Laserfiche WebLink
<br />TA~LE-2 <br />ST. V&\IN CREEK DRAINAGE A~AS <br /> <br />'0. <br /> <br />Location <br /> <br />Dn''''''ge <br />Area. <br />(sq. mi.) <br /> <br />DiHane~ <br />From <br />Mouth <br />(miles) <br /> <br />A number of pits along the St. Vrain Creek have been created froill past <br />sand and gra"el mining operations. Because the storagevolllme in these pits <br />is not adequ"telycontrolled, it is "ssum"d In this study th"t they "ill not <br />attenuate pe"k fl~.s a~d thus ~ill not provide any "ubst"oti"l storage of <br />flood ~ater. <br /> <br /> Confluence ". , ". <br /> ;C. Vrain <br />, Lyons Gage <br />1 Tributaries Above <br /> Below <br />, Upstream Study <br /> Limit <br />5 Lykins Glllch Aho",. <br /> Bela" <br />5 ,,' Creek '0 , Above <br /> 8elow <br />, Ldthand " , Abo"e <br /> TI.. Slou~h Below <br />5 Downstream Study <br /> Limh <br />, '" Creek , Abu"" <br /> Spring G"lcll Bela," <br />W Bo"tder CreeK <\hove <br /> 8,,10" <br />" Idaho Creek Above <br /> Below <br />" Right g<lnk Abov" <br /> Tribs Below <br />" Left 8ank Above <br /> Tribs ~I<' 10". <br />" Piattevill<' Gage <br />" Mouth <br /> <br />'" <br /> <br />31.27 <br /> <br />B. Study Reach Dcscription <br /> <br />m <br /> <br />30.95 <br /> <br />no <br />no <br /> <br />27.31 <br /> <br />The study reach for St. Vrain Creek extends fro", ) 19th Strc'et Up"tr"~m <br />to the Airport Road. The study covers only the main stem of St. Vrain <br /> <br />237 <br /> <br />25.45** <br /> <br />Creek. ", length 0' '" reach studied " approximatley 4.85 miles ""' <br />lies i, '"' ncar CO, City 0; L<>ngmont, Colorado. The av"raf,e stre"mb~d "lope <br />through '"' study reach i. approxilllately 11.6 fe"t per mil". <br /> <br />21+\ <br />252 <br /> <br />23.22.* <br /> <br />-l54 <br />'"' <br /> <br />18.61U <br /> <br />8ase low flo"s in the river channel during the win:er months are typicdlly <br />20 to)Ocubic feet per.econd. ThestteamchannelfrOllldownstr"amlirnits <br />of the study t" the railroad bridge has been channeli~ed. The channel <br />shape i. fairly "niform with a bottom width of approxirn"tely 50 tn ~o feet. <br />Typical oha"nel depths.ne 10 to 15 feu to the top of the defined bank. <br />The overbank of floodplain are~s e<.>ll.i.t pri_Ol~rily of developed properties <br />in the stream reach lying bet~een U.S. Highway 287 and Hover Road. Areas <br />downstream of U.S. Highway 287 consist primarily of scattered ind".trial <br />and commercial developments aloog ~ith pasture dnd cultivat~d land. Areas <br />upstream of Hover Road consist priOlarily of pasture "nd c"ltivated land. <br />Photegraphseftypicalconditiona along the sr"dy reach takendur ieg <br />April and May, 1980 arc incl"ded On pa~e' 17 througl] J~. <br /> <br />m <br />265 <br /> <br />22.06** <br /> <br />'" <br />'" <br /> <br />21.38H <br /> <br />'"' <br /> <br />20.60** <br /> <br />386 <br />m <br /> <br />16.37 <br /> <br />"" <br />8/.9 <br /> <br />13.4S <br /> <br />'}22 <br /> <br />1.22 <br /> <br />Read crossings of the stream ch"nnel and real eatate i~prcvements in <br />tile floodplain areas comprise the primary obstruction to the flood flows. <br />Existing bridges at a number of points do not have the conveyance capacity <br />tohandlctheIOO-y"arpeakflnws. At a nUillberof poil1tsthe,",stcria <br />diverted "tOund th" bridges. The details of the eife("t~ 01 these obstructions <br />are explained in the bydraulic analysis portion nf the study. <br /> <br />"''' <br /><<, <br /> <br />11.33 <br /> <br />'101, <br />no <br /> <br />l.bO <br /> <br />n', <br /> <br />a.oo <br /> <br />* COLltributing ,\r",a (rnc tudes Ar<'a Abov~ autto," Rock D..m) <br />Soarce - U.S. Army Corps of Engineers <br />U Distane_e" from the Corps St"dy Adjusted U~ing r"forOtation from the <br />U.S.G.S. Quadrani'll.' Sh"H~ <br />-15- <br /> <br />-]6- <br />