Proposed multiuse management plan for the Louisiana coastal zone Coastal Resources Unit, Center for Wetland Resources, Louisiana State University ; project director, Sherwood M. Gagliano ; staff, Penny Culley ... [et al.] ; prepared for presentation to the Louisiana Advisory Commission on Coastal and Marine Resources

[From the U.S. Government Printing Office, www.gpo.gov]

Coastal Zone 013 0
Information O
Center

L6 COR THE LOUISOURlA
NR FPOSED mULTIUS;E

LOUISIANAL zoSTATE UNIVERSITY

393 COASTAL RESOURCES UNIT
I, BATON ROUGE :

Coastal Resources Unit
Center for Wetland Resources
Louisiana State University
Baton Rouge, LA 70803

I
Property of CSC Library

COASTAL ZONE NLANAGEHENT STUDIES

Proposed Multiuse Management Plan
for the Louisiana Coastal Zone

U.S. DEPARTMENT OF COMMERCE NOAA
COASTAL SERVICES CENTER
2234 SOUTH HOBSON AVENUE
CHARLESTON, SC 29405-2413

Project Director - Sherwood M. Gagliano
Staff - Penny Culley, Daniel Earle, Jr.,
Curtis Latiolais, Phillip Light, Nancy Roques,
Alice Rowland, Roy Shlemon, Johannes L. van Beek

December 1972

2='

I z Ad Prepared for presentation to the Louisiana Advisory Commission on
o"~ ""~ Coastal and Marine Resources.
ba rI

COTNTE S

Page
Figures and Plates . . . . . . . . . . . . . . . . . . . . .

Introduction ....................... 1

Approach . . . . . . . . . . . . . . . . . . . . . . . . . . 3

The Plan . . . . . . . . . . . . . . . . . . . . . . . ... 6

Barrier Island, Reef and Gulf Shore Areas . . . . . . . . 7

Estuarine Nursery Areas . . . . . . . . . . . . . . . . . 8

Fresh-Brackish Marsh Areas . . . . . . . . . . . . . . . 9

Fresh Water Basins . . . . . . . . . . . . . . . . . . . 10

Areas Suitable for Development. . . . . . . . . . ...11

Development Corridors . . . . . . . . . . . . . . . . . . 12

Geometry for Development . . . . . . . . . . . . . . . . 14

Environmental Engineering. . . . . . . . ... . . . 17

Implementation . . . . . . . . . . . . . . . . . . . . . . . . 25

I~~~~~~~~~~~~~~~2

FIGURES AND PLATES

Figure Page

1. The Louisiana Coastal Area. .......... . . 2

2. Configuration of proposed man-made barrier islands. . .20

Plate

1. Proposed multiuse management plan for the Louisiana
Coastal zone. ............... map envelope.

INTRODUCTION

In early 1969 the Coastal Resources Unit adapted the development of

a management plan for the Louisiana Coastal zone (Fig. 1) as its major

research objective. Through a series of contracts from the New Orleans

District, U.S. Army Corps of Engineers, the NOAA Office of Sea Grant,

the Louisiana Wild Life and Fisheries Commission, and the State Mineral

Board, steady progress toward the objective has been made. Although

none of the contracts specifically authorized the development of a

management plan for the entire coastal zone, each contract has involved

specific tasks related to environmental setting or resource management

and land use.

Total funding of projects which have contributed directly to the

study during this three year period totaled $416,953. In addition,

invaluable data have been contributed by projects of the Office of Sea

-rant Develonment and the Coastal Studies Institute.

The studies have progressed through several distinctive stages:

1) Review of natural processes and forms and synthesis of
quantative data
a) Geological, ecological
b) Hydrology and water chemistry (salinity, temperature,
sediment load, discharge)
c) Water balance - runoff studies

2) Problem definition
a) Land loss
b) Salt water intrusion
c) Canals, dredging, land reclamation

3) Development of management plan and "creative" approaches
a) Land use recommendations
b) Dynamic Management: (water chemistry, levels, regimes and
controlled delta building)
c) Use of salt domes

AlexandriaC,

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O O Lake 'S PONTCHAR7-R
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Figure 1. The Louisiana coas tal area. (After U. S. Army Corps of E~ngineers, Lower Mississippi Valley Division,
1971.)

d) Corridors
e) Barrier Islands

Results of the individual control studies have been documented in

a series of technical reports and journal articles, listed in the

appendix to this paper. These reports provide much of the basic data

upon which the plan presented herein is derived.

As the title implies, the plan is proposed as an approach to multi-

use development of the resources of the coastal zone that will provide

for both growth and development of the area's population and economy,

management and use of those renewable and irreplaceable resources which

are vital to the nation, the state and the quality of life of the

region's inhabitants.

APPROACH

Throughout the many studies that have led to projection of a

management plan for the coastal zone, there has been a focus on the

development of a methodology for environmental evaluation. Proceeding

from the assumption that the best basis of projection is a sound under-

standing of the area that is to be planned, scientific processes and

knowledge have been applied to meeting immediate and practical needs.

