August 2003 Number 23
WATERMARKSWATERMARKSLouisiana Coastal Wetlands Planning, Protection and Restoration NewsLouisiana Coastal Wetlands Planning, Protection and Restoration News
www.lacoast.govwww.lacoast.gov
FRESHWATER DIVERSIONS:Revitalizing Louisiana’sCoastal Wetlands
FRESHWATER DIVERSIONS:Revitalizing Louisiana’sCoastal Wetlands
August 2003 Number 23
Please address all questions, comments,suggestions and changes of address to:
James D. AddisonWaterMarks EditorNew Orleans DistrictU.S. Army Corps of EngineersP.O. Box 60267New Orleans, LA 70160-0267(504) 862-2201E-mail: [email protected]
WaterMarks is published quarterlyby the Louisiana Coastal WetlandsConservation and Restoration TaskForce to communicate news andissues of interest related to theCoastal Wetlands Planning,Protection and Restoration Actof 1990. This legislation fundswetlands enhancement projectsnationwide, designatingapproximately $50 millionannually for work in Louisiana.The state contributes 15 percentof the cost of project construction.
For more information about Louisiana’s coastal wetlands and theefforts planned and under way to ensure their survival, checkout these sites on the World Wide Web:
www.lacoast.gov www.americaswetland.comwww.btnep.org www.crcl.org
Correction: In the graph on page 9 of WaterMarks Number 22, the projec-tions for precipitation by the Hadley and Canadian climate models werereversed. We apologize for this error.
ABOUT THIS ISSUE’S COVER . . .Traditionally used to enhance oyster yields,freshwater diversions today are an essential toolfor sustaining and restoring Louisiana’s coastalwetlands.
Photograph, “Tonging Oysters, 1938” used by permission ofMeriget W. Turner, curator, Fonville Winans Collection
Photograph of oyster shells by Rex Caffey,Louisiana State University Agricultural Center
SubscribeTo receive WaterMarks, e-mail [email protected]
For current meetings, events, and other newsconcerning Louisiana’s coastal wetlands, subscribe to
the Breaux Act Newsflash, our e-mail newsletter, at:
www.lacoast.gov/newsletter.htm
August 2003 Number 23
3 Restoring the Natural Flow:Diversions Rebuild Wetlands
5 Diversions:Routing Water into Wetlands
7 Diversion Critics Question Impacton Economy, Environment
10 Diversions Build Hope for Wetlands
12 WaterMarks Interview:Mark Schexnayder
WATERMARKSLouisiana Coastal Wetlands Planning, Protection and Restoration News
WATERMARKS August 2003 Number 23
3
WATERMARKS August 2003 Number 23
SWOLLEN WITH watersdrained from nearly half of thecontinental United States, theMississippi River in flood stageembodies the terrifying anddestructive force of nature. Inits wake it can leave a trail ofdevastated fields, uprootedtrees and ruined buildings.
To protect human life andproperty from the ravages offlood, a 1,600-mile system oflevees and control structuresnow constrains the river andfunnels its muddy waters intothe Gulf of Mexico. But, whileshielding cities and industryfrom disaster, these barriers ofearth and concrete are starvingthe wetlands to death. Deprivedof the floodwaters’ rejuvenating
Restoring the Natural Flow:Diversions Rebuild Wetlands
nutrients and sediment, thecoastal wetlands cannot combatthe degrading effects of subsid-ence and saltwater intrusionand are vanishing. To restorethe benefits of flooding withoutthe risks of flood, wetlandproponents advocate the strate-gic breaching of the levees,allowing river water to flow intoselected marshes and bays. Thehopes and challenges associatedwith this powerful techniqueare the subject of this issue ofWatermarks: RevitalizingLouisiana’s Coastal Wetlands.
