FLOOD00850

• Designation Number: 31
• County: Arapahoe
• Community: Unincorporated Arapahoe County
• Title: Major Drainageway Planning - Little Dry Creek, Report, Volume I
• Date: 2/1/1974
• Designation Date: 6/1/1974
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Future Land Use. In order to estimate the ultimate urbanization of land

within the basin, current zoning maps from all jurisdictions were laid

out on work sheets to relate sub-basin drainage to future urban density.

Future urbanization was taken to be full development of all lands as pre-

sently zoned, with one exception: where areas were zoned for agricultural

use, but were likely to be zoned for residential development, the con-

cerned planning departments were contacted for advice and the areas ad-

justed according to their estimates of future zoning.

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Using detailed low altitude aerial photos, the acreage of impervious sur-

faces was checked in l6 test areas to develop a composite building density-

imperviousness curve, as shown on Chart 3, which follows. These test areas

were selected in fully developed zones so that reference to the current

zoning would equate to a given density and correspond to an average percen-

tage of impervious area.

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Major Waterway Description

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The following is a brief description of existing conditions along the major

drainage channel reaches in the Little Dry Creek drainage basin. Emphasis

is given to conditions in the more intensely urbanized areas.

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Little Dry Creek in Englewood. Although the Little Dry Creek flood plain

is very wide between the South Platte River and South Santa Fe Drive, the

central drainage channel is restricted by recent man-made fill, and is

narrow. The South Platte River Drive highway bridge opening is insuffi-

cient to pass flood flows. (We are advised that this bridge will soon be

removed and replaced.) These restrictions will cause flood waters to flow

northward over Dartmouth Avenue. The railroad bridges near South Santa Fe

Drive highway bridge will restrict the lOO-year flood flow that may occur

under present conditions.

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The Cinderella City conduit is inadequate to carry the lOO-year flood flow

that may be expected under existing conditions and a substantial part of

such. high flood flows will pass overland and cause damage in the Cinderella

City shopping center area. From the entrance of the conduit upstream to

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