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<br />32
<br />
<br />FLOODS IN COLORADO
<br />
<br />MAJOR FLOODS~SOUTH PLATTE RIVER
<br />
<br />33
<br />
<br />Creek Canyon between Mt. Morrison a.nd Idlcdale is practically ruined. * '" '"
<br />The depth of the flood water '" * · failed to resch the height of the .aB-tjme
<br />l'ecord in Bear Creek established * * * July 24J 1896.
<br />
<br />The Geological Survey made a slope-area determination of the pcak
<br />dischargc at Morrison, abovo Mount Vernon Creok, and found it to
<br />bo 8,110 sccond-feot. The newspaper reports indicnte that the area
<br />rocoiving U,O heaviest rainfall was a strip not exceeding 4 miles wide
<br />across the basin, giving a drainage area of about 20 square miles, or a
<br />unit run-off of ahout 400 second-feet per square mile. Thc mean dis-
<br />charge for the day at the Idledale gaging station 3 miles, upstream
<br />from Morrison was 600 second-fcet. At the mouth 10 mIles down,
<br />stream thc pcak discharge was 3,000 sccond-feet, and the mean for
<br />the day 750 second-feet,
<br />On August 9, 1934, cloudbursts occurrcd on Bcar Creek just below
<br />Kittridge and at the head of Mount Vernon Creek, causing anotber
<br />flood in which sb, lives wcre lost and heavy property damage. The
<br />Jefferson County Republican reportcd:
<br />Unlike the flood of July 7 of last year when practically all of the Bear Creek
<br />highwa.y between Morrison and Idledale was wa..'1hed ont, the d~mage ill ~,hc
<br />canyon this year was comparatively small, the ne\~ Bear Creck lu~hw.ay whIch
<br />had just been opened to the public having suffered htHe damage, 'While III MOllllt
<br />Vernon Ca.nyon the wall of water was of much greater volume than la.'-\t year and
<br />ripped out much of the roadway in the canyon. .
<br />The business section of Morrilion did not suffer as great.1y a.." la..:.;t yea.r OWlIlp; 1.0
<br />the fact that the waters of Bear Creek and 1'Iouut Vernon Creek did not meet at
<br />Morrison this year, the Bear Creek water having pas..o:;ed Mord;:;on .before Mount
<br />Vernon Creek water rea.ched thQ junction with Bear Creek at Mornson.
<br />This newspapcr added that the flood on J\Iount Vernon Creek was
<br />12 to 15 feet high, and according to a resident who had liVl'd 40 years
<br />near the creek, was tho highest flood during that pcrlOd. It was
<br />exceeded, however, by the flood of September 2, 1938,
<br />The Office of the Stnte Engineer made a slope-area measurcment of
<br />the peak discharge of Bear Crcek at Idledale, 5% miles below Kittridge,
<br />and found it to be 4,620 second-feet; thc mcan dischargc for the day
<br />was 274 second-feet. At tho mouth of Bear Creck thc peak discharge
<br />was 1,300 second-feet, and the mean lor thc day 88 second-feet.
<br />The flood of September 2-3, 1938, was caused by a cloudburst tlll1t
<br />centered on the divide between Mount V ornon and Bear Crceks nellr
<br />the top of Genessee Mountain. UnfortUl~atc1y, this area had nO
<br />Weather Bureau precipitation stations, and tt was therefore nece.ssary
<br />to determine the locations and approximate amounts of rainfall from
<br />such information as could be furnished hy local residents who had
<br />measured the rainfall in improvised rain gages. The Bureau of Re~-
<br />larnation made a thorough search for such information, wluch IS
<br />. I ~_ LL_ f....ll......ur:no" t..A_hIA.
<br />
<br />Rainfall on Bear Creek and Mount Vernon Creek drainage basins dUM'ng nigh! oJ
<br />Sept. 2-3, 1938
<br />
<br />L1>ra.tlon Rainfall Method of measure- Remarks
<br />(inches) ment
<br />NW}(SeC.I~ 1'. 5 S., R. "ll W__u 3 2-1b. coffCQCll.n In open..
<br />INergroon,J. EUllec.10,'I'.5S., , Estimated____________ Rain btJRan about G p. m. Sept. 2
<br />n. 71 w. TIardest rain lasted only ahou
<br />K~~r~~RW,SWU SeC. 35, '1'. 4 S., OUSOJiD~ barreL__~.__ 30 mfnutCll. .
