FLOOD06561

• County: Montrose
• Basin: San Juan/Dolores
• Title: Hydrology Addendum Montrose County
• Date: 11/1/2000
• Prepared For: Montrose County
• Prepared By: CWCB
• Floodplain - Doc Type: Floodplain Report/Masterplan

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PREFACE

This Hydrology Addendum (HA) is part of a program by the Colorado Water Conser{ation 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 Montrose County Unincorporated Areas is the Flood
Insurance Study (FIS), dated July 17, 1986, The PIS was prepared by FEMA and cDntains both
detailed and approximate floodplain delineations. The approximate floodplains do not include any
engineering information to describe 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 objel:tives.

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 mformation,
the approximate floodplain delineations shown on the Montrose 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 infoonation for its
use in regulatory purposes, This HA provides a means for the PIS to meet that statutory objective.
As new and more detailed floodplain information becomes available, the approximat.: floodplain
areas shown on the FIRM panels will become superseded. The CWCB will designate lmd approve
new information, and rescind old information as appropriate.

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