They include diverting freshwater and
sediment into the marshes; changing the course of the Mississippi River; modifying patterns of water and
sediment flow to the marshes; maintaining wetlands artificially; restoring the barrier islands; and shifting
away from the types of canals, channels, and levees that have destroyed wetlands to alternative
transportation and flood protection strategies that have less adverse environmental impacts. This chapter
briefly describes each of these measures.
Table 2 lists several of the options that have been proposed for curtailing wetland loss; Table 3 lists
the measures that have been authorized by the Louisiana Legislature, planned by the Louisiana
Geological Survey, or constructed by other organizations.
Table 2
Options for Curtailing Wetland Loss
Barrier Island Restoration. Marsh Building and Restoration
1. Restore diked, drained, dredged wetlands
2. Build marsh with materials from dredging projects instead of re-suspending dredged material in the
lower river or creating spoil banks.
3. Require offsetting marsh creation for wetlands conversion due to development.
4. Raise the elevation, seal breaches, re-nourish beaches of barrier islands
Marsh Management
1. Construct tidal barriers and otherwise manage flow of water to and from marsh
2. Dike wetlands and manage artificially.
3. Thin layer deposition
4. Regulate marsh fires
5. Restore suitable marsh vegetation
Regulatory
1. Limit creation of new canals
2. Fill existing canals
3. Limit boat speeds in waterways
4. Restrict marsh buggies
5. Require mitigation for private wetland destruction
6. Subsidize new technologies
Diversion
1. Increase flow through the Atchafalaya River
2. Freshwater and/or sediment diversion to wetlands
3. Diversion to Mississippi River Gulf Outlet
4. Increase water flow to Bayou LaFourche
5. Separation of navigation from river flow using locks
6. Avoidance of additional levee construction in lower Atchafalaya
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
Table 3
Authorized, Planned, and Completed Projects for Curtailing Wetland Loss
Authorized by Louisiana Legislature (funded)
(1) Restore barrier islands and shorelines
(a) Isles Dernieres
(b) Fourchon Island
(c) Shell Island
(d) Timbalier/E. Timbalier Islands
(e) Holly Beach
(f) Grand Isle (Corps)
(2) Diversion
(a) Caernarvon Diversion (joint state/federal project)
(b) Pass a Loutre Marsh Creation (small diversion pilot project)
(3) Marsh Management
(a) Montegut-Terrebonne
(b) St. Bernard Parish
(c) St. Charles Parish-LaBranche Wetlands
Planned by Louisiana Geological Survey (presently unfunded)
(1) Barrier Island/Shoreline Restoration and Nourishment
(a) Plaquemines Parish Barrier Shorelines
(b) Timbalier/E. Timbalier
(c) Holly Beach-Cameron Parish
(d) Caminada-Moreau shoreline
(2) Diversion (joint federal/state projects)
(a) Davis Pond
(b) Bonnet Carre
(3) Large Scale Wetland Protection Program (Outgrowth of this Study)
Completed by Other Agencies
(1) Barrier Island/Shoreline Restoration and Nourishment
(a) Eastern Isles Dernieres Restoration (Terrebonne)
(b) Timbalier Island Repair Project (Texaco, Inc.)
(c) Grand Isle Hurricane Protection Levee (Corps)
(2) Marsh Management (numerous individual land owners)
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
Barrier Island Restoration
The measure with the highest priority has been the restoration of Louisiana's barrier islands~the first
line of defense against the sea—by raising their surfaces and closing breaches. (See Figures 16-19.)
Although storm protection has been the primary motivation, restoring these islands will also limit wave
erosion of interior marshes. Furthermore, they will help to prevent additional increases in the salinity of
the bays behind them by limiting tidal mixing with the high-salinity waters of the Gulf of Mexico.
PHASE I
SHORELINE AND BARRIER ISLAND RESTORATION
Plant dune
vegetation
Build up
dune using
overwash
sands
Hydraulically Plan*
fill marsh
vegetation
Pump sediment
from back bays
Build
retaining structure
Overwash
Sands
Figure 16. Cross-sectional view of shoreline and barrier island restoration plans
(Phase I of the Louisiana Coastal Protection Master Plan).
Restoring barrier islands has the advantage of not interfering with existing social patterns and has thus
faced little, if any, opposition. On the other hand, its ability to curtail wetland loss in the long run is
limited. This measure does not prevent wetlands from being submerged as relative sea level rises, nor
does it prevent marsh erosion along canals. The beneficial impacts on wetland salinity will generally be
small compared with the salinity increases caused by other factors.
Wetland Restoration
A widely used wetland mitigation approach throughout the United States is to require those who
destroy wetlands for a project to create wetlands nearby, either by lowering the surface of an upland or
filling a channel or bay and planting marsh vegetation. The general procedure could be applied in
Louisiana. For example, instead of resuspending material dredged from the Mississippi River, those who
maintain shipping lanes could use this material to build marsh, which is currently done with some dredge
spoil from Southwest Pass. Material dredged for canals could also be used to create marsh. Areas that
have been diked or drained could be converted back to wetland. The Corps of Engineers (1984) has
identified eight navigation channels where dredged material could support creation of 43,000 acres of
marsh.
Although marsh creation has been a popular mitigation measure in the United States, its practical
utility in solving the Louisiana wetland loss problem may be limited to cases where dredging of
navigation channels provides material. The Corps of Engineers estimates the incremental cost of creating
marsh at $700-4,100 per acre, given the existence of dredging projects that would require the disposal of
dredged material. However, due to the lack of available sediment and other logistical problems likely to
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
be encountered in creating fifty square miles of wetland per year, the cost per acre would almost certainly
be an order of magnitude greater if this method were applied as a general solution to wetland loss.
Accelerated sea level rise would further increase the amount of wetland creation required annually.
PHASE I COMPLETED
SHORELINE AND BARRIER ISLAND RESTORED
• SHORELINE EROSION REDUCED
• DUNES RESTORED
• ISLAND WIDTH AND HEIGHT INCREASED
• BACK BARRIER RETAINING STRUCTURE COMPLETED
• BREACHES SEALED
• MANMADE CANALS FILLED
Figure 17. Oblique aerial schematic of restored barrier island (Phase I completed).
PHASE II
SHORELINE AND BARRIER ISLAND NOURISHMENT
HydraulicaHy
nourished
beach
Dune enlargement
and revegetation
Figure 18. Cross-sectional view of shoreline and barrier island nourishment
(Phase II of the Louisiana Coastal Protection Master Plan).
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
PHASE II COMPLETED
SHORELINE AND BARRIER ISLAND NOURISHED
• SHORELINE EXTENDED SEAWARD
AND ISLAND EVEVATION INCREASED
• DUNES ENLARGED AND REVEGETATED
Figure 19. Oblique view of shoreline and barrier island nourishment (Phase II completed).
