FLOOD06085

• Designation Number: 570
• County: Douglas
• Community: Unincorporated Douglas County
• Basin: South Platte
• Title: FHAD - Cherry Creek Corridor - Reservoir To Scott Road
• Date: 5/1/2003
• Designation Date: 9/30/2003
• Floodplain - Doc Type: Floodplain Report/Masterplan

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SECTIONTHREE

north of Parker, about 4 miles west of Cherry Creek, 1 mile south of Franktown, and by the Douglas
County line on the east. Unofficial rainfall amounts varied from 1 inch to 3.5 inches, occurring in
about 2 hours. An estimated peak discharge of 8,700 cubic feet per second discharged from Bayou
Gulch. The discharge on Cherry Creek, 3 miles north of Parker, was estimated to be 17,000 cubic
feet per second. Although no damages were experienced in Denver, this was considered a major
flood for the upstream part of the watershed.

AU!!llst 1933. The storm of 2 and 3 August 1933 occurred over a 175 square mile area
upstream from Franktown. Unofficial rainfall amounts varied from 3 to 9 inches and occurred over
a 9-hour period between 6 p.m. on 2 August and 3 a.m. on 3 August. The most intense activity of
the storm occurred between 9 p.m. and 10 p.m. Waters in the then existing CastIewood Dam and
Reservoir, reached the spillway crest at about 11 p.m. The inflow was estimated at 35,000 cubic feet
per second. Water overtopped the crest of the dam and the structure failed at about midnight. The
sudden release of water caused a flood wave to move down the valley. The peak discharge is
estimated to have ranged from 126,000 cubic feet per second downstream from the dam to about
16,500 cubic feet per second near the South Platte River. The Cherry Creek Flood Commission
estimated the damages to be about $1,000,000 (1933 dollars); approximately $200,000 of this total
occurred upstream from Denver. This flood caused additional economic effects in the Cherry Creek
watershed. Loss of the dam cut off water supplies to about 3,000 acres of land. The watershed
suffered a severe recession and many families moved from the area.

Au~st 1945. A large storm mass moved into southeastern Colorado on 5 August 1945 and
extended over the Cherry Creek watershed. Unofficial rainfall amounts varied from 2 to 5 inches.
Severe flooding occurred along Cherry Creek in the Franktown - Parker area. The gauging station
at Melvin recorded a peak discharge of 10,700 cubic feet per second. Total damages were estimated
to be $200,000 (1945 dollars).

June 1965. On 16 June 1965, a major storm centered over the Plum Creek and Cherry Creek
watersheds. Rainfall amounts, reported by unofficial sources, ranged up to 10 inches. Most of the
rainfall occurred within a 3-hour period. Peak discharges along Cherry Creek were 1,000 cubic feet
per second upstream from Franktown, 39,900 cubic feet per second near Melvin, and 58,000 cubic
feet per second at Cherry Creek dam. An estimated peak flow of 14,100 cubic feet per second
discharged from Piney Creek, a right-bank: tributary of Cherry Creek. During the evening and night
of 16 June, the Cherry Creek reservoir impounded a flood that had a volume of 16,000 acre-feet. Of
the 18 small dams constructed by the Soil Conservation Service in the upper Cherry Creek
watershed between Franktown and Parker, 3 were filled. Two of these were subsequently
overtopped and sustained erosion damage. The remaining 15 structures were outside of the area of
high intensity rainfall and received only moderate runoff. The heavy runoff caused major flooding
along the main stem of Cherry Creek from the vicinity of Franktown to the Cherry Creek Reservoir.
About 2,720 acres were flooded. Most of the bridges across Cherry Creek were either damaged or
destroyed. One life was lost during the flood on Cherry Creek. Flood damages totaled $1,306,000
(1965 dollars).

According to historical information provided by Quandanska, Ltd., (1997) flooding of Cherry Creek
in the 1890s resulted in several feet of scour in the channel, which prompted water users to build
irrigation ditch extensions. In 1933, scour resulting from the failure of CastIewood Dam effectively
ended the use of irrigation ditches from Cherry Creek for local water supply. The breach occurred as
the result of several days of torrential rainfall upstream of the dam that saturated the soil and resulted
in peak runoff rates and volumes that exceeded the capacity of the dam. "On that fateful evening

PAST flOODS

when the CastIewood Canyon Dam breached, a wall of water came down, causing siguificant damages and killing
two people (Castlewood Canyon State Park, 1997):'

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