FLOOD00029

• Designation Number: 365
• County: Mesa
• Community: Fruita
• Title: Flood Insurance Study - Fruita, CO, Mesa County
• Date: 7/1/1992
• Designation Date: 7/1/1994
• Floodplain - Doc Type: Floodplain Report/Masterplan

Starting water-surface elevations for
Washs were computed by using the
elevations.

both the Big and Little Salt
slope-area method and known

Locations of selected cross sections used in the hydraulic analyses
are shown on the Flood Profiles (Exhibit 1). For stream segments
for which a floodway was computed (Section 4.2), selected cross
section locations are also shown on the Flood Insurance Rate Map
(Exhibit 2).

The hydraulic analyses for this study were based on unobstructed
flow. The flood elevations 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 and the
descriptions of the marks used in this study are shown on the maps.

4.0 FLOODPLAIN MANAGEMENT APPLICATIONS

The NFIP encourages State and local governments to adopt sound
floodplain management programs. Theref ore, each Flood Insurance Study
provides 100-year flood elevations and delineations of the 100- and
500 year floodplain boundaries and 100-year floodway to assist
communities in developing floodplain management measures.

4.1 Floodplain Boundaries

To provide a national standard without regional discrimination, the
1 percent annual chance (LOO-year) flood has been adopted by FEMA
as the base flood for floodplain management purposes. The 0.2
percent annual chance (SOO-year) flood is employed to indicate
additional areas of flood risk in the community. For each stream
studied by detailed methods, the 100- and SOO-year floodplain
boundaries have been delineated using the flood elevations
determined at each cross section. Between cross sections, the
boundaries were interpolated using topographic maps at a scale of
1:2,400 and 1:4,800, with a contour interval of 2 feet
(Reference 13 & 12 respectively).

The 100- and SOO-year floodplain boundaries are shown on the Flood
Insurance Rate Map (Exhibit 2). On this map, the laO-year
floodplain boundary corresponds to the boundary of the areas of
special flood hazards (Zone(s) A and AE); and the SOO-year
floodplain boundary corresponds to the boundary of areas of
moderate flood hazards. In cases where the 100- and SOO-year
floodplain boundaries are close together, only the laO-year
floodplain boundary has been shown. Small areas within the
floodplain boundaries may lie above the flood elevations but cannot
be shown due to limitations of the map scale and/or lack of
detailed topographic data.

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