Destructive Effects of the Estuary Dam on the 's Title Environment, and the Program for its Regeneration

Author(s) 粕谷, 志郎; 村瀬, 惣一; 青山, 己織

Citation [岐阜大学地域科学部研究報告] no.[20] p.[1]-[22]

Issue Date 2007-02-28

Rights

岐阜大学地域科学部 (Faculty of Regional Studies, Version University) / リバーポリシーネットワーク(NPO) (River Policy Network(NPO))

URL http://hdl.handle.net/20.500.12099/15555

※この資料の著作権は、各資料の著者・学協会・出版社等に帰属します。 BulletinoftheFaculyofRegionalStudies,GifuUniversityVol.20:1-22.(2007)

DestructiveE恥ctsoftheEstuaryI)amontheNagaraRiver,s

Environment,andtheProgram払ritsRegeneration

ShiroKasuya,SohichiMuraseandMioriAoyama GifuUniversity,Defunctperson,RiverPolicyNetwork(NPO) (Received:November27,2006)

Abstract

TheplanOftheNagaraRiverestuarydamwasissuedin1960･Thepurposewasasupplyofthefresh

watertoIseBayindustrialarea･Thoughitwastheplanforsupportlngtheeconomicgrowth･aWater demanddrasticallydidnotexpandafterwards,andtheoppositionmovementmainlyonthefisheryparty

wasalsointensified･Afterthe一一Anpachifl00ddamage叩in1976,however,thefloodcontroIpurposeof thedamwasemphasized･Theriverbottommustbedredgedinordertorunthefloodsafely･Thesalt

waterwillgoup,Whenitwillbesodone,andtheagrlCulturesaltdamagewillbecaused･Estuarydam,

whichstopsthis,Callsitthenecessity･Theoppositionmovementonceceases,anditbeganconstruction

in1988.It was almost simultaneous,and the new opposition movement mainly on environmental

problembecamepopular･However,theoperationwasstartedin1995,Whilethefearoftheadverse

effecttotheenvironmentdoesnotfadeaway. Afterwards,thesludgepilesupintheriverbed,benthosessuchastheclamsdisappearalmost,and

algaebreedinlargequantities･Sharpdecreasesintheareaofreed,andincatchofsweeげishand

satsukimasu salmon are being clarified･Whether suchlarge facilities and high controIcost are

necessaryforonlytheinhibitingofupstreammovementofbrine,andwhetherthedestructionofthe

environmentpermittedforonlysuchapurpose,Shouldbeconsidered･ Firstlyitisnecessarytorecoverthedestroyedenvironment･Furthermore,Weneedanewmanagement

ofthecatchmentareathatextendstotheseafromthemountain,inwhichpeopledon,tdependonlyon dam and embankment･Excluding the myth without the dyke break,it should changein the

countermeasuretothefl00dinganddykebreak･

1.NatiomalamdreglOnalbackgroロnd. NationalComprehensiveDevelopmentPlan,and

thenin1987bythe4thNationalComprehensive 1-1. Historicalbackground. DevelopmentPlan.ThroughtheseplansJapan

Postwar passed the Comprehensiv accomplished the so-Called'advanced economic NationalLandDevelopmentLaw(1950)andthe growth,,Whichhasattractedworldwideattention･ Comprehensive NationalDevelopment Plan Againstthisbackgroundoneissuebecamemore

(1962)in order to speed up the process of and more slgnificant:the maintenance of an

recovery･Thiswasfollowed,in1977,bythe3rd industrialwatersupplyfbrtheIseBayCoastarea･

At the same time,however,SOCiety's attention

Corresponding author‥ Shiro Kasuya;Tel& Fax WaS being drawn to the phenomenon of

+8ト58-293-3073,e-mail:kasuyas@gifu-u･aC･Jp `YokkaichiAsthma',CauSed by thepollutionof 2 ShiroKasuya,SohichiMul･aseandMioriAoyama

theairintheareaduetothedepletionofnature hlture.

and the destruction of the environment.From 1965,Certainproblems,namely,thepollutionof 1-3･ NagaraRiverBasin(Fig.1).

air and water,Started to be consideredin work 1-3-l･OverviewandtheHistoryoftheNagara SuCh as theIndustrial Pollution Preliminary River. Survey. TheNagaraRiver,alongwiththeKushiroRiver

(inHokkaido),isknownasoneofthelast`1impid l-2･ PrqjectHistory. rivers',and had no dam at any point･The The Nagara River Estuary Dam prqiect was Nagara River hasits source on the mountain COnCeivedin1960,then decided to buildin a Dainichidake(altitude1709m),inTakasuVillage Cabinetmeetlngat1968･DespltemanyOppOSition intheGujoDistrictofCentralHonshu.Itisa

movements,COnStruCtionbeganin1988,andthe ,With a main watercourse which dam started operatinginJuly of1995after35 extends166km,and a drainage area which years of expense･The purpose ofthe estuary extends to around2000square kilometers.It

dam was orlglnally that of water use.It was flowsintothePacificOceanattheIseBay･The intendedthatthedamwouldsupplyfreshwaterto upperpartoftheriverflowsfromthe sourceto theIseBayCombine(PowerStation),Whichwas Hachiman Town(altitude210m),aPprOXimately

also planned during the advanced economic 30km･From Hachiman Tbwn to Mino City

growth era･This growth slowed final1y as a (altitude approximately 80m)the river runs resultoftheoilcrises,andthedemandforwater through a valley for around35km,although

began to drop slgnificantly.Desplte this,the COrrOSiontothebanks,duetotherecurrlngStrata

governmentdraftedexcessivelylargefbrecastsfbr Ofhardchartlayersandsoftshalelayers,anda

Waterdemand･IntheKisoRiverWaterSystem Sandstone bed,in an areaofnarrow width,has Resources Development Master Plan(thefu11 meantthatarowofplainsnowstretchalongthis Plan),theprediction was madethatin1985the area･AstheriverentersMinoCity,itjoinswith additionalwater demand would belO8t/sec,aS thebiggestofitstributaries,theItadoriRiver,tO

OPPOSedto70usecin1973.Thispredictionwas formtheChunoBasin･NorthEastofSekiCity,

Criticizedashavingnobasisinreality,andbeing the southerly flow bends westwards,and heads merely a bureaucratic exercise.In actualfact, into Gifu City,deepln the NohbiPlain.It

resultsfrom1985to1995showedonly aslight reverts toasoutherly directionatHozumiTbwn Change,uPtO,butstayinglessthan80usec.The in Motosu District,and headsforIse Bay･In nextplanin1993,Whichwasreleasedinevitably, thisstretchitjoinswiththeqira,ArataandSakai reflected a decreasein the predicted water Rvers,andwastewaterfrom Gifu Cityandthe

demand,ShowlngaPredictedadditionaldemand SurrOundingareasisaddedwhentheseriversJOln･ Ofonly44usecfortheyear2000.Theadditiona1 Thereisnodeepval1eyatanypoint,anddueto 22.5t/sec,Whichhadbeenplannedasthecontents geomorphologic factors such as the continued

Oftheestuarydam,hadbeenproventobetotally existence ofhomes andfarmsin the area,any unnecessaryinthefaceofawaterdemand,Which plansfordamsontheriverhadbeenrqectedfor

WaSalmostatastandstill･Infact,nOtOnlythe manyyears.Asaresult,thenaturalenvironment

Nagara River Estuary Dam but also the WaS preServed to anextent,Whichisunusualin Tokuyama DaminIbiRiver,Which has been rivers,Which flow throughurban areas.Even COmpletedandfl00ded,WaS nOW unneCeSSary･ today,GifuCityboastsararity:ariverbathing

Thereiscurrentlynopossibilitythateithersocial areain the very center ofthe town.Fish of OreCOnOmicconditionswillchangesufficientlyto many sorts are plentiful;there have been126 requlre anincreased water supplyin the near SPeCies,includingseafisheslivinglnrivermouth, 3 DestructiveE鮎ctsoftheEstuaryDamontheNagaraRiver'sEnvironment, andtheProgramforitsRegeneration

l-3-2･TheGeographyoftheNagaraRiverBasin recordedintheriversofar,Whichbeatsthe120 from source speciesrecorded atthe ShimantORiver,in the The stretch the river's at Shikokuarea.Intestscarriedoutunderidentical DainichidaketoaroundShiratoriismadeupfrom

fromthe Tertiary to conditionsbytheEnvironmentAgencyin1985, VOIcanic rocks Quaternary NagaraRivercame3rd,With62species,beaten eras,While the area from Shiratorion to the onlyby Shinano Riverandthe ChikugoRiver, regionupstreamofGifucitycomprisesgeological bothofwhichrecorded63species.Plantlifein layers from the Paleozoic coalage to the theareaisalsoplentiful,With168speciesin44 MesozoicJurassic age.In places theselayers Mesozoic deposits classesbeingrecorded,includingtheMbnochoria COntainlate granite and korsakowiiandPend10rumChinese,bothofwhich Mesozoicquartztrachyte･AroundSekiCityand are mentionedin the Red Data Book as ClosetoGifuCitythebasinbecomesdiluvial,and becomes al1uvial. The `endangered species,･In thelower reglOnS Of further downstreamit theriver,therearemarshesandreedfields,Which distribution from anCient geologicallayers to supportmanySOrtSOfbirdlife･Therehavebeen moremodernlayersisaparticularfeatureofthe 133speciesofbirdrecordedatpresent･There area(2). areadditional1yllspecies(from8families)of mamma11ivinginthearea(1)･ ト3-3Hydrographiccharts TheareashowncontainstheNagaraRiver

Fig.1.NagaraRi▼打a代a 4 ShiroKasuya,SohichiMuraseandMioriAoyama

SyStem,theIbiRiver system,the YahagiRiver Pαmあe〃ZO如か～わあ〟椚,C′eめrαあαrあf乃erVムー,and ShonalgaWaRiversystem,allof SyStemandthe Witch hazel. The conifers mentioned above Which flowinto the Pacific Ocean,and the preferrockypeaksandsteeplylnCliningsummit

