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<br />Poudr~ River Msln "hich meet this crttHla are Fo~al1 Creek "ear Fort <br />Collins and Sheep Drll" near Greelu)'. LocAl Iutere~ta alao a""ig"ed <br />th"se Qu-eam_q priority (",study. Volulll" III of the Spec1al Study <br />covers Sheep Ora" and Volume IV covers Fossil Cre~k. The locations of <br />these Ms1na are aho"n on p1l!.te 1. <br /> <br />The present studY"8s hJ.sed on ncw t<>pographic "",pp1ng and crOB' <br />sections ~akcn a~ closer intervals than In the Flood tn.urance Study <br />(FtS). Also, the study reach ou Sheep Drs" "8S extended farther <br />upstream than in the FIS "hich endcd at U.S. ijighwsy 34. In this <br />study, the Environ.."ntal Prot.ectionAgency'. (EPA) StorlllWstHMal\ilge- <br />ment Model (S\ImI) ""8 used to deturllline flood dhcharges. Peak <br />discharges forflood.ofvar.lous frequencywerecolDputedu8.lngtheU .S. <br />Soil Con~erv&tfon Service (SCS) Technical Release No. 20 cOlDputer <br />program in the FIS. The 100-year flood discharge for the preaent atudy <br />averages sbout 90 percent of the discharge used io the FIS. Downstream <br />from County Road 29 (7lst Avenue), the IOO-year floodwater surface <br />profile for the present study generally ranges from 1 to 5 feet higher <br />than In the FIS "ith the depth variations increasing in the do"natream <br />direction. Up.tream from County Road 29, the lOO-year flood profile In <br />the present study generally varies leaa than a foot above or below the <br />IOO-year profile in the PIS. <br /> <br />Hydrologic ~deling studies were conducted to dete~ine the pea~ <br />~iBchargea for flooda of various probab1litiea of occurrence. This <br />information was developed first for ex1sting watershed land use. To <br />determine the effect of increastng urbanization 00 flood runoff, <br />posaible future urban land uae was s"per.lmposedon the Sheep Dr"" <br />badn. Vol""", II of thb study presenr. de:dls of the hydrologic atud- <br />lea. Hydraulic modelin~ studies were conducted to develop the flood <br />water surface profiles and flood plain boundaries. Flood profllea are <br />shown for exiating And future conditiona. Flooded urea mapa are ahown <br />for existing conditions. <br /> <br />ACKNOWLEDGEMENTS <br /> <br />LOCATION OF DATA <br /> <br />Principal cooperation and '~oordlnatfon for Volum.e HI was with <br />representatives of the Federal E"er~ency Mans~e~nt ARency (FEMA), the <br />Colorado> ;;ate< Cu"seo-..llo", ih,#;,Q (eileS). ""i<1 C""'''''1, ..lid the elty of <br />Greeley, <br /> <br />Copies of this report are available for puhlic distrihution at the <br />offi~~~ 1lst~d h~low. Tnpographic, hydrologic, and hyd<aulic data used <br />in this study are also on file in th~ Flood Pisin Ha,~g~~"nt S~rvl~".. <br />Branch, Omaha District Corpa of Engineera. 21~ North 17th St<eet, <br />OlDaha, NE 6ij102. <br /> <br />Sheep Dr~w was included in the report Flood Insurance Study, Weld <br />County, Colorado, Unincorporated Areas and Town of Eaton, Colorado, <br />Weld ~ount1., pubHshed by FEMA in Dece..ber 1979. Thh study Includ"d <br />Flood Boundary and Floodway Maps (PBFM) and FlUDd Insurance Rate Maps <br />(FIIlM), with "n <>fhctive date of 18 M""rch 1980. <br /> <br />Department of PlannIng ServIces <br />~eld County Centennial Center <br />9lSl0thSttcet <br />Greeley, CO 80631 <br /> <br />RELATED STUDIES <br /> <br />eountyEngln"er <br />W"lJCounty <br />P.o.So,,7S8 <br />Gre~lcy, co 80631 <br /> <br />, <br /> <br />; <br />