The subject area of environmental evaluation has progressed tremendously

in the past few years and using environmental data to plan is now a

well accepted technique. The approach recognizes that Louisiana's

coastal zone is unique in both natural landscape and cultural processes

and has used these inherent qualities and values as a basis of projection.

The natural setting of the coastal zone of Louisiana can be summed

up in one word, "dynamic." We enjoy one of the most rapidly evolving

I ~~~areas of the world. This causes many problems, but at the same time

offers many opportunities. The coast is the product of the delta-

alluvial system of the Mississippi River in contact with the marine

forces of the Gulf. The landscape forms the natural levees, the fresh

water swamps and marshes, the brackish marshes of the coast, the

terrace and prairie lands, the bayous and water courses, and the coastline

of offshore islands--all are in a changing and constantly evolving

relationship.

* ~~~~Changes are often so rapid and seemingly so complex that one might

view then as random and unpredictable, but that is not the case. Over

the years (based on our stu~dies of coastal wetlands) we have developed

3 ~~~a good understanding of the form and process relationships that exist

in this coastal area. It is now possible Lo predict with a high degree

* of accuracy the probably effect of any major modification upon thle

environment. It is this prediction capability that permits the develop-

ment and selection of possible alternatives for the future use and

* ~~~management of our resources.

The inherent values of the coastal zone are many and varied,

* ~~~and it is the retention and development of these values that makes the

planning essential. The economic values of the coas tal. zone have been

well documented. For example, oil and other mineral extraction industries,

commercial fisheries, the harvesting of fur animals, and the high

recreation use of the coastal zone are self-evident. Major cities,

dependent upon connection to the Gulf and inland areas, have developed

at high land points or on the fringes of the wetland areas. Of no less

value, the coastal zone is a scenic, historic and recreational resource.

I ~~~~~~~~~~~~~~4

Other renewable resource values include storage of surface and ground

water, and wildlife habitats.

The history of man's occupation of Louisiana's coastal area has

indeed been quite long, testifying to its past and current values as

a living environment. Man's presence in the area has been documented

back 12,000 years and there is evidence of more or less continuous

use since that time. Early Europeansettlers and more modern civili-

zations have tended to make extensive and often wise use of the land

as they settled, farmed, developed the levee lands, and fished and

hunted in the wetlands. Road and water transportation have long played

a major role in development of the region and are essential components.

In more recent times, as man has tried to overcome the hazards of

floods and storms, and as extraction of subsurface minerals and use of

other resources has become more pressing, the environmental base now

shows signs of serious, perhaps irreversible stress. There is a real

danger that many of the values traditionally cherished by the people

are being threatened or lost through environmental and cultural

pressures. The prime basis of a coastal zone management plan is to

achieve a compatible relationship between the land base and the needs

of people, one which will be mutually beneficial, now and in the future.

In concept, the plan recognizes environmental opportunities and

constraints. It recognizes that man must make adaptions of the

environment for his successful use and occupation of the land. It

points out that man must use restraint in manipulating the environment

if it is to continue returning long term values to him. Man is a user

and a steward of the land.

I ~~~~~~~~~~~~~~~5

I ~~~~The plan for the coastal zone is based upon two major concepts.

The first is that of a corridor-basin relationship. Within the coastal

zone are two broad, natural land systems, the natural and protected

levee ridges where historically human settlement has taken place, and

the wetlands that throughout history have been the major renewable

I ~~~resource base of the state. The plan recognizes the value of this

physiographic and historic pattern and emphasizes the levee systems

as sites for transportation and development corridors with conservation

* ~~~of the wetlands as water system recharge and natural resource development

areas.

I ~~~~The second concept recognize s the need for successive and changing

land use ini an 'orderly sequential manner. This is necessitated by the

dynamic nature of the natural systems of the coastal zone. We must

recognize and accomodate natural changes by modifying land use through

time. The system cannot be held in a static condition. The old

I ~~~engineering dream of "harnessing the river" will surely destroy the

* ~~~viability of the Louisiana coastal zone.

The concept of sequential use can be extended to man's activities.

Facilities for mineral extraction, industrial plants and certain public

works projects have a limited life expectancy. IWhen such facilities

I ~~~are designed an attempt to predict some future land use of the site

3 ~~~should be made to avoid irreversible environmental modifications that

are not compatible with predicted future use.

U ~~~THE PLAN

The map accompanying this report (enclosure envelope) is based on

major natural and cultural elements of the coastal zone landscape. It

* ~~~~~~~~~~~~~~~~6

I ~~~presents a broad-brush proposal for management and development of the

Louisiana coastal zone. Boundaries between units are drawn from

natural contacts, ranking of environmental opportunities and constraints,

and from hi storic and projected land use patterns.

