FLOOD01851

• County: Jefferson
• Community: Golden
• Stream Name: Clear Creek
• Title: Major Drainageway Planning
• Date: 9/1/1982
• Prepared For: Jefferson County
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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IV-l

SECTION IV
FLOODPLAINS

FLOOD DAMAGES
The flood profiles for the lO-year and lOa-year floods were used to deter-
mine the extent and depth of flooding for each frequency. Flood depths for
both frequencies were then related to the ground and first floor levels of
structures within the floEldpl ain. Structure elevations were determined by
field survey. Flood da-nages were then estimated and tabul ated on a reach by
reach basis according to the type of structure. For the case of vacant par-
cels of land within the floodplain, no future flood damages were projected,
since developnent of these parcel s would either not be allowed or strictly
controlled by the following:

GENERAL
The City of Golden and Jefferson County adopted floodplain ordinances to
promote the publ ic welfare, preserve the natural conveyance and storag~
capacity of the floodplain and reduce the liability of the City and County.
The Flood Hazard Area Delineation Study for Clear Creek (Reference 1) docu-
ments and delineates the water surface profile and boundaries of the
lOa-year, or "regul atory" floodpl ain and floodway and forms the basis for
the development of this master plan for upper Clear Creek. Sheets 1 through
6 of Appendix C show the limits of the lOa-year floodplain which were adop-
ted by the Colorado Water Conservation Board on January 30, 1980. The
depicted floodwater surface area is a pictorial representation of the
lOa-year flood profile in plan format which is used for regulation and land
use planning purposes.

1. The existing floodpl ain ordinlnces of the City of Golden and Jefferson
County,
2. The State of Colorado r-bdel Floodpl ain Regul ation (CWCB & HB1041),
3. The Flood Disaster Protection Act of 1973 (PL 43-234), and
4. The Water Resources Development Act of 1974 (PL 93-251).

Flood Profil es
The lO-year and lOa-year flood profiles presented in the Flood Hazard Area
Delineation Study were utilized in this master plan with the exception of
Reach 1 between Ford Street and Washington Avenue. In this area a special
analysis was done to determine the lOa-year and 50-year flood levels created
by the bridge structures, including the magnitude and depth of flow which
leaves the channel, inundating adjacent areas. The analyses in this reach
involved a combination of computer and hand calculations to arrive at the
best estimate for the combination of flow throu9h each bridge and flow over
and around each bridge. The results were presented to the Urban Drainage
and Flood Control District in the form of a letter report which may be found
in Appendix C of the Phase A Report.

Table IV-I 1 ists the average annual damages by reach as determined under the
Phase A study.

TABLE IV-I

AVERAGE ANNuAL FLOOD DAMAGES
(FROM PHASE A REPO~T)

Reach Damages
1 $ 96,300
2 *
3 $ 5,000

* Determined separately by Adolph Coors Industries