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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HYDROLOGY RESULTS

The SW];lM model was used to determine the 2-year, 5-year, 10-year,
50-year, 100-year and 500-year frequency discharges at selected
locations in the study reach. In addition, the 100-year event
was determined neglecting Douglas Reservoir. This discharge was
determined to show the effect of a bypass channel around Douglas
Reservoir on discharges in the Fort Collins area.

The study reach for this project extends from the Dry Creek

confluence with the Poudre River upstream through the SW4 of

Section 26, approximately 1/2 mile above U. S. Highway 287.

For the 2-year and 5-year flood events, the Eaton Ditch
intercepts all flows reaching its channel. Therefore, for these
events, separate runs were made upstream and downstream of the
ditch. The run above the ditch included only tributary area
downstream of the Larimer County Canal since this canal would
intercept all flows from the area upstream of its Dry Creek
crossing.

Por the 10-year, 50-year, 100-year and 500-year events, the

model was run to include the entire basin. Because of

uncertainties in the response of the canal systems to large

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