Barrier Island, Reef and Gulf Shore Areas

I ~~~~These features represent the first line of defense against hurricane

forces and marine processes. Tidal inlets and streams associated with

the islands, reefs and Gulf shore are the control valves of the estuaries,

regulating inflow and outflow of Gulf water. The islands are invaluable

as wildlife habitats and scenic-recreation areas. These features are

I ~~~undergoing rapid changes as a result of coastal erosion, accelerated

regional subsidence, and hurricane damage. For example, large shell

reefs in the vicinity of Atchafalaya Bay and Marsh Island lie within

areas leased for shell dredging and soon may be destroyed. Canal dredging

on the bay sides of a number of the islands for oil rig locations and

I t'~~ipelines has seriously increased their vulnerability to storm surge

* ~~~damage.

Grand Isle, the most stable of the Louisiana barrier islands, is

accessible by highway and is important as a recreation area, as a base

Tor the offshore oil industry and as a fishing port. Frequent hurricanes

I ~~~and coastal erosion are a continuous threat to life and property on the

island. Similar permanent development of other barriers should be

discouraged.

3 ~~~~It is recoimmended that top priority be placed on management of

these units as natural barriers against storms and marine forces

U (~~~including tidal inflow and outflow of Gulf water) a-ad as wildlife and

I ~~~~~~~~~~~~~~~~~7

scenic-recreation areas. Their maintenance is vital to the continuing

viability of the natural systems in the coastal zone. Detailed studies

of erosion and deterioration should be initiated immediately in order

to implement restoration and management. The islands are so vital to

the future of the coastal zone that they should be in public ownership.

Estuarine Nursery Areas

From the standpoint of biological productibility the estuaries

represent the most productive acreage in the state. Not only are they

the foundation of the stateTs fishing industry, but they provide important

habitats for migratory waterfowl, fur bearing animals, and reptiles, and

are important scenic-recreation-open space areas. The units are defined

on the basis of distributions of salinity, marsh vegetation, oyster beds

and length of land-water interface per unit area.

These areas should never be drained or reclaimed for other uses,

even agriculture. Recent overflights indicate that thousands of acres

of marsh in the estuarine nursery areas are in an advance state of

deterioration. Programs of marsh restoration and management should

have the highest priority and should be initiated immediately. Such

programs should include a detailed systematic evaluation of the marsh

condition followed by a water management program designed to conserve

runoff, reduce salt water intrusion and curtail erosion.

Although the map is intended to be a clear statement that the

primary management objective in these units is for renewable resources,

we also recognize that mineral extraction industries are active in

these areas. if it becomes necessary to drill new wells, develop new

fields or lay new pipelines, the surface modification associated with

these activities must be made compatible with the primary management

obetive.

The concept of sequential use is also important. Since an oil

I ~~~field has a life expectancy of 35-70 years, we must plan for future use

of areas now occupied by fields. In many instances creative planning

of canal geometry and spoil disposal could create new habitats,

conserve freshwater runoff, and enhance the environmental setting. In

general, canal dredging should be minimized. Directional drilling

I ~~~should be used to reduce the number of well locations and pipelines

should be confined to corridors. Surface features should be considered

in all future mineral industry planning. These same gutidelines ;apply

I ~~~to extract-ion industry activities in all of the renewable resource

management areas, and will not be repeated.

I ~~~Fresh-Brackish M1arsh Areas

Largely unbroken fresh to brackish marshes and associated lakes,

ponds, and waterways occupy a major portion of the estuarine zone

south of the Gulf Intracoastal Waterway (GIWW). They are delineated

on the basis of distributions of salinity, fauna and flora, configuration

I ~~~of streams and water bodies, and length of water interface per unit

3 ~~~area. Like the estuarine nursery areas, these marshes are vital

components of the highly productive estuarine zone. They are of primary

importance to migratory waterfowl, fur-bearing animals and commercial

species of reptiles (alligator). They provide scenic-open space-

I ~~~recreation areas and are of considerable value to the commercial fishery.

in addition, these marshes, along with other renewable resource areas

located south of the GIWW, provide a critical buffer zone against storm

1 ~~~~~~~~~~~~~~~~9

generated surge and prevent serious inundation of inland communities.

With regard to land-use it should be pointed out that in these units,

thick underlying deposits of peatsand, soft clays provide poor foundation

conditions.

Priorities and management recommendations are essentially the

same as those outlined for the estuarine nursery areas.

Fresh Water Basins

Seven major fresh water basins are identified on the map. All

lie north of the GINU. They are dominated by extensive swamps and marshes,

rounded lakes, and sluggish backswamp drainage networks. They are usually

underlain by thick deposits of peat and organic clay, which provide very

poor foundation conditions and limit land use. Their value as wildlife

habitat areas is well known not only to the sportsmen and naturalists of

the region, but to a large segment of the general public as well. These

basins are also ffiportant as natural reservoirs ensuring fresh water flow

into the estuarine zone south of the GITIW throughout the year. This

fresh water influx is one of the primary factors in controlling water

chemistry in the estuarine zone south of the GIIA. Alteration of the

flow regime in some of these basins through drainage projects, canal

dredging, flood control projects, and highway embankments is presently

one of the major factors in increased salt water intrusion in the

estuaries.

These basins must be managed as renewable resource areas. Forestry,

fisheries, and recreation are the main uses recommended. Dredging should

be minimized, and draining and reclamation prohibited. In most instances

highways traversing the basin should be elevated on piers or piles.

in general, introduction of any new linear elements should be dis-

couraged. If unavoidable they should be confined to corridors parallel

to existing highways, pipelines, etc. Water storage in the basins

should be managed in order to optimize water chemistry in the estuaries

to the south.

Existing corridors through these basins should be de-emphasized

from the standpoint of development. For example, Highway U.S. 90

between Boutte and Raceland is an important transportation link, but

should not be encouraged as a development corridor.

Guidelines pertaining to the mineral extraction industries are

essentially the same as those proposed for estuarine nursery areas. In

addition, construction of tramways or roadway embankments in inland

swamps and marshes should be minimized. Such features often redirect

freshwater runoff in the basins and provide obstacles to the movement

of aquatic and terrestrial animals.

3_reas Suitable for Development

In general, areas suitable for development are those places

that have good foundation conditions, good drainage, and are reasonably

safe from flooding. Pleistocene terraces, salt dome islands, and

natural levee ridges form the higher, positive topographic elements in

the Louisiana coastal zone that are designated as suitable for develop-

ment. Historically agriculture, industry and settlement have been

largely restricted to these areas. Attempts to extend these activities

to adjacent wetlands have often proved to be catastrophic.

The key to proper use of these areas is careful planning. A good

mixture of urbanization, industry, and agriculture in these area's will

insure both orderly growLh and economic development and a good place

for people to work and live. Soil and meteorologic conditions should

be mapped in detail and suitability for agrciculture ranked. Prime

agriculture areas should be identified and promoted in every way

possible. The rich rice growing area of southwestern Louisiana, for

example, should be maintained primarily for agricultural use.

Development Corridors

These are primary elements in the proposed multiuse management

plan. They represent areas that are already heavily developed or where

development is projected. In most cases, the corridors are confined to

land surfaces suitable for development. In some instances however,

"natural" corridors have been expanded to boundaries formed by prominent

,man-made features such as major navigation canals or flood protection

levees. For this reason some of the land included within the develop-

ment corridors has poor foundation conditions and is flood prone. The

rationale for expanding some natural corridors is to provide adequate

area for development so that random extension into renewable resource

areas can be controlled.

In addition to land suitability, locations of development corridors

are dictated by major land and water transportation arteries, historic

land use patterns, and the necessity to maintain rather than dissect

existing natural entities. The term development corridor is not to imply

blanket urbanization or industrialization. Creative planning is again

recommended to provide the best mix of land use in these areas. The

primary use however is for development.
* ~~~~~~~~~~~~~12

