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, 12/0~/'92 14:50 e303 945 8799. COLO RIVER DIST ~~~ USFWS RIP DNVR TRIP REPORT l..OCAnON: OAlI;S; AUTHORS: . Green ffl\ler~ Utah ..... May 1Z to 14,1992, .J.,'.' , MA Ha1veyandR.A. Mussetter. Ref:. Inc. ROE PmjectN().~-714-01.' Mr. Rq Tenrwjy.P.E. Cclorndo RTverW:der Conservation Distrfct SUSMI1TED 10: DATE: INTRODUCnON Between May 12 and 14, 1~ Drs. Mike Havey and Bob MusseIter df Resource ConsuItanII . & Engineers. Ihc. (RCE) in tM company of Indivldmls from the US FTsh and Wildlie Setvfce (llSFWt), the Cclcndo RiverWarer Con~ Dfstrid (CRWCO) and the U.S. Bureau of Reclcunatian (USBR] conducted a ~ field inspedian atho Green Riverfn::lm the TOW1'1 of Gmcm R"JVer. U1ah at River MUa (AM) 120 to Unknown Bottoms lit RM 28. During the ffeJd ln$pedJon the discharsiI& of 1he Gre@I' River was about 9,500 c:rs. . DecernIJa...t 3. 19S'12 The primary ob)edfve of1hetrfp was to provide sn InlerdfscipIina ovelVieW of this nmcb afthe Green RiV<< in ~ of tJstorfcal ~ prasent wmge of habitat by threatened and rmdangered nstiW ~ ~y the Corol"3do .Squawfish.. Specific areas of Interest were: 1) the effectS of Tamaristc.. (Tamarix chinensfs) on cmnnel morphology ~l'Id capacily wfthin the reach. 2) 1he eft'scts of water stomge projects on the frequrmCf of cMrbank flows wId1In 1he reach. l.V1d 3) the conseauences d both areas d Inferesf: on potenlbd wilhin and out-ol'-cl1annef (bottomlands) habiIaI: uti'lZalion by IaMll - juvenle stages of the. endangerod apj tl1reat:enoo specfes. ~ stages are distributed downttrearr from spawning des by the mechimism of pa!l~Ne drift and therefcre their dispQt'serner11 hto overbant: habitat:s is dependent on a temporal c:oncurrenoo oflaMlpresence (a function of drift rate) and greater than bahId'uII c:li8charge at a I~ where fhcl.re s a floodplain af detent wfdtfI to provide the low' wJccIty, shallow bY conditions reqtIted. by tre ~ $!ages. TRIP OBSERVAllONS 1) Tamarisk Brats (1978) study d the effeCts of the irrv'3sron of~ on the motphoIogy of the Green River within ~ Nationaf Palklnclk:ated hi: the est:ab1ishment r:i dime stands of the .-,: along the ~ margIns of the river h;,dC3U500 channel width to nam)W by about Z1 parcent beI.ween 1915 and 1951. E:!lttIbIishm~"It of the,vegatation 'WaS probably assisted by a period of draught 1hat ' lasted Into the 1~ Subsequent blgh laws in the 1950s did not appe&If' to remove the 1amariSk. In genn terms. esfabIIshment of dense stands of riparian wgetatfon Increases ltIe IlydrJuIIc resislance so that overbank lows tend to deposit their se::f1JT1Elrlt: loads tnOI'e rapkBy thereby sccelemling the process of ~ levee funmuon. With an effective in~ In the height of the bank ag a result of natural (awe fcrrnalion. the channel capacity Ulcreases and the frequsnc.y of overban~ ftOWS is diminished. On the Green Rrver. Graf (1978) oond'uded ttm priQrto coIonizalion cUhe channel tnalgins by1amari&k. CMHhahk 1Joocrmg was Infrequent cnJ ocourred only during the htghestfloods. He at'gUfJd . that c:hanrKII constrfctlon and reduceclerocfabllIty ofd1e banb due to I&IlIidli:j. coIanizatfon Ir1creued' the fmquenoy cfoverbank floodfng.lUCh~ flooding OCCUlTed even at mcdest ~ EvenIuaIJ.y, . if the klcreased hquenc.y of overbank tIQWS caused natIJ1'aIlcvee fattnatlon, the frequency of overbank lIOWG ~ Iem dacreated through time. . . 1 Resource Consultants & Engineers. Inc.. 141 003 1