Marsh Management
The term "marsh management" refers to a variety of activities. The philosophy behind this approach
is that human activities have so disrupted the natural wetland system that the best hope for maintaining
these ecosystems is for society to step in and limit further damage. The most common form of marsh
management in Louisiana is to regulate the flow of water in and out of the marsh, with the general goal of
limiting salinity and controlling water levels, and to plant vegetation.
DESIGN CONCEPT
OF SLUICE GATE AND VARIABLE CREST WEIR ---^ - -.
TOP VIEW
STOPLOGS
—- x -I
SIDE VIEW 4-J-'-!-)— ' --a -i - • • - -
* - -^lj--T]l'T '|-I|IJ>
MARSH LEVEL l ^ '-^Z/ t, , r, ll > ' jLT WHALER
:i;
os^LLJU J-J lU^t
V
'Jn
GATOR GATE
^
LOUISIANA GEOLOGICAL SURVEY \
Figure 20. Design concepts for sluice gate and variable crest weir structures.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
Such schemes typically involve regulating water flow in or out of wetland management units ranging
in size from several acres to about five thousand acres. Wetland tracts larger than this are difficult to
manage and are often partitioned into smaller units. Water flow is regulated by a system of retaining
levees or dikes and some form of water control structure. Commonlyused structures include fixed- and
variable-crest weirs, single- and double-flapgated culverts, and sluice gates. (See Figure 20 These
structures can be operated to allow juvenile marine organisms some access to internally managed
wetlands for use as nursery and feeding areas. Other management schemes involving forced drainage
(mechanical pumping) to regulate water levels may prevent marine organisms from using managed areas.
Currently, forced drainage is limited to populated areas.
Though goals of individual marsh management plans may vary widely, most plans usually
incorporate features that enable control of water levels and salinity by preventing inflow of excess
saltwater and by regulating freshwater output or inputs (rainfall, runoff, or introduced freshwater) until
the desired water level or salinity is reached.
Examples of wetland areas utilizing passive (gravity-operated) marsh management schemes include
much of the state-owned Department of Wildlife and Fisheries refuges and numerous privately
maintained marsh tracts. These areas are often managed to optimize vegetation growth and to maintain
water level conditions best suited for waterfowl that winter in these wetlands. Management of commercial
crawfish ponds and other aquacultural efforts typically involves active pumping to achieve desired water
levels.
An important advantage of this approach (as well as wetland restoration) is that major landowners can
implement these measures themselves. Since conversion of land to open water can deprive them of
income from mineral extraction, fishing, hunting, and trapping, landowners often have an incentive to
manage their marshes without help from the public sector. However, because federal activities that have
benefited all of society have contributed to much of the wetland loss, an argument can be advanced for
public subsidies of these activities. This may be particularly advantageous if such subsidies would result
in more wetland protection than equivalent expenditures for federal, state, and local wetland protection
projects. Although the recent reform of the federal tax code suggests that new federal tax incentives are
unlikely, the current code permits deduction of contributions to conservation groups that restore or protect
wetlands.
The restoration potential of these measures is also limited. Most important, as relative sea level rises,
passive management of water flow will become increasingly difficult. While tidal gates and gravity may
be sufficient to adequately drain wetlands today, if sea level rises a few more feet, it will be necessary to
actively pump the water out.
Terrebonne Parish is considering a plan for long-term marsh management. A tidal surge levee through
the interior of the parish would be built, and marsh inland of that levee would be actively managed by
forced and gravity drainage, even after the sea has risen a few feet above the marsh. The parish estimates
the cost at over $100 million. This plan, however, would only be a partial solution. Although birds,
animals, and some fish would benefit from the protected vegetation, active pumping systems currently do
not allow shrimp and other marine organisms to pass from one side of the levee to the other. Until cross-
levee migration becomes possible, this approach would do less to benefit commercial fisheries than other
methods of protecting an equivalent number of acres. Nevertheless, it might be more practical than
increasing sediment supplies in places that are far from active distributaries such as eastern Terrebonne
Parish, particularly if sea level rise accelerates.
A final marsh management technique involves periodic spraying of sediment on the marsh to increase
its rate of vertical accretion. Technologies to accomplish this goal have only recently emerged, and have
24
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
some of the same logistical and cost problems as marsh creation. In spite of these difficulties, this
technique may prove useful in certain areas that are just barely being submerged due to a sediment deficit.
Clearly, it would be far cheaper to supply sediment to an existing, living marsh than to fill a bay to the
level necessary to create a new marsh; it would also disrupt ecosystems less. (This practice is being
applied to a limited extent to marsh adjacent to new canals in Terrebonne Parish.)
Canals and Land Use
Thus far, we have examined specific technical solutions without regard to how they might be
implemented. Barrier island restoration will almost certainly be a public program, while marsh building
and marsh management can be undertaken either as public or private efforts. By contrast, decreased
speeds for boat traffic, a cutback in marsh buggy traffic, and less conversion of wetlands to dry land
would generally involve public regulation of private activities. Curtailing the adverse impacts of canals
could involve regulatory programs or public works.
Several researchers have proposed that the use of canals be replaced with less damaging alternative
forms of transportation, such as hovercraft, which are used by oil companies in Alaska but not Louisiana.
A halt to the dredging of canals would decrease the loss of wetlands. However, existing canals would
continue to convey saltwater into freshwater wetlands, and would continue to convert marsh to open
water as they widened.
For this reason, some have suggested that a portion of existing canals be filled or plugged. Such a
strategy might be accomplished either as a regulatory program or as a public work. A regulatory program
might, for example, require that for every mile of new canal, two miles of old canals must be filled or
plugged. Such a policy could gradually reduce the damage caused by canals. However, it might also make
the use of canals economically less attractive than alternative forms of transportation such as hovercraft,
in which case the dredging of new canals would end and no canals would be sealed off.
Although reducing canalization of Louisiana's wetlands would have environmental benefits, the cost
of doing so would be very great. Moreover, even a complete restoration of the original marsh would not
prevent wetlands from being submerged, which could destroy a large fraction of Louisiana's wetlands in
the next century if the present confinement of the Mississippi River continues.
Diversion
A class of options collectively called "diversion" would enable at least a fraction of Louisiana's
wetlands to keep pace with even an accelerated rise in sea level. These options have the greatest chance of
permitting the long-term survival of Louisiana's wetlands because they imitate the natural processes that
have created and sustained these wetlands for the last several thousand years. Unfortunately, these
measures would also impose higher costs than the shorter-term solutions discussed above.
The most imminent diversion strategy is the construction of freshwater diversion structures. (See
Figure 21.) Such projects would partly offset the freshwater starvation caused by the river levees,
decreasing marsh salinities and thereby slowing the rate of marsh loss. Although some sediment would
also be supplied to the marsh, the amounts would not be sufficient to enable extensive areas to keep pace
with current or projected rates of subsidence and sea level rise. Moreover, as long as there is a need for a
self-scouring main channel of the Mississippi, there will be a limit to how much water can be diverted
before the flow of the river slows more than navigation policy makers will accept. Nevertheless,
freshwater diversion structures could provide important protection of wetlands as part of a short-term
strategy to buy time while a long-term strategy is put into place.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
Figure 21. Freshwater diversion structure at Bayou LaMoque in Plaquemines Parish, LA.