Public works projects should be focused on the corridors to

strengthen and further define them. Highways, flood protection levees

and structures, drainage projects, should be incorporated into the

corridor plan. Such projects should be combined wherever possible to

minimize land acquisition and costs. There is no reason, for example,

why highways cannot be constructed on the crests of levees. This is

a standard procedure in the Netherlands and many other parts of the

world. Water resource management, mass transit systems, and regional

waste collection treatment systems should likewise be incorporated into

the corridors. Linear elements such as pipelines, power lines, should

be incorporated in the corridors.

The contact between corridors and intervening renewable resource

I ~~~management areas presents an interesting challenge to the planner.

Should it be smooth or crenulated? Should access points between develop-

3 ~~~ment corridors and marshes or swamps be linear or nodal? Only detailed

environmental analysis can provide the answer to these specific planning

and design decisions.

3 ~~~~In some instances the continuity of a development corridor depends

on a transportation link across a wetland area. A classic example

occurs between Lafitte and Larose. We believe that a transportation

* *~~link between these two places is important to orderly development of

the coastal zone. It is also recognized that excessive development across

this area is likely to cause serious deterioration of the rich Salvador-

Barataria estuary system. In these instances we propose, therefore,

I ~~~that future highways be elevated on structures with permanent restrictions

against off ramps. This same principal can be applied in a number of

critical areas; notably in the St. Charles Parish wetlands alongthe

south shore of Lake Pontchartrain where I-10 and I-410 will join,

and along the Atchafalaya Basin crossing of 1-10.

Geometry for Development

We believe that the development corridors shown on the plan

represent an excellent geometry for future growth and development of

the coastal zone that is compatible with management of renewable

resource areas. The great oval linking Lafayette, Baton Rouge, Hammond,

Slidell, New Orleans, Larose, Houma, Morgan City, Franklin, and New

iberia is one of the most basic elements in the orderly use of the

coastal zone. Reinforcement of this oval-shaped corridor should have

highest priority. The southern Lafayette-Houma-Slidell arc is of

Darticular importance. An interstate highway along this arc would

be very important. Improved transportation along this arc would

provide easy ingress and egress to the coastal zone making its opportun-

ities available without necessitating overpopulation. Urbanization

should be encouraged on the well-drained surfaces near the poles of

the oval. The Slidell-Hammond-Baton Rouge area and the Opelousas-

lafayette-New Iberia area satisfy most of the site requirements for

good urban development. Much of the southern arc is also suitable

for urbanization, but on a somewhat reduced scale. The Thibodaux-Houma

area, for example, would eminantly provide for urban growth. The

channels and natural levee ridges of the Mississippi River and Bayou

Lafourche represent major trans-coastal development corridors, and the

state's most important gateways to the Gulf. This corridor should be

reinforced although it must be asked what the capacity of it is. Is

there a limit to industrialization in this corridor or can every acre

of the natural levee be utilized? The banks of the Mississippi River

already are lined with industry and many additional plants are

anticipated. Air and water pollution are an inevitable consequence

of this industrialization. To what extent can the natural system

absorb even a minimum of pollutants?

