FLOOD00734

• Designation Number: 213
• County: Adams
• Community: Thornton
• Stream Name: Brantner Gulch and Tributaries
• Title: Flood Hazard Area Delineation - Brantner Gulch and Tributaries
• Date: 1/1/1983
• Designation Date: 5/1/1983
• Floodplain - Doc Type: Floodplain Report/Masterplan

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26

banks. This Reach is undeveloped for its full length with the

exception of two residential structures near Quebec street. The

present channel will contain the 100-year storm runoff within

its banks without flooding any inhabited structures along the

channel. A tin barn and a wooden barn are the only structures

affected by the 100-year flood in this Reach. High velocities

acting on unstable loamy soils may result in excessive erosion

of the channel. The culvert under Quebec Street does not have

the capacity to convey the 100-year flood.

This channel extends through the County Golf Course to the

Fairgrounds entrance road. Easterly from this point, the

channel is a deep open earth ditch on a flat grade with an

earth levee on the north and west side until it intersects the

South Platte River.

For the entire Reach, this channel is of insufficient

capacity to contain the 100-year flood. The flooding east of

Riverdale Road is widespread, inundating the County Race Track,

playground area and causing flood damage to the County Golf Club

building and related storage buildings. The 100-year flood also

damages many livestock exhibit buildings, two pump houses, and

the grandstand area of the County Fairgrounds. Areas inundated

as a result of flooding from the South Platte River are east of

the entrance road into the County Fairgrounds. These areas are

predominantly undeveloped.

Brantner Gulch from East Side of Quebec Street to East Side

of Riverdale Road (Sheets 7-10)

The Gulch through this Reach appears as a deep, narrow,

open earth channel on a moderate grade with steep side slopes.

In this Reach, land is undeveloped adjacent to the channel. The

present channel will contain the 100-year storm runoff within

its banks without a resultant flooding of inhabited structures.

A tin silo is the only structure affected by the 100-year flood

in this Reach. Culverts under East 128th Avenue and under River-

dale Road do not have sufficient capacity to pass the 100-year

flood.

Flooding from Brantner Gulch and the South Platte River

extends south of Henderson Road (south of the County Golf Course

and Fairgrounds) into a low-lying farmland area. The flow from

Brantner Gulch crosses Henderson Road between Riverdale Road and

the entrance road to the County Fairgrounds. A shallow depth of

flow is expected to cross Henderson Road and significant damage

to the roadway is not anticipated.

Brantner Gulch from East Side of Riverdale Road to the South
Platte River (Sheets 10-14)
The Gulch channel east of Riverdale Road consists of a
concrete-lined ditch on a moderate grade with steep side slopes.

Brantner Gulch Tributary V (Sheet 15)

The upstream end of Tributary V consists of Eastlake Dam

and Reservoir No.3, with an earthen dam approximately 9 feet

high. This dam presently contains irrigation water for local