FLOOD10363 ‎(2)‎

• County: Gunnison
• Community: Gunnison County
• Stream Name: East River, Cement Creek, Alkali Creek, Ohio Creek
• Title: Gunnison County Flood Hydrology, Contract # W99-D-0018 Final Report
• Date: 11/1/2004
• Prepared For: US Army Corps of Engineers, CWCB and Gunnison County
• Prepared By: Tetra Tech, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Figure 2.1
Figure 2.2
Figure 4.2.1

Figure 5.1.3.1
Figure 5.2.2.1

Figure 5.2.3.1
Figure 5.3.3.1
Figure 5.4.3.1
Figure 5.5.2.1

Figure 5.5.3.1
Figure 5.6.3.1
Figure 5.7.3.1
Figure 5.8.2.1
Figure 5.8.3.1
Figure 5.9.2.1
Figure 5.9.3.1
Figure 5.10.2.1
Figure 5.10.3.1
Figure 6.2.1
Figure 6.2.2
Figure 6.3.1

Table ES.1
Table 1.1
Table 2.1
Table 2.2
Table 2.3
Table 2.4
Table 4.2.1
Table 5.1.3.1

Table 5.2.3.1

Table 5.3.3.1

Table 5.4.3.1

Table 5.5.2.1

Table 5.5.3.1

Table 5.6.3.1

Table 5.7.3.1

LIST OF FIGURES

General Map of Study Area.... ............... ........... ............... ......... ........... ........... ........... ......3
Detailed Map of Study Area..... ......................... ............... .......... ............ ..... ....... ...... ........4
Comparison of Regulated vs. Unregulated Instantaneous Peaks at Taylor River

below Reservoir............................................................................................................ 13

Reach 2 - Flood Frequency Analysis Results.................................................................16
Reported Peak Flow as a Ratio of the Reported Daily Average Flow - East River
near Crested Butte and Slate River near Crested Butte .................................................18
Reach 3 Flood Frequency Analysis Results ................................................................. ..20
Reach 4 Flood Frequency Analysis Results ................................................................. ..23
Reach 5 - Flood Frequency Analysis Results................................................................25
Reported Peak Flow as a Ratio of the Reported Daily Average Flow - East River

at A1mont ..................................................................................................................... .27
Reach 6 - Flood Frequency Analysis Results.............................. ............................ ..... .29
Reach 7 - Flood Frequency Analysis Results................................................................32
Reach 8 - Flood Frequency Analysis Results............................................................... .35
Peak to Daily Flow Relationship - Gunnison River near Gunnison Gage .......................37
Reach 9 - Flood Frequency Analysis Results................................................................39
Peak to Daily Flow Relationship - Taylor River at Almont ..............................................41
Taylor River at A1mont - Flood Frequency Analysis Results ..........................................43
Peak to Daily Flow Relationship - Taylor River below Taylor Park Reservoir .................45
Taylor River below Taylor Park Reservoir - Flood Frequency Analysis Results..............47
Pattern Hydrograph for 1997 Snowmelt Runoff Event....................................................49
One Percent Chance Exceedence Balanced Hydrographs ............................................51
Reservoir Operation Model Results for Starting Water Surface Elevation of 9,328

feet.......................................................................................................................... .... .55

LIST OF TABLES

Flood Frequency Analysis Results.................................................................................. vi

Study Reaches...................................................................................... ..........................1
USGS Gages Referenced for this Hydrology Study .........................................................5
Average Daily Temperatures in Gunnison County (in degrees Fahrenheit) ......................6
Annual Precipitation (inches)................. ..........................................................................6
Average Monthly Rainfall in Gunnison (inches) based on 30 Years of Data .....................6
Gage Correlation Information....................................................................................... .11
Flood Frequency Analysis Results for Reach 2 Slate River above Confluence

with the East River........................................................................................................ 15

Flood Frequency Analysis Results for Reach 3 - East River from Slate to Cement

Creek............................................... .............................................................................1 9
Flood Frequency Analysis Results for Reach 4 - East River from Cement Creek

to Alkali Creek.............................................................................................................. .22
Flood Frequency Analysis Results for Reach 5 - East River from Alkali Creek to

Almont ......................................................................................................................... .24
Estimated Peak Flow Record for Reach 6 - Gunnison River below the
Confluence of the East River and Taylor River...............................................................27
Flood Frequency Analysis Results for Reach 6 - Gunnison River from A1mont to

Ohio Creek................................................................................................................... .28
Flood Frequency Analysis Results for Reach 7 - Ohio Creek upstream of the
Confluence with the Gunnison River........ .............................. ........ ......... ............ .......... .31
Flood Frequency Analysis Results for Reach 8 - Tomichi Creek from Confluence
with Gunnison River to Upstream of Gunnison Airport ...................................................34

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