FLOOD00158

• Designation Number: 123
• County: Adams
• County: Arapahoe
• County: Douglas
• Community: Denver Metro Region
• Stream Name: Little Dry Creek
• Title: Flood Hazard Area Delineation - Little Dry Creek, Adams & Jefferson Counties, Arvada & Westminster, CO
• Date: 6/1/1978
• Designation Date: 11/1/1978
• Floodplain - Doc Type: Floodplain Report/Masterplan

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From the confluence with Clear Creek, Little Dry Creek runs parallel to the
Colorado and Southern Railroad to Federal Boulevard. Just downstream from Federal, the
Colorado and Southern Railroad crosses Little Dry Creek on a fill with a 48" diameter
culvert to pass stream flows. Upstream from Federal the channel meanders through
residential and industrial properties. Only minor channel improvements have been made in
the reaches in Adams County and Westminster, and the channel does not appear to be
maintained.
In Arvada, upstream from Sheridan, residential developers have been required to
provide the City with 100 feet of right-of-way and the channel has been improved to carry
the 100-year flood. There are still a number of culverts placed beneath road crossings,
however, which restrict the channel capacity.
To the north of Little Dry Creek and west of Sheridan Boulevard, two tributaries
drain approximately 2.5 square miles and are detained by Lake Arbor before discharging
into the main stem of Little Dry Creek just west of Sheridan. The land in this tributary
area has rapidly developed and the tributary channels have been improved in some areas.
There are numerous places, however, where culverts with capacity insufficient for
conveyance of the 100-year flood have been installed.
The northernmost tributary into Lake Arbor, hereinafter referred to as Tributary
"B", rises east of Church Lake and flows along 84th Avenue, through two small detention
ponds, an irrigation lake, golf course, and behind residential properties before flowing into
Lake Arbor. For the most part, the channel is improved and regularly maintained.
Flowing into the west end of Lake Arbor is a small channel, hereinafter referred to
as Tributary "C", which follows the alignment of Pomona Drive before entering the Lake.
This channel is entirely underground west of Wadsworth Boulevard and has been improved
as a grass-lined channel east of Wadsworth.
Specific flooding problems on all study reaches are described further in the "Flooded
Areas" section of this report.

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HISTORIC FLOODING

There is little recorded information regarding past floods on Little Dry Creek.

There are no stream gaging records, no newspaper records, and few eyewitness accounts

of flood events. It seems likely that past floods have occurred but were not recorded

because of sparse development resulting in little or no damage.
Several complaints have been received by the Urban Drainage and Flood Control
District from residents of the area just west of Federal Boulevard in Adams County. A
representative of the District visited the problem area on June 10, 1975 and photographed
some of the flooding problems associated with the culverts beneath the railroad tracks and
Federal Boulevard, see Figures 1, 2, 3 and 4. No estimate of the peak flow of this flood
has been made, but the flooding problems shown in the photographs appear to be an annual

occurrence in this area.
Despite the seeming tranquility and insignificance of Little Dry Creek, a severe
flood hazard potential exists today in the lower reaches. Damaging floods have occurred
on other South Platte River tributaries in recent years and the same probability of occur-
rence exists on Little Dry Creek.