FLOOD02581

• Designation Number: 557
• County: Gunnison
• Community: Unincorporated Gunnison County
• Basin: Gunnison
• Title: Hydrology Addendum
• Date: 2/1/2002
• Prepared For: Gunnison County and CWCB
• Prepared By: Montgomery Watson Harza
• Floodplain - Doc Type: Floodplain Report/Masterplan

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PREFACE

This Hydrology Addendum (HA) is part of a program by the Colorado Water Conservation Board
(CWCB) to make approximate floodplain maps prepared by the Federal Emergency Management
Agency (FEMA) easier for local governments to use. This CWCB report provides limited
engineering information to support the approximate delineations on the FEMA maps, and it
provides floodplain management information to guide the local governments in the use of the maps,

The official floodplain information for Gunnison County Unincorporated Areas is the Flood
Insurance study (PIS), dated September 29, 1989, The PIS was prepared by FEMA and contains
both detailed and approximate floodplain delineations. The approximate floodplains do not include
any engineering information to describe the basis of the approximate floodplain mapping, The
initial purpose of this report, therefore, is to provide the county with limited supporting information
for the approximate floodplain delineations, This HA includes a description of available hydrologic
information for major flooding sources within or adjacent to the county. In addition, the HA gives
the county some basic information about floodplain management and it provides some alternatives
that could be considered in formulating and implementing floodplain management objectives.

A second function of this report is to assure that the PIS meets the basic technical requirements for
designation and approval by the CWCB, Without the inclusion of basic engineering information,
the approximate floodplain delineations shown on the Gunnison County Flood Insurance Rate
Maps (FIRMs) cannot qualify for CWCB designation. Colorado statutes require that local
governments obtain from the CWCB the designation and approval of floodplain information for its
use in regulatory pUlposes. This HA provides a means for the FIRMs to meet that statutory
objective. As new and more detailed floodplain information becomes available, the approximate
floodplain areas shown on the FIRM panels will become superseded. The CWCB will designate
and approve new information, and rescind old information as appropriate,

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