Kuzuryu River system,the Shou River system Slopes,Whilehorsechestnut,Wlngnut,Oakmaple,

andtheJintsuRiversystem,allofwhichflowinto and E岬telea po&andra,along with other theJapanSea. broadleaftrees,Predominateclosertotheva11eys･

Thesehillsidesdisplayvegetationthatistypical

ト3-4Vegetationinthe鮎verBasinArea neitherofbeechnoroakforests,butmoreinline

According to a survey by the Construction Withmid-rangetemperateforests. Ministry,thevegetationoftheNagara砧verbasin

is made up as follows.The river source area, Tothesouthernmostendofthemountainousarea,

arOundtheMt･Kuraidivide,COmPrlSeSSubalpine aqioining the Nohbiplain,the hi11sides of the Vegetation,While much of the river basin Val1eys and mountain slopes contain chestnut, downstreamofOwashi,TakasuVi11age(altitude Quercusserrata,pepperbush,Quercusacutissima, 750m),COmprisestemperatewhiteoakforest.It e〟e化〟∫ 用γr∫血αゆ肋,CJeγem カ甲0乃わα, COnSistsofverticaldistributionofthevegetation CbmelliaJqPOnica,aS Wellas other broadleaf

Oftheland,Whichislowerthanthebeechbandin trees,amOng a Predominantly red pine fbrest. the mountain slope･Hiba arborvitae,Japanese Allthetreesherearesecondaryforestvarieties, Whitepines,AbiesPrma,Sciadqpitysverticilhzta, andthepredominanceofredpineforestinthis COnifers such as Chamaecyparis obtusa and areaisproofofthetransitionprocesshappenlng

groundbambooaredistributedintheridgeareain Within forest vegetation.The most tommon the sub alpine belt slope,Showlng Vegetation typeofvegetationin this areaisthe temperate

distributionoftheJapan-Seatype.Areasabovean Chinquapln-Oak fbrest,Of which a particularly

altitude ofl,000mthe mountains are coveredin good example canbe seen on Mt.Kinka.For beech forest,mixed with oak(Quenu5 this reason,itis considered thatif the mongolica)andmaple(Acerpictum).Thelotver environment of the red plne forestsis not

reachesofthisbeechforestbecomeanoakforest, artificia11y changed,they willallgradually COntaining varieties of hornbeamincluding transitionintochinquapln-Oakfbrestswithintime

CalPinus tschonoskiiandred hornbeam,aS Well (3).

as ダrαr～乃〟∫ 血乃〟gg乃0∫α,Acer rゆerγe,and Prunusgrayana.Tbwardsthelowerendofthis ト3-5･Nagara River Flow and Quantity of WOOded arealie crests and convex slopes on SedimentDredged

Which some red pineis mixed with The volume ofwaterflowlngdownthe Nagara Serrataandpredominantlychestnutwoodland. Riverfrom1955to1999hasbeenshowninrIbble In the basin of theItadori River,One Of the l(SOurCe:Construction Ministry). The

Nagara River tributaries,areaS OVerl,000min minimum flow volume has beenin the range altitude show predominantly beech and oak ll･93～21･85m3/s,glVlngaStarkcontrastwith

(Que7ruS mOngOlica),While abovel,400m,the themaximumnowof6,026～1,677m3/s.The

Summitareas are covered with ground bamboo. maximum flow volumeis also slgnificantly beech fbrest Below the and oak areas,fir, differentin different years･The averageflow

Japanese hemlock,SciadqpityS Verticilhlぬ, VOlumeforthis period,however,is between90

CyPreSS,Whiteplne,redpine andother conifers and135m3/s,andthetotalnoweachyearwas

growalong with broadleaf trees such as oak, around3,000～4,000x106m3,Showlng nO Japanese horse chestnut,Quelt:uS Serrata, Significant disparityfrom year to year.The Chestnut,Wlng nut,Mdgnolia obovaぬ,maple, NagaraRiver'sflowvolumeisaroundl.5times DestructiveE鮎ctsoftheEstuaryDamontheNagaraRiver'sEnvironment, 5 andtheProgramforitsRegeneration

that of theIbiRiver(at a totalannualflow of m30fsiltduringtheyears1996and1997･This 2,400～2,700x106m3),andaround40%ofthat dredginglSCOnSideredtohavebeencarriedoutin line Nagara River oftheKisoRiver(atatotalannualflowof2,700 withthe operation ofthe EstuaryDam. ～9,500xlO6m3),Placingitinthemiddleofthe threeKisoRiversintermsofvolume.Looking ト3-6.The Cities,Tbwns Villagesin the attheflowvolumepermonth,typicallythepeaks and 鮎verBasin,andtheirPopulations. occurintherainyseason(June～July)andthe tyPhoonseason(September～October),andthe The9cities(Gl再0,Mino,Seki,Gifu,Yamagata, Hashima,,Motosuand Kuwana)and2 volumeisusuallylowbetweenNovemberandthe followlngFebruary･ 日gunn,,intheNagaraRiverbasinstretchacross

thetwoprefecturesofGifuandMie･Thevery Aichi Thereisno data availableforthe volume ofsilt much smallpartintheriver contacts now,buttheConstruCtionMinistry'sfiguresfor Prefecture･Theoveral1populationoftheareais

sedimentdredgedprovidesomereference･The about950thousandin2006. between1996 volume of silt dredged annually and2000from the upper reaches(30･2km～ l-3-7.hndUseintheRiverBasinArea 43.Okm)oftheNagaraRiverwasbetween60･5～ The populations ofal1the cities,tOWnSand 91.8xlO3m3,Whichwasmorethanthequantity vi11ages upstream of Mino Cityhave declined

dredgedfromthe ,and aroundfbur between1960and2000.Incontrasttothis,the

timesthattakenfromtheIbiRiver.Incontrast, areasdownstreamofSekiCityareincreasingin thequantityofsiltdredgedfromthedownstream population･Thisphenomenonhasbeenreflected

inland area areasoftheriversisrecordedaszerofbrtheKiso use,and the of agrlCulturalland River,andl,000xlO3m3foreachoftheNagara downstream of Sekiis declining,While

andIbiRivers.Itisparticularlynoticeablethat urbanizationisincreaslng. theNagaraRiverproducedmorethanl,000xlO3

Tablel FloodvolumeorThreeRivetちinKiso

ma裏mumnow minimumnow avemgeqow su∫nOr now/year Site year now now now Ontb.day.bon montb.day.bon (m3/secl (m3/secl (m3/secl (m3)

Inuyama 1995 7.3.18 5,766.13 l.1.5 50.31 226.48 7,142.37 213.17 6,741.08 (R.K由0) 1996 6.26.6 3,840.35 2.23.3 45.63 1997 7.12.16 5,372.79 1.2.5 48.73 301.44 9,506.34

1998 10.17.17 5,328.19 12.31.4 69.76 401.64 2,666.06

1999 6.30.11 8,570.55 3.6.5 54.67 297.45 9,380.34

Cyusetsu 1995 7.3.16 2,862.91 8.26.10 13.40 91.79 2,894.69

(R.Nagara) 1996 8.29.7 1,677.63 1.3.1 21.85 94.96 3,002.71

1997 11.27.2 3,281.39 11.11.13 13.34 129.14 4,072.46

1998 10.18.8 5,169.16 12.29.20 15.85

1999 9.15.19 6,026.41 6.14.23 11.93 134.91 4,254.51

Manngoku 1995 7.3.17 1,623.23 8.28.24 1.62 75.54 2,382.20

(R,Ibi) 1996 8.29.8 1,270.08 8.13.4 4.40 74.45 2,354.41

1997 7.12.17 1,266.22 11.12.6 3.94 84.04 2,650.13

1998 10.1&.8 3,285.18 9.13.18 3.67 1999 9.15.20 1,805.68 6.15.15 9.53 81.85 2,574.26

DatafromMinistryofLand,InfrastruCtureandTransport 6 ShiroKasuya,SohichiMuraseandMiol･iAoyama

l-3-8.Tourismandrecreationinthe Riverarea extend the river channelin order to release There are15 skiresortsin the mountains noodwatersafely,butwhentheMound(thearea

SurrOundingtheNagaraRiver.Therearealso20 approximately15kmfromtheestuarywherethe

golfclubs.Alongtheriveritself,thereisriver river bedis raised)is dredged,agricultural Streamfishing ofamogo salmon(OncoTIEynChus damagecanoccurduetoseawaterrlSlngupthe 〝∽SOuishikawai)and other fish,aS Wellas river channel･Thereis a theory,thereR)re, VariousformsoftourisminvoIvingthesweetfish, Whichstatesthattheestuarydamisnecessaryln

as fishing,Weir SuCh sweetfish fishing and Order to achievefl00d control.In1978,the fishing. COrmOrant There are also 3 governOr OfGifu Prefecture,Where mostof the Prefecturally Designated Parks,in Oku Nagara, flood damage occurred,gaVe COnSent tO the Senbonmatsubara,and SeseragiValley.There buildingofthedamforthesereasons.

are over12hot sprlng reSOrtS,mOre than19 Contents 3･ Compensation for the fishing Val1eys and waterfal1s,mOre than 22lakes, industry. 1imestonecaves,mOuntainsandplateaus,making Atthebeginnlng,almostallthefishermeninthe

the area extremely famous and wellvisited. areaopposedtheprqiect･In1973,agrOuPOf Thereare17castlesorruinsofcastles,including 26,000plaintiffs,Withthefishingco-Operativesat

GifuCastleandKanOCastle,aSWe11asmorethan itscenter,began1egalactiontohavethebuilding 93templesandshrines.Ma皿yhistoricalartifacts Of the estuary dam abandoned.IJater,the remaininthearea,SuCh astheKotozukaancient PrOblemofcompensationwassettled,andin1978 tomb,Oda Nobunaga's house,and the Houreki thatactionwasdropped,andthe3co-Operatives

era'swaterworks. that maintained their stand right untilthe end, includingtheAkasukaco-OPerative,droppedtheir

2.Plams伽rtbeDam. OppOSitionin1988･Oncetheseagreementshad beenglVen,theworkwasabletobeginin1989,at

2-1･ThemaincontentsandpurposeoftheplanS agrossbuildingcostof150bi11ionyen･ fbrtheNagaraRiverEstuaryDam･ Contents4･VariousaQCOmPanylngfacilitiesand Contentsl.Provisionoffreshwater. buildings.

