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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The maps in Volume II delineate the lOQ-year flood plains. For zoning

purposes, the flood plain should be used for the waterways without im-

provement. Any flood control ordinance should at least prohibit obstruc-

tion of the natural waterway by structures, earth fill, fences or other

obstructions, and should establish some meanS of having obstructing brush

and weeds removed as a natural channel maintenance measure.

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The preservation of natural waterways can be expected to have a positive

environmental effect. Wildlife habitat would be preserved, and open

space and greenbelt benefits would accrue.

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Capital Improvements

The major drainageway capital improvements that are proposed to provide

protection from a 100-year flood to existing urban areas in the lower

Little Dry Creek basin are shown on Drawings 4 and 5 and 30

through 35, in Volume II of this report. The improvements include

channelization, conduits, and detention dams. Either grass-lined or

concrete lined channels are used to contain the lOO-year flood waters.

Conduits are used to carry flood waters underground, and detention dams

are used to reduce peak flood discharges in downstream conveyance chan-

nels and thereby reduce the size and cost of improved channels and conduits.

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Channelization. The channelization proposed in this report is primarily

in the lower part of the basin, as shown On Drawings 4 and 5. Both

grass-lined and concrete lined channels have been used, the choice depending

largely on availability of right-of-way. In general, channelization

benefits exceed their cost only marginally and the channelization

proposed using public funds is limited. In specific areas in the basin,

land developers may conclude that channelization is justified based on

their individual appraisal of potential land values, and they may wish

to undertake limited local channelization using private funds. If this

is permitted, and there do not appear to be any serious objections to

carefully designed channel modifications, the developer should be required

to grass-line any new earthen channels and to make provisions for continuing

maintenance of the modified channel. Blue-grass sodded channels must be

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