FLOOD01357

• Designation Number: 107
• County: Jefferson
• Community: Unincorporated Jefferson County
• Stream Name: Green Mountain Area
• Title: FHAD - Green Mountain Area
• Date: 4/1/1978
• Designation Date: 7/11/1978
• Floodplain - Doc Type: Floodplain Report/Masterplan

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The flood plain for Drainageway G-3 is also shown on Sheet 43. The

I, Drainageway J
Drainageway J (which is known as Rooney Gulch) is a left bank
tributary to Bear Creek one mile below the Town of Morrison. The channel
drains the southwest flank of Green Mountain and the hogback area adjacent

channel in the lower portions of the reach consists of a shallow V-shaped
section which disappears in the upper reaches. The flood plain is not
contained within the channel area and meanders across the residential

area with shallow flood depth. The flows combine with the flows in
Drainageway G at 7th Avenue, resulting in shallow flooding north of 7th

to the gul ch.

1. ~_atio~ 271-+00 to O+OO_~ Ups_tt:..e:1m_ ~_t:\J.QLL(mits to Bear Creek
ConfJuence [Sheets 47 to 56)

The channel in this reach, designated Drainageway J, is the main

Avenue.
The flood hazards in the reach consist of erosion, debris removal and
cleaning, content and structural damage to the residences, interrupted
traffic and services, and a low life hazard due to the shallow flooding.

channel for Rooney Gulch. In the lower portion of the reach from Morrison

Road to the confluence, the channel is a natural broad parabolic shaped

The channel in the lower reach (average slope of 1.3%) consists

section with minor amounts of meandering, obstructions, and vegetation. The
channel has an average slope of 1% in this reach. In the reach from Alameda
Parkway to Morrison Road, the channel cross section is an incised trapezoidal
shape with moderate to appreciable amounts of meandering, obstructions and
vegetation. Three stock ponds (Station 94+00, 102+50, and 193+20) have
been constructed in the channel with inadequate capacity earthen spillways.

H. Drainageway H
Drainageway H is a right bank tributary to Lena Gulch at Orion Street
draining the north flank of Green Mountain.
1. Station 39+00 to 0+00, 1-70 to Confluence (Sheets 45 & 46)

of a shallow ditch along Orion Street, with a small detention pond in the

Pleasantview Recreation District Park. Above US-40, the channel consists of

The channel immediately above the ponds is heavily choked with vegetation,

shallow flooding,
The flood hazards in this reach consist of erosion, debris removal

The channel has an average slope of 1.5% in this reach.
In the reach above Alameda Parkway, the channel cross section is an
incised trapezoidal shape with minor amounts of meandering, obstructions and
vegetation. Two stock ponds (station 211+25 and 250+80) have been constructed
in the channel with inadequate earthen spillways, The lower pond has been
breached and the upper pond is in danger of being breached during minor
floods. The channel in this reach has an average slope of 2.5%.

a poorly defined, broad V-shaped section, with an average slope of 3.9%.
Inadvertent detention occurs at the drainageway crossing of US-40 and

6th Avenue, which significantly reduces the 100 year flood peaks. Due to

the lack of adequate channel capacity, the flood covers a broad area with

and cleanup, interrupted traffic and services, structural and content
damage to the residences, and a low life hazard due to the shallow flooding.

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