FLOOD09323

• County: Arapahoe
• Community: Arapahoe County
• Stream Name: Sand Creek, Cherry Creek
• Basin: South Platte
• Title: Floodplain Information Report
• Date: 4/1/1964
• Prepared For: Denver Regional Council of Governments
• Prepared By: US Army Corps of Engineers
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

THE FLOOD PROBLEM:

TOll G....TE CREfK

S....ND CREEK

On Toll Gat~ Cre~k, th~ ~rbsn r~ach extend8 some 6.5 ~iles from its

On Sand Creek, the urban reach extends some 13 miles from the mouth

contl~ence ~ith Sand Creek to s point eq~ival~nt to Sn extension of

upstres'" to Buckley Field. Inth1sre,,"chthed1schargeatvhichflooding

~ississippt Avenue. This incl~de8 abo~t 2 ",iles of the West Toll Oat~

begins ranges from 1,400 to 30,000 cubic feet per second depending on

Creek channel. On Toll Gate Creek, sOMe flooding cen be expected st

location. In the reaches of lowest channel capacity some overbank flooding

discharges of 2,000 cubic feet per second in c~rtstn locations, while in

10 low areae may be expected 00 the average of once in two y~ars. However,

others the channel can safely carry discharges up to 12,000 cubic feet

at other locations, the channel hos aufficient cspacity to cerry discharges

per second. On West 'toll Gote Creek, flOOding discharges ronge frOOl 700
to 5,500 cubic feet per second. Discharges of 2,000 cubic feet per

with aD averllge reCurrenCe interval of once in one hundred years. The

attached flood outline mapa illuetrate llreas of potential flood1og at

second can be expected to Occur On ao average of once in seveo years st

discharges equivslent to the 1957 flood under current channel conditions;
the 100 year frequency flood (reflecting a flood risk of 1 chance in 100
in any year); and the greater probable flood (Standard Project Flood).
Aa ill<lstrated by the flOOd ol.ltlines, the greater probable flood

current levels of watershed urbsnif.et1on. However, ~ith the level of

u.rbanhation anticipeted by the year 2000, the "'"currence intel'Vl'll for

a discharge of 2,000 cubic feet per second would become sbout once in

five yeers. The sccompanying flood outline mapa illustrate aress of

~ould flood extensive areas over the entire reach, totaling approximately

potential flooding On ~ll Gate Creek at diacherges equivslent to the

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4,000 acres exclusive of the channel area. Flood depths in the overbanK

1957 flood; the 1 percent probability flood and the greater prObable

aress ,,"ould range up to 6 feet.

floorl. Th..".. ..Al''' tllIlRt,.",to> thAt Approxi"Rt"oly 500 8cr..a, <,ycluat_

~ith the iocreaaed urbsnization in the ~atershed anticipated by the

of the chsnnel, would be flooded under discherg~ conditions eq~ivalent

year 2000 the greater amount of rooftops and paved areas can be ..xpected
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to incresse flood discha"gea as much 8e 20 percent over currant conditions,

to 1957, ~hile about 235 acres would be flooded st 1 percent frequeocy

discharges and 635 ecrea under conditions repl'ftBenting the greater

f'J;'00l storm reinfall or equivalent intensities. Thus, while the flood

probable flood. Overbank flooding up to 9 fef!t in depth et certain

history of Sand Creek demonstrates a sufficient flood hszard under curNlnt

"loeeticne would ~e~t U?OD oec'~rence of tee ~ate~ ~~obeble flcod.

~atershed conditions to compel prudence in use of the flood plain, the

increased flood potentisl inherent in future urbanization of the vetershed

LOWER CHERRY CREE~
The length of the Cherry Creek channel frOlll Cherry Creek !llIm to the

justifies added preea\ltio::t.s "gllin8t u..'lwiae en~ro>lchmente.

mouth is approximately 11.8 m11e8. The lower 3.3 mll~s of thi.s rellcn ~

to Eaet First Avenue - have been improved with II concrete-lined channel,

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with channel capacity cl.lrrent1y ranging from 4,700 to 23,200 cubic feet

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