River Water BuildsCoastal LandsFor eons the Mississippi Riverhas shaped the coast of Louisi-
ana through cycles of growthand decline. Jumping its natu-ral banks and engulfing thedelta, the river pushes backsaline water driven toward landby wind and tide while deposit-ing nutrients and sedimentcollected from upstream.Particle by particle, the sedi-ment settles into the alluvialsoil of bayous, swamps andmarshes. Plants, nourished byriver water, take root, trapmore sediment, die and decayto create a biomass that trapsyet more sediment. Incremen-tally, wetlands emerge, support-ing marsh vegetation, providinghabitat for fish and wildlife, andbuffering the coast from stormsurge and sea. As land accretes,the river inevitably seeks ashorter route to the Gulf,eventually carving out a newchannel and abandoning the oldwetlands. Deprived of an influxof nutrients and sediment,wetlands sink, succumb to saltwater and disappear.
Though today’s levees andcontrol structures successfullyrestrain floods, they alsointerrupt the age-old process ofwetlands formation. TheMississippi, constrained withinits banks, is forced to carry its
Courtesy of David
Seawell
Fresh water flooding into the marshes delivers nutrients and sedimentvital to a thriving wetlands ecology.
WATERMARKS August 2003 Number 23WATERMARKS August 2003 Number 23
4
21 3 4
5 6
WATER MARKS
load of land-building sedimentinto the Gulf of Mexico, whereit tumbles to the ocean floorand lies useless for restoringland. Without the rejuvenatingsediment and nutrients of theriver, existing wetlands decline.No new wetlands emerge. Saltwater, advancing rapidlythrough navigation channelsand pipeline canals, invades theestuaries. Vegetation recedes,marshes erode into the ocean,and coastal Louisiana vanishesat the rate of one acre every35 minutes.
Reclaiming Benefits byMimicking NatureThe best antidote for thedecline of Louisiana wetlandsmay lie within the MississippiRiver itself. Purposeful breach-ing of the levees, known asdiversions or river reintroduc-tions, can mimic the naturaloverflow of the river, routingfresh water, nutrients andsediments into marshes tonourish vegetation and todeposit the material needed tobuild emergent land.
Although diversions differ in
construction and scale, theprimary goals of all diversionsare to supply marsh-buildingingredients and to alter thesaline content of the outflowarea, boosting critical plantgrowth and providing a healthyhabitat for fish and wildlife.
Expanded Purpose for anOld PracticeThe first levees along theMississippi River were built inthe early 18th century. In the1830s the first intentionalbreaching to enhance oyster
yields was recorded, and diver-sions to irrigate crops andstimulate fish productionbecame common. The idea ofusing diversions to restorewetlands emerged over half acentury ago, and is now aleading strategy as agenciesaffiliated with the CoastalWetlands Planning, Protectionand Restoration Act recognizethe Mississippi River as theirmost powerful ally in combatingthe current crisis of Louisiana’scoastal land loss.
Courtesy of NO
AA
While historically threatening to human life and property, river floodsplay an essential role in building and sustaining healthy wetlands.
1. Floodwater carries nutrients and sediment. 2. Sediment settles. 3. Plants take root.4. Plants trap more sediment. 5. Biomass increases. 6. Wetlands emerge.
River Water Builds Wetlands
1 3 45 6
2
WATERMARKS August 2003 Number 23WATERMARKS August 2003 Number 23
5
Diversions: Routing Water into WetlandsON AN AVERAGE DAY, theMississippi River propels overhalf a million metric tons ofnutrients and sediment intothe Gulf of Mexico, while thewetlands just beyond its banksstarve for lack of these veryelements. To deliver the river’smarsh-building ingredientswhere needed, four major kindsof diversions penetrate thelevees and direct river waterinto the wetlands.
Crevasses, Old and SimpleThe simplest type of diversionis a crevasse, a fissure in thenatural levee where the riverspills through. The earliest
crevasses occurred at weakpoints in the embankment, butagencies managing the coastalregion today are cutting newones to assist in wetlandsrestoration. For example, theDelta-wide Crevasses Project inlower Plaquemines Parishproposes to make and maintainup to 30 breaches over 20 years’time, producing a net increasein the area and quality of freshand intermediate marsh.
