BOARD01259

• Board Meeting Date: 11/23/1998
• Description: CF Section - Non-Reimbursable Studies and Investigations - Statewide Floodplain Management and Storm Drainage Criteria Manual Request for Non-Reimbursable Funding from the Construction Loan Program
• Board Meetings - Doc Type: Memo

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Colorado Water Conservation Board
Department of Natural Resources
721 Centennial Building
1313 Sherman Street
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]

STATE OF COLORADO

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Roy Romer
Governor

MEMORANDUM

James s. Lochhead
Executive Director, ONR
Daries C. Lile, RE.
Director, eweB
Peter H. Evans
Acting Director, ONeS

TO: Colorado Water Conservation Board Members

FROM: Larry Lang v-fV

DATE: November 10,1998

SUBJECT: Agenda Item 26e, November 23-24, 1998, Board Meeting --
Statewide Floodplain Management and Storm Drainage Criteria Manual
Request for Non-Reimbursable Funding from the Construction Loan Program

EXECUTIVE SUMMARY
The staff presents a scientific project for the development of a Statewide Floodplain Management
and Storm Drainage Criteria Manual, and requests non-reimbursable funding from the Construction
Logan Program in the amount of $125,000. The Criteria Manual would address Colorado's need
for consistent guidelines, criteria, and regulations regarding stormwater detention, storm drainage
conveyance, and floodplain management. At this time, existing criteria manuals consist of a
handful of publications developed by local govemments and special districts. Some are very
comprehensive and have been used extensively within specific geographic areas (i.e, Urban Storm
Drainage Criteria Manual), but this is not the statewide norm, Over 75% of Colorado communities
do not have a formalized plan for dealing with specific floodplain management and stormwater
runoff issues! Development of a statewide manual was previously identified as one of the top
priorities according to the "Statewide Stream Rehabilitation and Floodplain Management Needs
Assessment".

INTRODUCTION and PROBLEM DESCRIPTION
Why does Colorado need a floodplain management criteria manual? Tremendous population
growth and resulting land development has created an intense pressure to build in or near flood
prone areas of the state. Local govemments struggle to deal with floodplain and drainage issues
related to the growth, and are in need of uniform criteria that can be applied in a consistent and
equitable manner. Also, new developments, both commercial and residential, convert thousands of
acres of natural pervious areas into rooftops, parking lots and roadways, The growing amount of
impervious area contributes to increased stormwater runoff, Greater runoff volume can increase
flood peaks above their naturallhistoricallevels, and can have adverse impacts to stream channels
(erosion) and to downstream landowners. A statewide detention and stormwater policy would help
to provide consistent criteria between Colorado communities and alleviate the problems associated
with increased stormwater runoff from developed areas,