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<br />10/.23/200~ 10: 37 FAX <br /> <br />t ' 'f <br /> <br />! <br />i <br />I <br /> <br /> <br />~ <br /> <br />[4]005 <br /> <br />)0.2 <br /> <br />ENVIRONMENTAL ASSESSMENT DOl: 10.1007l50Q267-002.2751-2 <br />Trout Population Responses to Restoration of <br />· Stream Flows <br /> <br />J" SCOTT COVINGTON <br />WAYNE A.. HUBf:Rr- <br />us Georogk:al Survey <br />Wyomrng Cooperative Ash and VVHdlife Research Unlt 1 <br />University of Wyon:1ng <br />Larami~, VvyomrnQ' 82071.3166, USA <br /> <br />ABSTRACT I Ther!3 are numerous demands for the UmUed <br />water su pp!ies in the Rocky Mountajn {USA) ragion, and can.. <br />troversies surrounding instrearn 'flows abound. A specifrc <br />problem lnvo)ves water cfwerslons ~. ell small crams that shunt <br />water out of stream channels) during ~he summ~r irrlg,atlon <br /> <br />Since the scrding of arid regions of wesrer., North <br />America by Europeans~ W3.ter has bec;:n a precious rt:- <br />source. COllsequent:lyJo laws ofpriC)t appropriador. (i.e._ <br />first in time is first in right) developed in the weSte.r:n <br />United States CTreleas:e 1974) I Howevert traditional <br />hcnetici;a.J use$ for :tgrlculuin:. indwrry. and municipal <br />water su.pplies have be~n questionC'd by cOn5c::rvatian"" <br />ists and recrearlonistS 'Who are asking for hur.ream flo'VJ'fi <br />tl1at m"intain fi.sh and wildlife reS(lurces and provide <br />vvater...based t~ec:re:ation (Morris 1 9 761 El.Ashry and Gnr <br />bODS 1 ~84. Ta,rlock 1991).. <br />One- aspel;t: or d:te Dverall icst:rear:t1 flow iR~UC in the <br />western United States is the effect of multiple... ~ma11 <br />dams (te.:II Water diversjon.s} that .shunt 'Water from <br />~t:rcam channels {oJ" agricultural and municipal U.!iC5 <br />(Dwyer and Rost!olund ] 988, GerlSung 1988, Nie180n <br />and Lenuch 1988). Stream flows are affected by the size <br />and nun, ber of Yr.i:Lter dive;n;io'n strUctures that ca.l11eave <br />streams widl Utde 0'1;'"" no 'Wa[er. SmaU streams are often <br />dc:wa.tered during the agricultural irTigarlol1 $ea.~Ol1 <br />(Clancy] 98B) - Dc:w:l\tering impacts .Bsh pop1.dations by <br />reducing the amOunt of fish habitat, limiting food re- <br />sources, blocldng fisl1 movemenl.s~ and increasi11.g sum- <br />mer vrd.teJ~ temperatures. If streama ars totally dew:a- <br />tered. local e)l:tirpation of fi$h can occur. . <br /> <br />KEY WOROS~ Srream habr~ Aivar rescor61t10n: Stream flow; SPat~l <br />varl8bm~ RGtt10ta ssnsJngl. Trout <br /> <br />'Thc unir: ig.j(li~tJ,.. stlppan:\!11 by Ole Unlvel'!Jey ClfWV(JR11~ '\t'iyoming <br />Game an.d ~:'ih Dcparon~l. US G~logICil Sl.l("'/ClY, Clnd '"",UdJife M3n. <br />iJ.gemdn [ InnitUIC. <br />"'Author to whom eon-espcndr.ncc> ..hcndd be' addrd~d, <br /> <br />Environmentallvlanagement Vol. 3'. No, 1, pp. 1 :$5-146 <br /> <br />Season~ We developed an approach to assess the effects of <br />rGStoration of naturar ~r Jooa..th,an-natura.1 summer ~OWSi: on <br />troUt thal accounts for variation in habitat over long segrnef1ts <br />or low...gracUant alluvfaf-varJey streams. The approach has utn- <br />tty (or manag~rs beoause it OSn be conduoted with hydotogic <br />data. aerla! photogra.phs. topographic maps, and a sprGad.. <br />shel3t without e.xtt:~n$r\le 1IeJdworl(. We applied 1he approach <br />by assa:ssing the effaots of dJffsrsnt summer flows en abun.. <br />dance of brown trout {Sslma trutta) In severa~ strsams arlnually <br />dewatsred in the Saft River Vafley of westem Wyoming. The; <br />assessment approach ct\n be callbrat-ad for other trout spe" <br />cies and areas of the Rocky Mountain region. <br /> <br />:Restorarl on of fish .s tocks hits be come a primary task <br />of fisheries man.agcrs (:Ebersole :and others 1997) I and <br />numerous tc~hniq1).es have been developed to ~ssess <br />interactions between instream flows and fish habitat <br />quaIhy (Wesche and Rechw-d J 980). For o:.arnpJe. the <br />most vvidcly.advocated method to appraise f1ow~ reJa... <br />Live to fuh species is the physical habital simuiatiorl <br />~ysttm (Pl-IABSIM) (Milho~ :and others 1984:7 Bovee <br />1985) and instream flow incremental method (IFIM) <br />(Bovee 1982, 01'"lh 1987).. This a.pproach in "oIves sclec- <br />tIon of rept'esen tativC' rc:acl1es (Bo'Ve~ 198~lr 1986) :and <br />evaluation of the effec[$ of changes in stream. flow on <br />availability of sui ta blc microhabitat for target. spt:'t:ies <br />using ex~enslvc physical habi(at. .n1e3SUTements made at <br />different flom. Inferences are made using the amouCl t <br />of weighted usable area (WUJ\) within the reprcsenca.. <br />Live: :reacll computed for the target species at different <br />flows, Studies have sbol41I1 reladonships beMeen \'VT.)A <br />and populations of fishes in some stream Systcnls <br />(]OWc!:tt 19927 Nehring apa A.nclel"'S"on i99S, Sbuler and <br />Nehring 1994). PUt 'NUA is ge:ncraHY.fiot a predictor <br />of popula.tion responses (0 changes- In flows fOrth <br />1 '987). Use of rcpr€scnr.a.tive rcoacbes t.o characterize <br />long streanl segments also must be viewed with cau- <br />tion (Kershnc:.r and others 199~) giv~n the spatial vari.. <br />:abiliLY in physiaI habitat o\ler a.saeam segment (Jowett <br />1995). .Because of the eX[ell3ivt: field .sam.pUng I't'quired <br />to conduct a PHABStM analysis on a representative <br />reacb and the limited ability to exr.rQPolate WUA r.o <br />population....leveJ .responses over a long stream s~gn'lent. <br />PI!A.BSIM: is often not applica.b)e~ <br />Resl.ora 0011 of 6sh populatloAS i:o. small streamS d., at <br />are annually dewalercd for ;r~gation crea[e~ Ut1iquc <br /> <br />c 2003 Springer.Verlag New York rnc. <br />