FLOOD03888

• Designation Number: 388
• County: Summit
• Community: Unincorporated Summit County
• Basin: Colorado Mainstem
• Title: Flood Insurance Study - Summit County, CO, Unincorporated Areas
• Date: 11/1/1994
• Designation Date: 11/1/1994
• Floodplain - Doc Type: Floodplain Report/Masterplan

The hydraulic analyses for these studies were based only on the
effects of unobstructed flow. The flood elevations, as shown on the
profiles, are, thus, considered valid only if hydraulic structures
remain unobstructed, operate properly, and do not fail.

All elevations are referenced to the National Geodetic Vertical
Datum of 1929 (NGVD). Elevation reference marks used in the study
are shown on the maps.

4.0 FLOOD PLAIN MANAGEMENT APPLICATIONS

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A prime purpose of the National Flood Insurance Program is to encourage
State and local governments to adopt sound flood plain management pro-
grams. Each Flood Insurance Study, therefore, includes a flood boundary
map designed to assist communities in developing sound flood plain manage-
ment measures.

4.1 Flood Boundaries

In order to provide a national standard without regional discrimina-
tion, the 100-year flood has been adopted by the Federal Insurance
Administration as the base flood for purposes of flood plain manage-
ment measures. The 500-year flood is employed to indicate additional
areas of flood risk in the county. For each stream studied in
detail or limited detail, the boundaries of the 100- and 500-year
floods, as applicable, have been delineated using the flood eleva-
tions determined at each cross section; between cross sections, the
boundaries were interpolated using topographic maps at scales of
1:600, with a contour interval of 2 feet (References 17 and 18);
1:1,200, with a contour interval of 2 feet (References 12 and 14);
1:2,400, with a contour interval of 2 feet (References 19 and 20);
and 1:24,000, with a contour interval of 40 feet (References 21,
24, and 27).

The approximate 100-year flood boundaries for Blue River and Soda
Creek were delineated by use of information from topographic maps
(References 12, 20 through 22, and 24) and the computed flood
elevations.

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The approximate 100-year flood boundaries for Snake River were delineated
using information from topographic maps (References 19 and 23), the
Flood Hazard Boundary Map for Summit County (Reference 28), and
computed flood elevations. The approximate 100-year flood boundary
for South Barton Gulch was taken from the Flood Hazard Boundary Map
for Summit County (Reference 28).

The approximate 100-year flood boundary for French Gulch was taken
from a Flood Plain Information report for Breckenridge (Reference 8),
and studied in conjunction with the computed flood elevations.
Lower portions of French Gulch have been relocated since the Flood
Plain Ihformation report was completed. The new stream location and
flood boundary were adjusted using photoquadrangle and topographic
maps (References 25 and 26).

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