Despite these unknowns, the Mississippi River is, and will

continue to be, the state's most valuable asset. Its channel should

be improved to a navigation depth of 55 feet. The lower end of the

Mississippi corridor should be reinforced. Venice is destined to

become an even more important support facility for the offshore oil

and gas industry and future superport development.

The Lafourche corridor should be reinforced with improved highways

and flood protection. However, flood protection levees should not be

extended south of Golden Meadow. The proposed Lafourche by-pass channel

would define the western margin of an expanded natural corridor. Old

beach ridges near the mouth of Bayou Lafourche at Port Faurchon may

serve as the foundation for onshore port facilities, related to a deep

water harbor. Although some port facilities may be permitted, development

of petrochemical, or other heavy industry should be discouraged because

of incompatibility with recreation uses in immediately adjacent areas.

Minor trans-coastal corridors include Bayou Terre aux Boefs, Bayou

Petite Caillon, Bayou du Large, the Atchafalaya River, Bayou Sale, Bayou

Cypremont, Fresh Water Bayou, the Calcasieu River, and the Sabine River.

Each of these corridors will play an important role as outlets for

recreation, the fishing industry, the offshore mineral industry and to

some extent, as commercial ports. However, further widening and deepening

of associated navigation channels is discouraged because of the salt-

water intrusion problem.

The roles of other minor development corridors in the upper

coastal zone are apparent from their locations and form. The geometry

of the development corridors and environmental management units lends

itself well to evaluation of both the proposed deep water port to be

located off the Louisiana coast, as well as regional air carrier

terminals. In previous paprers we have indicated that the best probable

site for the superport would be in the west delta area south of Grand

Isle. The Lafourche corridor can adequately service an initial oil

port. As later stages of the facility develop, which may include

containerized and break-bulk cargo handling, a 55 foot navigation

canal with a control lock should be constructed to link the superport

with the Mississippi River at Venice.

If surface transportation in the corridors is improved as suggested,

two major regional airports should be adequate for serving the region.

A long term plan for gradual upgrading of the Lafayette Airport should

accomodate the western half of the corridor network. A new facility

located in the vicinity of 1-10 and the proposed 1-55 near Laplace

would serve the eastern half of the corridor oval. The site should be

on the natural levee ridge if at all possible. The Bonnet Carre floodway

is a good potential site. However, if the Bonnet Carre lands are used

for this purpose an equal acreage of adjacent wetlands should be purchased

as a recreation area. The airport should not be built in the swamps

south of Lake Maurepas or along the southern shore of Lake Ponchartrain

because of exceptionally poor foundation conditions and the value of these

areas for open space and recreation use.

There is presently a rash of proposals for new towns and harbor

towns in the coastal zone. A number of these proposals involve the

use of public lands or require government assistance in the form of

flood protection, drainage, access roads and other aspects of site

preparation. A number of the proposals would involve significant loss

of wetlands and create major water pollution problems. There are many

excellent sites for new towns within the development corridors and

those areas suitable for development. The consumer will pay heavy

penalties in increased site preparation, maintenance costs, and tax

burdens for any urbanization or development in wetland areas of the

coastal zone. All land reclamation, including "Florida type" canal and

homesite developments, for urbanization should be prohibited.

The new community concept is an excellent one. New towns

property placed within development corridors would guarantee a more

orderly growth of the region. A limited number of harbor towns at

carefully selected locations would also be a major asset. However,

the locations should be pre-determined by the geography and hydrology

of the region and not simply by the wishes of land developers. Since

harbor towns can have major environmental impact, additional study is

recommended to determine favorable locations and sizes.

ENVIRONMENTAL ENGINEERING

When coastal Louisiana was in a virgin condition nature did a

superb job of environmental management. Balanced environmental con-

ditions resulted in high biological productivity, and in general the

system was self-maintaining. Erosion occured along some parts of the

coast, but this was more than compensated for by new land built -in

I ~~~the vicinity of the active outlets of the river.

'Han's impact has caused serious imbalance in the systems. One

symptom is massive marsh deterioration and land loss. Land in the

I ~~~coastal area is being lost at a staggering rate of 16.5 mi2 per year

and a 30 year loss of almost 500 mi2 has been measured. It is not an

I ~~~exaggeration to say that the delta is dying.

We must restore the delta and manage it to optimize natural

productivity. This can be achieved by directing natural processes.

