FLOOD00475

• Designation Number: 157
• County: Adams
• County: Arapahoe
• County: Douglas
• Community: Denver Metro Region
• Stream Name: Bear Creek
• Title: Flood Hazard Area Delineation - Bear Creek
• Date: 12/1/1979
• Designation Date: 3/1/1980
• Floodplain - Doc Type: Floodplain Report/Masterplan

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feet. A large flooding area upstream of South Wadswor,th Boulevard

is caused by backwater from the bridge crossing. The water ponds

up behind South Wadsworth Boulevard, reaching depths of 1 to 2 feet

before flowing over the road just south of the channel. Very little

development exists in this area, and therefore very few structures

are in the floodplain.

In the reach from South Estes Street to South Kipling Street,
floodplain limits are approximately 400 to 500 feet in width and
are mostly confined to undeveloped land. There are, however, a
few structures upstream of the South Kipling Bridge which would
be inundated by the 100-year floodplain.

From South Kipling Street to the end of the study at Bear
Creek Dam, the floodplain narrows down to widths between 100 and
300 feet. Land in this area for the most part is undeveloped.
No structures are in the floodplain along this reach.

The floodway data presented show floodway widths to the right
and left of the channel centerline, along with the floodway eleva-
tion and total width of the floodway.

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- FLOOD VELOCITIES -

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Maximum flow velocities characteristic of a 100-year flood
event on Bear Creek are tablulated at typical cross sections on
the water profile sheets.

The flow velocity in the channel generally ranges between
5 fps and 15 fps. Velocity in the overbanks would range between
2 fps and 7 fps.

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- FLOODPLAIN AND FLOODWAY DATA -

Water velocities greater than 6 to 8 feet per second can
cause severe erosion of stream banks, and are capable of trans-
porting large rocks and debris. Velocities in this range can
also erode fill around bridge abutments, causing possible bridge
failure. Lower velocities of approximately 2 fps or less will
deposit debris and silt.

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The Flood Hazard Area Delineation Maps show the outline of

the 100-year flood event for fully developed basin conditions and

present channel conditions. The maps are supplemented by Table II,

"Floodplain and Floodway R~ference Data."

- SUMMARY -

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The tables contain a listing of potential 100-yoar flood dis-

charges, streambed elevation, 100-year Cloed elL'vation "nd 100-

year floodplain width for cross sections utilized in this study.

This report has identified the probable flooding limits of
a potential 100-year flood event in the lower Bear Creek drainage
basin below the Bear Creek Dam.

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The flooc1wuy data cont.uin.(~d in this tdbJe dt.'Filh~::-; :1 flt'l\\' ,11't.~,1

required to convQY the 100-yo<1r l'vellt wi [ltout InCI-,'"'' I nq t-It"

IOO-year W.J.tPI- ~:::;urfLlcc by more th<l11 {)..~} f-t'l'l. '['Ill' :"ll)lhl\\".l)' 1 ~~ ,\

high hazard .:J.r0t1 char(JctcrlzC'd by doc'>p w,lh'l' ,-[tld hiqll \','ll)I.'ity

flow clurinq flood cv('nt~;, and should l'c,t\I;lill l-l"I.'I.' elj ,\11\' dl'\'l'l,,!'!\\,'td

which would obstruct flow.

The floodplain limits are based on (1) planned future devel-
opment in the lower basin; (2) existing, mapped floodplain condi-
tions; and, (3) hydraulic calculations assuming no blockage of
existing bridge structures. Even with these assumptions, floods
of greater magnitude can and will occur in which the limits of
flooding will exceed those shown in this report.

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For thc "caclt of
furUwr n,strietr'd by
inchc':;.. 'I.'h(,30 ar{~ I-he'

Bc:ar' Cr'('('k 111 Ill'I1Vl'l- 1.)[11')', Illl' t-l{){)l!\\!.l~' I:;

illCll1dinq Zlll dl-{',l W!H't-C d{'flll1:; 1.':':'l'I.'I.',! l~;

.:ldordC'd cl-jtct"i;l fOt" !h(' l'il~' ()! l~l'lt\'I.'l-.

Presently there are sections of Bear Creek in which extensive
flooding may occur. The preservation of the floodplain will serve
at least to limit flood damage potential at its present level while
any improvements will serve to minimize or reduce the flood damage
potential.

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