Table 4 illustrates estimates by the Corps of Engineers (1984b) of the potential for two proposed
freshwater diversion structures in Barataria Basin and Breton Sound. The projected wetland loss of close
to one half million acres in these two basins by 2035 could be reduced by almost one hundred thousand
acres. These projections illustrate both the potential and the limitations of diversion structures.
Table 4
Potential Wetland Acreage Saved by Two Proposed Freshwater Diversion Structures
(thousands of acres)
Barataria
Breton Sound
Current (1985) Acreage
Remaining Wetland by 2035*
Without Diversion
With Diversion
430.5
245.1
327.8
182.9
131.4
147.8
*Assuming current rates of sea level rise.
Planned structures would reduce to 23 percent the expected 39 percent wetland loss in the next fifty years. This
would represent a 20 percent reduction in the rate of statewide wetland loss.
Source: U.S. Army Corps of Engineers (1984b).
A widely advocated diversion scheme that might have a greater long-term impact would be to allow
the Mississippi River to change its course to the Atchafalaya River. If this happened, the sediment
flowing down the river into the shallow waters of Atchafalaya Bay would create new wetlands, rather
than be carried off the edge of the continental shelf, provided that the Atchafalaya River was not
subsequently modified in the fashion that has occurred with the main channel of the Mississippi River.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
This latter qualification is important because the river levees being built and planned along the
Atchafalaya would prevent sediment and freshwater from reaching western Terrebonne Parish. We are
not certain whether the Atchafalaya will be engineered to deliberately convey all sediment off the
continental shelf, or whether there will be the same need for a deep draft (50-foot) self-scouring channel.
While permitting the formation of a major new delta, diversion to the Atchafalaya would cause
problems for many people. Substantial sedimentation would occur in the part of the Mississippi River
immediately below the Old River Control Structure. Fortunately, the need for increased dredging in this
area would not be prohibitive, because ocean-going vessels do not venture this far upstream. Another
important consequence is that saltwater would be able to move farther up the Mississippi, perhaps
reaching the drinking water intakes for New Orleans. (Although a shift to alternate supplies would be
costly, such costs might prove to be a "blessing in disguise." The current water supply is of such low
quality that one-third of the city's residents drink bottled water; Houma is currently making such a shift.)
Increased Mississippi River salinity would also force some industrial users to install corrosion-resistant
pipes.
An increased flow down the Atchafalaya would require the federal government to change its policy of
maintaining the present flow ratio, in which it has invested billions of dollars. Finally, a new course for
the river would require Morgan City and other communities along the Atchafalaya River to be either
abandoned or protected with ring levees. Although abandoning a few communities voluntarily on a
planned basis may be preferable to a subsequent eventual involuntary (unplanned) abandonment of the
entire coastal zone, our political system might tend to avoid wrestling with difficult short-term problems
by gravitating toward the latter no-action alternative.
Another diversion option that would permit wetlands to keep pace with an accelerated rate of sea
level rise would be to separate navigation from the flow of the river. The rationale for such a measure is
that navigation's need for a rapidly flowing self-scouring channel and the wetlands' need for freshwater
and sediment are mutually exclusive.
Several measures for separating navigation from stream flow have been investigated. The New
Orleans Dock Board considered diversion of shipping to a set of parallel canals along the Mississippi
River Gulf Outlet, and the Corps has investigated a new channel to replace Southwest Pass. If ships used
locks instead of the main channel, it would not matter if the flow of the river were slowed by freshwater
diversion structures or breaches in river banks south of Venice, and new wetlands could form in
substantial numbers.
The major disadvantage of this approach is the initial construction costs. In addition, shellfish
production in some areas would decline, although the long-term reductions in production throughout the
state would be far greater if no measures were taken. Other options, such as a new, deep water port, might
also be feasible, but would have greater initial costs.
Other diversion schemes may also be worth investigating. Bayou Lafourche was an active Mississippi
River distributary until it was sealed off by the Atchafalaya and Lafourche Levee Boards under the
authority of the River and Harbor Act of 1902. Although the substantial development that subsequently
took place (and still exists) along Louisiana's original "main street" would make a complete reactivation
costly, the bayou might be used to convey a limited amount of freshwater to Terrebonne and Lafourche
Parishes. The Corps has also investigated schemes to divert freshwater down the Violet Canal; however,
much of the water could be lost down the Mississippi River Gulf Outlet, bypassing most of the marsh.
Although diversion of the Mississippi River to the Atchafalaya or separation of navigation from
streamflow would be likely to achieve the maximum degree of wetland protection and creation, we have
serious reservations about whether they would be politically feasible. Nevertheless, assessments of
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
technically viable options should consider these measures and allow the political process—not this panel--
to accept or reject options due to political feasibility.
SUMMARY
Although the loss of wetlands in Louisiana is becoming increasingly serious, it is not for a lack of
options to control that loss. The problem is that the conditions that have created wetland loss are
intertwined with such indispensable activities as flood prevention, shipping, and petroleum extraction.
Projects have been authorized—though not funded—which would significantly slow the rate of wetland
loss due to saltwater intrusion. But restoring the sediment supply necessary for the wetlands to keep pace
with current subsidence (as well as projected sea level rise) would require an end to the current situation
in which most of the sediment of the Mississippi River flows into the Gulf instead of the wetlands.
Given the practical realities of today, many of the panel members doubt that this will ever happen.
Diversion of the Mississippi River to the Atchafalaya would require a reversal of a major long-standing
policy and separation of navigation from streamflow would increase the cost of shipping. Both measures
would cost billions of dollars, and no other methods have been identified to completely restore sediment
supply. Nevertheless, the panel has concluded that if no politically feasible means of stopping 50 to 100
percent of the wetland loss can be identified, it is more prudent to consider measures that do not appear to
be politically feasible today than to limit a long-term evaluation to measures that can only delay the
inevitable.
However, it would be wrong to conclude that long-term evaluations warrant delay or reconsideration
of authorized projects. If costly long-term programs of diversion or canal filling must ultimately be
implemented, the planned freshwater diversion and barrier island restoration projects will still be
necessary. Whether or not sea level rise accelerates, these short-term measures complement development
of a long-term strategy and will help buy time for its eventual implementation.
