FLOOD03677

• County: Larimer
• Community: Fort Collins
• Stream Name: Dry Creek
• Basin: South Platte
• Title: Major Drainageway Planning Dry Creek Technical Addendum
• Date: 4/1/1980
• Prepared For: Larimer County
• Prepared By: Gingery Associates, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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of the Eaton Ditch and the Terry Inlet. No adjustment of

infiltration rates was necessary. Depression storage was

dropped from 0.3 to 0.2. The resulting 5-year discharge was
280-cfs.

The second calibration run included all areas upstream of

the Larimer County Canal with peak discharges not to exceed

125-cfs, the excess capacity of this ditch. No modifications

to the preliminary loss values were necessary. The resulting

5-year discharge was 60-cfs.

Above Douglas Reservoir, little information was available for
calibration. Known information was that the reservoir has not

been overtopped in the 70-year period of its existence. From

field observation, erosion on the spillway indicates that the

spillway has operated with a substantial flow, however, not

large enough that erosion is excessive.

In the basin upstream of Douglas Reservoir, irrigation canals

again have the capacity to intercept significant drainage flows.

The Poudre Valley Canal, often referred to as Flood Ditch, is in

use for only short periods of time and, therefore, would

likely intercept drainage flows up to its full capacity of 350-cfs.

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