For example, the freshwater outflow and transported sediment load

represent a tremendous amount of energy and supply of materials. The

I ~~~delta has literally been const ructed by this energy source and material

supply. By redirecting flow and helping the river to initiate new

cycles of delta building, new marshlands and estuaries can be built.

* ~~~Prime areas for these activities are designed as controlled delta

building areas on the map. Our studies indicate that the Atchafalaya

I ~~~has been building a marine delta lobe since about 1950 and if not

interrupted, some 100 mi2 or more of new marshland will have been

added to the coast by about the year 2000. Similarly for relatively

small investments of flow and sediment, very large areas of land could

be constructed along the lower Mississippi River in relatively short

I ~~~periods of time (30-50 years).

Our work has also documented a need for supplementary fresh water

for estuarine management. Supplementary water introduced through

control structures from the Mississippi and Atchafalaya Rivers into the

estuaries could be used to optimize salinity conditions and restore

* ~~~~~~~~~~~~18

a more favorable balance in these systems. A comprehensive surface

water inanag~ament plan is now being developed for south central

Louisiana (Terrebonne-Barataria area) and will be presented in a

forthcoming report.

Erosion control is fundamental in the coastal zone, but is

especially challenging as there are over 30,000 miles of land water

interface south of the GIWW and much of it is eroding. We have no

suggestions to make regarding erosion control along the barrier

islands except to re-emphasize that the problem is critical.

One approach to erosion control along the muddy shorelines of

large lakes and bays would be the construction of barrier islands.

I As shown in Figure 2, the islands typically would be 1/4 to 1/2 mile

in length and separated from the shore by a shallow lagoon. Passes

would be left between individual islands. The islands would be con-

structed around a rigid structural core of interlocking metal sheet

piles, concrete tetrahedrons, or some similar rigid skeletal-material.

The body of the islands would be composed of lake or bay bottom

sediment supplied by suction dredges or large drag lines. The seaward

edge of the islands would be veneered with gravel, shell, sand, or some

other coarse grained material that would absorb wave energy. The

(tidal) passes would be lined with rip-rap or some other rigid, erosion

resistant material. A soft edge would be left on the lagoon side of

the islands and would be planted with marsh grass.

Although this type of erosion protection would be relatively

expensive, it has a number of important advantages. Islands would not

only prevent erosion, but would also reduce storm surge without

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'ORIGINAL SHORELI

I I R O C K J E T T Y ~S H E L L F R I N G I N G
ROCK JETTY I BEACH C MARSHI SHALLOW LAGOON M ARSH

FISHING I 1 . ,,

ISLAND 1C."ONCEP ?T

Figure 2. Configuration of proposed man-made barrier islands.

20
I~~~~~~~-_ -*~

destroying the important natural land w ater interface along the

I ~~~estuary mar-in. Marshes and swamps could be maintained in a natural

condition landward of the lagoons. The islands would not only reduce

significantly the erosion problem without damaging the estuary, but

would actually enhance the total environment.

Island construction would create new, more diversified habitats.

I ~~~These would include beaches, vegetated island crests, lagoon fringing

marshes, tidal passes and lag-oons. Increased recreation opportunities

resulting from this approach are particularly attractive. The beaches

and passes would be ideal for (surf) fishing and other water contact

recreation. Island backslopes and crests provide picnic areas and

I ~~~camp sites, and lagoons could function as small boat shelters. The

new natural environments could also provide for wildlife and fish

habitats. These would include lagoons for oyster beds, passes for

fin fish and crustaceans, fringing marshes and lagoons as estuarine

nursery areas and habitat for migratory waterfowl, fringing marshes

I ~~~and regulated island crests as mammal and reptile habitats, and beaches,

passes and island crests as habitats for shore a-ad wading birds.

As shown on the map, man-made barrier islands should be constructed

on the margins of large lakes and bays in places where the wetlands

are of high value for recreation and/or as estuarine nursery areas and

I ~~~wildlife habitat. A typical application would be along the western

margin of Lake Borgne, where erosion is not only destroying valuable

marshes, but also is destroying a number of historic and archeological

* ~~~sites.

The barrier islands illustrate an important concept of environmental

engineering. That is, if energy and resources must be expended to

solve a problem it is often possible to~ reap additional benefits by

creative planning. Subtle changes in elevation and geometry alter

natural processes to create favorable opportunities for desirable

fauna and flora. The same approach could be applied to the geometry

of oil field canals and spoil disposal sites that might result in

environmental enhancement instead of deterioration for the same

eXpenditure of energy and resources.