The next chapter discusses the currently authorized projects in moredetail, while the following
chapter lays out a plan for assessing the long-term options.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
CHAPTER 4
AUTHORIZED AND PLANNED PROJECTS FOR CURTAILING WETLAND LOSS
For over twenty years, the Corps of Engineers, the State of Louisiana, coastal parishes, and university
scientists have been studying the problems associated with wetland loss in coastal Louisiana. Under a
1967 U.S. Senate resolution the Corps' Louisiana Coastal Area Studies have evaluated mitigation options.
The "Freshwater Diversion to Barataria and Breton Sound Basins" study has identified two major
diversion sites that would reduce saltwater intrusion and wetland loss and improve the habitat and
productivity offish and wildlife resources. The "Land Loss and Marsh Creation" study is now focused on
determining the monetary value of wetlands as (1) real estate, (2) a buffer against hurricane-induced
flooding and saltwater intrusion, and (3) a producer of commercial and recreational fish and wildlife
resources. Cost-benefit analyses of specific marsh creation and erosion reduction projects will follow.
The "Shore and Barrier Island Erosion" study acknowledges that continued deterioration of the barrier
islands and retreat of the shore will accelerate marsh loss. Yet in this study, due to the low economic
value assigned to marshes, projects in only two areas had benefit-to-cost ratios that justified further
federal involvement. The "Water Supply" study assessed the scope and magnitude of the water supply
problems in the coastal communities whose present sources are frequently subject to saltwater intrusion.
Other Corps projects that would offset wetland loss include the diversion into Lake Pontchartrain
proposed in the Mississippi and Louisiana Estuarine Areas study, and the Grand Isle and Vicinity
Hurricane Protection and Beach Erosion project.
STATE/FEDERAL COASTAL PROTECTION PROJECT LOCATIONS
LEGEND
1 HOLLY BEACH
2 ISLES DERNIERES
3 TIMBALIER
4 EAST TIMBALIER
5 FOURCHON ISLAND
6 BELLE PASS TO CAMINADA PASS
7 GRAND ISLE
8 SHELL ISLAND
9 PLAQUEMINES PARISH BARRIER SHORELINE
10 PASS A LOUTRE MARSH CREATION
11 CAERNARVON FRESHWATER DIVERSION
12 ST. BERNARD MARSH MANAGEMENT
13 ST. CHARLES PARISH - LA BRANCHE WETLANDS PROTECTION
14 TERREBONNE PARISH - MONTEGUT MARSH RESTORATION
15 DAVIS POND FRESHWATER DIVERSION
16 BONNET CARRE FRESHWATER DIVERSION
Figure 22. Map of coastal Louisiana depicting locations of state/federal coastal protection projects.
Act 41 of the 1981 special session of the Louisiana Legislature established the Coastal Environment
Protection Trust Fundand appropriated $35 million for projects to combat erosion, saltwater intrusion,
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
subsidence, and the loss of wetlands along the Louisiana coast. In 1985 the legislature approved the
Coastal Protection Master Plan, which maps a 10-year strategic program for dealing with the problems the
coast is experiencing. Although funds are available for implementation of the first two years of the Master
Plan, future years will require additional appropriations. The thrust of the plan is to restore the barrier
islands and shorelines during phase one (first five years) and to implement the wetland protection
program in phase two. Figure 22 illustrates the locations of the projects to be implemented in phase one.
We briefly summarize the authorized and planned projects.
Authorized Projects
(1) Restore barrier islands and shorelines
(a) Isles Dernieres~The major project scheduled to begin in the first year of the Louisiana Coastal
Protection Master Plan is the stabilization of the IslesDernieres barrier island, which involves
restoring of the low dunes washover breaches,and sealing minor breaches (Figure 23). With a total
estimated cost of $23,250,000, the project will relyupon placing dredged material for a width of up to
one thousand feet along sixteen miles of barrier island to stabilize the dunes and to enlarge the island
base, thus reducing its susceptibility to storm breaching.
(b) Fourchon Island~A cooperative project was undertaken by the state, Port Fourchon, and private
interests in 1985 to protect the Fourchon Island shoreline. The efforts included closing old Pass
Fourchon, relocating a beach road, and restoring the dune. Damages resulting from the 1985
hurricane season necessitated further state emergency work involving use of a hydraulic dredge to
pump approximately 700,000 cubic yards of beachfill material into spoil-retention areas to restore the
beach and dunes. The Greater Lafourche Port Commission is expected to revegetate the area for
continued stabilization.
ISLES DERNIERES STABILIZATION
EXISTING IStANO
• CONSTRUCTED SAND DUNE
BACK BAY SIDE
! _____ _ LIMITSJpJLVEGETAJION — __ *J
I ^_ ___ 1QQO_JL_ _____ „ , «_ I
,— — CONSTRUCTED SAND DUNE
IL..^
'TRENt
DUNE
BACKFILLED FROM BORROW AREA
1.0 MSL \.x J%
F]LLED FOR UAnSH CHE,T|ON FROM
BACK BAY BORROW AREA
.--•*-C MARSH CREATION FILL TO BE
HYDRAULICALLV PLACED FROM
PROJECT BORROW AREA.
I i ~ 1
,., , APPROXIMATE LIMITS OF * | PROJECT |
, S* ^ EXISTING SAND FILL ON . BORROW AREA I
/ / ISLAND |__ |
ANA GEOLOGICAL SURVEY
i END OF ISLAND
Figure 23. Restoration and stabilization plan for Isles Dernieres in Terrebonne Parish, LA.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
(c) Shell Island~The second major project of the Master Plan allocates $7.2 million to restoration efforts
in Plaquemines Parish at Shell Island. The project will extend five miles from the Empire Waterway
jetties to Grand Bayou Pass and will produce much the same result as the Isle Dernieres project.
(d) Holly Beach—Louisiana Highway 82 is directly exposed to the Gulf waves and storms west of Holly
Beach in Cameron Parish. The Office of Highways and the Department of Natural Resources have
jointly experimented with heavy revetments (Figure 24) and offshore breakwaters (Figure 25) to
protect the highway. These efforts appear to be working and would be complemented by the next
phase of the project to continue protection measures for an additional two miles eastward from the
project area.
(e) State funds will be used to match Federal Emergency Management Agency funds to replace eroded
beach materials from east and west of the existing Timbalier Island seawall. More state and private-
sector funds will be used to fill adjacent canals and slips to help prevent breach formation during
future storms and hurricanes.
(f) Grand Isle-Portions of the sand dune were heavily damaged by repeated storms during the 1985
hurricane season. Surveys are under way to determine the exact scope of damages. In addition, a
repair plan is being developed involving replacement of eroded dune segments, extension of the
existing jetties on the east and west ends of the island, and installation of some type of breakwater
structures in critical areas.
Figure 24. New revetment installed to protect the shoreline
and Highway 82 in Cameron Parish, LA.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
Figure 25. Six experimental breakwaters constructed west of Holly Beach, LA.
To help protect Highway 82 from storm impacts.
(2) Diversion
(a) Caernarvon Freshwater Diversion (joint state/federal project)~This project was authorized by
Congress in 1985. Advanced engineering and design has been completed for the Caernarvon
Freshwater Diversion structure to introduce freshwater into the marshes and estuarine waters of
Breton Sound, and the project is now ready for construction. That project will reduce marsh loss by
an estimated 16,000 acres over the next 50 years. Although state matching funds for construction
have been allocated in the Master Plan, federal funding for construction were not provided in the
1987 executive budget. Construction will take two years once funding is received.
