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<br />IJ[JJ7;7
<br />
<br />EXECUTIVE SUMMARY
<br />
<br />The us fish and Wildhfe ServIce
<br />(USI'WS) takes lhe pos'lIOn thaI Ihc quahty
<br />and quanllty of halma! ,0 a l~.mlll"teach of
<br />lheul'perColoradoR,vcrmuslbeproll'Cled
<br />and enhanced lfColmarlo Il.IH'r popul.tlons
<br />(l(lwo endang<.",ed speCICS are 10 be main.
<br />!.,ned and fCC<lVe,!.>d The reach c~lends
<br />upsUt'am from tile Gunl",on River con!1u-
<br />ence In Grand Junction, ('olorado to the
<br />(Orand Valley [),ver.mJn dam 31 Pahsade.
<br />Colorado Thel1owrcglmeoflhcleachha,,;
<br />been al1ered In two primary ways (1) up-
<br />stream dlvcr",m dams have slgmficanll~'
<br />rcduced summer l1n\O.'Sslncclhelumoflhe
<br />cenllllY: and (2) head....-ater dams have re-
<br />ducedspnngrunolTl1oW'>slncelherniddlenf
<br />lhecenlury. [k"I"letheseandntherlmpacts,
<br />the I~.mile reach and the IS-m,le teach
<br />Immediately d""'Tlstrc.am conlml.e 10 be
<br />conn'nlrallonaruasforarcmnanlC'olorac.!o
<br />Rlvelpopu\allonofthcclIdaogercJC'olorado
<br />p,~cml11n(Jw,and unlll recent ycaf5, forthc
<br />endangcred ra70rhack ~u"ket. now almost
<br />e~llrpatC'd ThIS repo.t allCmpl~ 10 summa-
<br />n7C thc bIologIcal b:tsis for why the l~-mlle
<br />reach.andlheClTandVa\l~'YlOgcncTllI.arc!lo
<br />crltH;.ally nnportomt to lhc malntcnana' and
<br />r~=veryoflhesepopulallOn.
<br />Floodplains conrainhahualscmicalto
<br />thereplOducu,'c slralegyofra:7whal.'l slick-
<br />er~ AlIu"lal vallcysconulO,ngsuch hab,tals
<br />appcarlohavehecnccntCl'>ofdmnhullon
<br />for lhls SpecIes III the upPf'r C'olorado RI\cr
<br />The!.c alcas mdude lhe G.and Valley as well
<br />as the more upslrC<lm I).., Ileque-lo-Rlfle
<br />rc:lch IJolhareassllouldthe'cforebcthe
<br />focu~ of'ecovery dTol1S for thIS SpeCIes In
<br />the upper C'olotado River
<br />For C'oloradoplkemlnnOW,m(l\,cmcnts
<br />a,caolntegralpatloflhehfeh"toryslral..gy
<br />adults mIgrate 10 spa,^,n, larva" duft long
<br />d,slancc. down fiver, and !lub- and young
<br />adullSdlsperse from nursery arcas 10 reaches
<br />roOta,ologmoresultahlcadullhshltat Asa
<br />cons..quence. an lIIdl\idual fish IS ltkely 10
<br />uwmanysectllJOsofnverdunnglhecourse
<br />Or,tshre FachpanoflhetJ"erlSthe,cfmc
<br />Importanl,howcvel.hasedonlhcdi'U1butlon
<br />
<br />oflheschfc stages, some areasarcclcarly
<br />olorelmponantthanothen;.l'oryoung,lhe
<br />reach downslreamofMoah,Uuh cVldemly
<br />oontainsthemostImp<lflanlre.annghahiul10
<br />the rivet Converscly,lhercachupweamof
<br />WCSlwalet, Utah e\'identlyoonulOs the most
<br />.mponantadullhahllat
<br />UpSlre.am or We-;I....1l.ter. lhe B-mlle
<br />lrmgCifand Valley consislemly supports lhc
<br />grealL"Sl conccmrahons of adult Colorado
<br />plkemlOnow The relatIvely hIgh g,adlcm,
<br />c1ea'water, hrood DoodplalO and ad,verSlly
<br />ofhabltatlyJ>eSmaletheseupslteamscctwns
<br />of river more prodllcll~e lhan more down.
<br />stream5ocllons IIlghelslandlOgsloclsof
<br />pellphyton and tovcrtehrates ~upport tela-
<br />lIVely 11Igh numhers of forage fi,h,lo turn
<br />providlOggrcsletroodavallahtlltyforlhe
<br />rI~c(~ top plSclvOTe. the Colora,lo plh'mlO-
<br />now IlowevcI,maln-ehanncl temperatu'es
<br />de<;hnewnhd,stan.-cupsirc.lmandupstream
<br />mov.ements lhe,efore take lhe:;e wann....'3ter
<br />fIsh I"..ay froto I more preferred thcrmal
<br />regIme, The(ifandValleY.lncludlnglhe I~-
<br />mIle reach, may represent lhehest balance
<br />bctwecn food ,upp\y and preferred tcmpela-
<br />lures illS nOl kno....n ho...., much farther
<br />upstream of lhe ,nand Valle,- Ihese fisll
<br />wOl.lldC'ltahhsh home rang."S wcre II not fN
<br />lhed,\etSlondamsthalcurrentlyblodthell
<br />movement lIo....'e~cr, rcsullll of an analY~ls
<br />ofpllemtono..... dislrlbutlon m lhe Yampa
<br />R"...r(....,hereadults have unllmlledupslrcam
<br />acccss).lIndacompaflSunbetweenlhether-
<br />mal regIme thc'e and that 10 lhe C'olorado
<br />R,V'e..suggeststllalsullablelCmpe.alutesto
<br />the C'olonldo RIver may extend approxl'
<br />OlalclyI4mll"slOlocanyonllabiUllup.lream
<br />of the Grand Valley
<br />AlIuvlalvalleysw;thlloodplamhab1\slS.
<br />hIgh produetlvlly and relatIvely warm malO-
<br />channel temperatures arc to short supply 10
<br />the upper Colo.ado RIver The Grand Val-
<br />ley, mcludmg lhe I ~-mtle rCllch, IS the ~cntt"
<br />ofd"tnbullOn fm adult C'olmadoplleftlto-
<br />nOw In lhe upper Colorado RIver and may
<br />lIave hlStoru;ally h...,o So fOlthe nl7mba~l
<br />sucker histhcrct"o,ccle.a,thalthisarcawl\l
<br />bccrlllcal In reco\ctlOgpopuhUl<msofthese
<br />endang..redfish
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