Siphons’ Scale Adaptableto Location“Siphons are like huge strawsarching over the riverbank,sucking river water in at one
end and spewing it out into thewetlands at the other,” saysChuck Villarrubia, coastalscientist for the LouisianaDepartment of Natural Re-sources. “To establish suctionyou have to prime siphons, andship traffic or low river levelscan break the suction, makingthese diversions difficult tooperate.” They are relativelyinexpensive to construct,however, and numerous smallsiphons can be used up anddown the river to pinpointdelivery of fresh water.
Gated Structures ControlOutflowLarger-capacity gated struc-tures employ box-like culvertsthat tunnel through the levee,diverting water into a receivingarea or canal before it entersthe estuary. Operators can openor shut gates fitted into themouths of the culverts tocontrol the timing, volume andvelocity of the freshwater flowinto the outflow area, and toseasonally moderate the salin-ity level.
Results from the project atCaernarvon in Breton Sounddemonstrate the advantages ofa gated structure. In its 12
Courtesy of USA
CE N
ew O
rleans District
Gated structure at Caernarvon, Breton Sound
Canal ▼▼
Gated culvert
Mississippi River
Outflow Area
WATERMARKS August 2003 Number 23WATERMARKS August 2003 Number 23
6
Crevasse
▼
years of operation, Caernarvonhas increased over seven-foldthe size of freshwater plantcommunities, reduced the areaof saltwater vegetation by over50 percent, rejuvenated fish andwildlife populations, and stabi-lized the marshes. Built withfunds from the Water ResourcesDevelopment Act, Caernarvonis a model for other gatedprojects, guiding their responseto changing weather conditions,growth cycles of shellfish,natural threats such as marsh-grass dieback, or requirementsof commercial and recreationalusers of the wetlands.
Experiments indicate thatpulsing — releasing a largequantity of water over a rela-tively short period of time —may best simulate natural
floods. According to John Day,professor of oceanography andcoastal sciences at LouisianaState University, pulsing pushes
fresh water and nutrients overa wide expanse without over-freshening the outfall area. Asdemonstrated when Caernarvonoperated for brief periods at itsfull capacity, pulsing may alsoprove useful for land-building
purposes.
SedimentDiversionsBuild LandLargerparticles ofsediment arecarried deepin the river’schannel. Toclaim themfor land-
building purposes, sedimentdiversions would make largecuts down into the river bank toallow tens of thousands of cubic
feet of sediment-laden water topass into the marsh everysecond. Slated for constructionin 2003, the first diversion ofthis kind, West Bay, is expectedto create almost 10,000 acres ofmarsh. The U.S. Army Corps ofEngineers suggests that moresuch diversions, placeddownriver from populatedareas, can effectively combatthe problem of coastal land loss.
Coastal restoration requiresa variety of techniques, includ-ing the use of diversions ofvarious scales, to achieve theage-old accomplishments ofnature. Diversions combinescience and engineering tobenefit the natural world andthe human population that sodepends on it.
Courtesy of NO
AA
Man-made crevasses direct waterborne nutrientsand sediment into specific areas of the wetlands.
Crevasses occur naturally as the river breaks through weak points inthe bank and floods the adjacent marshes.
Courtesy of NO
AA
WATER MARKS
Natural Crevasse
Man-made Crevasse
Crevasse ▼
Crevasse
▼
WATERMARKS August 2003 Number 23WATERMARKS August 2003 Number 23
7
TO THE MODERN mindaccustomed to highway speeds,time in the Louisiana wetlandsmay appear as fixed and eternalas the unblinking eye of analligator. But the rate of changeis quickly accelerating aslevees, canals and other man-made structures contribute tothe wetlands’ rapid decline.
To counteract their detri-mental impact, advocates ofcoastal restorationstrongly urge usingdiversions to replicatenatural processes andrejuvenate the wetlands.However, when humansimpose control overnature, disputes inevita-bly erupt over how toexercise that control andwhom to hold responsiblefor the consequences.Debates over usingdiversions concentrate onfour issues: fisheries,water quality, floodingand navigation.
