FLOOD03140

• County: Denver
• Community: Aurora, Denver
• Stream Name: Westerly Creek
• Basin: South Platte
• Title: Flood Hazard Area Delineation
• Date: 1/1/1977
• Prepared For: Aurora, Denver
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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4

January, 1976. "Report on Drainage Master Plan for

Westerly Creek" (Camp Dresser & McKee Inc.)

This report indicated that the basin is fully urbanized

in the lower reaches and is rapidly approaching a state

of full development in the upper reaches. In the area

upstream of the Highline Canal, three stormwater deten-

tion ponds and a concrete-lined flood channel have been

constructed by the City of Aurora and have alleviated

the flooding problems in this area. Below the Highline

Canal, the construction of Lowry Air Force Base has

obliterated the historical Westerly Creek Channel. The

Kelly pond is inadequate to serve the total upstream

watershed. The Westerly Creek channel and flood plain

between Kelly Pond and Stapleton Airport have been great-

ly altered by development and encroachment. Existing

open channel sections and drainage structures have in-

sufficient capacity to receive even local tributary flows.

The drainage structure passing through Stapleton Airport

has capacity for only an 8-year storm event. A combina-

tion of detention pond storage and flood channel improve-

ments below Highline Canal was recommended by this report.

DRAINAGE BASIN CHARACTERISTICS

The Westerly Creek drainage basin is fully urbanized in the

lower reaches and is rapidly approaching a state of full

development in the upper reaches. This latter development

is characterized by the now typical new construction in the

Denver area; i.e., townhouses, condominiums., apartments, motels,

large shopping complexes, streets, parking areas, and highways.

This construction results in an increase of impervious surfaces,

which in turn causes increases in the quantity and rate of

runoff of stQrmwater flows -- flows which in large measure

formerly seeped into the ground and for which the rates of

runoff were formerly much lower. Flooding then results be-

cause of the inadequacy of existing conveyance facilities,

or the lack of conveyance facilities, in the lower reaches of

the basin.

Westerly Creek traverses a number of separate jurisdictions:

the City of Aurora, Lowry Air Force Base, the City and County

of Denver, and Stapleton International Airport, as well as

small portions of unincorporated Arapahoe County.

The Westerly Creek drainage basin (Drawing No.3) is a crescent
shaped area draining in a northwest-to-north direction to
its confluence with Sand Creek, a right-bank tributary of the
South Platte River. The headwaters of the watershed rise on
a low rolling divide between the Cherry Creek and West Toll
Gate Creek drainage areas. The basin is about 8.5 miles long,
3 miles wide at its widest point, and consists of 17.6 square