Theensuringofanewsupplyof22.5usec(water Inadditiontoembankmentstrengtheningandthe forindustrialuse:14.8 t/second,Water for Strengthening of waste water pumps,basic domestic use:7.7t/second)offresh waterwas lifestyle expansion, agricultural basis themainpurposeofthedam.AichiPrefecture improvements,improvements to Sansen Park,

and Nagoya City,Who had rightsto the water, 1eisure facilities such as the`Michino Eki' gave their consentearly on,but Stationandboatfield,andtheseedingcenterof

OPPOSedtheplanfbrfinancialreasons.Intheend, Culture sweetfish wereal1funded from national AichiPrefecture and Nagoya City agreed to budgets.

undertakepartofthefinancialburdenofusingthe

Water,andin1987Mie Prefecture gave their =nOtel=

COnSent. Thedykebreakwasdoneinthe stepofthefireman

Contents2.Floodprevention. Whopatrolledthe embankment.The2personsdied

After visiting the area,Which suffered the and the about60,000door received theinundation `AnpachiFloodDamage'in1976(notel),Where damage.

intensive rain had caused the banks of the main

riverto collapse,the planSfor the estuary dam 2-2･BenefitsoftheEstuaryDam･ Changed toinclude the purpose of controlling 2-2-1･Presentwateruseandprofitfromtheuse

Waterlevels･Thereis a need to dredge and Ofthenewlyprovidedwater. 7 DestructiveEffbctsoftheEstuaryDamontheNagaraRiver'sEnvironment,

andtheProgramforitsRegeneration

Beforethedamwasbuilt,NorthIse'sindustrial communityOrganizations･ =nOte2= watersupply(allocationof2･95t/sec),Fukuhara O･256t/sec for Themaximumflowvolume,COnSideredtooccuronce irrigation supply(allocation of in90years,is8,000m3/second･Theupstreamdam agriculture),Nagashima Tbwn's water supply, irrigationsupplyandchannelmaintenanCeSupply intributarylSCapableofadjustlngflowbyupto500m3

(allocationl.22t/sec),aSWellasHashimaCity, /second,givlngthevalueof7,500m3/second･ KaizuTownand HirataTown'sirrigationwater 3.Anticipatednegativeeffbcts･ supply(COmbinedallocationof8･78t/sec)werea11 takenfromtheNagaraRiver･TheConstruction Ministryassertsthatsincethedamhasstopped 3_1.Thethreatofenvironmentaldeterioration. In1990,the NGO known as the Nagara River seawaterfromrlSlnguPtheriver,ithasstabilized Area BiologlCalSurvey Group the water supply fbr these areas･No new Downstream K･Yamauchiof Gifu demand fbrindustrialwater supply has been (headed by Professor Universlty,andknownhenceforthastheSurvey recorded.Asaresult,thewatersupplyhasbeen divertedintotapwater,CauSlngtheproblemsthat Group)wasformedtoinvestigateeffectsonthe arerecordedfurtheroninthisdocument. ecosystem,andbegantOSurveythedistributionof dam organismsin the Nagara Riverbefore the

2-2-2.Benefitsoffloodcontrol. wentintooperation･The SurveyGroupfeared

i)The design-fl00d discharge ofthe Nagara negativeeffectsonthebiota,andissuedquestions River(Calculatedbytakingthevolumeaqiusted on49su句ectstotheConstruCtionMinistrytothis bytheuseofthedametc･fromthemaximum effect･Inresponse,theConstructionMinistry's Water Resources Development Corporation flow volume)was4,500m3/second at the SunomataControIPoint(in1949).Thiswas issuedthe'ResponsetotheQuestionsregarding the Nagara River Estuary Dam'(hereafter the revisedto7,500m3/secondin1963(note2)･ ii)Theincreasein design-flooddischargeis `Response').In this Response,the Ministry biota dam's dealtwithbydredging13millioncubicmeters stated that the effect to the of the

fromtheriverchannelbetweenapointat30 operation would be extremely small,Or eVen kmandthedamupwards･ non-eXistent,andinresponsetosomeoftheareas

iii)Asaresultofthisdredging,thehightide raised as concernS they promised artificial

to a limitis extended from a point at18km countermeasurestoreducetheeffecttozero.

point at28km,Which causesincreased salt damage･Thedamcutsthisoff･Inotherwords, 3-2The Construction Ministry,s predictions of

thedamfacilityhasmadeitpossibletoprevent environmentalimpact･ Low water damage caused by dredging the river 3-2-1. oxygenlevelsin the riverbed

channel. upstreamofthedamduringthesummerseason･ TheConstructionMinistrybeganmainoperations

2-2-3.1burismandrecreation. of the dam without having test data for the ThereservOirarea,Whichextendsover30km,is summer season.In place of this,it published

course. data from dam areas throughout the utilized as a marina and triathlon similar OccasionalIybassfishermenorcarP/cruciancarp country,and asserted that`inferring from

fishermenhavealsobeensightedinthearea･ fbrmation conditions of thermoclinesin similar

water areas,thereis no clear threat of

2_2_4.Embankmentreinforcement thermoclines being fbrmedin even extreme

Reinforcementofembankmentwascarriedoutby droughtconditionslikethoseexperiencedinthe

no fear the Nationalgovernment and assisted tolocal summer of1994,and thereis ofthe 8 ShiroKasuya!SohichiMuraseandMioriAoyama

dissoIvedoxygen(DO)1eveldroppingtoextreme thereshouldbenochangeinthebrackishwater lowlevels'･Thiswasthe'conclusion,published Clam population･,`The construction and in Nagara River Estuary Dam the Research dredging willhave some effect on the brackish Report,VOlume2,4-625,1ines5-8･TheReport WaterClam.'(`theResponse') COntainedahugevolume-123pages-Ofmaterial

inordertogivethisconclusion(p.145to267). 3-2-5･ Sweetrish(Pおcogわ∫∫〟∫ α招ve揖 altivelis)andsatsukimasusalmon(SmOlting-type 3-2-2･Waterbloomandoutbreakofalgae･ OfO〃CO祓ッ乃Cゐ〟∫∽α∫0〟i∫ゐ読αWαi). `Astheareaupstreamoftheweiralwayshasa It was confirmed that new丘shway have been plentifulsupplyofwaterflowlngthroughit,itis effectivefbr sweetfishand satdukimasu salmon. unthinkablethatwaterbloomoranyothersortof Given that there are alarge number oflarval deterioration of water conditions should occur., fishesbeingreleasedintotheriver,itwasjudged (`MoreNagaraRiver4'). that there would belittle effect on their `Insimilardamsalreadyinoperation,thereisno POPulations. PreCedentfbrtheoutbreakofalgaetotheextent

thatit has caused the phenomenon known as 3-2-6･ The Palaemon (肋cTVbrachium Waterbloominanycasewherethewatervelocity 血中ゐcり血∫)

isoverlcm/sec･Assuch,thereisjudgedtobe `In the case of the Kiso River Dam,the Tone almostnopossibilitythattherecouldbeanalgae Estuary Dam,and the Chikugo Estuary Dam,

OutbreaktotheextentofcauslngWaterbloomin Where spawnlng aCtivities were monitored,the the Nagara River Estuary Dam area.'('the Palaemonwasconfirmedasuslngthefishroutes

Response'). and mlgrating up river･ Thisled to the

COnClusionthat there should be no slgnificant 3-2-3.Brackishwaterarea. effectonthelifecycleofthePalaemonfromthe `The brackish water areain the Nagara River EstuaryDam･'(`theResponse'). extendsforapproximately15km.Oncethedam iscompleted,thewaterupstreamofthedamwill 3-2-7･TheEriocheir(Eriocheirj4ponicus) become freshwater,and the brackish water area Thiswillmoveontodeepwaterinthebrackish

Willbe that below the dam only･This will areasdownstreamofthedam,andinthesea,OnCe reducethebrackishwaterareatoonly5･4km,but thedamiscompleted･ it willnot removeit completely.'(`the Response'). 3-2-8■ Theeel(A乃g〟iJ仏力甲0乃王cα). `Proftssor Kasuya has been making remarks `Enough"shirasu"eel(1arVae Of Anguilkz Whichsuithisowncause,andwhicharenothing j4ponica)willbeabletoascendtheNagara砧ver morethanpoints,andtheideathatthisisgolngtO to ensure continued productionin the area. becomethe estuary ofdeath has nothing to do "ShirasuMeelscanclimbthefishwayeasilywitha

Withscientificreason,butissimplyaproductof O･4m/sec water velocity,Or al.5m/sec water his imagination･..'(Rivers Section Chief Velocityoncetheyreach15-30cminlength.'

Takemura,minutes of the丘rst new dialogue meeting,p.45) 3-2-9.CottidaeandGobies Regarding Cbttuspollux,itisjudged thatthere 3-2-4. Brackish water clams(Cbrbicuhl Wi11be minimaleffectonitslife cycleoveral1,

カ甲0乃わα) withcountermeasures being putinto place to

`Fromthedamtotheestuarymouth,thesalinity COmbat any Smalldecreasein population･ Oftheriverbedwillshownochange,andassuch Gobieshaveastrengthadvantageinascendingthe DestructiveEffectsoftheEstuaryDamont･heNagaraRiver'sEnvi1･011ment

andtheProgTam払1･it･SRegeneration

riveroverCottidae,becauseoftheirsuckers,and assuchtheeffectontheirlifecyc)eisjudgedto beminimal.