FisheriesHistorically, oystermen havebeen proponents of riverdiversions, citing as benefits thereversal of saltwater intrusion,the increase in areas of optimal
Diversion Critics Question Impacton Economy, Environment
salinity for oyster production,and the decrease of predatorsfound in high-salinity areas.Lately, however, oystermenhave voiced concern thatmodern large-scale diversionsdamage present-day fisheries bychanging the salinity of estua-rine waters, resulting in thedisplacement of aquatic popula-tions and the reduction of catch.“Restoring normal and healthy
salinity levels throughout anestuary is an important goal ofdiversions,” confirms AllenBolotte, district conservationistfor the Natural ResourcesConservation Service. “We’dlike to return marshes to thegraduated levels of an earlier
time, when the interface offresh water and salt was opti-mal. This would promotevegetative growth, marshdevelopment, and a greaterdiversity of plants, animals andfisheries throughout the coastalzone.”
For Bolotte, and many othersstudying the issue, a keyquestion is how to ensure thesustainability of coastal Louisi-
ana while protecting thelivelihoods of people whodepend on the wetlandstoday. “In the long run,diversions enhancehabitat and increaseproductivity,” Bolottesays, “but in the shortterm, in the life of coastalfishermen relying on adaily catch, their effectcan be costly and disrup-tive.”
Because oysters grow instationary beds, unable tomove when salinity levels
change, oystermen are espe-cially vulnerable to the effectsof diversions. Acknowledgingthat people who suffer economicdamage are justified in seekingreasonable compensation, thestate of Louisiana and otherconcerned parties have devised
Courtesy of LA D
ept. of Tourism
Oyster fisheries benefit in the long run asdiversions enhance and sustain Louisiana’scoastal ecosystem.
WATERMARKS August 2003 Number 23WATERMARKS August 2003 Number 23
8
a method for calculating lossesincurred by oyster leaseholdersthat considers the value of boththe oyster beds themselves andthe crops they support.
Water QualityBy mid-20th century, pollutionpouring into the Mississippifrom agricultural run-off,municipal sewage systems andindustrial wastes earned theriver a reputation as a dirtytoxic soup. Although the qualityof river water began to improveafter the passage of the Clean
Water Act in 1972, fears aboutcontaminants such as insecti-cides, herbicides and fertilizerspersist.
Scientific studies over thepast decade document thehealth of the river. Tests for 100toxic chemicals revealed thepresence of only five, and thesein low concentrations. Traceminerals detected in fish arewell within safe limits foredibility, and concentrations ofmodern pesticides fall belowEPA standards for drinkingwater. Throughout the water-
shed, improvements to wastetreatment facilities havedramatically reduced bacteriallevels in the river.
Overabundance of nitrogenand phosphorus could causeexcessive algal growth harmfulto the marsh ecosystem, but, asBolotte points out, “At theirpresent scale, diversions simplydo not convey enough waterinto the wetlands to make algalblooms a threat.” Wetlandshave been able not only toabsorb river-borne nutrientsbut actually to benefit from
Oyster Yields Increase After Caernarvon Diversion OpensOysters Available on the Public Grounds East of the Mississippi River
5,000
4,500
4,000
3,500
3,000
2,500
2,000
1,500
1,000
500
Barr
els
X 1
000
Year
'74 '76 '78 '80 '82 '84 '86 '88 '90 '92 '94 '96 '98 '00'75 '77 '79 '81 '83 '85 '87 '89 '91 '93 '95 '97 '99
Courtesy of LaDN
R CRD
Seed and Sack Oysters(Barrels X 1000)
Pre-diversion
Post-diversion
▼
Freshwater diversionsbegin at Caernarvon
WATERMARKS August 2003 Number 23WATERMARKS August 2003 Number 23
9
One Percent of River Currently Flows Through Diversions
Percentagesbased onaverage flowand rounded
Capacitybased on alldiversionscurrentlyoperational
them. Furthermore, prelimi-nary research at LouisianaState University indicates thatfiltering river water throughthe marshes decreases thenutrient load carried by theMississippi, thereby reducingthe size of the hypoxic area, or“dead zone,” in the Gulf ofMexico.
FloodingA unified system of levees alongthe Mississippi River allowsmillions of people from BatonRouge to the Gulf to enjoysafety from floods. To them,purposefully breaching thelevees may appear to be folly.
