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 entire channel on Drainageway J has adequate capacity to
contain the IDO year flows with overflows only occurring as a result of
stock ponds or roadway embankments. The flood hazards in the reach

Drainageway J-2 has an incised channel from the confluence to the

consist of erosion, debris removal and cleanup, washout of the stock pond

stock pond at Station 11+1D. The slope in this reach is approximately
4.4%. The drainageway from the stock pond to Station 57+00 is a broad
expanse of sheet flow with minor discontinuous channels with depths of
1 to 3 feet. The channel crosses Alameda Parkway in this reach. The

embankments, interrupted traffic and services, inundation of the small

structures near Station 116+00, and a moderate life hazard due to the

to Confluence

drainageway slope in this poorly defined reach is 3.2%.
The upper portion of Drainageway J-2 has an incised trapezoidal
to V-shape, with adequate capacity to contain the 100 year discharge.
The slopes in this reach vary from 5,0% to 25%. Drainageway J-3 has
a very incised V-shaped channel adequate to convey the 100 year flood.
The slopes range up to 23%.
The flood hazards in this reach consist of erosion, debris removal

high velocity, deep channel flows.

The channel in this reach, designated Drainageway J-1, is
tributary to Rooney Gulch (Drainageway J) at Station 259+00 near Rooney
Road. Drainageway J-1 has a westerly aspect and the channel section is
generally an incised V-shaped except for the alluvial fan immediately
above the Rooney Road crossing. Dense shrubbery crosses the channel in a

and cleaning, interrupted traffic and services, and a low to moderate

few places in the upper reaches causing the flow to spread; otherwise,

life hazard due to the shallow high velocity flow.

the 100 year flows are contained within the channel. Channel slopes
vary from 3,7% near Rooney Road to 20% in the upper reaches,

J, Drainageway K

Drainageway K is a left bank tributary to Bear Creek about 3/4 mile

below the Bear Creek Dam. The channel drains the south flank of

The flood hazards in the reach consist of erosion, debris removal

high velocity flow,

3. Station 106+00 to 0+00, Upstream Study Limits to Confluence
with Drainageway J (Sheets 59 to 63)

Green Mountain and a portion of the Green Mountain Subdivision Filings

below Alameda Parkway.

1. Station 206+60 to 53+00, Upstream Study Limits to Morrison Road
(Sheets 64 to 69)

and cleaning, and a low to moderate life hazard due to the shallow,

The channel in this reach, designated Drainageway J-2, is

The lower portion of Drainageway K has a broad parabolic channel
with a slope of 2,4%. This portion of the drainageway contains a trickle
channel with only minimal flow capacity, Above the confluence with Drainageway
K-1 (Station 78+00) to Alameda Parkway, the channel is a very incised
trapezoidal shape with an average slope of 3.0%,

tributary to Rooney Gulch (Drainageway J) at Station 154+00. A small

branch of Drainageway J-2, designated Drainageway J-3, is also included
in this reach (Sheet 63),

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