(b) Pass-A-Loutre Marsh Creation (small diversion pilot project)—Artificial breaches in the natural levees
of the Mississippi River and its distributaries near the mouth of the river will allow water and
sediments to flow through and fill open bays and ponds thus creating deltaic marsh. The project calls
for three diversions in different locations on the Pass-A-Loutre Wildlife Management Area. Figure 26
shows their locations and the extent of new marsh expected to form. The construction has been
completed. Figure 27 shows the breach at the Loomis Pass site.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
PASS A LOUTRE WILDLIFE MANAGEMENT AREA
FRESH WATER DIVERSION SITES
L
LEGEND
BOUNDARY
Q^] BROKEN MARSH
==^ STREAM
~=^s CANAL
• PRIVATE FACILITY
A LIGHTHOUSE
PRIVATE PROPERTY
PASS A LOUTRE
SOUTH PASS
LOOMIS PASS
PORT IADS
LIGHTHOUSE
LOUISIANA QEOLOOICAL SURVEY
Figure 26. Location of the Pass A Loutre, South Pass, and Loomis Pass breaches
and extent of New Marsh expected to form.
-f -?
Figure 27. Loomis Pass Breach on the Pass A Loutre Wildlife Management Area.
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(3) Marsh Management
(a) Montegut (Terrebonne)--The Master Plan provided for this project in the Point Au Chien Wildlife
Management Area to use levees, fixed-crest weirs, and a flapgated culvert to stabilize water levels in
the area and reduce salinity and turbidity. Anticipated benefits include a reduction in present marsh
loss rates, increased production of desirable plant species, and increased fish and wildlife benefits.
The project specifications are currently being prepared for advertisement and bidding. Figure 28
illustrates the project area.
(b) St. Bernard Parish—Repair or construction of levees and water control structures by the Parish will be
funded by the Trust Fund to allow implementation of the wetland management plans for two of the
environmental management areas. This will help offset previous loss of habitat as well as reduce the
rate of future habitat degradation and wetland loss. The Parish is obtaining permits and finalizing
plans and specifications on the project.
(c) St. Charles Parish-LaBranche Wetlands—This environmentally sensitive area on the southwest margin
of Lake Pontchartrain has experienced severe shoreline breaching and erosion. The project calls for
restoring the lake shoreline with new material and stabilization or shore protection measures to
maintain the new shoreline. The project is currently being advertised for engineering service
proposals.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
LAFOURCHE
PARISH
TERREBONE
PARISH
MONTEGUT
PROJECT AREA?
4186 acres
PROPOSED LEVEE
& CANAL
PROPOSED WEIRS
CHAUVIN
PROPOSED
POINTV FLAPGATE WONDER
BARRE
MONTEGUT MARSH
RESTORATION
PROJECT
MADISON BA Y
Figure 28. Map of Montegut Marsh Restoration Project.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
Planned Projects
(l)Barrier Island/Shoreline Restoration and Nourishment
(a) Plaquemines Parish Barrier Shoreline—Assuming the
availability of additional state funding in 1987, the
Master Plan allots $31,550,000 to restore the
Plaquemines Parish barrier shoreline from Sandy Point
to Barataria Pass. A request for engineering services
proposals could be advertised upon Legislative
approval and authorization of these funds.
(b) Timbalier/E. Timbalier—With a projected initiation
date in 1988, the restoration of Timbalier and East
Timbalier (Figure 29) will cost $6.5 and $20.3 million,
respectively. Again, the future funding of this Master
Plan project will depend upon availability of additional
state funds.
(c) Belle Pass to Caminada Pass Shoreline~In the last
year of Phase I of the Master Plan (1989), the
restoration of the shoreline between Belle Pass and
Caminada Pass in Lafourche and Jefferson Parishes is
scheduled to begin. Costs are estimated at $21.1
million.
(2) Diversion
(a) Davis Pond-As part of the Louisiana Coastal Area,
Freshwater Diversion to Barataria Basin study, the
Corps of Engineers, in cooperation with the Governor's
Coastal Protection Task Force and St. Charles Parish
officials, has selected a diversion site at Davis Pond
near Luling to introduce freshwater and sediment into
the Barataria Basin. Marsh losses will be reduced by 82,700 acres over the next 50 years if this
project is constructed. Advanced engineering and design studies requiring no more than four years to
complete can begin after federal funding approval, with construction requiring two additional years. If
approved by the Chief of Engineers (Corps of Engineers), the project would be constructed under the
authority of Public Law 89-298, passed in 1965.
(b) Bonnet Carre—The Corps' Mississippi and Louisiana Estuarine Area study has recommended that a
large freshwater diversion facility be built just north of the Bonnet Carre Spillway. Planning and
engineering studies are continuing on this project, which will enhance estuarine habitats in the Lake
Borgne-Chandeleur Sound area. The project also awaits Congressional authorization.
(3) Large Scale Wetland Protection Program—Outgrowth of the Study Proposed In Chapter 5
(a) Coastal Vegetation~A component of the Master Plan, the Coastal Vegetation Program will
complement the major restoration projects by providing plants, planting machines, and the technology
necessary to revegetate the restored barrier islands (see Figure 30) and shorelines. This component
will also provide for work in areas where plantings alone will reduce erosion, restore wetlands, or
enhance formation of new wetlands.
Figure 29. East Timbalier Island. Note that
the island has continued to subside and
wash away despite all company efforts to
encircle the island with rock sea walls.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
Figure 30. Sand fencing and vegetation plantings help build and stabilize barrier island sand dunes.
(b) Wetland Protection/Basin Approach~An essential part of Phase I of the Master Plan is to develop a
wetland management and protection program that can be implemented during Phasell (the second
five years of the of the Master Plan). This study will help form the basis upon which this wetland
protection program will be developed. The best strategy for addressing the problem appears to be
adopting a basin approach that uses discrete drainage basins as management units. This approach
enables comprehensive protection efforts to address the individual problems and needs of each basin
or region.
The Need to Move Forward
A large number of projects for curtailing land loss in Louisiana have been identified and become part
of the state's Master Plan. Nevertheless, it would be very misleading to say that these measures will solve
the problem. Many of them still await funding from the federal or state government. Because these
projects primarily benefit Louisiana, they may be viewed by some as "pork-barrel" projects that tax the
nation to support a small constituency. However, a closer examination reveals that proposed federal
projects are largely in the nature of corrective action to mitigate adverse environmental impacts of federal
activities. Because the benefits of these projects will accrue over many decades, it may be tempting for a
state in the midst of a financial crisis to delay these projects a few years. But a realistic look at the costs of
protecting wetlands suggests that if the relatively inexpensive means that have been identified are not
implemented soon, far more costly solutions will have to be implemented in the 1990s.
