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<br />restQratron"five of which (Reaches 2 through 6) ate withirtthe proje.ct1imits.'fhe reaChes to be Lncludedin the
<br />'Col!PsofEtligi!:reers $ectiou206projeetate theMasterP~anrea~hes 3anEl4.
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<br />. Rea:en Jislocatedbetween N. H~9th Streetand1<enosblliRoadeN.ll$lh Street). , ThisteiWthisiJ;l.~is~d
<br />and'~nsta1!lleand is the mostdist'll'bed rea\ihofthe pr,oj.eet.,wea. Master Plan,recomrnendatilllMirtelJrrde
<br />eliiai'Melrestoratiouandwetlandscreatiou in the valleylilbor.
<br />
<br />. ~ea~,4isaloeatedhetweertI~eJ3.0shaRoadandthe,P'L'llM)te Siervilil'e'~ement.. This is, a,depolli1li!iJ~1
<br />re.ach.:wi1ilira;1!lrlli~d,chmwelins0ine see.tiofls. .ltiptaph~1!leertplac~attb.fujlP'maintllinaeo$,'Q~'l'ttG
<br />the Nowell DitchdiversiGn.RipariaiJ. enhancementand,reYe;getatiou;reconstructit\g the HOi\V[eff!~:i~h
<br />dh<ersiort,and testdring,the hycltologic fmiction.ofthe ,lilxb6wslo~ghate recGmmen:deatbr;t1ll'sit.elu.lh.
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<br />
<br />Wltyis.rt;IJ'liing,pl'llpose.d? , ,
<br />A!!1!lib\l'llP9'g'e)jie:impacts. 'Historic and receritae:riatphotos' slroWdJ~a:ticll1teratioJ1ofthe B'01l1dfl\rCi:eekapd
<br />Coal'Qreekonapnels and fJ.ood~lawsinthe stu1iyatea. TheChantiel.1ilelt,or;ictive f!cyodpr,)l1<>ateit;histo1'ica11y
<br />extended:aW1i>rl'l*im:ately 1 ,0UJ04 ,2'(')@feet overth.e valley.t'l1o@r; Pi.etlaf~h(i)tograpl1s ftotl!l1~a"7sh0Wl?~l!il(l:e
<br />marshes, wet nreadowwetland:s andextensiveripatian woodlapds'l'ii the viciffit.yoft1re stud:yarea.
<br />
<br />lIheimpaetsare typical of most areas subject to urban growth. Inthetnidl800s, na.tivegrassland:swelie
<br />cO!1verted'to pasture and cropland.s, pritnarilydue to the aVllil~biMty lilfirrigati:onwater.Esta15~~SlJ.eawe'tlaill:d:s
<br />weree;ft'e!:r' clt-aiinedto anew for' cu1tivation, and grazing; tnean~h1lenewwetland.'c0mmunities,ide,,~lQ:(iled"hi
<br />irrigate(;Uands.Riverbartk dikes were constructed toprotectagijcultui'a11llnds.frorn t'lo'0,ding, With
<br />Uiban:izatiou,gravehnlnesbecame cOI11Unoufea:tures of the' laftdSei:\pe.Th.eqtiantityandq1J'a1ity~fwaterln the
<br />strellrl1SaJrcl'f1ow regimes were altered. Streamm:versio!1sredVlced flootf ihfensit'i,es,anddep'letea thee:tllC11gy ,
<br />needed}tMllaintaihthe channelandf1:oQdplain. Teday, long reachesdfBouMei'Creek hllvebeenchatnte1iZed, .
<br />reducing.channetsinuosity. the Boulder and Coal Creek chaimelsare instates of disequilibrimn. La:nd
<br />dev,ell'lpm.ert.t,is occutring.,rllpidly'ineasfem, Boulder County a.n:d'rt.eighboring WeldCounty'fut1iherred'ucingthe
<br />ntralagrlcultutallancls that formerly surrouncling the projeiltatea
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<br />Because of changes to the channel and its flow regime, the stream no longer dissipi:\tesits energy acr\!Jssits
<br />floodplain or irtto meanders. Instead, theertergy is spent erodfugthestreambed. DOWIlcutting, or
<br />entrenc1:rment, is a,pparentou BqulderCreek throughout theprQjectarea. POWIl cutting has inereasedt.hebed
<br />load of material in thisstrearn and caused deposition in flatter areas ofthechannel,creating braidedchattnel
<br />sections. Jnessence, Bo1:Ilder Creekno'1on:gerhas an,activefloodplain. '
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<br />Coal Creek, once an upland, interrnitteJ3.tgulch with a clay and silt substtate,now carnes perennial flows. I&s a
<br />result of the increased annual and periodic high flow eveuts,CoalCteek exhibttsextreme entrenchment,
<br />exceeding 25~fO'ot clepths, in some sections. Erosion in CoalCreei<:a:1sostgnificantly increasessuspen<t~cl
<br />sediments enterin:gBoulder Creekattll:e cortfluert'ce intmediately dcl'wnStteatn.
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<br />Fish Habitat. Fish habitat in the projectarea was assessed in 1998; and four of the five stations werejUl'lged to
<br />be poorqualit'yfishhabitat. . The one station, which'scoredbetter,l1adrecerttly co~leteds~elUJ:l
<br />illlprovements.Fact<lrs identifiedaspoterttia:l problems incluclelack ofin~strearnandstreamsiclecl'lVer>l10'or '
<br />pool quanti,tyandqua1ity, poor bank stability, andort.ly fair channel staJ:iility artafood abundartce(Bou-1c1~r
<br />County 1995Master Plan). The numoeroffish species foutrdin the BbulclerCteekandCoalCreek drainages
<br />have diminished overtime. Species currently found in the pmject reach include: 10hgnosedace(Rh'inicthys
<br />catar4cta~), sand shiner (Notropis dorsalis), fathead minnow (Pimeph41espromelas), stoneroller .
<br />(Campastomas anamalum), ancl white suckers (Catastomas commersonii). Nowever nativespec:iessu<!has
<br />creek chub (Semotilus atromaculatus), longnose sucker (Catastomus catastomus), green sunfish (Lepomis
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<br />L:ISectlon FolderslSECAIBoard MeetlngslSeptember 2002\Agenda Item 19-Corps report altachement.doc
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