FLOOD10068

• Designation Number: 15
• County: Adams
• County: Arapahoe
• County: Douglas
• Community: Denver Metro Region
• Stream Name: Goldsmith, Lilley Gulches, Dutch, Coon Creeks
• Basin: South Platte
• Title: FIR - Denver Metropolitan Region - Volume VI
• Date: 10/1/1971
• Designation Date: 12/1/1971
• Floodplain - Doc Type: Floodplain Report/Masterplan

POTE~TIAL FLOODS

r&dvce peak disch~rges dow~stre~~ from the hI9hw~y. This effect 15
show~ in t~ble 7.

This section discusses the lntermedl~te RegIonal ~nd
St~nd~rd Project Floods ~nd theIr effects. The Intermedi~te RegIonal
Flood repre!ients ~ f 1 oed with an average frequency of occurrence of
~bovt once In 100 y~rs and Is Increo!lslngly being accepted by the
public as ~ minimum limit for ~ppllc~tlon of loc~1 regul~tlons. The
St",nd",rd Project Flood Is of greater magnitude and represents '"
re~sonable upper llmlt of expe<::ted flood I ng. However, It 15 oot the
largest flood th~t cou Id occur. It Is eonph"'!ilzed hera that floods
which are sma Iler th~n the InTenned18te Reglona I Flood would be more
frequent. Although these lesser t loods wou Id I nulld~te sm.,ller .,rellS
they would a Iso c~use dtl""'Qe, hardshIp and Inconveniences.

T~ble 7
FLOOD D1SCHARGES

STream Loc~tlon

Intermediate Standard
Reg i Ollll I Project
"""" Flood
Discharges Dlsch~rges
(c.f.s.l (c.f.s.l
no 1,900
3,500 6,800
2,260 3,300
3,200 8,300
2,550 4,600
2,900 7,070
2,620 7,800
3,800 11,300
5,750 16,600
5,000 15,800
;80 2,000
1,100 2,750
2,100 4,800
620 1,400
2,130 5,300
2,280 6,000

Intermediate Regional Flood
Since dlschtlrge measurements are not available speclti-
cally for the stre~ms stud led In this report, the frequency-dlsch~rge
relaTionshIps were developad fr= a correlaTion of datil tor similar
str&ams where records aro ~v~ll~ble. Recognizing th~t the flood
potentl~l retlected by current ~sin development would be quIckly
outdated by the rapid development t~klng pl~ce in the basins. To
show a tlood potential whiCh would be ~pproprlate tor a reasonable
length of time the hydrologic analysIs was basad upon ~sln develop-
mentprojectadtol980condltions. The Goldsmith Gulch basin was
considered to be 92 percent developed and the Dutch Creek basin was
consIdered to be 36 percent developed. Table 7 shows the Intermedl-
ate Reglorllll Flood discharges lit specific locations along each str....m.
The discharges between the deslgna~ed points v~ry In proportIon to
the distance between points. The water retention reservoirs In the
Outch C~eek basin were dlsreqllrded ~s factors In retarding flood
flows sl nce they are usually full or without slgnlf Ic~nt flood stor-
"ge capac Ity o~ fIv.Iy be rA'l'.:lVed at some future time. Interstate Hlgh-
way 225wlll,whenbullt, Impedestorrnrunoff InGoldsmlthGulchan<:l

Goldsmith Gulch Above Dayton Street
Above Interstate 225
Below Interstate 225
"'""
Dutch Creek At the Hog~ck
Kipling Street
Aoove Lilley Gulch
Below Lii ley GulCh &
Above Coon Creek
Below Coon Creek
Mouth
Lilley Gulch Kipling Street
C"rr Stroot
Mouth
Coon Creek Si","s Street
Carr Street
"'""

Standard Project Flood
The Standard Project Flood Is presented In this report
as tho practical upper 11mltoffloodlng. Storms that would produce
this flood are uncommon, and It Is difficult to assign frequencle!i
of occurrence with any reasonable degree ot accuracy. Two storms
near C~stle Rock On 16 and 17 June 1965 produced sufficiently Intense
ratnta I j 1"ha1" it similar stonns occurred over the drain~ge basins
of the streams studied in this roport They would produce a Standard
Project Flood. As high as 10 and 12 Inches of ralntall were measured
during these stonns..hichoccurred only 20 miles a,"",y. The Standard

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