FLOOD11741

• Designation Number: 277
• County: Arapahoe
• Community: Arapahoe County and Unincorporated Areas
• Basin: South Platte
• Title: FIS - Arapahoe County and Unincorporated Areas
• Date: 8/1/1977
• Prepared For: Araphoe County
• Prepared By: FEMA
• Floodplain - Doc Type: Historic FEMA Regulatory Floodplain Information

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Community Description

Arapahoe County is located in central Colorado, just
south and east of Denver. The general physical boundary
is that of a rectangle 12 miles by 72 miles, which
extends from near the foothills of the Rocky Mountains
to the open plains of eastern Colorado, covering approx-
imately 864 square miles.

The climate in Arapahoe County varies slightly from
the Denver metropolitan area to the prairie lands
on the eastern end; but, generally, it is characteristic
of the temperate high plains. The mean annual tempera-
ture is 50.20P with a mean annual snowfall of 45 inches
and rainfall of 14.05 inches. Agriculture flourishes
with a mean growing season of 139 days.

Arapahoe County was the first designated county in
the state even though at that time, the county, which
comprised over one-fifth of the present Sta-te of Colorado
was the western part of the Kansas Territory. Prom
then (1858) until April of 1903, the county changed
shape and size many times and on two occasions was
nonexistent. During the early days of expansion
and exploration, Arapahoe County was visited by many
explorers and trappers until gold was discovered at
the mouth of Little Dry Creek, after which intensive
growth was experienced throughout the region. The
territory in and around Arapahoe County also became
known as one of the greatest cattle ranch areas in
the west. With the advent of the railroads, towns
like Deer Trail became the natural termination points
for cattle drives originating in Texas.

Today, Arapahoe County is still basically an agricultural
and residential comnunity, 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 metro-
politan area urbanization and subsequent extensive
suburban development. County population figures for
1970, 1975, and projected for 1980 are 161,000, 224,800,
and 263,400, respectively. This kind of suburban devel-
opment pressure is now, and will continue to be, evident
in and along the flood plains of Big Dry Creek, Little
Dry Creek, Cottonwood Creek, Cherry Creek, Piney Creek,
Sand Creek, Coal Creek, and the South Platte River.
Box Elder Creek and Comanche Creek have also experienced
residential growth along their banks.

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