Nor does the necessary exercise of developing a long-term plan to address subsidence and sea level
rise provide a justification for delaying these projects. The long-term plan will benefit from the
experience of testing the proposed measures outlined in this chapter. Moreover, there is little reason to
believe that the long-term plan will devise strategies that would in retrospect prove these projects to have
been unnecessary. Any long-term solution to the problem of subsidence and sea level rise would, at a
minimum, require the diversion of freshwater into the marsh to prevent saltwater intrusion and the
restoration of barrier islands. A long-term solution will probably require more substantial actions as well--
how much more will depend in part on how long we delay the implementation of measures that have
already been approved.
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CHAPTER 5
TOWARDS A STRATEGIC PLAN: A PROPOSED STUDY
The Need To Examine the Big Picture
Coastal scientists and government officials have known for several decades that human activities
could destroy the bulk of coastal Louisiana's wetlands, and the way of life for the people who depend on
them. Since the 1970s, scientists and officials have been aware that such a rapid destruction is, in fact,
taking place. In 1981, the Louisiana Legislature created a $35 million trust fund to research, develop, and
demonstrate methods to curtail land loss.
Since then, many possible solutions to wetland loss have been identified, and major projects have
been planned. Nevertheless, the currently authorized projects are not expected to slow the statewide rate
of wetland loss by more than 10-20 percent. Yet each major construction action to date has been hard
fought and provides limited protection. The "big picture" of all possible actions, costs, and benefits is
missing. To gain this view, a strategic plan will be required that places each action to be taken in a context
that addresses the entire problem. To a large extent, such plans can be developed for particular hydrologic
units. Nevertheless, some options would affect more than one unit, particularly freshwater and sediment
diversion. Thus, a comprehensive plan must look at all the wetlands of the Mississippi deltaic plain.
It is now evident that a program to save a major fraction of Louisiana's wetlands would cost two or
more orders of magnitude more than the resources currently allocated to the problem. Moreover, it would
require federal government and private-sector interests to cooperate in state initiatives, which may imply
restraints or major modifications of their policies and activities.
The political process must resolve whether these costs are justified by the protection of America's
largest coastal wetland ecosystem. A political solution, however, will require scientists and analysts to
provide policy makers with one or more comprehensive plans for addressing the issue. Thus far,
professionals have developed numerous options that could slow wetland loss. But they have not yet
provided policy makers with a map of what coastal Louisiana will be like thirty to one hundred years
hence for each of the possible options. People have tended to focus on specific projects rather than on
determining what must be done to achieve the desired level of wetland protection.
This panel was convened to chart a course for removing this impediment to the planning process.
Although much research is still necessary, we believe that the information base is now sufficient to make
first-order assessments. Below we outline a study to synthesize available information to evaluate the
likely consequences of twenty alternative plans of action.
We do not dismiss the concern of many that after years of research, the time for studies has passed
and it is now time for action. But we doubt that sufficient action can take place without a clear picture of
the likely economic and social consequences of taking or not taking the necessary measures. This is
especially true because many of the parties that must ultimately play a role in the eventual solution are
largely unaware of the problem or are not yet convinced that the problem warrants their attention.
In the study we envision, a wide variety of wetland protection options will be considered. For each
option or combinations of options, a map of future wetland loss will be developed, along with a cost
estimate. When this study is complete, it will be possible for policy makers to say: "If we want to have 50
percent of our wetlands by 2100, it will cost this much; if we want to retain 10 or 25 percent, it will cost
this much. In each case, here is what a map of Louisiana would look like." It will also enable policy
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
makers to assess the economic and social costs of losing the land (with no protective efforts) and to
compare these long-term revenue losses with shorter-term restoration expenditures.
This information will not guarantee adoption of major actions to protect Louisiana's wetlands. But
without such information, implementation of the necessary measures will be extremely unlikely.
Table 5 illustrates the major steps of the proposed study, which can be divided into two parts: (1)
Estimating the cost of particular levels of wetland preservation, and (2) evaluating the benefits of various
levels of wetland protection and the long-term costs of the no-action alternative. In the first phase, the
study will project statewide land loss in the next century for a variety of remedial measures and estimate
the cost of implementing those options, for three scenarios of future sea level: current trends, a medium
scenario, and a high scenario. It is particularly important that this study consider scenarios of accelerated
sea level rise because the many studies conducted by the Corps of Engineers have only used historical
trends, which may provide misleading results regarding the relative merits and cost/benefit ratios of
various projects. The second phase will consider benefits such as reduced flooding and flood mitigation
costs, greater seafood harvests, increased hunting and trapping, and achievement of the nation's
environmental goals.
Table 5
Outline of Proposed Study
Phase 1: Strategies for Achieving Particular Levels of Wetland Protection
1. Use existing data to project wetland loss through the year 2100, assuming current trends and
two scenarios of accelerated sea level rise, if no additional mitigation measures are taken.
2. Estimate the loss of wetlands likely to result for each of the mitigation measures listed in
Table 6 for each of three scenarios of relative sea level rise.
3. Estimate the costs of implementing each of the options in Table 6. Cost estimates include
capital and operating costs.
Develop maps to show future shoreline.
For each of the major uncertainties in projecting wetland loss, base estimates on high and low
values that bound the uncertainties.
Phase 2: The Desired Level of Wetland Protection
6. Project values through 2100 for flood damages, navigation, resource production, and all of
the other factors that depend on Louisiana's wetlands (listed in Table 7 assuming no
additional loss of wetlands.
7. Estimate the value through 2100 of each of the factors listed in Table 7, for each of the
scenarios of wetland loss considered in task 2, above.
Phase I: Strategies for Achieving Particular Levels of Wetland Protection
The first step is to project the likely loss of wetlands if current conditions continue. The ongoing study
of future coastal conditions by the Louisiana Geological Survey will provide estimates of future
conversion of wetland to open water. The conversion to dry land for building sites will also be considered
in this base line.
As described in the previous chapter, this panel has reviewed a wide variety of measures for slowing
the rate of wetland loss. Those measures can be broadly classified into (1) diverting the Mississippi River
in directions that would better enable marsh creation; (2) reducing the number of canals; (3) barriers to
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
prevent flooding and/or intrusion of saltwater into the wetlands; and (4) modifying land-use and land-
creation practices.
One of the most difficult challenges facing us has been to pare down the list of options to a
manageable set for purposes of a comprehensive analysis. We have used two main criteria: (1) likelihood
of implementation; (2) degree of wetland protection offered. Table 6 lists options that we believe should
be assessed. Of those measures, we believe that carrying out planned and authorized projects (option 2),
construction of additional diversion structures (option 5), a 50 percent reduction in canal dredging (option
6), and marsh management (option 11) are all reasonably likely to occur. Unfortunately, there is little
reason to believe that these measures will reduce the loss of wetlands in the next fifty years by as much as
50 percent, particularly if sea level rise accelerates.