The major diversions cancontrol the release of water,however, adjusting the timingand volume to local conditionsand to meet specific needs. Forinstance, increasing flow might
counter saline-borne threatssuch as brown marsh and redtide, or restraining it couldaccommodate the needs offisheries or seasonal sportsmen.Channel banks and physicalbarriers in the receiving basinsregulate outflow speed anddirection, further diminishingthe threat of flood and prevent-ing unintentional erosion.
NavigationReducing water levels in anavigation channel that cutsthrough the wetlands couldrestrict ship traffic and requiremore frequent dredging, or forcethe relocation of the channel.Presently, however, diversionsdo not draw enough water fromthe river to threaten navigation.Implementing a huge diversionsuch as the Third Delta atDonaldsonville would certainly
increase federal navigationmaintenance costs. Shippingmight also have to adapt byutilizing new channels if largediversions cause changes in thegeography of the coastal region.
Balancing Needs forSustainabilityDiversions attempt to replicatethe natural processes that buildhealthy wetlands while limitingpotential damage to the peopleand economy of coastal Louisi-ana. Inevitably there areconflicting opinions over settingpriorities and managing change.“For the benefit of the entireregion,” says Bolotte, “we needto develop consensus among thevarious concerned parties andmake wise choices that assurethe vigor and sustainability ofthe wetlands.”
6% of river’s volumecould flow through
diversions operating atfull capacity
Mississippi River
1% of river’s volume flowsthrough diversions operating
at current levels
WATER MARKS
WATERMARKS August 2003 Number 23WATERMARKS August 2003 Number 23
10
Diversions Build Hope for WetlandsThe expense of constructing andoperating diversions is a fractionof the estimated cost should the
nation fail to protect and restorethe Louisiana wetlands. Overthe next 20 years, these diver-
sion projects are expected tostabilize or create over a millionacres of wetlands.
Diversion Projects in Louisiana’s Coastal Wetlands
Diversion Project
Avoca Island Diversion & Land Building
Benney’s Bay Sediment Diversion
Caernarvon Freshwater Diversion*
Caernarvon Diversion Outfall Management
Channel Armor Gap Crevasse
Davis Pond Freshwater Diversion
Delta-Building Diversion at Myrtle Grove
Delta-Building Diversion North of Fort St. Philip
Delta-wide Crevasses
Freshwater Introduction South of Highway 82
Grand Bayou/GIWW Freshwater Diversion
Lake Boudreaux Basin Freshwater Intro &Hydrologic Mgmt
Mississippi River Water Reintroduction intoBayou Lafourche
Central and East Terrebonne Basin FreshwaterDelivery Enhancement*
Myrtle Grove Siphon
Naomi Siphon*
Naomi Outfall Management
Opportunistic Use of the Bonnet Carre Spillway
River Reintroduction into Maurepas Swamp
Small Freshwater Diversion to theNorthwestern Barataria Basin
Small Sediment Diversions
South Lake DeCade Freshwater Introduction
West Bay Sediment Diversion
West Point-a-la-Hache Siphon*
West Point-a-la-Hache Outfall Management
143
5,828
77,000
1,132
936
777,000
8,891
2,473
2,386
296
1,808
619
104,399
To bedetermined
1,119
Notmeasured
633
117
36,121**
5,134**
6,719
201
9,831
Notmeasured
1,087
Description of Project Work Acres
BenefitedProject #
TE-49
MR-13
N/A
BS-03a
MR-06
N/A
BA-33
BS-10
MR-09
ME-16
TE-10
TE-32
BA-256
TE-42
BA-24
BA-03
BA-3c
PO-26
PO-29
BA-34
MR-01b
TE-39
MR-03
BA-04
BA-4c
LeadAgency
COE
COE
COE;State ofLouisiana
NRCS
COE
COE;State ofLouisiana
COE
COE
NMFS
FWS
FWS
FWS
EPA
FWS
NMFS
State ofLouisiana/PlaqueminesParish
NRCS
COE
EPA
EPA
State ofLouisiana
NRCS
COE
State ofLouisiana
NRCS
TerrebonneBasin
Mississippi RiverDelta Basin
Breton SoundBasin
Breton SoundBasin
Mississippi RiverDelta Basin
Barataria Basin
Barataria Basin
Breton SoundBasin
Mississippi RiverDelta Basin
MermentauBasin
TerrebonneBasin
TerrebonneBasin
Barataria Basin
TerrebonneBasin
Barataria Basin
Barataria Basin
Barataria Basin
