FLOOD01785

• County: Larimer
• Community: Fort Collins
• Stream Name: South Platte Tributaries
• Title: Hazard Mitigation 404 Grant Application Floodproofing
• Date: 9/1/1999
• Prepared For: Larimer County
• Prepared By: Fort Collins
• Floodplain - Doc Type: Miscellaneous

City of Fort C ol/ins

Hazard Mitigation 404 Grant Application

is controlled by Horsetooth Reservoir, which was constructed by the
Bureau of Reclamation in 1954.

Floods occurred on Spring Creek in 1902, 1904, 1938, 1949, 1951, 1975,
1977, 1983 and 1997. During the July 1997 event, the Spring Creek
drainage basin within the City of Fort Collins received the most intense
rainfall, and was the site of the most damage_ It is estimated the July 28th,
1997 flood was greater than a 500-year event.

Since 1990, the City of Fort Collins completed a series of channel and
floodplain improvements along Spring Creek for flood protection (100-
year design) and recreation. The multiple projects removed a number of
properties from the flood hazard area_

3.

Dry Creek

~

Dry Creek is a left bank tributary of the Cache La Poudre River and has a
drainage area of about 65 square miles_ Dry Creek flows south through
the northeast portion of Fort Collins before joining the Cache La Poudre
River south of Fort Collins Airpark In the upper portion of the basin, the
stream is steep, narrow, and deeply incised with active headcutting.
Lower in the basin, the Dry Creek channel is relatively stable with wide,
shallow floodplains except in Fort Collins where the channel does not
exist in several areas. Extensive pre-FIRM commercial and residential
development is located within the Dry Creek floodplain and floodway.

Flooding occurred in Dry Creek in 1904 and 1924 with flows several feet
deep. Due to the shallow flooding, the Dry Creek floodplain is an
appropriate area to implement floodproofing measures.

4. Fossil Creek

Fossil Creek is a right bank tributary of the Cache La Poudre River with a
drainage area of approximately 21 square miles. It flows from east to west
through Fort Collins. The Fossil Creek channel is generally incised and
characterized by bed and bank instability and meander migration and
channel cutoffs.

Floods occurred in Fossil Creek in 1902, 1938, 1965, 1977, 1979 and 1997
with little damage since the basin was relatively undeveloped. Major new
development is now occurring in this region, however, adherence to new
drainage criteria in planning and construction has lowered the flooding
hazard in this basin.

5, Boxelder Creek and Cooper Slough

Boxelder Creek is a left bank tributary of the Cache La Poudre River and
has a drainage basin that covers an area of 251 square miles in Wyoming

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