FLOOD00589

• County: Denver
• Community: Denver
• Stream Name: South Platte
• Title: Costs to Denver of 1965 Flood Recurrence
• Date: 9/14/1977
• Prepared For: CWCB
• Prepared By: G. Ahmad
• Floodplain - Doc Type: Flood Documentation Report

in four hours, and 12 inches in the same period fell at Castle Rock. The
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average rainfall was estimated by the,L~S. Army Corps of Engineers as 4.8 inches

for over 1000 square miles within six hours.

,

Streams Flooded

In view of orientation of the storm, only the Plum Creek and the Piney

Creek, a tributary of Cherry Creek, were flooded directly by the storm.

The Northern fringe of the storm flooded Westerly and Toll Creeks, which

are tributaries of the Sand Creek that runs through Aurora. These

streams were flooded by drainage water from the west of Denver, (See

4" isohyet in figure 1).

Plum Creek discharged its floodwaters through the South Platte, which

runs across the city of Denver. Further downstream the Cherry Creek joins

the South Platte in the city. Piney Creek is a tributary of Cherry Creek,

and the floodwaters of these creeks were contained in the Cherry Creek

.

reservoir. This prevented the floodwaters from these creeks from flooding

into the already flooded South Platte and aggravating an already worsening

condition.

The flood of 1965, therefore, occurred only in three of the thirty eight

creeks which pass through the Denver metro area. Even with Denver not

impacted directly, discharge was much higher than had been noted before.

The U.S. Geological Survey had previously worked out 50 year flood discharge

figures for the region. Figure 3 reflects this conclusion and gives the

actual discharge on some of the streams compared with the 50 year flood.

Population and Development

The population of the city of Denver has been growing ever since 1910,

the growth rate varying between decades from 12 to 28.9%. The population

of the city of Denver between 1910 and 1960 is given in figure 4.

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