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<br />FLOOD HlST0RY
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<br />floudi~R un Great PLains streams in Colorado is caused by summer
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<br />Th" "ulist known flo"d """s in 1904, The fl"ud <if i'lav2r1 and 2\, 19r14,
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<br />st<it1's. C<ilorad" Fr"l1t Ran;:estreams floud from su",rner rains as ""U as
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<br />resulted irv'" rains "f "doudburH inten,Hy" in the fuothtlls at abuut
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<br />from sno",",,,it and occasionally fr"", a combination of ~he t....o. The &lXelder
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<br />7.ODOfeotelevlltionontheheadwater,..,ftheNorthForkC""helaPcllldre
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<br />Creek Hadn i" "",r~ ch"r..."-terl~tic of th~ Gr.."t "lains "treams h""-,,us~ of
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<br />River and BQ~elder Creek. DamaJl:e was heavy at FQrt Cotiins and Il<".:e\d~r
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<br />its Qricntation and elevation. The relatively rec~nt "B1~ Tho~pson River
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<br />Creek, duwn$tr~am of Fort Collin~, Colorado. contributed hi~h flows. The
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<br />Flood of 197b" 15 an indication of the ma~nitude of rainfall (12 in.) that
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<br />Greeley Tribune stated:
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<br />A"-cordinl'l to the "Watershed Wnrk Plan, Bo~elder Creek Wsterh$hed",
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<br />"The1k>xeldet",asmallsrreamQrdinarilyonlyafewfeet wl.de, ,,"s
<br />tearing do,"" throu~h a fertile valley filled fruill bluff to bluff ",ilh a
<br />sheet of water a mile "ide, carrying bulldin~s and bridges away...
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<br />can o"-cur in this pat"t of Colarado. This was a July 31-Au~ust 1 stot~.
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<br />Because of the recentness of reservQir constru"-tion (proje"-t ,,-ompleted
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<br />Information obt31ned in Au~ust Ig69 from landowner" in the flood plain
<br />for the years 1959 thro'I>\"h 1%9 indi,,-ate th,~t flood da~a~e o"-"-urs gomewhere
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<br />damaging floud~ occurred on Bo~elder Creek on an avera~e of once every year.
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<br />1981), there is no flood history of the study area f~r post project
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<br />in the ....atershed each ye~r. Estimated damage from these storms follo~s:
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<br />square miles vr 70 percent of the drsinal'le basin, Tbe level of flood
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<br />Au~u8t I, 1.961; one 50- to lOo-year freq,,~ncy ~torm in ~he vidnHy of
<br />Wellington, Colvr~do. Forty basements "~re flooded in addition to
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<br />"-ondftions. The reservoirs retain runoff from a combined area of 175.5
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<br />prote~tion decreases. ho....ever. as the dtAtan"-e below the gtructures
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<br />al(ricOlUural and non-a~ricultur..l crops and property, with d"ma~es at
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<br />In"-rc~ses. The project ~~rk plan estimated that at Highway 14, east of Fort
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<br />$7b,150.
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<br />Collin9, the pr~-prujea 100 year flood woul~ be rcdu,,-cd hy the project to ~
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<br />Jun.. 1963: one 25- to 50-year frequency StofT, over a ,,~ry ,<m1tll1 ares.
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<br />4 'fear f~..quency.
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<br />E$tim~ted damal'les, $7,200.
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<br />The ~b()ve information however is baoed on uniform r"infall over the
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<br />June 14 thNU,'lh 17, 19b5, on.. 2-yetlr, two I-year. and on~ 25-year
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<br />entire basin. Thi~ is generaliy not the way storms occur historically.
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<br />fnquc,,"Y "~ut"'~ "ail So,,,,, uved"ppillg 0' "t"eas. Estima~ed d"mage.~,
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<br />Fioodinl( from fIIO"in~ storm cell~ can o~_cur Alon~ "ny porUon of th" hA~tn,
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<br />S96.000.
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<br />includinl( the area un"-ontroll"d by reservoirs, therefore, recvrd~ of past
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<br />~"y 30 "nd June 4. 1967: t"" 25-year frequency ~to~ms "ver\~pptn,:( nVH
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<br />fiood ..v"nt~ in the ba~in are ~U1i ll~eful inf()rma~i"n. A dh"-u~si"n of
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<br />" reluUvcly s,"all ~re" in the vi<.:inity of Io'elllngton, C"lor"do. E~ti'Mted
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<br />recorded floodi,,?, follows.
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<br />dama~eB vf 546.100 ....ith four lives lo"t Bt a cvunty road hrtdl(e wa~hout.
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<br />Rox,<\der r,r..~k tm~ _, l()n~ history of f1o"dinl1_ flood" of rec<ird
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<br />August 4, 1969;" I-year frequen"-y "to!"Ill "ccnTring ewer" "maU "rea,
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<br />oc,,-urred in 1969.1967,146'.191>1. 1947, 1913. 1930. 1922. 19M. and lQ04.
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<br />D"'Ildl(e' estimated at $~ ,ono.
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<br />Ther~ 1s Ll" off!dal ~au;\lnll H~t1un III the "a~ershed a.nd no kLlO'1L\ 0",,<\
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<br />nnw, hi\v~ hQ"" "'ea~ur~d_ 1n .~en~ri\l. lnf"r,",~U.'m "n p,,~t floods i~ h",~d
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<br />co
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<br />on ne"SPd~cr accounts and lntervie"" with resld~nt$ of the area.
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