FLOOD05064

• Designation Number: 205
• County: Larimer
• Community: Fort Collins
• Basin: South Platte
• Title: Master Drainageway Planning - Cooper Slough, Boxelder Creek, Fort Collins, Larimer County, Colorado
• Date: 8/1/1981
• Designation Date: 1/1/1983
• Floodplain - Doc Type: Floodplain Report/Masterplan

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taxcH, pollee and health deparLmcnt involvement, and inconveniences due to

repair or r~location. Indirect damages are very diffic~lt to assess on an

individual basis and are based on percentages of property value given by

Grigg, 1974 (reference 19) for commercial and industrial property;-'Indirect

damages for residential areas were calculated by estimating the time required

for clean-up and was based on ten dollars per hour. This calculation also

covers time lost from work.

Other direct damages include repair of utilities, roads, bridges and

canals. These damages were estimated individually on a time and materials

bas is.

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Table 18, Flood Damage Factors.

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RESIDENTIAL

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Value Per
Dwelling

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Structure

$75,000

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Damages to agricultural land were developed using data collected by the

Soil Conservation Service. The Soil Conservation Service developed a com-

posite acre of land in the Boxelder Creek floodplain and estimated flood dama-

ges to crops for each month of the growing season. From these data, an

average flood damage per acre cost was developed. The Soil Conservation

Service agricultural price index (prices paid to farmers) was used to update

crop values to the present. The Soil Conservation Service also developed a

unit cost per acre of all other damages associated with agricultural land.

These include damage to fences, irrigation ditches, roads, and costs for

debris removal. This factor was updated to reflect current costs by using the

agricultural cost index (prices farmers pay for supplies) developed by the

Soil Conservation Service. The agricultural flood damages were estimated to

be $160 per inundated acre.

Vehicular damages were estimated as a percentage of value for each flood

depth. Vehicle value was estimated at $2500 per vehicle and 8 vehicles per

acre for residential property and 16 vehicles per acre for other land use

Contents

$37,500

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Vehicles

$ 5,000

Indirect Damage $BO/day

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Total Damage Per Dwelling:

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COMMERCIAL.

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Value Per
Acre

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Structure

$470,000

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Contents

$235,000

Vehicles

$ 40,000

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Indirect Damage*

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Average Damage Per Acre

Flood Damage Factors
l' depth 2' depth 3' depth 4' depth
0.06 0.16 0.22 0.26
0.18 0.31 0.44 0.52
0.05 0.25 0.68 0.75
1 day 2 days 3 days 4 days
$11,580 $25,035 $36,640 $43,070

Flood Damage Factors
1 ' depth 2' depth 3' depth 4' depth
0.07 0.14 0.21 0.26
0.10 0.22 0.34 0.43
0.05 0.25 0.68 0.75
0.35 0.35 0.35 0.35
$78,140 $168,625 $268,310 $331,390

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.commercial damages were assessed on an individual basis based on assessed
property values updated to 1980 dollars. The values presented here are
average property values found in the Cooper Slough basin.

The dollar damage for each property for flood depths of one, two, three

and four feet and the selected flood damage factors are given in Table 18.

The total flood damage by reaches for the 2-, 10-, 100-, and 500-year storms

are given in Tables_ 19 and 20 for Boxelder Creek and Cooper Slough, respec-

tively. From these flood damage totals, damage-frequency curves were deve-

loped for Boxelder Creek and Cooper Slough and are given in Figures 11 and 12.

Annual flood damages were calculated from these curves by measuring the area

under each curve. The annual flood damages are given in Table 21.

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*Indirect damages are based on a percentage of total structure and content
damages.

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