<br />, Over 3 inches measured In barrel
<br /> Sept.6.
<br />In Cold Spdn~ OUkh, SE!i sec. " Gallon ca.n_______~____ Rain started about ':J' m'j Seg,t.
<br />25,'1'.4t)"H,7IW. aud CQntfnued ha unt I a ou
<br />Muuth of Colll SvJ"\n~ Gulch, , Wheelbarrow S Inches 8:30 p, m.
<br />~rlUtllwe5teornerscc.30,'1'.4S., deep.
<br />n.iOW.
<br />Southwest Mrner see, 29, T. 4- S., , Two buekets in open.~ Both buckets meusured exactly tb
<br />H.70W. same.
<br />NE.!4 sec. 32, '1', 4 S., R. 70 W.___ , on barreL__...._..... Hard rain started at 6:40 p. m.
<br /> Sept. 2, and continued at leas
<br />Morrison, sout.h quarter C()rncr 4 hours.
<br />3 Estlmated___._..~____ Rain started about 7:15 p. m,
<br />SI.!c.35, 'r.4S-.R-i'vW. Scpt.2. Mosto(lI.ftlllin2hours
<br />NE.!4 Stlc. 30, T. 4 S., n. 70 W ____ 'Ii Gallon ca.nu__________ Rain stnlted about 6 p. m., Sept. 2
<br />~orthf'.ast corner ~e. 20, T. 4 S., 6 2-gallon buckeL_______ Hnined all nlRht.
<br />7 Inches measured in Raring bucket
<br />Ft. 7JJ W. computed at Glllehe.'>. '
<br />SW.l{~c. 7, T. 4 S., n, 70W____. 6J< 4-inch rain gage_______ OBgO ran over; Mdmated overflow,
<br /> I Inch. Emptied ~nKe and i
<br />SF.!4st>c.13, T.4 S., n.1i W._.u 8 Wash tub...._________ read 1M inches additional.
<br />nard rain 6:30 to 9 p. m., Sept. 2.
<br />North quatt.er COtner sec. 13, '1'. 'if Partly covered CWl____ Most of rain feU in about 2 hours.
<br />4~.,H..71 W.
<br />Southwest. corner sec. 12, '1'. 4 S., , Straigl1t-slded C3Dm__
<br />H.71W.
<br />NJ<:Uscc.ll, T. 4 S., R. "l1 Wu__ 81i Wash tub_~__.._______ Tub 10 inches deep ran over; no
<br /> estimate of splash. 'l'wo hard
<br />HUM Lodj!:C, sout.heast corner ~e. 8 lV-inch buck:eL._____. rainSteported.
<br />Bucket set on slopC tan ovpr; es.
<br />10,'1'.4::1., H.11 'Yo timat('d betwoon 8 and 9 Inches,.
<br /> lIarde,<;t rain between 6:30 aDd 7
<br /> p. m., Sept. 2.
<br />
<br />2
<br />I
<br />
<br />,
<br />
<br />1 Approximate.
<br />
<br />This precipitation resulted in floods in Cold Spring Gulch and
<br />Mount Vernon Creek, which caused the flood on Bear Creek. Above
<br />Cold Spring Gulch, the upper of these two tributaries, Bcar Creek
<br />expericnecd only a small rise. Within a short time after the flood
<br />slope-area determinations of the peak flows were made at controllin~
<br />pomts.
<br />C?ld S~ring Gulch, a tributary of Bcar Creek, in the area of highest
<br />preelpLtatlOn III SE~ sec. 25, T. 4 S., R. 71 W., had a peak discharge
<br />of 9,000 second-fect from a drainage area of 4.48 square miles, or
<br />2,010 sceond-fcct per sqnare mile. A small gulch is tributary to
<br />Cold Spring Gulch between this point of measuremcnt and the
<br />eonOuence of Cold Spring Gulch and Bear Creek. A sJope-arCll
<br />measurement of this gulch at its mouth near the southwest corner of
<br />SN:. 30, T. 4 S., R. 70 W., showed a peak discharge of 2,050 second-feet
<br />from a d~ainage arca of 0.63 square miles, or 3,250 second-fcet per
<br />squarc mIle. The watermarks and erosion at the mouth of Ulis
<br />tributary gulch show cd that its peak discharge CllIDe before tho peak
<br />all Cold Spring Gulch and therefore should not bA Jl.(],IMI in t.hn nn...
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