3p2-10,Short-neCked clamsa皿dhaTdclams.

The efFects of the construction on the short-neCked and hard-neCked clams,Which せ⊂こも l光軸t8t加 0†叩釘にm8t摘も inhabit也e sea areas and the estuary area,are 亡=三)㈹lerstre8m 一価g叩8n細 judgedtobeminima】･ Fig.2 IuⅥSl柑血刀 o†h短b 姐1i山曙1モ▼ds,low OXygemle▼ekaltd亡Otln也rt】○､-(Sl■Idgebllild■1p)叩 3-2-11.Sesarma(5e∫αr〝之叩∫f〃把r′乃ed山肌). r如erbedbelowdam.

Canmovetoupstreamofthedambywalking.

3-2-12.Reds(朗r(7g〝lお∫α〟∫如上`∫).

Since arcas upslream of the damwil1lose tidal in什uence,SOmee8℃CtCanbeexpectedonthereed

血e g【OW血in 血e a【ea,aⅢd Teplantlng Of

∇egetation willbe ca汀ied ouL In00nneCtion with dledamconstruction,thereedfields,Which we†e apprOXimately 300 hain a∫飽,Willbe reducedtoapproximatelylOOha.

3-2-13.Cbirol10mid.

`Itisjudgedthat there willnot be slgnificant enollghchangeinthewaterqua】ityorriverbed the dam conditions after completion of the constmct10n,tO becotne 也e cause of ala【ge volume outbreak of chironomid.'(`the RespoロSe')･

3-3.Provennegativeeffectsontheenvironment.

3r3-1.Effectsprovenbytestflooding.

lJlana)yzlngthedatagatheredbytheConstruction

Ministry from a test flooditlg CarTied outin

October1994,itisclearlyshownthatdownstream

Of血edam,Wben【hegatesareclosed,haloc【ineis

formed,OXygen Levelson the riverbcd become

extremely Low,and thereis a counter-flow

gerlerated･AdditionalIy,in a test designed to

examine the viabi[ity of brackish water cIaTTIS,

clamswereplacedinwireboxesontheriverbed,

and contrary to expectations,the clamsin thc F短.3Riverbdo一也eR加erNagara(叩per)aⅦd血e

seawaterbe]ow thedam,ratherthan thosein the RiYerIbi(11IWer)at4km poi山上 npper:black

fresh water aboveit,Were a】most comp)ete]y Sludge ⅥFi仙 brown 引1rbα･l01V¢r:姐nd witb

Wipedout,TheseresultscausedNGOmember b■aCkishw且ter亡l乱mS.(AllgtlSt,200后) 10 ShiroKasuya,SohichiMul･aseandMiol･iAovama

toissuethewarnlng,alongwiththefiguresissued Surfacelevelintheareabelowthedamwas7.2, in the chart(Fig.2),at the"round table 7･l,and6.2mg/1,Whilethelevelsinthelower

discussion"(note3),Whichprecededthestartof layer were2･3,l･9,andl･4mg/1,reSpeCtively･

Operations of the dam,that the prqJeCt WaS ThisshowedtheextremelowtowhichDOlevels

Creating profoundinnuences.Theoperation of had fa11en.This was a deathblow to brackish

thedam,however,WaSapprOVed WaterClamsandotherorganisms,Whichhadlived inthebrackishwater,andthebrackishclamsdied

=mOte3= Outalmostcompletely,1eavlngOnlyshoals･The

Exhibition paneldiscussion withNGO member and `EstuaryofDeath,hadindeedprovedworthyof

peopleofIearn1ngandexperienceandtheMinistryof itsname.

ConstruCtionwascarriedoutbeforeoperationsofthe Inaddition,theconstantlyoccumngcounternow

dam. CauSeSOrganismsandmudtobecarriedtowards thedam,andtopileup･Sincealmostal11iving

3-3-2･ Observed negative effects on the CreatureS On the riverbed died,there was no

environment. COnSumPtionofthe organisms,and the material 3-3-2-1.The destruction of the brackish water COntinuedtopileup,rOttingandcreatingasludge･

area. Strainingthesludgeshowsthatitismadeupof

Inthebrackishwaterareasaltandfreshwatermix nothingbutrefuse,inwhichnolivingorganism

periodica11y(With tides,and at the spring and Can eXist.A short time after the dam barriers

neap tide),and dynamica11y(the verticaland Were Closed,an eXamination of this sludge horizontalsalinitygradients).Thisleadstothe Showedlarge quantities ofdead brackish water Creationofmanyandvariousenvironments,and Clam shells･In the aqjoiningIbiRiver,Which thenumberofspecies,aJldquantityOforganisms has no estuary dam,the continued existence of thereis per arealiving high,eVen On an brackish water clamin sand standsin stark intemationalscale.Thedamwoulduni年these COntraSt(Fig.3).According tothe brackish environments dramatically.Seawater would be WaterClamfishermen,thesandontheriverbedof

COmPletely stoppedfromflowlng upStream,and theNagaraRiverusedtobeveryfine,makingthe

theperiodicanddynamicmlXlngOfseawaterwith area the best place for brackish water clam to the fresh would cease.The fresh water,Which breed･Thesludgeatpointsreached2mdepth･

buildsupbehindthedam,WOuldbereleasedinto The Construction Ministry refused to

the seawater below the dam.Asthefresh water acknowledgethisassludge,reCOrdingitas'silt'

islighter,anddoesnothaveaproperchanceto instead･Siltis defined by the size of the mix,thereis an upperfresh water and alower Particlesofsoil,ranglngfrom50pmto2t↓min SeaWaterlayerformed,With adistinctboundary diameter･Nothing,however,Can be deduced

between the two.Subsequent tothe start of regarding the makeup of the materialfrom the

Operationofthedam,the SurveyGroupcarried particle size.Itis necessaryto also recordthe Outanultrasoundsurvey,andfromthereflection factthatthereisnooxygen,andthatthematter

Oftheultrasoundwaves,foundthatthereisaclear includeslargevolumesoforganicmaterialsina

fbrmationoflayers.Itwasshownthatthereare rotten state･In defining this state,NGO actually 31ayers at some times(4).Itis memberschosetousetheexpression'sludge,･

extremely difficult fbr oxygen from the air to

CrOSStheselayersandreachtheriverbed.Even 3-3-2-2.Increase in marshiness.

WhenDOlevelsinthesurfaceandlowerIayersof Close to the source ofthe Nagara River,the

the nooded area above the dam were almost COnCentrationofphosphoruSisO.01mg/1,Whichis

identical,When the barriers were closed,the Verylow.Itincreases as the river flows 11 DestructiveE鮎ctsoftheEstuaryDamontheNagaraRiver'sEnvironment, andtheProgramforitsRegeneration

from downstream,butis stillunder O.02mg/1by the the river water,did decreaseinlOOha timetheriverreachesGifuCity.Theincreaseis approximately300habytheconstructionofdam being markedbeyondGifuCity,andattheestuaryarea and connection.AIso,it continuouslyis is O･1mg/1･ The concentration of nitrogen destroyedafteroperation,diminishingto46hain to 1998. Besides this,theincidence the changesin a very similar way that of of destruCtiveinsectchironomid,Whichisthesource phosphoruS,andincomparisonwiththecentral area where the concentrationis O.5mg/l,the ofallerglCreaCtions,hasincreasedexponentially estuary areahas aconcentrationofas muchas untilabouttheendofthecentury. 2.Omg/1(5).Theseconcentrationsexceedthose 3-3-2-3.Obstacles ofLake Biwa,and are equalto those ofIAke tothepassageofmigratory Suwa,Whichis known for being extremely 丘sb. Withnodamonitsmainriver,theNagaraRiver eutrophicOO).wastewaterfromGifuCityandits was one the surroundsiscollectedintoArataRiverandSakai ofthefewlimpid rivers up which 砧ver,andtheseemptyintotheNagaraRiverata naturalsatsukimasusalmonwasabletoclimb.It point34kmfromtheestuary･Asaresult,the sustainedenoughfishforprofessional丘shermen stretchfrom34to30mfromtheestuaryisthepart tomakealivingfromit.As soonasthedam ofthe river,Which has always had the highest operationshadbegunitwas acknowledgedthat concentration of organic substanCeS･Thisis therewasadelayintheclimbingoftheriverby dilutedasitmovesdownstreambytheadditionof thetrout.Adelayofaround2weekswouldnot hugeamOuntOfconcern,but tributary river waters,Which are comparatively normal1y cause a lowinorganicsubstances,andcleanedfurtherby once the fish arrived,the catch statistics thewater,CleanlngenVironmentofthereedfields confirmed that there had been a huge fallin

etc. numbers･Fig･4istheConstructionMinistry's

Thiscurrenthasnowbeenforcedtostagnateby publishedfiguresforthe successivenumbersof

theintroduction of the estuary dam.Between fishcaughtinthe38kmarea･Itshowsasteady

sprlng and autumn,repeatedalgae outbreaks yearlydecrease･Thepointatwhichthe graph

occur,andonsomedqyschlorophyllalevelswere Showsaparticularsplitisbetweenthefirsthalfof

recorded at over80LAg/1(6).Previously,When 1995(theyearthedamwentintofulloperation), therehadbeenaflowofwaterthroughthearea, when there were 7 fishing areasin which

thenormalrecordedlevelwasthatofafewIAg/1 professionalfishermen were working,and the

