FLOOD03485

• County: Denver
• Community: All
• Stream Name: All
• Basin: South Platte
• Title: Comparison of Estimated Flood Peaks with Historic Floods
• Date: 1/1/1986
• Prepared For: State of Colorado
• Prepared By: USDOI
• Floodplain - Doc Type: Educational/Technical/Reference Information

26. Dark Gulch and North Fork Tributary to Big Thompson River

near Glen Haven, Colorado

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In the evening of July 31, 1976, a sec;es of violent thunderstorms released unprecedented volumes
of water onto the mountain terrain of the northern Colorado front range from Estes Park to the
Wyoming border. The Big Thompson River and its many small tributary streams west of Drake,
Colorado, were especially hard hit. The stream valleys were a favorite vacation spot and summer
residence, The Big Thompson flood caused 139 deaths and 5 miSSing persons, It ranks as one
of the worst natural disasters in Colorado history,

Although heavy rain began at Glen Haven about 7:30 p,m" the first report of heavy flooding in
the area was at Fox Creek, which reached a peak stage at 9.00 p.m, at Glen Haven. Much of the
most intense rainfall occurred in the area of Glen Haven and along the divide between the North
Fork Tributary and the main stem of the Big Thompson, Isohyets drawn for the total flood area
show more than lOin of rain near Glen Haven and point rainfalls as high as 12 in. The rainfall
generally began about 6:30 and ended by 11 :30 p,m,

In the area of this divide two of the most intense runoff events were later established by slope-
area measurements, The North Fork of the Big Thompson near Glen Haven had a reported discharge

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HISTORIC ,l00D JULY 31 !S8'1 PEAK .. ">?I12 CtS
KL.B 7/11,'8<;

PHF ?EA~ ~ 1290e =rS
~ ?MF 3~ nR VOLUME ~ 13~~ ~CRE FErT
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i.1 HiSTORIC FLOOD = 7210 CF,S \
I: 56% OF PMF PEAK

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BURE:1L; OF" PECLAMfnIO~

PI"~F COHP::iR I so;..... STUDY
DRRK GULCH NERR GLEN HRVEN COLOR?J:;O

LRG ~ 0.26 HR 3~C~HORN DUH

PMP BASED eN HMR 55

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[; !? 18 24
TIMe F RC1 B[C;:-~NE.~ OF" .~Rlf\,'F,~LL (hrs)

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Plate 29 - Computed PMF hydrograph and hisTOriC flood peak for Dark Gulch near Glen Haven, CO.

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