* ~~~~There are several unique features in coastal Louisiana that may

be of considerable value in solving problems of regional waste collection

and treatment. As previously mentioned, regional sewage collection

systems should be confined to development corridors. Urban sewage has

some nutrient value to the estuary system if bacteria can be eliminated.

* ~~~Pilot studies of marsh enrichment are presently in the planning stage.

As shown on the map, aquifer recharge areas of the Terrace Uplands

I ~~~are in relatively close proximity to coastal urban centers. Using

these areas and the seaward sloping aquifers that they supply, soil

filtration of sewage may be highly feasible in south Louisiana.

Another approach, currently under investigation by the CRU research

group, involves use of large solution cavities in subsurface salt

I ~~~domes as reaction chambers for generating methane gas and other usable

byproducts. Man-made solution cavities in salt domes are presently

used on an operational basis for storage of liquid propane. We propose

that raw sewage could be introduced into such cavities, where with the

introduction of selected catalysts and temperature control, gas gener-

ating reactions might occur.

Although rapid transit does not fit comfortably within the category

of environmental engineering, it is viewed as an important consideration

in future development and management of the coastal zone. The proposed

development corridor geometry lends itself well to application of rapid

transit systems. It would provide one means of allowing people to work,

use, and recreate in the lower coastal zone without destroying it by

overpopulation. In this region the very large capital outlay required

for design and construction of a rapid transit system and even subsidy

for operation might be justified in terms of renewable resource

savings.

Although an in-depth discussion of navigation channels is beyond

the scope of this paper, a few specific comments may be in order. It

is recommended that a 55-foot deep navigation channel be constructed

from the Mississippi River southwest to the Gulf in the vicinity of

the Jump at Venice. A major lock that would accomodate ocean-going

vessels should be included in the project. Although initial costs

would be very high, major benefits would accrue from the project. The

channel would bypass the shoal areas associated with the mouths and

lower reaches of South and Southwest Passes. The lock would greatly

reduce the costs of maintenance dredging and alleviate the threat of

salt-water intrusion during low river stage. The channel would provide

a link between the Mississippi and the recommended superport site. If

this channel and lock were constructed, maintenance of Southwest Pass

for navigation could be discontinued, representing a considerable cost

savings. Further, this closure would release approximately 30% of

the lower river's discharge and flow for environmental management

purposes. This water and sediment could then be used for controlled

delta building. The project would have both economic and environmental

benefits.

In general widening and deepening of natural channels and dredging

of canals from the Gulf inland creates serious environmental problems.

Salt-water intrusion, accelerated runoff, and increased tidal exchange,

all accelerate marsh and swamp deterioration and erosion. In this

regard, the Mississippi River Gulf Outlet (MRGO) has had catastrophic

environmental effects. The channel has greatly accelerated deterioration

of what was once one of the state's most productive estuary areas.

Economically, the project has been a failure. It was originally

constructed as a short-cut for ocean going vessels between the Gulf and

the Port of New Orleans. Because the channel is narrow (500 ft) and

shallow (35 ft) and prone to shoaling as a result of massive bank

failure, it is little used. Only a small fraction of ocean-going

traffic uses the channel. Primarily because of the unstable banks,

maintenance costs have been exceptionally high--averaging $3.9 million

per year. Because of these reasons and because the Mississippi River

can and will continue to serve the navigation needs of New Orleans,

Baton Rouge, and other river ports, it is recommended that maintenance

of NRGO for ocean-going vessels be discontinued.

Proposals to improve navigation in the lower Atchafalaya

(Atchafalaya River and Bayous Chene, Boeuf, and Black Project) have

serious environmental considerations. Little consideration has been

given to the impact that this channel would have on delta building

processes presently occuring in the bay. This project should not be

--iplemented until the environmental impact is thoroughly understood.

EILEMNTATION

Obviously, the implications of the proposed plan are far

reaching. While beneficial to some landowners, many communities and

zhe state and the nation in general, implementation would undoubtedly

impose financial and social hardships on a considerable number of

individuals. The emphasis of our studies has been on the environment

and suitability of the landscape for certain uses. Although not

considered here, social, economic, engineering, and legal considerations

are equally important.

The necessary legislation and authority to partially implement

such a plan may be already in effect. Large public works projects can

be used to reinforce development corridors and to direct gyowth into

suitable areas. Without indirect subsidy in the form of highways, flood

protection, and drainage, wetland reclamation usually is not economically

feasible. Further documentation of the value of renewable resources

and consumer penalties associated with misuse of wetland areas will

strengthen this argument.

It is fully recognized that private land owners must be compensated

for loss of property rights and revenues, or for participation in

environmental management programs. This has been done in other states

through tax reliefs, scenic and use easements, and direct lease. Public

acquisition is recommended for the most important renewable resource

areas, and unique environmental and cultural features.

of environmental and land use research
