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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liability arising from mishaps with the structure; and the Urban Drainage

and Flood Control District is willing to assume ownership and improve the

dam to meet current standards, since it serves the valuable function of

substantially reducing downstream flood peaks.

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Highline Canal

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The serpentine course of the Highline Canal across the basin may be seen

on Chart 2. The canal normally carries about 200 cfs. No provision has

been made to pass runoff from the Little Dry Creek basin over or under

the canal from any waterway except at Little Dry Creek where there is an

inverted canal siphon. The canal presently blocks surface runoff until it

is overtopped. Hydrologic studies show that the Highline Canal may be ex-

pected to intercept and carry off 2-year frequency and smaller storms,

but that storms of lO-year and longer recurrence interval can be expected

to overtop the canal banks and breach the canal.

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Channel Changes

Urbanization has made only a few changes in the historic course of water-

way channels and these are in the lower part of the basin. A 3,265-foot

portion of Little Dry Creek through Englewood has been enclosed in a box

conduit. The lowest mile or so of Greenwood Gulch has been obliterated

for many years. From detailed contour maps, it appears that Greenwood

Gulch once ran in a channel or shallow swale separate from Little Dry

Creek through Englewood from Clarkson Street to Huron Street. The exis-

ting high roadway fill of Clarkson Street now totally blocks off the his-

toric channel. A portion of Greenwood Gulch flood waters flow up-grade

in City Ditch to join Little Dry Creek flows and pass through the Clarkson

Street bridge on Little Dry Creek. The roadway fill blocks the remaining

flow and increases the flooding problem above Clarkson Street. In the

May, 1973 storm a large pond was formed upstream of the Clarkson Street

roadway fill, flooding houses and a church. Flows then spilled over the

roadway fill and caused damage below it. The State Highway Department is

planning a storm sewer from Greenwood Gulch to Little Dry Creek on the up-

stream side of Clarkson Street to reduce this flooding problem.

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