FLOOD00457

• County: El Paso
• Community: Colorado Springs and Manitou Springs
• Title: Paleohydrologic Flood Investigations for Streams in Manitou Springs and Colorado Springs
• Date: 12/3/1987
• Floodplain - Doc Type: Flood Documentation Report

peak discharge for recent flows is estimated to be 160 cubic feet per
second.
Wellington Gulch joins Fountain Creek at an elevation of 7,520
feet and has an estimated drainage area of 1.5 square miles. There
are no significant flood deposits or flood debris in the channel. The
channel is about 2 feet wide and less than 2 feet deep. The stream
banks are covered with grass and small willows. Recent discharges
have been less than 40 cubic feet per second. This lack of flood
evidence indicates that flows have not exceeded the erosion threshold
discharge of 200 to 300 cubic feet per second for 100 years or more.
Just upstream from Highway 24 is a gravel pit that completely covers
the floodplain. If significant streamflow were to occur, it would
disrupt the mining operation. Has gravel mining been di,srupted?
Sand Gulch joins Fountain Creek at an elevation of 7,550 feet and
has an estimated drainage area af 145 square miles. There is no
significant flood deposits or flood debris in the channel. The
channel is about 2 feet wide and about 1 foot deep. The stream banks
are covered with grass and indicate very minor bank erosion. The
recent peak discharges have been less than 20 cubic feet per second.
This lack of flood evidence indicates that flows have not exceeded the
erosion threshold discharge of 200 to 300 cubic feet per second for
100 years or more.
At an elevation of 7,800 feet, Fountain Creek has an average
channel width of 8 feet. The banks are well covered with grass and
moss and channel boulders are well covered with lichen to about 2 feet
above the streambed. Recent peak discharges probably have been less
than 160 cubic feet per second. There is no flood evidence higher in
the channel. The drainage area upstream from here is estimated to be
8 square miles. The maximum peak discharge in Fountain Creek probably
has been less than 800 cubic feet per second (Figure 5, for 8 square
miles times 100 cubic feet per second per square mile).

Summary of Previous On site Paleohydrologic Investigations

Because of the catastrophic 1965 flood which centered on the
Palmer Divide, John Costa, then Professor at the University of Denver
(currently with the U.S. Geological Survey. Vancouver, Washington)
and Robert Jarrett conducted paleohydrologic investigations as part of
the Colorado district's flood hydrology study (Jarrett, 1987). The
purpose of these onsite investigations was to visit mountain channels
to search for stratigraphic and geomorphic evidence of catastrophic
flooding. One area of concentrated study was in the tributaries to
Plum and Monument Creeks. These studies indicated that large floods
left easily identifiable deposits of the magn~tude and frequency of
flooding in mountain channels. It was during this fieldwork that
paleoflood investigations became identified as a tool to compliment
conventional streamflow-gaging station records in identifying an
elevation limit of rainfall flooding in Colorado. Only the pertinent
information of those studies is summarized here. That being that
large floods have occurred in all foothill basins but that there is an
elevation limit to this flooding and needs to be summarized

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