A continuing program or environmental and land use research, and

I ublic education is vital. Systematic ranking and evaluation of our

resources and a oublic awareness of their value will insure responsible

decisions from elected and appointed public officials. It is essential

that the state and local areas gain control of their destinies.

Decisions that -ay result in the deterioration of the environment and

the quality of life of coastal zone citizens cannot be made in distant

corporation board rooms or administrative offices.

WiTe must learn more about the capacity of the region to absorb

increases in population and industry. The natural systems already

exhibit clear signs of imbalance. Rigid control standards must be

imposed on industry. Nexw industry must be compatible with the

environmental setting.

Historic studies document that random, unplanned development in

the coastal zone results in environmental destruction by attrition.

Although impact of individual actions may seem insignificant, the

culmulative effects are often of catastrophic proportions. For the

past 30 years the natural environment of the Louisiana coastal zone

has seriously deteriorated as a result of the impact of growth and

development. The deterioration is accelerating at an alarming rate.

These historic changes are documented and can be measured and future

changes, if controls are not imposed, can be predicted with a high

degree of probability.

The plan presented here can be compared to a single photographic

frame in a very long motion picture. It represents one step in a long

and continuous process. It should be modified and changed as our

understanding of the natural setting of the coastal zone increases and

I
our ability to analyze human processes is sharpened. However, we
believe that it does represent a specific point of departure and a
geometry that will allow for an orderly increase in population and
use of the resources of the region for continued economic growth
without destroying those aspects of the region which are so
fundamental to the quality of life of the people who reside there.

2* 7

TECHNICAL REPORTS AND PUBLICATIONS

Coastal Resources Unit
CENTER FOR WETLAND RESOURCES
Louisiana State University
Baton Rouge, LA 70803

Reports done under U.S. Army Corps of Engineers contract Nos.
DACW 29-69-C-0092, DACW 29-70-C-0272, and DACW 29-71-C-0219 constitute a
series titled "Hydrologic and Geologic Studies of Coastal Louisiana."

Report No. 1. Gagliano, S. M. and J. L. van Beek, 1970, Geologic
and Geomorphic Aspects of Deltaic Processes, Missis-
sippi Delta System, 140 p.

Report No. 2 Gagliano, S. M., Kwon, H. J. and J. L. van Beek,
1970, Salinity Regimes in Louisiana Estuaries, 62 p.

Report No. 3 Gagliano, S. M., R. Muller, P. Light and M. Al-Awady,
1970, Water Balance in Louisiana Estuaries, 98 p.

Report No. 4 Gagliano, S. M., H. J. Kwon, P. Light and J. L. van
Beek, 1970, Summary of Salinity Statistics, Coastal
Louisiana Station, 1946-1968.

Report No. 5 Gagliano, S. M., Kwon, H. J., and J. L. van Beek,
1970, Salinity and Temperature Atlas of Louisiana
Estuaries. (oversized)

Report No. 6 Muller, R., 1970, Seasonal Precipitation Surplus and
Annual Precipitation Deficit Maps of South Louisiana,
1945-1968.

Report No. 7 Coastal Resources Unit, Center for Wetland Resources,
1970, Louisiana Wild Life and Fisheries Water Chemistry
Survey Data, Louisiana Estuaries, 1968-1969.

Report No. 8 Gagliano, S. M., Light, P., and R. E. Becker, 1971,
Controlled Diversions in the Mississippi Delta System:
An Approach to Environmental Management, 134 p.

Report No. 9 Gagliano, S. M., Kwon, H. J. and J. L. van Beek, 1970,
Deterioration and Restoration of Coastal Wetlands, also
published in proceedings of the 12th International
Conference on Coastal Engineering, Sept. 13-18, 1970,
Washington, D.C.

Report No. 10 Gagliano S. M., Kwon, H. J., Light, P., Peake, J. S.,
and J. L. van Beek, 1970, Selected Environmental
Parameters Coastal Louisiana, 1945, 1946, 1959-1965.

Report No. 11 Gagliano, S. M., P. Light and P. T. Culley, 1972,
Statistical Models of Salinity Distributions,
Southeastern Louisiana Estuaries, 47 p.

Report No. 12 Becker, R. E., 1972, Wave Energy Studies Along the
Louisiana Coast, 22 p.

Report No. 13 Shlemon, R., 1972, Growth of the Atchafalaya Delta.

Report No. 14 Environmental Effects of Canals, Dredging and Land
Reclamation in the Louisiana Coastal Zone (draft).

Report No. 15 Becker, R. E., 1972, Measurement of Louisiana
Coastal Shoreline, 16 p.

Gagliano, S. M. and J. L. van Beek, 1971, Hydrologic
and Meterologic Data from Coastal Louisiana, Evaluation
of Data Gaps, 8 p., 2 plates.

Coastal Resources Unit, 1972, Environmental Evaluation
of the Terrebonne Area, Preliminary Report, 21 p.

Light, P., Shlemon, R. J., Culley, P. T. and N. A.
Roques, 1972, Hydrologic Models for the Barataria-
Terrebonne Area, South Central Louisiana, 46 p.,
4 plates (draft).

Miscellaneous Reports and Publications

Earle, D. W., Jr. and S. M. Gagliano, 1972, Some
Environmental Considerations Relevant to the Growth
of New Orleans, Coastal Resources Unit, Center for
Wetland Resources, Louisiana State University, 15 p.

Chatry, F. M. and S. M. Gagliano, 1970, Shaping and
Re-Shaping a Delta, Water Spectrum, Fall, p. 20-28.

Gagliano, S. M., Earle, D. W., Jr., Rowland, A. C.
and P. J. Templet, 1972, Environmental Evaluation of
the New Orleans East Area, Coastal Resources Unit,
Center for Wetland Resources, Louisiana State
University, 222 p.

Gagliano, S. M. and J. W. Day, Jr., 1972, Environmental
Aspects of a Superport Off the Louisiana Coast in
Center for Wetland Resources, Louisiana Superport
Studies, Report No. 1, Preliminary Recommendations and
Data Analysis, p. 281-317.

Gagliano, S. M., Day, J. W., Jr. and J. R. Van Lopik,
1972, Environmental Aspects of Louisiana Deep Water
Port Development. Preprint, Second Biennial Symposium
on Environmental Conservation, Lafayette, LA, Nov.
13-14, 1972, 20 p.

Shlemon, R. J. and S. M. Gagliano, 1972, Birth of a
Delta, Atchafalaya Bay, Louisiana, the 24th International
Geological Congress, Sec. 6, Montreal, Canada, p. 437-441.

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