FLOOD09485

• Designation Number: 206
• County: Larimer
• Community: Fort Collins
• Stream Name: Fossil Creek Drainage Basin
• Basin: South Platte
• Title: Master Drainageway Planning - Fossil Creek Drainage Basin, Fort Collins, Larimer County, Colorado
• Date: 8/1/1982
• Designation Date: 1/1/1983
• Floodplain - Doc Type: Floodplain Report/Masterplan

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VII. FLOOD DAMAGES

Table 25. Flood Damage Summary in Dollars.

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Damages due to flooding were estimated to establish a baseline condition

for economic analysis. Damages were estimated on a reach by reach basis for

existing conditions. An inventory of structures in the flooded areas deter-

mined that potential damages were associated with road crossings only. There

were no buildings or crops in the flooded areas.

Damages caused by the 2-, 10-, 100- and 500-year recurrence interval

flood were estimated for each reach. Road crossings that had water ponded

upstream of the embankment and were overtopped were assumed to fail. The

length of the road failure was assumed to be the same as the width of the

water ponded behind the embankment. The cost of the failure was the replace-

ment cost of fill and roadway of that length. The existing culvert was

assumed to be recoverable and undamaged. Indirect costs associated with

emergency service, clean up and rerouting traffic were assumed to be 35 per-

cent of the total replacement cost. The total flood damages by reach for the

2-, 10-, 100- and 500-year recurrence interval floods are presented in Table

25 for Fossil Creek and the four tributaries. Average annual flood damages

are presented in Table 26. Damage frequency curves as developed from these

tables for Fossil Creek are presented in Figure 28 for reaches 1 and 2 and in

Figure 29 for reaches 4 and 5.

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Location

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Flood Recurrence Interval in years
10 100 500

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Fossil Creek
Reach 1
Reach 2
Reach 3
Reach 4
Reach 5

165,900 169,000 169,700
156,800 199,300 205,900
11,600 13,000 14,400 15,400
39,600 41,800 43,300
50,900 96,000 109,600
168,200 172,700

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Stanton Creek
Reach 6

Lang Gulch
Reach 7

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Smith Creek
Reach 8

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Burns Tr ibutary
Reach 9

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