PontchartrainBasin
PontchartrainBasin
Barataria Basin
Mississippi RiverDelta Basin
TerrebonneBasin
Mississippi RiverDelta Basin
Barataria Basin
Barataria Basin
Location Project Status
Planning phase
Construction scheduledMarch 2004
Construction completed 1991
Construction completed 2002
Construction completed 1997
Construction completed 2002
Engineering and design phase
Construction scheduledMarch 2004
In construction (1st dredgingcycle completed; three moredredging cycles scheduled)
Construction scheduledspring 2004
Construction scheduledApril 2005
Construction scheduledMay 2004
Engineering and design phase
Proposed complex project
Not scheduled
Construction completed 1993
Construction completed 2002
Not scheduled
Construction scheduledJanuary 2005
Construction scheduledMay 2005
Construction completed 1993
Construction scheduledSeptember 2004
Construction scheduledSeptember 2003
Construction completed 1991
Hydrologic modeling phase
WATER MARKS
*Non-CWPPRA project**Acres of swamp
Sediment diversion
Construction of conveyance channel, sedimentretention devices, dikes, weirs; 50,000 cfs
Construction of five culverts and inflow and outflowchannels
Construction of flow-through culverts with watercontrols at eight sites, three plug closures with armor;restoration of 13,000 feet of spoil bank
Enlargement of existing crevasse to allow additionalflow and sediment deposition
Construction of four gated culverts, inflow and outflowchannels, guide levees and rock weir
Installation of five gated box culverts and a conveyancechannel; construction of a pump station
Construction of new conveyance channel with cutsallowing fresh water to divert into adjacent open waters
Construction of five new crevasses; dredging ofexisting crevasses; installation of plug in Raphael Passcrevasse to force more water through splays
Installation of water control structures; plug removal,structure modification; canal enlargement
Deepening existing channel and installation of weir toreduce saltwater intrusion and retain fresh water
Dredging and installation of sluice gates and outfallmanagement structures for fresh water introduction
Installation of receiving intake structure/siphon system;1,000 cfs
Improve distribution of fresh water from the GIWW
Installation of six siphon pipes; construction of leveedoutfall channel to facilitate distribution of fresh waterand sediments; 2,100 cfs
Installation of eight siphons
Installation of two weirs to maximize sedimentretention and nutrient uptake
Raising spillway pins to allow flow and reduce salinities
Installation of two culverts; construction of receivingpond; 1,500 cfs
Installation of siphons; gapping of spoil banks andculverts
Construction of conveyance channels
Installation of water control structures on south shoreand enlargement of canal
Construction of a conveyance channel; 20,000 to50,000 cfs
Installation of eight 27-inch tubes to siphon water
Installation of three earthen plugs and three weirs;restoration of channel banks to enhance distributionand reduce saltwater intrusion
WATERMARKS August 2003 Number 23WATERMARKS August 2003 Number 23
11
WaterMarks Interview ... continued from back cover
really a kind of toxic soup thatwill kill off our wetlands ratherthan restore them, but waterquality testing has shown thatthe river is remarkably free oftoxins.
WaterMarks: So you’re notworried about toxicity at all?
Schexnayder: Not at all. Thereal concern has been aboutexcessive nutrients, and that’snot been a problem to date.Nutrients themselves aren’ttoxic. Coastal wetlands assimi-late nutrients rapidly — in factthey respond by actually in-creasing their capacity to utilizethem. Additional nutrientseventually express themselvesfurther up the food chain asmore shrimp, more fish, morebirds and so forth. Even the so-called “toxic” blue-green algaeare an important food to manyestuarine organisms.
WaterMarks: What aboutdiversions’ effects on fisher-ies? Don’t oyster fishermenoppose diversions?
