FLOOD05173

• County: Routt
• Community: Routt County Unincorporated
• Basin: Yampa/White
• Title: Flood Insurance Study - Routt County Unincorporated Areas
• Date: 9/29/1989
• Prepared For: Routt County
• Prepared By: FEMA
• Floodplain - Doc Type: Historic FEMA Regulatory Floodplain Information

2.4 Flood Protection Measures

At the preBent time, there are no flood-protection measures within
the study area other than small levees constructed by local
entitieB. However, flow of the Yampa River is slightly affected by
Catamount Lake, Lester Creek Reservoi r (also known aB Pearl Lake)
and Steamboat Lake. These lakes do not provide flood protection.

3.0 ENGINEERING METHODS

For the flooding sources studied by detailed methods in the community,
standard hydrologic and hydraulic study methods were used to determine
the flood hazard data required for this study. Flood events of a
magnitude which are expected to be equaled or exceeded once on the
average during any 10-, 50-, 100-, or 500-year period (recurrence
interval) have been selected as having special significance for
floodplain management and for flood insurance rates. These events,
commonly termed the 10-, 50-, 100-, and 500-year floods, have a 10, 2,
1 and 0.2 percent chance, respectively, of being equaled or exceeded
during any year. Although the recurrence interval repreBents the long~
term average period between floods of a specific magnitude, rare floods
could occur at short intervals or even within the same year. The risk
of experiencing a rare flood increases when periods greater than 1 year
are considered. For example, the risk of having a flood which equals
or exceeds the 100-year flood (1 percent chance of annual exceedence)
in any 50-year period is approximately 40 percent (4 in 10), and for
any 90-year period, the risk increases to approximately 60 percent (6
in 10). The analyses reported herein reflect flooding potentials based
on conditionB existing in the community at the time of completion of
this study. MapB and flood elevations will be amended periodically to
reflect future changes.

3.1 Hydrologic Analyses

Hydrologic analyses were carried out to eBtablish peak discharge-
frequency re1ationBhips for each flooding Bource studied by
detailed methods affecting the community.

Peak discharge-drainage area re1atiortBhips for the Yampa and Elk
Rivers are shown in Table 1.

TABLE 1. SUMMARY OF DISCHARGES

Flooding Source
and Location

Drainage Area
(Square Miles)

Peak Discharges (cfs)
10-Year SO-Year 100-Year 500-Year

Yampa River
At downstream end of
the study reach

666

__1

1

8,930

__1

Approximately 250 feet
upBtream of the Steamboat
Springs corporate limits

520

__1

1

5,000

1

5