FLOOD04884

• County: Moffat
• Community: Craig
• Stream Name: Yampa River, Fortification Creek
• Basin: Yampa/White
• Title: Flood Hazard Information Hydrology
• Date: 9/1/1976
• Prepared For: State of Colorado
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Floodplain Report/Masterplan

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The 1914, 1917, 1920, and 1957 events are primarily snowmelt while the 1921
and 1974 events were augmented by rainfall. The 1974 flow at Hayden is one
of the controlling floods on the envelope curve of his toric flood peaks,
chart: .4. This high peak flow is believed to have been caused primarily by
rainfall on the non-snow covered areas between Steamboat Springs and Hayden.
The 1921 event is part of the general flooding that occurred throughout
Colol'ado as the result of snowmelt: augmented by the genera.l rains on 4-9
and 1,40-15 June.

F'l,)w records on Fortification Creek are meager. Maximum flows occur
during the March-JWle period and result f:roDl snowmelt or a combination
of sno,;melt and rainfall. The highest re,:orded peak flow occurred on
23 Mar,~h 1947 and was 841 cfs. Rainfall oat Craig on this date was 0.15 inches..
There are indications that actual peak flows may hav.a been higher due to ice
condit:lons causing inaccurate gag!' readings or overb,ank flows that were not
mea~ur,~d. A recent study by the Colorado State Department of Highways
(R.eference 1) reports the results of a slope-area computation based on a'
recent high water mark (date unknown) on Fort:ification Creek. A peak flow of
1800 cfs was estimated. Data pre"ented in reference 2 indicates that flooding
at Cra:lg in the late 1940' s was caused by spr:ing tha,.s and ice Jams in the
stream channel. In 1949 the Corp" of Eng:lneers completed emergency
work OIl Fortification Creek consi"ting of channel enlargement and
straightening and levee construction. As a r"sult of this work, plus
substantial channel degradation tl1at has occurred in recent years, the
ice jam problem is not as severe now. Discussions with local interests
indicate that ice jams occur occa"ionally at a sewer line crossIng
immediately upstream from Highway 40 and "t the DRG&W Railroad belo,,,
Highway 40 and that these jams are removed by city and railroad
maintenance crews.

ThE,re are no stream gages on the small trilbutaril~s to Forti:E:ication
Creek c,r on Pine Ridge Gulch. A gage was installed on Cedar Mountain
Gulch i.n 1974. The largest recorded flow '..as 102 cfs and occurred on
20 July' 1974 as the result of a small thunderstorm. A snowmelt flood
occurre,d on 26 March 1971 on Cedar Mountai.n Gulch and caused flooding
of some residential property. Information provided by the Colorado
State Department of Highways (reference 3) indIcates that 'i:ater ponded
behind Highway 40 to a height above the 72" culvert but did not How
over the top of the road. Based on this l:!mi.t:ed infclrmation it :ls
believed that the peak flow was between 200 and 300 ds.

The only thunderstorm to occur in the Crai.g area where a gagE!d
streal.flow record is available was the 20 .July 1974 event on Cedar
Mountnin Gulch. A precipitation gage located at the stream gagE!
recorded 0.45 inches of precipitation in 2--1/2 hours for this e"I'nL
Newspaper accounts indicate that thunderstorms have c:aused floodi.ng in
Craig. A recent event of particular interest occurred on 7 August 1970
when 2.04 inches of rain fell in one hour and caused substantial flooding
ill Craig.

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