Table 6
Wetland Protection Options
Baseline
1. No action.
2. Currently authorized and planned proj ects.
Diversion
3. Increase the share of the Mississippi River water flowing down Atchafalaya River from 30
percent today to 70 percent over the forty-year period 1990-2030.
4. Free the natural processes of the active delta by constructing locks and canals from the
Mississippi River to adjacent open waters, and abandon artificial channels, levees, and bank
maintenance projects along the river below the canals.
5. Construct twice as many diversion structures as have been currently planned.
Canals
6. Slow the projected rate of net canal dredging by one-half
7. Fill existing canals at the same rate that new canals are created, importing material where
necessary. Fill existing canals for a net reduction of 1 percent per year for the next fifty years.
Land Use
8. Restore one-half of wetlands that have been diked and/or drained for conversion to pasture or
cropland.
9. Wetland creation and maintenance to offset conversion of wetlands for development.
10.
Other
11. Marsh management (weirs, floodgates, restricting marsh buggy traffic)
12. Hurricane levee/saltwater intrusion barrier parallel to Gulf shore.
Combinations
A. Options 2, 5, 6, 11 E. Options 2, 5, 8, 11
B. Options 2, 3, 6, 11 F. Options 2, 4, 7, 11
C. Options 2, 3, 7, 11 G. Options 2, 4, 8, 11
D. Options 2, 3, 8, 11 H. Options 2, 5, 6, 11, 12
To save a substantial fraction of Louisiana's wetlands in perpetuity would require implementing more
costly measures. Allowing the river to divert its flow to the Atchafalaya has long been proposed, and
would enable a substantial acceleration of marsh creation to take place at this emerging active delta;
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
option 3 proposes to increase the Atchafalaya share by 1 percent per year for the next forty years. (This
option would not necessarily imply a uniform increase for all parts of the year. Diversion of the excess
during late winter and early spring would be likely to provide greater sediment with fewer adverse
impacts on navigation.) Separating navigation from the natural processes of the active delta through
construction of bypass canals and locks from the river above the delta to nearby open waters (option 4)
would make it possible for natural deltaic processes to return to the current active delta. Each of these
measures ould be expensive. However, they would protect a larger fraction of the wetlands even if sea
level rise accelerates.
Filling canals would decrease the loss of wetlands from saltwater intrusion and wave action. Option 7
requires no new net canal formation, while option 8 requires a net reduction in canals of 1 percent per
year for the next 50 years. Converting areas that once were wetlands back to wetland (option 9) would
offer a one-time opportunity to increase the area of marsh. Hurricane levees with pumping systems
(option 12) would be mainly designed for flood protection, but might also slow the loss of wetlands by
preventing saltwater intrusion and the drowning of wetlands provided that no development were allowed
within the new levees. As discussed above, such areas would no longer serve as nurseries for estuarine
fish unless special exchange structures were built to enable fish to cross the levees.
To gain an understanding of the usefulness of the measures at our disposal, it will be necessary to
examine various combinations of these measures, also shown in Table 6. All of the combinations we
suggest would include currently planned and authorized projects, including the restoration and
maintenance of barrier island chains, and enhanced marsh management. In addition to those measures,
Combination A would involve a doubling of the construction of river diversion projects and a 50 percent
reduction in the rate of canal dredging. Combination B would be similar except that instead of additional
diversion structures, we would stop preventing the natural tendency of the Mississippi River to switch to
the Atchafalaya channel by allowing increased flow to the Atchafalaya to take place at a rate of 1 percent
per year for the next 40 years.
Combinations C and D would be similar to B, except that C would also require no net increase in
canals while D would require enough filling of canals to reduce the area of canals by 1 percent per year
for the next 50 years. Combination E would also incorporate the drastic reduction in canals dictated by
option D, but would only require a doubling of planned diversion structures instead of the major diversion
to the Atchafalaya River.
Combinations F and G would employ a different diversion scheme: restoring the natural deltaic
processes of the lower Mississippi River by separating navigation from river flow. If shipping were
restricted to canals with locks, say, near the existing Mississippi River Gulf Outlet, it would no longer be
necessary to maintain river banks and channels downstream of Venice, and sediment could be diverted
into shallow water instead of continuing to wash off the edge of the continental shelf. Combination F
assumes that this "rediversion" scheme is employed, along with no net increase in canals. Combination G
adds the 50 percent reduction in canals to this diversion scheme. Finally, option H offers a completely
different combined strategy of slowing the rate of canalization, doubling the number of diversion
structures, and employing hurricane levees as barriers to saltwater intrusion.
This list of combinations is not exhaustive. However, by analyzing these combinations it should be
possible to better understand the extent to which various strategies complement one another. Options 9
and 10 could also be employed along with these combinations; we left them out of the list only because
their contributions could reasonably be expected to be independent of the other options employed.
Projecting wetland loss for these options would be an ambitious task. The many uncertainties suggest
that precise estimates will not be possible. Nevertheless, it should be possible to bound the uncertainty
limits to provide decision makers with a clearer picture of the likely outcomes of various strategies.
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
The study we propose would be based on existing information; it would not undertake additional
basic research to answer questions that are still hotly debated, although such research should be continued
to improve the existing data base. For example, some people may believe that canals are responsible for
25 percent of wetland loss while others believe that they are responsible for 75 percent. Regardless of the
relative blame, filling of canals alone would not save the wetlands if the sea level rises rapidly in the
future; irrespective of the relative blame, saltwater intrusion resulting from canals can be curtailed either
by closing off the canals or by introducing additional freshwater to inland wetlands. In cases where
uncertainties about particular processes impede projections of the impacts of particular options, the study
will make projections assuming high and low limits to these process contributions, in a manner similar to
that employed by the Environmental Protection Agency report Projecting Future Sea Level Rise.
Phase II: The Benefits of Wetland Protection
Phase I will make it possible to provide maps depicting coastal Louisiana as it will appear in the
future to the public and to policy makers. This information may be sufficient for some people to decide
the level of effort appropriate for protecting Louisiana's wetlands. However, others may require
assessments of the implications of various levels of protection.
Table 7 lists the more important impacts that we believe should be estimated. Increased flood
damages and the costs of preventing flood damages could be very important to many coastal parishes and,
eventually, the City of New Orleans. The impact of such increases on flood insurance rates and claims
could be important to the federal government, particularly the Federal Emergency Management Agency,
which manages the National Flood Insurance Program. In addition to flood damages, the value of land
and structures lost to erosion should also be considered, including infrastructure financed by the federal,
state, and local governments.
