FLOOD01863

• County: Morgan
• County: Logan
• County: Sedgwick
• Community: Northeastern Colorado
• Stream Name: South Platte River
• Title: Report on the Floods of June 1965
• Date: 1/1/1967
• Prepared For: State of Colorado
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Flood Documentation Report

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velocity flash floods which are particularly hazardous to life and
property. The foothills regions have flash floods similar to the
mountain regions, but generally reflect a greater hazard because dry
washes become raging torrents with high velocities that erode the
normal boundaries of stream flow. As the foothills streams converge
to form the main tributaries and tributary streams converge on the
main. stream, the valleys and flood plains become broader. The
broader valleys and flatter stream slopes reduce the discharge rate
of the flood by combinations of temporary overbank storage and lower
energy gradients. ,The lower velocities increase the duration of
flooding and permit the sediment load and debris load carried from
upstream areas to be deposited on the more productive lands of the
lower valleys. Consequently, the damaging effects in the lower
valleys are a combination of destruction by erosion and inundation
with reduction in the productive quality of valley lands by flood
debris and sediment. The .damaging effects of floods /;lore also governed
significantly Qy the nature of storm patterns and tributary runoff.
Rainfall concentrated over one tributary watershed generally limits
the destructiveness of floods to the tributary stream affected.
However, the runoff from larger storm patterns results in flood dis-
charges on many tributaries which converge on the main stream, thereQy
causing more widespread destruction, prolonged inundation, and greater
flood damages over larger areas.

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III. EXISTING IMPROVEMENTS

14. FEDERAL IMPROVEMENTS

a. Corps of Engineers.

(1) The Cherry Creek Dam and Reservoir on Cherry Creek was
completed in 1953 at a cost of $14.1 million. It is situated
approximately 11. 5 miles above the mouth. of the stream at central
Denver. It controls 385 square miles of the 409 square mile Cherry
Creek watershed. The dam is a rolled earth fill structure, with a
reservoir storage capacity to the crest of the emergency spillway of
96,000 acre-feet. This storage capacity consists of 81,000 acre-feet
for flood control storage and 15,000 acre-feet for conservation storage.
The conservation pool also serves the project's recreation function.

(2) The Kelly Road Detention Dam is a small capacity (380,
acre-feet) flood detention project on Westerly Creek situated near the
Lowry Air Force Base at Denver, Colorado. It provides flood protection
for portions of Aurora and Denver, Colorado. It was completed by the
Corps of Engineers in 1954 at a cost of $221,000.

b. Soil Conservation Service. The Soil Conservation Service has
constructed three watershed projects in the South Platte River basin
which include a total of 106 floodwater retarding structures. The

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