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<br />Technical Issues: This report was prepared by Baker for the CWCB in order to provide discharge
<br />information for approximate stream reaches portrayed on the countywide Flood Insurance Rate Map
<br />(FIRM) for the affected communities. This study did not determine new discharges for these approximate
<br />reaches. Rather, the study aggregated infonnation previously available from a number of different sources,
<br />and presented it in one location for ease of use and reference. There is no hydraulic data to suppOli the
<br />approximate floodplain delineations for the subject stream reaches. This study backs up information
<br />already presented in the FIRMs for the affected communities. No floodplain delineations were revised by
<br />this report.
<br />Community response: The affected communities were contacted by telephone and were receptive to the
<br />CWCB's proposed action to designate and approve the floodplain information in the subject study. In
<br />addition, this study merely supports the regulatory FIRMs already adopted and used by the affected
<br />communities, and does not modify any regulated floodplain areas.
<br />Staff findings: CWCB staff has detennined that the subject 100-year approximate floodplain information
<br />for the studied stream reaches is conformance with the CWCB's mles and regulations for floodplain
<br />designation and approval. The CWCB staff has relied on the technical competence of Michael Baker, Jr.,
<br />Inc., who produced the study, but also performed an independent technical review of the report. Staff
<br />therefore endorses this study as containing the most current floodplain information available and urges the
<br />affected communities to adopt said study for land use regulation purposes pursuant to statutory authority.
<br />Staff recommendation: Staff recommends that the Board: 1) designate and approve the 100-year detailed
<br />floodplain information contained in said report within Jefferson County, City of Arvada, City of Bow Mar,
<br />City of Edgewater, City of Golden, Town of Lakeside, City of Lakewood, Town of Morrison, Town of
<br />Mountain View, City of Westminster, City of Wheat Ridge, and 2) authorize staff to prepare a floodplain
<br />resolution to be signed by the Director and transmitted to Jefferson County, City of Arvada, City of Bow
<br />Mar, City of Edgewater, City of Golden, Town of Lakeside, City of Lakewood, Town of Morrison, Town
<br />of Mountain View, City of Westminster, City of Wheat Ridge, and to the Urban Drainage and Flood
<br />Control District and FEMA. This action is recommended in order to meet statutory requirements.
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<br />5) Consent A2enda Item 2.e
<br />Floodplain resolution number: FPR 07-606
<br />Affected communities: Elbert County
<br />Name of study to be formally acted on: "Hydrologic Study Report, Drainage Basins: Running Creek,
<br />Kiowa Creek, Comanche Creek, and West Bijou Creek, Elbert County, Colorado" dated June 2007, by
<br />Michael Baker, Jr., Inc.
<br />Studied streams: Running Creek, Cabin Gulch, Gold Creek, Hay Gulch, Henderson Gulch, Timber
<br />Claim Gulch, Whiskey Gulch, Kiowa Creek, Dry Creek, Gopher Creek, Little Dry Creek, Neffs Gulch,
<br />West Kiowa Creek, Comanche Creek, West Bijou Creek, Big Gulch, East Gulch, Spring Branch,
<br />Spring Gulch, Station Gulch
<br />Technical Issues: No FEMA floodplain maps exist for Elbert County. Elbert County has expressed an
<br />interest in participating in the National Flood Insurance Program and having official FEMA Flood
<br />Insurance Rate Maps available for adoption and use for regulation. This study was prepared to develop a
<br />hydrologic base for further development of floodplain mapping for the critical stream reaches within the
<br />County. Detailed hydrology was developed for the subject stream reaches using HEC-HMS, a hydrologic
<br />modeling software developed by the Hydrologic Engineering Center of the U.S. Army Corps of Engineers.
<br />HEC-HMS uses numerous watershed variables including design precipitation, soils information, watershed
<br />size, land use information, times of concentration, and stream reach physical characteristics to estimate
<br />nmoff at a given point. As a check of the HEC-HMS results, representative watersheds were also analyzed
<br />using regression equations. In general, the discharges fall within the confidence limits of the regression
<br />
<br />Flood Protection. Water Project Planning and Financing. Sn-eam and Lake Protection
<br />Water Supply Protection. Conservation Planning
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