FLOOD04017

• County: Jefferson
• County: Denver
• Community: Columbine Valley, Denver
• Stream Name: Dutch Creek, Lilley Gulch, Coon Creek,
• Basin: South Platte
• Title: Flood Hazard Area Delineation
• Date: 5/1/1978
• Prepared For: Jefferson County / Arapahoe County
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Coon Creek: Beer's Sisters Lake, Grant A & B Lakes and other
small retention ponds within Denver and Jefferson
Counties.
Three Lakes Tributary: Five small retention ponds within Arapahoe
County.
Future Basin development within the study area was consipered by utilizing
land use plans, zoning maps, and Denver Regional Council of Governments growth
and development projections for the City of Denver, Arapahoe County, and
Jefferson County. In general, it is anticipated that the future develop-
ment will have a significant effect on the hydrologic factors which
govern the drainage characteristics of the study area since the Basin
at present is primarily open space with small pockets of low density
land use.

the location of 21 design points and corresponding sub-basins.

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Not included in this listing of sub-basins is the area located east
of Platte Canyon Road in and around the vicinity of the Town of Colum-
bine. The topogr9phy of this area is very flat and includes the flood
plain of the South Platte River. Much of the area and the resulting
runoff drains directly into the South Platte River without affecting
the flows in Dutch Creek or the undefined sheet flow from the Three
Lakes Tributary.

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Sub-Basin Delineation

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The study area was divided into 21 sub-basins which were defined in

relation to the following parameters:

I. Significant differences in land use and ground cover;

2. Major drainageway crossings;

3. Significant differences in topography;

4. Geographic significance of jurisdictional boundaries.

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Drawing No. I II, Basin Boundaries, shows the location, limits and size

of the 21 designated sub-basins within the total Basin study area.

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The physical data for each of the 21 sub-basins is shown in Table A-I

of Appendix A. The tributary area for each sub-basin varied from

approximately 0.22 square miles to 2.31 square miles with an average

sub-basin tributary area of approximately 0.74 square miles.

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To facilitate the evaluation of intermediate points on the various

drainageways within the Basin, 17 design points were selected to permit

a more detailed hydrologic investigation. Drawing No. I II also shows

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