FLOOD09349

• County: Larimer
• Community: Fort Collins
• Stream Name: Spring Creek
• Basin: South Platte
• Title: Previous Study Review Spring Creek Hydrology Reports
• Date: 1/23/1980
• Prepared For: Larimer County
• Prepared By: Gingery Associates, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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1623.001

Report Summary #1

"Spring Creek Flood Flow Investigation"
by R. V. Lord and Associates, Inc.
Report Prepared in 1960

The purpose of this report was to establish a runoff hydrograph for
several points along Spring Creek within the City of Fort Collins.

Analysis was based upon an empirical solution, correlating historic
rainfall records and surface runoff characteristics to arrive at the
peak flow for a design storm and approximate stream hydrographs.

The drainage area is in a semi-arid climate, with a ~ean annual rainfall
of l4.7-inches. Surface soils are primarily clayey, sandy silts of
low to moderate permeability.

Canals were assumed to overflow during maximum storms, hence contributing
to the maximum flow at the lower end of the basin.

The Rational method was used for this study. The rainfall intensity used
was determined from curves for a 10-year storm recurrence at a tiQe
equal to the time of concentration at each of the points under consideration.
Flows as high as 1,470-cfs may be anticipated from such a lO-year storm,
which is greater than the capacity of the existing channel.

The basin outline used for this report along with rainfall graphs and the
runoff hydrographs are included here. The age of this information makes
it nearly useless because of current fainfall data available and advances
made in hydrologic analysis.