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<br />Study Reach Description
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<br />"rld <Quincy Railroad are also in th" flood plain and h.lVe been ~"bjected to inunda_
<br />tic" in ~ast years, as have portions of Highway~ 34 and 385. $~veraL bridges cross
<br />the river within the city of Wray. DeveLopment in the county a~eas has been limited
<br />to a few lsolated structures. hlturede,'elopmentoIthec()uncywillprobablycon_
<br />tin~ to foLlow this pattern.
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<br />The scudy H".ch extends approltilnately 42 miles frolD channel 5t,lt10<1. O+DO, just
<br />upstream (ro!ll the CQlorado_~"brllska State line, to station 2216+00, Located-abc""
<br />22.6 ",Ues south~'est of the city of ;;ray.
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<br />The '.lray port 10" of ~he study, from statio:>. 636+20 to station 1478+20, require.d
<br />,"ore detailed ""~pplng (one inch equals 200 feet .~ith 2_foot contours), due to
<br />develop~en~al pressures in and around the city. The rest of the study area, from
<br />stations 0+00 to 686+20 and stations 1~78+20 to 221&+00, is not experiencing the
<br />snme degree of developrrent AS the area around Wray (and, therefore, was ",.p~ed at
<br />a scale of one inch equals 400 feet ",ith:.-foot contours].
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<br />Obstructions to f1oodf1o~'s ",1thin the study reach include natural obstructions,
<br />such as brush and other ve,.etation growing alon8 the stream b.onk, and man-mad" ob-
<br />structions, such as bridges, buildings, and Culverts. During floods, debris ~llecting
<br />on bridges can decrease the river's carrying capaCity and Cause great~r depth upstream
<br />of the structures (back~ater effect). As floodflows increase, masses of debr~s may
<br />break loose and Cause ~ "wall" of water and debris to surge downstream until '!lnother
<br />obst!l:uction is encountered. lnso:meins.tances, debris OIay collect to the point
<br />where structural capability is exceeded and the bridge La destroyed. Since tbe
<br />ocCucrence and amount of debris are in~eterminate factors, only rhe physical cbarac-
<br />teri~tics of the structures ",ere considered in computi~g the water surface profiles.
<br />Si~ilarly, maps of the flood~d areaa show the backwater effect of obstructive
<br />bridge" and culverts, but do not reflect increased water surf ate elevations that
<br />could be caused by debris colleccinl', against th.."tructur"s or the de position of
<br />6ilt in the stream channel under structures.
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<br />The flood plain i" th" :;,,-.:th ,vd-. R..puLlican Rivet valley haa a ,"odcrate "iclt~
<br />nveraging from one_fifth ~ile in the upper reaches to one-half mile in the most
<br />downstream reaches. In Wray, the flood plain is ab<>ut one-quarter mile wide. The
<br />strearn vaUeygradually slopes froOlthe creek banks to the fooc of stee pbluffs
<br />whi~h riae as much as 100 to 150 feet above the flood plain. This is particularly
<br />the ".as~ in Wray. The entire ci~y is bordered on tlte south, and to a lesser e"Hnt
<br />on the north, by sheer clIffs ~hi,h ri~e 150 feet above the stream. The riverbed
<br />~lopes ab<>ut 10 fe_"t per ..ll" ",ieh a ch<lnnel "..rying from one foot loIide in :he
<br />upper reaches to ZS feet ~ide in the downstream areas. The channel banks vary
<br />from One foot deep to about 12 feet deep.
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<br />Topographic barriers existing on the northern and southern edges of Wray have
<br />forced expans1cm i"to th" "orth Pork Republicar, River floed plain. In 1934, th~
<br />city obtained aid through the Works Progress Administra~ien a~d attempted to improve
<br />~o~e of the bottom area So it could be developed fnr busi~ess purposes. The river
<br />channel "as straightened and a levee built at the ,,,,,,,t edgo< of .\<lams Street. A
<br />divQcsion dam loIaS 3L"0 placed in the ~orth POck at the ",~st edge of town, and a mill-
<br />race "'''-s constn:",ced parallel to and on the south side of the river channel. Lack
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<br />Planned effective flood damage prevention ~easure" have not been taken in ~~ay
<br />or YU!:l<l CoUtlty ,lith regard to high flo'~< oc,,"rTjng on th.. N"...th Ft<fk ~.~r'Jblie"n
<br />giver. Businesses and residences in th~ flood plain have raised floors as a yesult
<br />of ~st flood experiences and are effectively protected fro~ low to moderate flooding,
<br />bu~ no general protect ive measures for extreme events have b"en accomplished.
<br />Flooding from hillside runoff, which had heem a prOhhm hec"'lseof inadequate
<br />chapnels, has been relieved since 1961 by the completion of a ~at..rshed tr~t~ent
<br />proj~ct which induded six ...'tarding dams. The dams have a ~otd capacity of 340
<br />acre-feet and were designed to control the runoff from a 100_vear ,.'of,"
<br />, u O""r the
<br />thr...... square ",ih, drainage area above the ~t:ructur".s. Th.. uncontrolled outlets
<br />tl>tOUllh ,he structures "ere designed to litnit the outflo... to the d<>'-"'~t,."..... ~t,"nnel
<br />c"p"cittes. Th"pr01ect wes d"-signed by the 5011 COnsetvationSe....1ceoftheDepar t_
<br />ment of Ali;riculture under sponsorShip of the Hale Soil Cons"rvdtion District and
<br />t~." city .of Wr.ay.
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<br />of knowlcdge of the flooding potential, <:oupled "tth th~ aval1abl1ity of flat, \lnuaed
<br />Lind, h.aB ~purred ,!evc1op"",r.t up ~o the ..diles of the c:~annel. ?re~~_nt;.y., husine."s
<br />establishment. are Located on heth .ldes of the channel at l".ain and Ada~s Stree~$.
<br />A "hopptn~ ~.mLer IlDudn" ~everal bus'-nes~es has ~lso bc~_n construct,,-d in t!,,, flood
<br />plain bet,.."an M,,",s Street and Htghlolay 38:'. The tracks of the Chicago, Burlington,
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