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

raln fell near the Monument Divide at Palmer Lake
in 4 hours. Overnight, westerly winds shifted the
storm front to an orientation over the Kiowa and Bijou
Creek basins to meet with thunderstorms forming just
south of Agate, where 5.25 inches fell in 45 minutes.
The net result: six persons drowned, two other deaths
from flood-related activities, and estimated damages
of $500 million in the South Platte River basin of
which $300 million was in the Denver area.

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Flood problems in the area have been the result of
not only rare storm events but also of improper flood
plain development. Visual accounts of floods have
noted the debris which was picked up by the flood-
waters. Included were natural debris of trees, rock
and soil, but mostly items foreign to the flood plain
such as houses, bridges, automobiles, heavy equipment,
lumber, house trailers, butane storage tanks, and other
flotsam. With these items plugging bridges and culverts,
flood levels rise and cause more extensive damage.
Property which was not structurally damaged by flood
depths and velocities experienced much damage and
clean-up cost related to mud and silt deposition and
property erosion. (References 4 and 9).

Scenes of past flooding in Arapahoe County are shown
in Figures 2 and 3. The pictures were taken from
photographic records of the Denver Post and the Arapahoe
County Planning Department.

2.4 Flood Protection Measures

The first tangible contribution to flood control on
the streams flowing through Arapahoe County was made
in 1890, when the Castlewood Dam, primarily intended
for irrigation storage, was completed by the Denver
Land and Water Company on Cherry Creek, 35 miles upstream
from Denver. The dam, with a storage capacity of
4 billion gallons, was mistakenly regarded by many
as protection against deluges. In August 1933,
the dam burst under pressure of water from severe
thunderstorms in the upper Cherry Creek basin. Flood
control measures were again taken on Cherry Creek
in 1936 with the completion of the $800,000, 55-foot
high Kenwood Dam, 5 miles southeast of Denver, near
Sullivan, Colorado. Despite its apparent guarantee
of security, Kenwood Dam was not regarded as the complete
answer to flood control on Cherry Creek and was abandoned.
In 1950, the Cherry Creek Dam was constructed just
upstream of the former Kenwood Dam at a cost of $20

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