(6).Thefirstever-reCOrdedcaseofwaterbloom latter half of1996,When the current had drift fishing had become wasseenontheNagaraRiver.Inthesummer, disappeared,and net thermoclines fbrmed,and water containing impossible,puttingmostofthefishermenoutof

oxygencannOtSinktotheriverbed,SO thatthe business. The 38km site became thelowest

oxygenlevels atthe riverbed arelow,and pointfordriftnetfishing,andeventhereitwas

to a marsh-1ike phenomena haveincreaslngly been almostimpossible･According survey Of noticed.The Construction Ministry stated that people by Niimura,Y･,in1994 the area

there was no threatofthis happenlng,but"the downstream ofthe38km polnt had a recorded

prediction1.cameoff･ CatChof4,650fish,Whichin2005haddroppedto In time,Sludge began to build upinthe areas less than one hundredth ofthe amount,36fish.

upstream of the dam too･Theincidence of ItcannOtbelongbeforethesatsukimasusalmon

methane gasincreased sharPly from autumn to StOpClimbinguptheriveraltogether･ hadin the far SPrlng･Additiona11y,thereedfields,Whichwere The catch of sweetfish past habitationformanyanimals,andwhichprovided exceeded the numbers of fish releasedintothe

SuChanimportantnaturalcleanlng function for river,andthedifferentialwasalwaysconsidered 12 Shil･oKasuya,SohichiMul･aseandMioriAovama

tobecausedbythevolumeofnatural1yoccurrlng Professor Wada stressed(at the"round table SWeetfish comlng up the river.From1995 discussion")thattheywouldbeabletoclimbthe

0nWards,With the beginnlng Of the dam fishways,butthemlgratOryfishthatliveonthe

Operations,bothfiguresreversed,andthenatural riverbed(CottuspolluxandCottuskazika)have SWeetfish were tota11ylost(Fig･5).Thelarge beendestroyedtosuchanextentthattheyareno floodedareawasalsoprovlnganinsurmountable longerseenintheriver.Incontrast,blackbass fbr barrier sweetfish heading down to the sea. (Micrqpterus salmoidbs)and bluegill(L,q)Omis Thedensityofyoungsweetfishdroppedtol/5up macTVChirus)areincreasing. totheestuarydam,andtheaverageageroseto

OVer13･4days(7)･In general,theriverwateris 3-3-2-4･Changesinwildbirdlife. poorin plankton,SO that they have to reach From the year after the commencement of the brackishareawithinseveraldays. estuarydamoperations,therewasanincreasein In Construction the`Response',the Ministry numbers of some of the ducks such as Anas StreSSedthatthelarvaeofeel(=Shirasu)wouldbe クOeCfわ祓γ乃Cゐα,Aγ吟ydβrおandA柁α叩e乃eわpe. abletoclimbbeyondthedam,but"shirasu"eel Aythyabliguklincreased sharplyin the year fishing was destroyed(1istening comprehension after dam operations began,but subsequently fromfishermen). havedroppedsharply(8).This appears to have

RopeswereprovidedfortheEriocheirtoclimb, been caused by the disappearanCe Of an but numbers have descended year after year. environment,Which sustained the bivalve fishing has Palaemon almost been destroyed Shellfish,Which the Aythyabligula fed on. from (1istening comprehension fishermen). AcTVC甲halus arundinaceus,Whichlivedin the SesarmahavereachedthepointwherenothinglS reedfields,havealsodeclinedsharply･

Seen Of them other than olderindividuals.

A丘sherman'sdata

Fig.4.Cbamgesinsatst)kimasusalmon鮎hingstatistics(at38kmpoiJ)t) DestructiveEffbctsoftheEstuaryDamontheNagaraRiver'sEnvironment, 13 andtheProgramforitsRegeneration

dadafromstatisticsofGifuPrefecture

Fig.5 Cbangesinam翰tCbesandeatcbesorⅣ1easd(Ⅹ10)sweet6sbes

350,000 皿血rofpersms 50,000 1 45,000 .′＼ 300,000 ′l ■ l ■ 40,000 ′､■

′l - - ■ .･＼ - -一 250,000 ■■ t l 35,000 ＼ / レ ー `･t-･.､ i†.ノ■･､ノ 30,000 200,000 ＼∴､ ′･･･25,000 150,000 20,000 ･+-R･NagaraatG叫紙axisis) ■~一･叫..J

--J--R.Kisoatlnuyama(rightaxisis) 0 100,000 ▼

0

50,000

0

▼･- ▼- くO ｢- ⊂○ くb O ▼ N の 寸l∫)く｣⊃ ｢- ⊂○ ⊂わ く⊃ N 亡つ 寸 uつ くO r■､ CO ⊂わ く⊃ N ぐつ 寸 uつ q> リ ●● ●● ■● … ●● ●● … -● -● ------一 - - 一 ------r く⊃ ぐ可

Fig.6 NumberofboardingpersonsohCOrmOrantfishingship datafrombothCities

3-3-2-5.Influencetoseaarea completelymistaken.

Short-neCked clamnumbers have declined atthe

Sea areanear the river mouth ofNagara River 4.Negativee批ctsonthefishingandtourism (data from Construction Ministry).AIso,the industries. prediction of Construction Ministry was 14 ShiroKasuya,SohichiMuraseandMioriAoyama

4-1.Thefishingindustry. nolonger any clams fishermen working the

4-1-1. The destroyed brackish water clam Nagara River.Thesefishermen now eke outa fishingindustry. livelihoodbyspendingfarlongerperiodsoftime

AlthoughbrackishwaterclamscannOtreprOduce traveling toeithertheKisoortheIbiriver,and

in fresh water,they can1ive there,and so the fishing for their clamthere.The'3Rivers of AkasukaFishermen'sCooperativewerebringlng KisoClamFishingStatistics'aretheConstruction

brackish water clams from theIbiRiver,and Ministry'swayofmakingfboIsofthefishermen,

releaslng themin the Nagara Riverupstreamof anddecelVlngthenation. thedam,tOharveStlater.Therewerealsomany

brackish water clamsleftin the Nagara River 4-1-2･Satsukimasusalmonfishing.

frombeforethe closureofthedambarriers,and InthelowerriverreglOnS,aSurVeyWaSCarried

SO Clam fishing was stillpossible.Indeed,it OutamOngfishingcooperatives.Thenumberof

Seemed for a while thatit was thriving,aS PeOPlewhorepliedthattheythoughttheamount

freshwaterclams,Whichhadpreviouslyonlybeen Offishtobecaughthaddroppedsubstantiallywas

abletoexistfurtheruprlVer,begantoreproducein 52%,and when the numberwho thoughtithad theformerlybrackish waterarea.The brackish droppedslightlyareincluded,thisfigurereaches

WaterClamnumbersbegan,however,tOdecrease, 73%,Showlngthatahighproportionbelievethe

and eventually even the clamsintroduced from numbers of fishin the river has fallen.35%

theIbiRiver could not be caught any more. believe that the fish have become slgnificantly Freshwater clam numbers have also declined laterintheirclimbingupriver,andafurther31%

Sharply.The riverbed has become coveredin thinkthattherehasbeensomedelay.

refuse within5 years,andis not the sort of environment,Which could support clam any 4-1-3･Sweetfishfishing. longer(by"Clam prqiectin Kuwana").The TheNagaraRiverusedtobeknownastheMecca conditionoftheareadownstreamofthedamisas OfsweetfishfishingamongstthosewhoeIt)Oyed

notedabove.Therehasbeensandspreadinan this sport･The salesfigures fbryearly fishing

areaapproximately4kmfromtheestuary,Onthe PaSSeS from the3Nagara fishing cooperatives leftshore,Whichhasbeendesignatedasa'beach (Nagara,NagaraCentralandGl再0)afterthedam

plan'area by the Construction Ministry. beganOPeration,however,havedroppedsharply,

Brackish water clam and hard clam have also recordingaloss.

beenintroduced here･Taxpayers money has In a survey done among fishing cooperative

beenspentinordertobringenqulrerStOthisarea COmmittee membersin the centralreglOn,90%

andshowthemthat`theriverbedhasnotturnedto responded that they thought fishing conditions Sludge.Itisasandbed,andtherearebrackish hadworsenedoverthelastlOyears.Asareason

Water Clamliving here.' Not only has a R)rthis,137peopleoutofatotalof182gavethe

manufactured sand bed,Which coverslessthan fact that naturally occurrlng SWeetfish had

l%ofthe whole area,been createdin order to StOPPedclimbinguprlVer.Whenaskedaboutthe COVer uPthe sludge problem,butalsothis has levelofthedecline,32%statedthattheybelieved beendonewithtaxpayers'money,addinglnSult thenumbershadfallenbyover90%,andadding

to叫ury,and makinglt a doubly criminalact. thenumberofpeoplewhothoughtnumbershad The Construction Ministry has repeatedly stated hllenby between50and90%takesthetotalto

that`therehasbeennodamagetoclamfishingln 90%ofrespondents.

the3ⅢversofKiso.'Inoneway thisistrue. SurveyS amOng the fishing cooperativesin the The3RiversofKisoincludetheKisoandtheIbi lowerriverreg10nSalsoproducedsimilarresults.

mvers,WhichflanktheNagaraRiver.Thereare 91%responded that the numbers of fish had DestructiveEfEbctsoftheEstuaryDamontheNagaraRiver'sEnvironment, 15

andtheProgramforitsRegeneration

dropped,Of which63% believed thatit has =mOte4= droppedsignificantly･75%alsorepliedthatthe `,,Expo2005Aichi"pushed up the boarding person fishhavebeenclimbingupnvermuchlater･ nember.