Table 7
Impacts of Wetland Loss (units in parentheses)
1. Flood Damages (probability of storm equal to current 100-year storm, number of residences lost
per decade, dollars)
2. Flood Control Costs (dollars)
3. Flood Insurance Claims and Rates (dollars)
4. Lost Infrastructure (type, quantity, dollars)
5. Private Land and Structures (number of residences, businesses, acreage, dollars)
6. Commercial Seafood Production (pounds, dollars)
7. Commercial Hunting and Trapping (catch, dollars)
8. Recreational hunting and fishing (recreation days, dollars)
9. Other Recreation and Tourism (recreation days, dollars)
10. Shipping (tonnage, costs per ton)
11. Channel and River Maintenance Costs
12. Drinking Water (costs, health effects)
13. Cost to protect hurricane, navigational and flood protection levees from storm waves as protective
marsh and barrier islands disappear, (dollars)
14. Employment (jobs, dollars)
15. Water quality improvements (cancers prevented, increased yields)
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
The value of lost seafood, hunting, fishing, and trapping will also be important. The dollar value will
have significance to the local economies; moreover, the resulting drop in nationwide seafood production
will be important to a variety of national constituencies, including the restaurant industry and the general
public, and the poultry industry, which relies on Louisiana's menhaden. Adverse impacts on tourism
should also be considered. Finally, potential increases in some seafood species must also be considered.
Because wetland loss is caused in part by activities designed to aid navigation, shipping-related costs
may increase as a result of measures to curtail wetland loss. River diversion projects would slow the flow
of the Mississippi, perhaps necessitating additional dredging. Diversion to the Atchafalaya may require
dredging downstream of the Old River control structure, although it might also result in decreased
dredging costs in the lower part of the main channel. Separating navigation from river flow with the
construction of canals and locks would increase shipping costs by the additional time spent waiting for
the use of the locks (however, the shorter route with no downstream current to fight may partially or
totally offset waiting periods or delays, and save in fuel costs).
Drinking water would also be affected by wetland loss and proposed mitigation options. Wetland loss
and many of its causes are likely to continue to increase the salinity of water supplies. On the other hand,
diversion of the Mississippi River to the Atchafalaya would enable saltwater to reach farther up the
Mississippi channel and may render existing water intake supplies too salty for use. The costs of
developing an alternative water supply for New Orleans would thus have to be considered; because such a
supply would most likely be of higher quality than the city's current supply, the reduction in the use of
bottled water and increased level of health of the city's population would also have to be factored in.
Finally, the negative impacts of wetland loss on employment must be considered.
To a large degree, the decision regarding the appropriate level of wetland protection will depend on
the cost of mitigation and the benefits of protecting wetlands. Many of the members of this panel are
concerned, however, that an overreliance on conventional cost-benefit analysis may justify a level of
wetland protection far less than the public at large would favor. Our concern falls into two categories: (1)
cost/benefit analysis only considers readily measured commodities traded in the marketplace, and
overlooks nonmarket values of environmental resources and societal goals; and (2) formulas commonly
used to estimate the benefits of small wetland protection projects may not be consistent with economic
theory when applied to projects to protect all of coastal Louisiana.
There is a national interest in maintaining our cultural heritage and environment for future
generations. Methods of estimating the value of an acre of wetlands do not generally consider these latter
factors. For example, methods used by the Corps of Engineers to estimate the value of wetland protection
in Terrebonne Parish generally conclude that the marsh is worth about $2500-6400 (Costanza and Farber
1985). Yet federal, state, and local governments have often required mitigation for wetland destruction
outside of Louisiana at costs of $25,000-$35,000 per acre (OFA 1986). This discrepancy suggests that the
actual value to society of maintaining coastal ecosystems is far greater than the current cost/benefit
methods would lead one to believe.
Even when a conventional market analysis is employed, the value of the entire ecosystem will be far
more than what one would estimate by multiplying the value of one acre by the number of acres. A loss of
10 percent of Louisiana's remaining wetlands would increase the risk of flooding in some areas; but if 60
percent of the wetlands are lost, the last 10 percent could significantly increase the risk of flooding in
major urban areas.
Furthermore, an accurate analysis of the value of Louisiana's wetlands should include a sound
treatment of what economists call "consumer surplus." The economic cost is reflected not only by current
market prices, but by what people would be willing to pay for the resources supplied by wetlands. If
shrimp costs $3.00 today but would rise to $6.00 with the loss of Louisiana's wetlands, an economic
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Report of The Lousiana Wetland Protection Panel, EPA #230-02-87-026, April 1987
valuation of lost shrimp production should reflect values of shrimp ranging from $3.00 to $6.00, perhaps
for an average value of around $4.50. The same situation applies to residential land values. Although a
native of coastal Louisiana may have only paid $50,000 for his house, his heritage and fondness for
hunting and fishing may so tie him to the area that it would be worth considerably more to him to stay in
coastal Louisiana, as long as the character of the area is maintained.
Finally, the choice of an interest rate by which to "discount" future costs of wetland loss into current
values plays a very important role. The use of the high rates that have prevailed during the 1980s can be
used to trivialize the distant future. Care must be taken to ensure that the discount rates used in the
analysis reflect society's tradeoff between present and future generations.
It is important that assessments of the benefits of protecting wetlands focus not only on "bottom line"
dollar estimates, but on the uncertainties in such estimates and on noneconomic ways of viewing these
benefits. Although middle-level managers must often make decisions on the basis of quantitative
cost/benefit information, the achievement of nonquantitative values and objectives can be equally
important to political leaders and the public at large.
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Saving Louisiana's Coastal Wetlands: The Need for a Long-term Plan of Action
CHAPTER 6
CONCLUSION
We have reviewed the body of literature concerning the causes and potential consequences of wetland
loss in Louisiana. We have tried but have been unable to find any evidence that this ecosystem can be
saved without massive efforts to correct the cumulative damage that has occurred over the last fifty years,
efforts that will require the assistance of federal, state, local, and private organizations.
Wetland loss in Louisiana is a problem for the nation. The United States benefits from the shipping
that passes through the Mississippi River, both economically and in terms of national security; but for the
last century, efforts to maintain the shipping lanes have taken a toll on the natural ability of the river to
supply the wetlands with sediment. The entire nation has benefited from the extraction of oil and gas,
which has been permitted by the federal government; but the canals that were necessary to provide access
to the wells have left a legacy of conduits by which saltwater can invade and destroy the wetlands. The
federal government has participated in the construction of flood control levees and dams along the
Mississippi River and its tributaries, which also deprive the wetlands of sediment.
The Louisiana Legislature has recognized that wetland loss is also a problem for the state, and created
the Coastal Environment Protection Trust Fund. Several coastal parishes also have programs to address
wetland loss. Private landowners have important economic incentives to take measures to protect their
wetlands as well.
While moving forward with the initial set of projects, it is now time to examine the big picture
regarding the fate of coastal Louisiana. A lengthy public debate may be necessary. Neither this panel nor
its individual members mean to prejudice the outcome of the study we propose in favor of a particular
long-term solution. But only if all the facts are laid out on the table for all the technically viable options
will it be possible for the state and the nation to arrive at a plan that will make the next generation happy
with our actions rather than regret our lack of foresight. While various parties may have different views
on the best ways to manage the effort to protect wetlands, we all have a common interest in ensuring that
these decisions are based on the best possible understanding of their likely outcomes.
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