FLOOD10800

• Designation Number: 592
• County: Routt
• Community: Routt County and Incorporated Areas
• Title: FIS - Routt County and Incorporated Areas
• Date: 2/4/2005
• Prepared For: Routt County
• Prepared By: FEMA
• Floodplain - Doc Type: Current FEMA Regulatory Floodplain Information

significant degree of overtopping would occur at each of the five road crossings during
a loo-year flood event. Culvert capacities are insufficient to pass the loo-year flow in
each case. Only minor blockage of the culverts was assumed at each creek crossing.
Insufficient culvert capacity at the CR 27 crossing would cause water to back up south
of the D&RGWRR tracks nearly to the Bell Avenue bridge over Oak Creek. Several
low-lying residences would be flooded as a result of this backwater effect. Insufficient
culvert capacity at the crossings of Bell and Sharp Avenues, in conjunction with
adjacent low-lying ground to the north of the creek, would cause flooding of some of
the buildings in the downtown area. The area at the baseball field to the east of Moffat
Avenue would be flooded because of insufficient capacity at the Moffat Avenue
crossing.

Oak Creek headwaters are located at an approximate elevation of 10,240 feet. The
highest point in the basin is Sand Point, at 11,182 feet. Oak Creek, at the northern
Town of Oak Creek boundary is at 7,390 feet. The length of Oak Creek from its
headwaters to its intersection with Oak Creek's northern corporate limit is
approximately 14.4 miles. The creek travels in a northeasterly direction for this entire
distance.

The drainage area of Oak Creek is 22.7 square miles. There are no major tributaries to
Oak Creek.

The study reach along Oak Creek covers the area within the Town of Oak: Creek
corporate limits. The length of the study reach is approximately 1 mile. Oak Creek
formerly meandered widely through the town. However, over the years, it has been
rerouted and straightened (Reference 9).

City of Steamboat Springs

As noted earlier, most of the annual precipitation in the Yampa River Basin occurs as
snow, and a deep snowpack accumulates in the high elevations. General rainstorms
covering large areas for extended periods can occur in the Steamboat Springs region
from late spring through early fall. Convective cloudburst storms of small areal extent
can be expected frequently during the summer.

Major floods in Steamboat Springs have been the result of snowmelt augmented by rain
in spring or early summer. In general, snowmelt in spring or early summer constitutes
a frequent but comparatively minor flood threat. General rainstorms alone have not
caused significant floods in the Yampa River Basin. However, rare but very large
floods resulting from general rain are possible in the Yampa River Basin. Records
show that major flood producing rainstorms almost always occur during the months of
September and October in western Colorado. Precipitation produced 1.13 inches of
rain over a 2-day period, and a storm in September 1939 produced 1.64 inches of rain
in a 3-day period. The highest runoff of record on the Yampa River, in June 1921, was
the result of heavy rain falling on a melting snowpack. There is little definitive
information available on flooding from cloudburst storms in the Steamboat Springs
area. The storm that caused flooding in the city in 1921 may have been a cloudburst.
This storm produced more than 2.5 inches of rain, but its duration is conjectural. A
maximum of 2.04 inches in 3 hours has been recorded elsewhere in the region. Thus,
flooding from cloudburst storms is a probability in the Steamboat Springs area.

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