ca2a_ 2e

• Board Meeting Date: 9/18/2007
• Description: Flood Section - Designation and Approval of 100-Year Floodplain Information
• Board Meetings - Doc Type: Memo

who produced the study, but also performed an independent technical review of the report. CWCB staff
therefore endorses this study as containing the most current floodplain mapping available and urges the
affected communities to adopt said study for land use regulation purposes pursuant to statutory authority.
Staff recommendation: Staff recommends that the Board: 1) designate and approve the 100-year detailed
floodplain information contained in said report within Jefferson County, City and County of Denver, City
of Wheat Ridge, City of Arvada, and City of Golden and 2) authorize staff to prepare a floodplain
resolution to be signed by the Director and transmitted to UDFCD, Jefferson County, City and County of
Denver, City of Wheat Ridge, City of Arvada, and City of Golden, and to FEMA. This action is
recommended in order to meet statutory requirements.

2) Consent A2enda Item 2.b
Floodplain resolution number: FPR 07-603
Affected communities: Routt County, City of Steamboat Springs, Town of Oak Creek, Town of Hayden,
Town ofYampa
Name of study to be formally acted on: "Floodplain Information Report, Hydrology Addendum, Routt
County and Incorporated Areas, Colorado" dated June 2007, by Michael Baker, Jr., Inc.
Studied streams: Trout Creek, Middle Creek, Unnamed Tributary, Unnamed Tributary to Walton
Creek, Unnamed Tributary to Burgess Creek, Walker Ditch, Shelton Ditch
Technical Issues: This report was prepared by Baker for the CWCB in order to provide discharge
information for approximate stream reaches portrayed on the countywide Flood Insurance Rate Map
(FIRM) for the affected communities. For the Walker Ditch and Shelton Ditch, the Colorado Decision
Support System (CDSS) was used. Stmcture Listing Reports identified the Decreed Total Rate of Flow
that can be legally diverted into these ditches. The Decreed Total Rate of Flow is assumed to be the 100-
year peak discharge in these ditches since the amount of flow diverted is controlled and regulated. For
other subject stream reaches use regression equations developed by the United States Geological Survey
(USGS). This methodology is consistent with that described in the Colorado Floodplain and Stonnwater
Criteria Manual. There is no hydraulic data to suppOli the approximate floodplain delineations for the
subject stream reaches. This study backs up information already presented in the FIRMs for the affected
communities. No floodplain delineations were revised by this report.
Community response: The affected communities were contacted by telephone and were receptive to the
CWCB's proposed action to designate and approve the floodplain information in the subject study. In
addition, this study merely supports the regulatory FIRMs already adopted and used by the affected
communities, and does not modify any regulated floodplain areas.
Staff findings: CWCB staff has detennined that the subject 100-year approximate floodplain information
for the studied stream reaches is conformance with the CWCB's rules and regulations for floodplain
designation and approval. The CWCB staff has relied on the technical competence of Michael Baker, Jr.,
Inc., who produced the study, but also pelformed an independent technical review of the report. Staff
therefore endorses this study as containing the most current floodplain information available and urges the
affected communities to adopt said study for land use regulation purposes pursuant to statutory authority.
Staff recommendation: Staff recommends that the Board: 1) designate and approve the 100-year detailed
floodplain information contained in said report within Routt County, City of Steamboat Springs, Town of
Oak Creek, Town of Hayden, and Town of Yampa, and 2) authorize staff to prepare a floodplain
resolution to be signed by the Director and transmitted to Routt County, City of Steamboat Springs, Town
of Oak Creek, Town of Hayden, and Town ofYampa, and to FEMA. This action is recommended in order
to meet statutOlY requirements.

3) Consent A2enda Item 2.c

Floodplain resolution number: FPR 07-604
Flood Protection. Water Project Planning and Financing. Sn-eam and Lake Protection
Water Supply Protection. Conservation Planning

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