FLOOD00197

• County: Hinsdale
• Community: Lake City
• Stream Name: Henson Creek
• Title: Reconnaissance Study Henson Creek at Lake City
• Date: 11/1/1991
• Prepared For: Lake City
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Floodplain Report/Masterplan

boulders. The ban~: protection is weakest in the area where
floodwaters escapecl the bank in 1975.

This side of t:he creek has not experienced: as much erosion
and flooding; the natural soil bank appears rea.sonably stable.
The right bank is composed of natural ground, partly vegetated,
with no rock protection and no discernible flood control.

In 1985, Lake City (via a consult:ing engin.eering firm)
completed a report titled "Henson Creek Flood Control
Improvements, Lake City, Colorado." The report. included a
preliminary design for flood control works. The proposed plan
has not been implemented by Lake City, since the city requested
that the plan be rewiewed by the Corps and modified as needed to
account for all pot.ential flood problems.

The preliminary flood insurance s.tudy for Hinsdale County,
which includes the study reach, was completed in 1986 for the
Federal Emergency l'-:anagement Agency (FEMA). The study provides
preliminary results of hydrology and hydraulics, which were based
on the aforementior'.ed study for Lake city.

6. Flood Problems. Most of the annual floodflows on Henson
Creek result from Iapid melting of the snowpack in the high
mountain basins whi.ch comprise the majority of the drainage area
for the creek. Peak flows occur primarily from May through early
July. Snowmelt may occasionally be augmented by rain. Periods
of thunderstorm activity, however, normally occur dl.lring the
summer after the spring snowmelt has ended.

It has been stated by some residents that Henson Creek's
original course was, a straight alignment to Lake Fork of the
Gunnison River as the creek exited Henson Creek Canyon. During
the early 1900's, t,he channel was realigned to make room for
contiguous development of the downtown area on the left overbank
of the channel. The channel realignment consisted of curving the
creek to the right as it exited the canyon, then continuing on a
more or less straight course to intersect the :Lake Fork of the
Gunnison River at a right angle as it presently does. Flood
problems and current concerns relate to that segment of the
channel as it exits the canyon and curves t:o the right.

Flooding from Henson Creek would most likely occur when high
flows overtop the north (left) bank about 600 feet upstream of
the Gunnison Avenue (Highway 149) bridge (Plate 2). The water
would escape the bank due to a low profile of the left bank and
the curvature of the channel to the right at that point. After
escaping the bank, the water would disperse into a sheet flow as
it approached the lower elevations where the bulk of the
vulnerable structures and goods are located. Floodwaters would
continue in a sheet flow until reaching 1:he Lake Fork of the

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