FLOOD03281

• County: Boulder
• Community: Boulder County
• Stream Name: Boulder Creek
• Basin: South Platte
• Title: Hydrology Addendum to FIS Boulder County and Incorporated Areas
• Date: 10/1/2000
• Prepared For: Boulder County
• Prepared By: Montgomery Watson
• 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 Boulder County and Incorporated Areas is the Flood
Insurance Study (F1S), dated June 2, 1995. The AS was prepared by FEMA and contains 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 and incorporated areas 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 AS meets the basic technical requirements for
designation and approval by the CWCR. Without the inclusion of basic engineering information,
the approximate floodplain delineations shown on the Boulder 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 purposes, This HA provides a means for the AS 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shown on the FIRM panels will become superseded, The CWCB will designate and approve new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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