=nOte5=

4-l-4.Eriocheirfishing. Hotel Nagarakann, Hotel Hakuunnsou, and

AccordingtoofficialfisherystatisticsfromGifu NagaragawaHotelwereclosed7yearsago,4yearsago,

Prefecture,the amount of Eriocheir caughtin andat2,000,reSpeCtively･Renaissancehotelisunder 1998wasO.8ton,aSharpdropfromthealmost discussionforcloslng･

l.5tons caughtin1996･In comparison,the 4-2-2.Visitingfishermen amountscaughtintheKisoandIbiRiversduring Itisfearedthatthedeclineinvisitingfishermen thesameperiodshowednodecline･ wi11havehadanegativeimpactnotonlyonthe

Shops,Which sellfishing tackle and decoy 4-l-5.ShirasuEelfishing sweetfish for angling by decoy,but also on Shirasu flourished formerly at the eelfishing accommodationandtouristfacilitiesinthearea. NagaraRiverestuary･Itwasnotunusualtohear

fishermen hundreds of who would make of 5.FearS SurrOunding the newIy generated thousands of yen from one night's fishing･ drinkingl柑ter. Afterthedambeganoperations,thereweresome

yearsinwhichshirasueelwereabletopopulate 5-l.Diversiontotapwater. theareadownstreamofthedam,butnowshirasu Inthefiveyearssincethedamwasopened,there

eelfishing has died out completely(1istening hasbeenabsolutelynonewdemandforindustrial

comprehensionfromfishermen)･ WaterSupply･Inordertostemcriticismthatthe

dam was a meanlngless facility,and to avoid 4-2.Destructionoftourism. havingtoreopenthebarriers,inApril1998the

4-2-1.Cormorantfishing. Construction Ministry began todivertthe water fishing,by Nagara River,s Cormorant the intotapwatersuppliesof5citiesand5townsin

cormorantfishermen oftheImperialHousehold theChitaPeninsula.Thisrequiredcarrylngthe Agency,Whichhasbeencarriedoutontheriver water across the Kiso River.In addition there

forl,300years,hasdeclinedsharply(Fig･6,nOte WaSanallocationofO.732t/secsuppliedto2cities City,Whicharelocated 4).ThehotelsinGifu and8townsintheCentralIseWaterSupplyarea, alongthebanksoftheNagaraRiver,havebeen andwatersupplytoNorthIseareawasalsobegun fbrced,Onebyone,intoclosure(note5)･There (note 6).The waste of the dam has been isnoattractioninwatching the cormorantcatch COmPOunded by the wasted expenditureon new

andswallowsweetfishwhicharenObiggerthana WaterSuPplyfacilities.Recently,KameyamaCity few centimetersinlength.Sweetfish of20, hasreJeCtedthewaterusefromtheDam･ sometimes30centimetersglowlngOnanOpenfire

hasbecomeasightofthepast･Theflavorofthe =皿Ote6=

fish,Which was thelifeblood of the tourism Thereportoftheliesurfaced.Itwasnotusedactually･

industry,has alsoinevitably beenlost･The

cormorantfishermenseetheirlivingfadingaway･ 5-2.Fearssurroundingthetapwater. Thereis the tourism stillno oneinvoIvedin Tap waterin the Chita Peninsula has been industrywhohasbeenabletoexpressopposition describedas'foul-Smelling'and`havingasharp

tothe'approvalfortheEstuaryDam'grantedby taste'.Thereis a movementin progress

the`PrefecturalOffice'. CamPalgnlngtOhavethewatersupplyreturnedto 16 ShiroKasuya,SohichiMuraseandMioriAoyama

its orlglnalsource,upStream Ofthe Kiso River. NorthernIse,sindustrialwater supply has an InChitawaterpurifyingplant,theybegantouse allocationfromKisoRivertoo,OfO.9usec,andits

active carbon.Since the estuary area receives actualwater useis underl.16t/sec,OrlOO,000

WaSteWater and sewerage, CauSlng an tonsper day･The water supply from Nagara

environmentinwhichalgaecanoccur,theestuary Rver only becomes unstable at the hightide

Water COntains many elements,Which makeit upperlimits duringlow rainfall,Or drought

highlydangerousfbruseasdrinkingwater･ periods･Irrigation water for Hashima City,

Kaizu rIbwn and Hirata Town has to be taken

5-2-1.Carcinogenictoxins. from a point at which thereis no seawater The toxic mycrotisitin,Whichisin the influence･TakinglntOCOnSiderationthepolntS

Waterbloom-formlng algae,and trihalomethane, raisedin5-2,ifirrigation and tap water for bythechlorinatingofwater Whichis generated Nagashima Town was to be switched over to a COntaining organic substances,have both been SupPlyfromMaga10ntheKisoRiver,anybenefit Shown to be carcinogens. There is fromtheuseofnewlyprovidedwaterwouldbe

epidemiologicaldatatoshowthattrihalomethane almostcompletelynegated(Table2.). is also related to stillbirth.This datacannot be

lgnOred. TabIe2WaterrightofwateraccumuIatedinthe

damandactualuse ton/sec 5-2-2.Infectiousdiseases. Pn叩OSe Area Waterright Actualuse Water AichiR 2.86 1.60 Normal chlorinating cannOt kill off Supply NagoyaC. 2.00 0 Cryptosporidiumprotozoa,Whichcauseepidemic MieP. 2.84 0.73* diarrheawhenallowedtocontaminatetapwater. Industrial AichiP. 8.39 0

Water MieP. 6.41 0 Thereis no known cure for this condition,and Total 22.5 2.33* withlowimmunitywho contract PeOple this *note6 COnditionmaydiefromit.

7.Veri蔦cationofnoodcontrole鮎cts. 5-2-3. Chemicalsubstances,Whichinterfere

WithreproductiveorganS. 7-1･The Significance ofIncreased Dredging Itis now common knowledge that certain Volume Chemical substances known as endocrine Plans were contained within the Construction disruptersarepresentinthedownstreamareasof Ministry'sinternal(Classified)planning/ almostal1rivers.These substanCeS have been COnSideration document`Nagara River Estuary to have a destructiveinfluence on Shown the DamSurveyResultsReport'(published1965)to According to reproductive organs of animalsL dredge2･2mi11ionm3inbetweenthe-0.6kmand Construction Ministry's the survey,Water 7.Okmpoints(thedamisat5.4km),`inorderto COllectingabovethe EstuaryDamintheNagara eliminatetherisingwaterlevelsbythevolumeof River had the highestlevels of adipinic acid thedamcolumn'.Subsequently(around1962- di-2-ethylhexylin the to country.In addition 1963)i)thewaterlevelabovethedam(reservOir this,Our reSearCh shows that active substances, level)was revised from T.P2.2m to between Whichreactwiththeestrogen-hormonereceptor, O･80m(atneap tide high tide)andl.30m(plus arealsopresent･Itissurelybeyondconscience O･10m during spring tide high tide);ii)an that water contalnlng SuChinevitable dangers additional13millionm3tobedredgedbetween

Shouldbepresentedasdrinkingwater. 7.Okmand30.Okm;andiii)the2.2mi11ion m3 dredgedatthedampointwasrevised(from1966 6.VerificationofprofitabilityofwateI･uSe. DestructiveEffbctsoftheEstuaryDamontheNagaraRivel･'sEnvironment, 17

andthePl･OgramfbritsRegenel･ation

onwards)to6million m3between｣).6km and and2.10m(atflowvolumeof7,500m3/second). 3.Okm,and6milIion m3between3･Okm and ThiswasroughlyequlValenttothe2･00mspaces 7.Okm.Intermsofaveragewaterflowvolume, thatarerequiredontheNagaraRiver(note9)･ thewatersurfaceheightreachesT.R2.2matthe lncontrast,theareawithleastspaceavailablewas

30kmpoint･Inotherwords,thevolumeofwater the stretch between 8.Okm and12.Okm(at intheriverchannelbelowthewatersurfaceinthe Nagashimatown,Whichwasfl00dedduringthe stretchbetweenthedamandthe30.Okmpointis Tonankaiearthquakein1944),atO.50m,andthe the reserved water volume(note 7),but the O.60m～0.70matthesouthernendofKaizutown, but by reductioninreservedwatervolumecausedbythe the reductionin waterlevels possible dredgingatthesepointswasconsideredtobeonly reductioninwaterlevelabovethedamfromT.R 2.20mtoO.80misasfollows:37.4millionm3- O.60m～0.70m(notelO).As a result,it was

23.7millionm3=13･7millionm3･Thedredging COnSideredthattheonlymeasurespossiblewere of the13 million m3 above the dam can be the ralSlng and repalrlng Of the embankment･

considered to have been a trade-0ffmeasure for (notell). thisreduction(note8).

=nOte,=

=mOte7= Therequiredspacebetweenthemaximumwaterlevel

Theeffectivereservedwatervolumeisplannedas30 andthetopoftheembankmentwasdefinedaccording

to as 2･00m for rivers with million cubic meters(totalreserved water quantity, ministry criteria minuslowwaterquantity)･Thewaterrightspecified designed-flood discharge oflO,000cubic meters/

forthedam(22.5cubicmeters/second)ishalfthelow secondorabove,andl.50mforriverswithflowbelow

watervolume.Iftheflow volumeis reduced to half this.TheNagaraRiver(max,nOWVOlume7,500m3/

bydrought,thedeficiencycanbemadeupforamonth SeC)hasareasofembankmentthatbackontotheKiso bythe3000cubicmetersinthereservOir･ River(max.flowvolume12,500m3/sec)andsothe

=mOte8= 2.00mru1ewasappliedtoNagaraRiver,tOO･

Thedredgingofthedampolntisinvaluableinorder =mOtelO=

to maintain evenness around the bed of gates･Itis ThewaterlevelwaslowerthaJltheplannedmaximum,

POSSibletointerpretthisasmeanlngthattheeffective but some struCturalfaultsin the embankment meant

reservOir volumeincrease can be 鱒djusted to a thatitwasnotabletobearupto4daysofheavyrain. Itisthoughtthatthisisduetothefactthatthesection reductionin the reservOirlevelthroughdredging all

areas of the reservOir,eSPeCially river bed of inquestionwasbuiltduringtheMeijiperiod(1868-

fl00dTChannel.The area aroundthe damis a sand 1912)by丘11inginaneXistingpondknownas`Maruike

layer to30m below groundlevel･A reductionin Pond',andtheembankmentwasbuiltwithoutanyland

waterlevelisnecessarylnOrdertoreducepermeation. Strengtheningmeasuresbeingapplied･Cf･Notel･

