FLOOD01643

• Designation Number: 517
• County: Denver
• Community: Denver
• Title: Flood Insurance Study - Denver, Volume I
• Date: 9/1/1998
• Designation Date: 5/1/2000
• Floodplain - Doc Type: Floodplain Report/Masterplan

area. Until recently, the First Creek and First Creek Triblltary
floodplains were entirely agricultural.

No specific information regarding higtoric flood magnitlldes or
extent of flooding and damages is available for Coon Creek,
Lakewood Glllch, West Harvard Gulch, and Dry Glllch (Harvard Glllch
Triblltary).

2.4 Flood Protection Measures

There are numerous dams,
within the South Platte
protection measures affect
flow through Denver.

reservoirs, and channel
River Basin. Many of
flood peaks on the flooding

improvements
these flood
sources that

In addition to an active floodplain management program, the major
flood protection measures, by basin, are listed below:

South Platte River

The Chatfield Dam and Lake along the South Platte River were
authorized for construction by the 1950 Flood Control Act. The dam
is located on the South Platte River just downstream from the mouth
of Plum Creek, south of Denver. The reservoir has a storage
capacity of 385,000 acre-feet, including 215,000 acre-feet for
flood storage and 20,000 acre-feet for sediment control. The
project provides a high degree of protection for metropolitan
Denver and for extensive agricultural lands downstream
(Reference 4).

Clear Creek

There are 11 major reservoirs in the lower Clear Creek basin, 3 of
which, Ralston Reservoir, Maple Grove Reservoir, and Leyden Lake,
are on-stream and provide some residual flood control effects down-
stream from each site. None of these reservoirs has a specific
flood control function.

Ralston Reservoir, located west of Denver and northwest of the City
of Golden, was built in 1938 by the City and County of Denver. It
receives water from Ralston and South Boulder Creeks and is uged
for municipal water supply. The outlet works deliver water to the
Moffat Treatment Plant and have the capability of forcing the
natural inflow back into Ralston Creek. Although Ralston Reservoir
is not operated for flood control purposes, there is approximately
2,400 acre-feet of gtorage available between the primary spillway
crest at elevation 6,046.0 feet and the top of the dam at elevation
6,060.0 feet. This storage provides incidental flood control.

Maple Grove Reservoir, which is located on Lena Gulch in the City
of Lakewood, is owned by Consolidated Mutual Water Company and is
used for municipal water-supply storage. The reservoir provides
some attenuation of flood peaks. Approximately 452 acre-feet of

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