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<br /> <br />FAX <br /> <br />. I <br /> <br />136 J. S& Covington and W. A~ Hubert <br /> <br /> <br />llr:eds that are nOt mer by available techniques of itl- <br />, stteam..fJow tlSSessrnent. BccalU~ of the large l':1iUmbc::rs <br />of streams that may be jn\lolved~ none of which may <br />yield signifiean~ fisheries. the time and money to do <br />~K[eIUiY~ field sampling may not be available. Thc:.5C <br />!trea.n1s often $how ~ubs;tan ~al wriadon iri physical ha~ <br />ilat co nditions oVer s.tream segmentS due to a.nthropo- <br />genie tLII:ICa, 'of t~C Jand, thereby m::tldng it diffirult w <br />extrapolate itJ.fonnation from representative reaches 10 <br />long su-eam segments. Such strea.ms otten flow through <br />private lands where &;ces", by mana.gers may be difficult'. ' <br />Moreover, many streams ate dewa.tered throughout the <br />agricultUral growing season. making it difficult to ob- <br />. tala field measurement:! at different dW:ha:rgcs. <br />We developed an alternative co standard in stream- <br />flow auessmcnt methods [0 evaluate the .benefits of <br />now r'CSCOliltlo n to trout populaa'Oh& in .se:rcams annu.. <br />ally cleW3.teced for agril:ultu.ral and municipal water <br />ll.(jes. The approach USes remote sensing to ~S~ fish <br />habitat quality over long stream. &egments. '&t.tcnsivl: <br />field sampling and ~Gc.ess to private IMd arc not nec- <br />es~ary~ Estimates of the average uumber a.nd biomass of <br />.spOrt fish over Jong Stream sc:gt!l~nts can be made :at <br />various S IJmmer fl ows [0 enable: a.sscssment of uade-roifs <br />betvJeen fish populations .and agricultural or municipal <br />-......;a t.er us c s ~ <br />Three conc.C'pwa.l frameworks proyjded a founda... <br />don fo f 0 U.. :ApprQach; (]) a hierarchial model of <br />strealll sysrcms (FriS8cll and othc~ 1986), {2} a madel <br />of ,vate t'Shed--scale stream. habitat restoration (E.bersole <br />and others 1997>, and (3) th e i:Ollcept that restoration <br />or degrac1ed stream systems must foGUS on natu~\ hy- <br />drology (Strange at'ld Q[bcrs 1999)" The frarnework of <br />FrisseU and others (1986) provided a basis for measur- <br />ing sCream h:a.bitat. within 11 reaeh and eonsiden:d :lira.- <br />ria 1 variabjJl ty over longer stteam segrnc:n IS. Sirni1a.rry~ <br />Eber.sole and ochers (1997) provided the conceptual <br />linkage: tor use of bo lh reach a.nd watershed (eatu.rcs 1:0 <br />predict the poten~al mrrying capacity of trout in a <br />stream .segment. Su-ange and others (19Q9) gave us r.he <br />concepl that the natural hydrology could serve as a <br />baseline for d~fiJling the potential ahul1dant;c of trflUt <br />given specific reach and watershed featllrcs and tbat <br />an thro,pogenic r.=ciu.:tions in summer- flow would lead <br />[0 conCUrT~n( reductions in m:rut abundance.~ <br /> <br />Assessment Approach <br /> <br />The approacb is itlus~ted in Figure 1. The first <br />.t\lep of the: p["Q.......-.C$$ is: to identify Stc-eam ~gat~nts (sc:o <br />Frissell and ochers [986 fat definitions) with homo.. <br />geocou5 substra.te and flows that tire the fOGUS of <br />management ano t() sepa.rate the segments i~to <br /> <br />, , <br /> <br />l4IUUt1 <br /> <br />2 <br /> <br />lelanDfy reaches with similar <br />riparian f~mres over c:acb segment <br />of 5tre2ltD with hQmogcneoQ$ flOW' <br /> <br />~ <br /> <br />Describe hD.bital b.1U~S fer <br />eat:h reach (elevation., gradient.. . <br />Wetted width.. cO\'er) <br /> <br />~ <br /> <br />Estima~ mean biomass <br />for each Nacb at <br />natural nows <br /> <br />- <br />-I <br /> <br />I <br /> <br />Predict 1Ile4n <br />biomass at Q. giv~ <br />flow (Qf eacll reach <br /> <br />~ <br /> <br />Prcdigt bJomas.s at a <br />gi'f'OQ flow for stwttrl <br />I ot' stream. segment <br /> <br />..,.... <br /> <br />P..-cdict abundance: <br />Bt .a gJven flow <br />for I!ach reaeb <br /> <br />~ <br /> <br />Predict nbundane= at a <br />given flow for Stream <br />Qr stream segma.nt <br /> <br />Figure 1 ~ Flowchart of the asse$5ment approaeh illustJ2.ting <br />lbe meth<Xbi wf!d to d~riTJe estimates. of rrout biomass and <br />abl.:l nd~ncc= a.t nalLlnl (Lve-rag.; .summer ngWS and reduced <br />summer tlo'W,. <br /> <br />,reaches wirh homogeneous riparian vegetation, bank <br />features" and cban.ocl slope4 The st;cul')d st~p i:! to <br />detet.mine the habitat fear.ures within each reaeh that <br />can .affect the abundance of Ctaul specie.!' that are the <br />ta;rgCt of Ma."agcmcllt~ The t.hil~ $tep 1~ [(J us.e vali- <br />dated fish-habitat relationship models ro estimate <br />the biomass of the rargc:tspecies in each reach under <br />naruraJ l1ydrologic feginu~:s. The fourth Step i~ tlJ <br />pr~dtct th'e chan~ in biomass as summer flows .are <br />reduced by increments Jess tha.n me na.tural summer <br />low ilow:i within eacb :rcach~ The (ifLh step is Lu <br />aggregate the estimates of biomass In eaeh' reach (0iestimate biomass over the entire stream .segment at <br />eac:h increment af t1ow... Alternative seeps ca.l include <br />prediction of the abundance of the targer.. species in <br />each strearn segment at eacb increment of lIow fram <br />knowledgrc of populaclo11 sU"Uc[uroc.. <br /> <br />p..3 <br /> <br /> <br />j <br />,:1 <br />";\1 <br />