=nOtell=

7-2.ConcernSthatdredgingwi11notcontributeto Actua11y,theralSlngandrepalnngOftheembankment

floodcontroI in this section between Kaizu townand Hirata town

According to the Nagara River Longitudinal WaSCOmpletedbefore丘nishingtheestuarydam･The

CrossSectionDiagramintheconstructionplans Weak polntin Nagashimatown was repaired uslng a

of1973forthedam,the maximumreductionin ParaPet(COnCreteWal1),buttheraisingandrepairingof

the was dam Waterlevelthatwould be achieved by dredging embankment carried outinline withthe

theriver channelwould be tol.40m at30km. COnStruCtion.The construCtion ministry emphasized Thespacebetweenthewaterlevelandtheupper thefactthatralSlngtheembankmentwouldrequlrethe

edgeoftheembankmentbeforedredginglnthe replacementofbridges,butinfact,theonlybridgesthat

areabetween25kmand35kmwasbetweenl.85m WOuld requlre rePlacementwiththe ralSlng Of the 18 ShiroKasuya≡SohichiMul･aseandMioriAoyama

embankmentaretheIseOhashiBridge,theJRKanSai allowtheConstruCtionMinistrytoapplyforfunds LineBridgeandtheKintestuBridge,andthesethree fromtheFinanceMinistry(note12).

bridgesin fact requlre rePlacement by aglng eVen

without the ralSlng Ofthe embankment.In other Table3 Thedistribtltionofconstructionconsts

WOrds,dT-f3dgingtherivercouldnotbeareplacement Nationd Benehting Govemment forralSlngtheembankment･ Prefecture(S) Domestic 1)(Ministryof 4) 2/3 WaterSuPPly Healthand 7-3･Organizationsothatprcuectcostscannotbe pa止 Welfare)1/3 Industrial 2)(Ministryof 5) 0.70 metwithoutfloodcontrol. WaterSuPPly International Ingeneralfloodcontrol,alongwiththesupplyof pa止 Tradeand IndustIγ)0.30 Waterandthegenerationofelectricity,hastobe Floodcontml 3)(Construction 6) 0.30 OneOfthepurposesofdamconstruction.Thisis pa托 Minist町)0.70 Partlyduetothefactofthenationalgovernment's 1),2)3)andO･300f5)(paidinadvance)aswellas6)

ratherunlqueOrganizationofprq)eCtCOStS.The are paid annual1y according to the progress of the

construction costs fbr a dam are distributed as COnStruCtion,While4)andO･700f5)areprpcuredasa Table3. loanbyapubliccorporation,andarerepaid,including

Ifthepurposeofadam'sconstructionissimplyto interest charges forthe construCtion period,tO the

SuPply waterfbr domestic use,the ConstruCtion benefiting prefecture once the damis completeand

Ministry,despite being the agent of the beginsoperation,bybeingrolledoverintothetreasury COnStruCtionprqject,infactpaysfornoneofthe investmentandloanprogram. COStS.Asaresult,prqiectsofthistypedonot

SuCCeed.InordertorespondtotherequlrementS =nOte12=

Ofriverenglneerlng,ithasbecomenecessaryto Minutesof`Meetingtodiscusstherequestforbudget Plan suchprqiectsinthenameo[fl00dcontrol. for dam COnStruCtion,,30thJuly1965･Present: Floodcontrolisonlypossiblebythelargestdams, ConstruCtionMinistry(DevelopmentDivision,Flood however,fbramaximumofaround15hours.If ControIDivision,Rivers Planming Division)and thedambecomesfu11,itisnecessarytobeginto regionalconstruCtionbureaus(PlanningDept.,Rivers discharge water,Which can be extremely PlanningDept･,KisoRiverDownstreamDept.) dangerous.Itisimportantthatwelearntolower (1)-(4)abbreviated

Ourdependenceondams･ (5)Itis not possible to use the prevention of salt

Table4showsthetransitioninthedesigned-flood damage as the only purpose offl00d control.In

dischargeintheKisoRiversystem･Inlinewith addition,includingthe construCtion of damsinthe

Plans for a newlarge-SCale dam,it can be related building works required for dredgingis

assumed that the designed-fl00d discharge has SOmethingthatwillhaveaneffectonotherrivers,and

hadtobeaqustedconstantly,1nOrdertoshowthe Shouldthereforebediscussed,andaconclusionreached,

need for flood controlas one ofthe prq)eCt,s bytheFloodControIDivision O切ectives. EstuarydamsareusuallyconstruCtedatthepolnt 乳TheOc川rremCeOrSaltI)amage.

just before which a riverflowsinto the sea.

Thereis no merit herein uslng the resulting 8-1Salt damage to rice fields was eliminated reservOirinfloodcontrol･Aseparate'logic'is duringtheearly1970s. requiredhere･Theprocessoflogicthatmoves TheconstruCtionministryemphasizedthefactin

from revISlngthe designed-fl00d discharge,tO itsdiagram`Effectsofincreasedsaltdamage,that dredgingtheriverchannel,tO Saltdamage,tOa thedredgingoftheriverwouldcausesaltdamage damappearstohavebeencreatedsimplysoasto toextendfromNagashimatowntoKaizutown 19 DestructiveE鮎ctsoftheEstuaryDamontheNagaraRiver,sEnvironment, andtheProgramforitsRegeneration

Table4 Thetransitionofthedesign･fLooddischargeOfKisoRiver;IbiRiverandNagaraRiver Theunit:m3/s

Theyear 1887 1921 1936 1949 1953 1963 19(i8 K由oRiver 7350 9738 9738 12500 12500 12500 12500 IbiRiver 3336 333(i 3400 3400 2850 3850 3900 NagarRiver 4170 捕5 4445 4500 4500 7500 7500 DatafromMinistryofConstruCtion

andHiratatown.ThesaltdamageOCCurrlngln saltreachesaroundOm.RiceplantSarereSilient Nagashimatown,however,WaStheresultofthe tosalt,anditisdi伍culttoimaglnethatraisedsalt levelswoulddamagethem,eVenifthehightide high tides caused by theIsewan Typhoonin September1959,duringwhichabout30%ofland limitroseasaresultofdredging.Inadditionto between usedforcrop growlngeXperiencedsaltdamage this,a COmpenSation agreementforged (Table5). 1980and1981gave both towns waterintake Katsuga Previous to thetyphoon,the water used for facilities from the Nagara River at irrigationinthesetownswasreverseflowwater (27.Okm)and Seko(25･Okm),Welloutside the

takenfromtheNagaraandKisorivers(note13), areathatmightexperiencesaltcontamination･

andthesaltdamagerecordedwasbetween20ha

and40 ha(rice fields experiencing a yield 9.ContingeIltValuationMethod(CVM)･ We a the reductionof30%ormorewerecompensatedby conducted questionnaire survey Of basinofNagaraRiver,NagoyaandTokyo･The agriculturalmutualinsurance)･ mainquery ofthisquestionnaireis,▼一IfNagara

=mOte13= Riverecosystemwereimprovedbyremovlngthe

Thesetownsweretakingtoplayerriverwaterforced dam,COuldyoupay****yenbytax?"Weasked

backuptheriverathightideforirrigation･Thisis each respondent with double-bounded

known as reverseflow water.Beforethe adventof dichotomouschoicemethod.Ifthefirstresponse

motorizedintake,thiswastheonly wayofobtainlng isyes,thesecondbidisgreaterthanthefirstbid･

to While,ifthefirstresponseisno,thesecondbidis water forirrigation･ Subsequent theIsewan 5000 Typhoon,the townsin quesdon switched to uslng smaller.We mailed a questionnaire to

householdsin October2000,and we an groundwaterforimgationinordertoavoidsaltdamage, got

andlater,reCeivedawatersupplyfromtheMagai-dam･ answerfromeachl132household.Weestimated

Throughthese measures,Salt damage WaS almost theeconomicvalueofNagaraRiverecosystemby amounts eliminatedbytheearlypartofthe1970s(Table5)･ survivalanalysIS,aJld got of payment willat9,772yen,8,636yen,and6,818yenfrom 8-2.WhethersaltdamagewouldspreadtoKaizu basinpeople,Nagoyacitizen,andTokyocitizen,

townandHiratatownasaresultofdredging. respectively(9)･The value throughout was TherearevarioustypeSOfsaltdamage･Ofthese, estimated at about8tri11ion yen(note14)･By Nagara River a concentration of chlorineions higher than Showlng the economic value of lOppmmakeswaterunsuitablefbrindustrialuse, ecosystem,PeOplecouldreconsiderNagaraRiver

to fromanewviewpoint,andrealizetheimportanCe whilelOOppm ormore starts makedrinking

waterunpleasant,andaconcentrationoflOOOppm OftheNagaraRiverecosystem･

willdamage rice seedlings,and more than 2000ppmwillrestrictthegrowthofriceplants･ =n(lte14=

The bed of the Nagara Riveris-6.Om atits 9,772yenxl,240,000houses=12,117billionyen"(1)

deepestpointinNagashimatown･and-0･4mat atotalamountofbasinpeoplefbroneyear･

8,636Ⅹ2,348,000=20,277billionyen thesouthernendofKaizutown.Athightidethe --(2)atotal 20 ShiroKasuya,SohichiMuraseandMioriAoyama

amountofNagoyacitizenfbroneyear. 10･Tbward5reCO▼eⅣOrtbeecosystem. 6,818x4031200=274,847billion yen--(3)a total amOuntOfotherareaPeOPleforoneyear. 10-l･Theoperationofthedamandrecoveryof

(1)+(2)+(3)=307,241bi11ionyen--(4) theecosystem. (4)/4%(thesocialdiscountrate)=7tri11ionand6810 10-1-1･Controllingthebuildupofsludge･

billionyen. Thebuildupofsludgeis the main causeofthe

destruction ofal11ife on the riverbed,aS the Tab)e5 The secular change of paddy rice salt Organicsubstances,Whichfeedthebenthosthat, damageintheNagashimatowminMieII代鎚c加代 1ivetheredisappearduetothelowoxygenlevels.