Schexnayder: The shortanswer is no. Oystermen havelong recognized that freshwater improves oyster produc-tion. If we can return to moretraditional salinity levels it’llbe a big positive for oystermen
in the long term. It’ll eliminatethe cost of improving oysterbeds higher in the estuariesand reduce the dangers frompollution. And most impor-tantly, oyster production willincrease significantly.
WaterMarks: Isn’t there a“Yeah, but …” here?
Schexmayder: The problem isthat we are talking long term.The data we have show that thefirst two years after a diversionbecomes operational can be themost disruptive. After that thebands of fresh and brackishwater expand and oysterproduction begins to increasewell beyond what it was beforethe diversion. We need a bridgefor the fishing industry that willtake us over the short-termproblems and get us to the long-term advantages. It’s criticalthat some form of reasonablecompensation for losses, in
addition to the oyster-leaserelocation program, be includedin our thinking about diver-sions.
We need to reach out andinvolve user groups likeoystermen, commercial andsport fishermen — not blamethem. They could become apowerful force in the effort tosave coastal wetlands.
WaterMarks: You emphasizethe difficulty and complexityof really addressing theproblem of coastal wetlandsloss in Louisiana. Howhopeful are you about thefuture?
Schexnayder: I’m concernedthat coastal wetlands loss willalways be a Louisiana problem— that it won’t ever become apriority for this nation and wewon’t ever have the dollars toseriously address the issues.But I’m also very concernedthat if coastal wetlands lossdoes become a national priority,it will be because Louisiana hassuffered a catastrophe — onecosting significant loss of lifeand billions of dollars indamage. My hope is that wehave the foresight as a nationto act now rather than react toa disaster later.
Every link in the food chaindepends on nutrientsin the ecosystem.
Courtesy of LA D
ept. of Tourism
WATER MARKS
First Class MailPostage and Fees Paid
U.S. Army Corps of EngineersNew Orleans District
Permit No. 80
DEPARTMENT OF THE ARMYNEW ORLEANS DISTRICT, CORPS OF ENGINEERSP.O. BOX 60267NEW ORLEANS, LOUISIANA 70160-0267
OFFICIAL BUSINESS
continued on page 11 …
Schexnayder: We tend to talkabout diversions as if they wereall the same. But diversionsrange from small siphons movingwater at 250 cubic feet per secondto proposed structures with thecapacity of 200,000 cfs. So it’s notso much a case of limitations as amatter of matching the rightdiversion to the project. In somecases, a series of small siphonsmight be a better fit than onelarge structure.
WaterMarks: I’ve heard youuse the term reintroductionsinstead of diversions. Why?
Schexnayder: Diversions imply
WaterMarks: Many plannersargue that diversions are theonly option available to saveLouisiana’s coastal wetlands.Are diversions really theanswer?
Schexnayder: While we wouldall like to find a silver bullet,there just isn’t one out there.And as powerful as they are,diversions are only one tool inthe toolbox. Protecting what’sleft of Louisiana’s coastal wet-lands is going to require mul-tiple, complex and expensivesolutions.
WaterMarks: So diversionshave their limitations.
that we’re changing a naturalprocess, taking something awayfrom the river. The facts are justthe opposite. Breaching a leveerestores a natural process offlooding that has always beenpart of the river. We’re re-introducing water to wetlands ina way that replicates whathappened before the leveesystem was built.
WaterMarks: But isn’t theriver is full of chemicals andfertilizers that will damagethe wetlands?
Schexnayder: Some peopleworry that the Mississippi is
The WATERMARKS Interview
Mark SchexnayderMark Schexnayder serves as a regional coastal advisor forfisheries in the Louisiana Sea Grant College program andthe Louisiana State University Agricultural Center. He hasalso worked as director of the Marine Biological Lab onGrand Terre and as manager of the state crustaceanprogram. He is shown in the photograph with hisdaughter Ava Eugenie, fishing in New Orleans City Park.
WATERMARKSWATERMARKSLouisiana Coastal Wetlands Planning, Protection and Restoration NewsLouisiana Coastal Wetlands Planning, Protection and Restoration News August 2003 Number 23August 2003 Number 23