FLOOD06686

• Designation Number: 10
• County: Pueblo
• Community: Pueblo
• Stream Name: Saint Charles River
• Basin: Arkansas
• Title: FIR - St. Charles River
• Date: 3/1/1970
• Designation Date: 6/1/1970
• Prepared For: Pueblo
• Prepared By: USACE
• Floodplain - Doc Type: Floodplain Report/Masterplan

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~AIN fLOOD SEASO~ for the St. Charles River watershed is during
the summer months from May through August. The severest storms
often occur in the transitional late spring and early fall Peri.
ods, floods on the St. Charles River are characteristically of
moderately short duration with attendant high peak flows.

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VELOCITIES Of WATER during the Standard Project flood would range
up toamax1:numof about 21 feet per second (approximetelyl8
miles per hour) in the river's main channel, Velocities outside
of the main channel would vary widely, depending upon location,
but would reach about 12 feet per second (approximately 8 miles
perhovr) insorne overbank areas. Thesehighvelocitiesdvring
a major flood would be extremely dangerous to life and property.
Volocities greatar than 3 feet per second combined with depths
of 3 feet or more are goner ally coneidered hazardovs.

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DURATIO~ OF flOOOS on the St. Charles River is relatively short
as compared to those on the Arkansas River at Pueblo. In the
stream's lower reach, the Intermediate Regional Flood and Stand.
ard Project flood wovld remain above bankfull stage for about
23 and 29 hours, respectively. The maximum rates of rise for
these floods, 3.6 and 4.2 feet per hovr, wovld be greatest in the
middle reach dvo to the 10caliLedeffect of the Creenhorn River
whore it flows into the St. Charles River. As the flood crests
svbside in traveling downstream, the rates of risa would deoline
to 1.4 and 2.1 feet per hour, respectively, near the river's
mouth.

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flOOD DAMAGE PREVENTION MEASURES by local interests consist of
channel improvemonts and levee constrvction work, principally on
the Arkansas River mein stem and fountain Creek. In so~e

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inatances, these works have extended into the lower reaches of Wild
Horse.Ory Creek and Dry Creak near their mouths on the Arkansas
River. Regvlatory city end county zoning ordinances exist which
govern development in specified special flood plein districts along
fountain Creak, Dry Creek, Wild Horoe.Ory Creck, and the Arkansas
River. AdditionaiflooocontrollllCasuresaraproposoointheCorps
of Engineers' "Report on Review SUfvey for flood Conhol and AI.
lied Pvrposes Arkansas River end Tribvtaries above John Martin
De.., Colorado."

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fUTURE fLOODS of great magnitvde can be expected, but the StanM
derd Project flood repreoents the reasonable vpper limit of ex.
pected flooding. floods the size of the Intermediate Regional
flood have occurred in the pest and will recvr in the future.
Comparisons between fvture ond past floods havo not been made be-
Cause interim flood plain development and changing Channel condi.
tions generally depreciate the practical value of such data. Con_
sidering that comprehensive plens for the city and county of Pueblo
envision e future of vigorovs growth, it can be reasonably con.
cluded that futvre flood damages ~ould be more extensive dve to tho
continuing development and greater us~ of land in the flood plains.

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