FLOOD04421

• County: Arapahoe
• County: Douglas
• Community: Arapahoe, Douglas
• Stream Name: Piney Creek, Cottonwood Creek, Lone Tree,
• Basin: South Platte
• Title: Flood Hazard Area Delineation
• Date: 10/1/1975
• Prepared For: UDFCD
• Prepared By: Arapahoe, Douglas
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Today, Arapahoe County is still basically an agricultural and

residential community with most of the population concentrated

in the western one third of the county. In the past 15 years the

County has experienced a rapid growth in population resulting

from Denver metropolitan area urbanization and subsequent ex-

tensive suburban development. County population figures for 1970,

1975 and projected for 1980 are 161,000, 224,800 and 263,400,

respectively.

portions of Piney Creek and Cottonwood Creek in Douglas County.

The study reach for each stream ranges from the confluence with

the receiving stream to the upstream limit either at the Urban

Drainage & Flood Control District boundary or at the headwaters

of the creek. All four creeks flow in a generally north to

northwesterly direction. The regional location of these streams

is shown on Drawing II-I'

Douglas County is located directly south of Arapahoe County. The

county covers approximately 885 square miles. It extends into

the foothills on the west where the county adjoins Jefferson

County along the South Platte River. On the east the county

extends onto the high plains. The county was designated in

1861. The present population is approximately 15,000 and the

estimated growth is to 25,000 in 1980.

The tributary streams are intermittent flowing streams. The

stream gradients are hydraulically steep and generally flow

through erodible, sandy, clay loam soils.

Piney Creek, Cottonwood Creek and Lone Tree Creek are tributary

to Cherry Creek and the Cherry Creek Lake. Murphy Creek is

tributary to Sand Creek.

Douglas County is bisected by 1-25 and thus has experienced much

growth from the expansion of the outer fringes of the metropolitan

area. Improved transportation systems will continue to bring de-

velopment pressures to the county.

No major flood control facilities exist on any of the streams.

Some residential development has occurred along the flood plain

fringe of Piney Creek and Cottonwood Creek in Arapahoe County.

Other major improvements in the study areas are major streets,

including 1-25 on Cottonwood Creek, and the Arapahoe County Air-

port east/west runway on Lone Tree Creek.

Study Reach Description

This report covers the study areas of Piney Creek, Cottonwood

Creek, Lone Tree Creek and Murphy Creek in Arapahoe County and

Drainage Basin Characteristics

The stream locations and drainage basin boundary limits are

shown on Drawings 11-4 and 11-5. The streams are located on