Theyear Thesaltdamage Theproportionatthe The release ofthe sea waterlayer would be ricepadarea(ha) CrOPaCreage(%) as a 1947 41 5.1 effective countermeasure･One way to 48 22 2,4 achievethiswould be to allow seawatertonow 49 24 2.9 upstreamattimeswherethereisastrongmlXlng, 50 28 3.4 as 51 28 3.4 SuCh at the high tide of sprlng tides. 52 40 4.9 Additionally,lnOrdertostopthecounterflowin 53 70 8.6 thelowerlayeratebbtideofneaptide,thegates 54 42 5.2 55 34 3.5 needtobeopenedthentoo. 56 20 2.1 57 10-1-2.Regeneration of brackish water clam 58 (TheIseBaytyphoon) 59 丘shing. 60 143 15.3 Asaresultofthedam,soperationtheriverbedhas 61 264 25.8 becometotal1y unable to sustain brackish water 62 228 27.0 63 177 17.0 Clam,and animmediate recovery of suitable 64 165 15.9 COnditionscannOtbehopedfbr.Iftherewasa 65 115 11.6 largereleaseofwaterto thelevels seenon15th 66 123 12.7 67 118 12.3 September1999(approximately5900tons/sec),

68 107 11.4 thesand bedscould recover,and subsequentto 69 126 14.0 this clams could be reintroduced from theIbi 70 131 16.4 River･It 71 94 11.8 could safely be assumed that they

72 76 9.6 WOuld repopulate the riverbed under these 73 5.6 0.7 COnditions.AIso,brackish waterclamS are 74 4.3 0.6 made 75 3.8 0.5 tobethefertileifitallowsgolnguptheseawater 76 4.9 0.6 totheupstreamofthedamforegg-1aylngSeaSOn･ 77 1.8 0.2 78 1.4 0.2 79 1.2 0.2 10-1T3･Reintroductionofmigratoryfish･ 80 2.9 0.4 Migratory fish pass through the brackish water 81 1.5 0.2 82 1.1 0.2 areathroughouttheyear(Fig.7).If,however, 83 1.2 0.2 thegateswerecompletelyopened,OrOperations 84 1.0 0.1 COuld be continued withthe gates atan almost 85 1.2 0.2 OPen POSition,during the upstream and 86 1.2 0.2 87 1.5 0.2 downstreammlgratOrySeaSOnSforsweetfishand 88 1.5 0.2 SatSukimasu salmon,these and other fish who 89 1.3 0.2 mlgratethroughthebrackishwateratthesetimes, includingCottuscouldbeexpectedtorepopulate

theriverrelativelyquickly･ DestructiveE鮎ctsoftheEstuaryDamontheNagaraRiver,sEnvironment, 21 andtheProgramforitsRegeneration

10-1-4. Recovery of the reed beds,and mi11ion,Cf.9-2),the cost of construCting the countermeasuresforthechironomid. NagaraRiverEstuaryDam(150billionyen)came Ifthedamwascompletelyopened,OrOperatedin to 780 years,worth of this compensation･ anopenposition,thewaterlevelwoulddropby Alternately,theareas,Whichareconsideredtobe more than2m at maximum.This would give insuchdanger,COuldbepurchased,andusedin suitable conditions for reeds. With some theregenerationoftheswamp･ replanting,itcouldbepossibletoseearecovery of aroundlOOhain aroundlO years.On the 11-2.Securlngthefloodplain otherhand,theuPstreamflowofseawaterwould ThetownsbetweentheNagaraRiverandthelbi limit conditions for chironomid larvae. River,namely Anpachi,Wanouchi,Hirataand Chironomidlarvae havein the past been Kaizu,and those between the Nagara and Kiso

COntrOlledbymethodsincludingreleaslngCarpOr Rivers,namelythesouthernpartOfHashimaCity crucian carp,Or by hormone spraylng,but a andNagashimatown,arebasicallyfl00dplains, have for noods by saltwater counterflowisin factthe safest and and historical1y prepared fortifications. As surestcountermeasure.Inthis case,Onlytypes making the embankments with salinity resistance can SurVive,and WereStrengthened,andsafetymeasureSimproved,

more towns･ chiTDnOmuSyOShimatuiandEi′酵Idia,Whichtend moreand peoplemovedintothese tooccurinhugevolumes,Willdieoff･ However,ifthe embankmentis strengthened to

the extent thatit can stand up to a

10-2.Saltdamagemonitoring. OnCe-in-a-hundred-yearSheavyfl00d,itmaystill

Isthere really a need for such expensiveand glVeWayinthesortoffloodthatcouldoccuronce noxiousfacilitiesinordertostopsalinityandsalt in150years,Thestrongertheseembankmentsare damage? There should be a fullscientific made,thelargerandmoreseriouspotentialflood discussiononthissubject.Thereisapossibility damage becomes･The need for some sort of thatsaltwatercouldseepintoundergroundwater, response tothisfl00d plainissueis startlng tO butthereis nothreatofsaltwater crosslng the become a serious problem.The mostimportant

Claylayer from below and enteringfarm areaS publicfacilitiesbelonglngtOtheareaareshould (PerSOnalcommunicationfromProfessorOkuda, be surrounded by embankment.In other areas, S.,a member of monitoring committee)･ dwellings have been built on stone walls,and Additionally,runnlng fresh water for farmlng boats are kept on hand,tO allow effective fromupstream,andbuildingwaterchannelsalong responsetoafl00d,Shouldithappen･Insurance the riverbank, PrOVide multiple cheap andcompensationcouldcoverthedamage,Which

COuntermeaSureS for sa)t damage.Thereis a af)00dcouldpotemial1ycause.Thesepractical need to monitor saltlevelsin soiland water responsesneedtobeglVenCarefulconsideration

Channelsasaresultofopenlngthedamgates,and inthecurrentclimate.

COllectenoughdatato be able tolower salinity The cheapest countermeasure for the fl00d 1evelsatfloodtideofneaptidebyoperatingthe damageistoglVemOreSpaCetOtheriver.The gatesassubmergedweir･ Government orlocal governments should buy groundoriginallyafloodplainstepbystep. ll.Managementofthefloodedarea.

11-3.Changlng Waterintake over to a more

11-1.Countermeasuresforsaltdamage upstreamarea･ Potentialsaltdamagetofieldscausedbyopenlng TheNorthIseIndustrialWaterSupplyshouldbe thedambarrierscanbeoffsetbycompensation. Changedovertoasourcefurther11PStream,Where

Evenimagining the maximum amount(192 thewaterisnotsalty.Ifthiswasachieved,the 22 ShiroKasuya,SohichiMuraseandMiol･iAovama

damCOuld be opened,Or Operatedin a nearly 4)Yamauchi,K.,Kasuya,S.zmd Tbnaka,T. OPenedstate. Researchoftheconditionofriverbedandsalinity inthedownstreamofNagaraRiverestuarydam･

11-4･Safeguardingthepurityofdrinkingwater inlnfluencesofNagaraRiverestuarydamonthe

Watersuppliesfordrinkingwatershouldnotbe naturalenvironments･ed･byMonitoringresearch from taken the estuary area,but should be groupforthe NagraRiverestuary dam prqject COmpulsorilychangedovertoamoremidstream andNatureconservationsocietyOfJapan.15-19, OrupStream area.This should be accorded the 1999,Tokyo. highestpriority. 5)Murakami,T.,Saijo,Y.aJld Okuda,S.The

estuarydam･52-68,2000,Kodansya(Tbkyo), 11-5･ImprovlngWater-holdingcapacity･ 6)Murakami,T.,Saijo,Y.and Okuda,S.The Holddevelopmentassociated withupstream ski estuarydam･80-88,2000,Kodansya(Tokyo). resorts,gOlfclubs,andlumberingoffbrests.Not 7)Koya,Y.,Adachi,T.andYamauchi,K.Flow

CaredJapanese cedar(Cryptomeria jqponica) Oflarvae Of sweet丘sh(Plecoglossus altivelis forest andJapanese-CyPreSS(Cんamaecyparis altivelis)in Nagara River.inInfluences of befelledinorderto Obtusa)fbrestshould make Nagara River estuary dam on the natural thedeciduousbroad-1eavedfbrestband. environments･ed･byMonitoringresearchgroup

fbr the Nagra River estuary damprqleCt and Ackn0wiedgment Nature conservation societyofJapan.109-116, 1999,Tokyo. Thisreportwasfinancially supportedbyWWF 8)Kumazaki,A･andOhtsuka,Y.Changes of Japan. thenumberofanseriformesinlowercurrentarea Re鎚rences OfNagaraRiver･inInfluencesofNagaraRiver

estuarydamonthenaturalenvironments･ed･by l)Goto,M･,Adachi,T･,Senndo,K.andNagano, Monitoring research groupfor the Nagra鮎ver H.Theichtyofaunainthe Nagara River.in estuary dam prqJeCt and Nature conservation Report of research on the biotain thelower SOCietyofJapan･147-149,1999,Tokyo. CurrentareaOftheNagaraRiver.64-78,1994. 9)Goto.R.and Kasuya,S Evaluation ofthe 2)Kazita,S･ed.AboutGeographyofGifu.1-29, LostEnvironmentby NagraRiverEstuaryDam 1988,Tsukuisyokann(Tokyo) by Using ContingentValuation Method(CVM). 3)NaturalEnvironmentoftheRiverBasin,inthe Journalof Water and EnvironmentalIssues.16; Construction Ministry Chubu Regional 41-48,2003. Construction Bureau's publication'The three KisoRivers-theirBasinsandRiverTbchnology'

(Published 5th september1988).pp.83-84, Chapterl.