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

I

I
I
I

I
I
I

I
I
I
I
I

I
I

I
I

I
I
I

Completion of this study also includes an independent technical review (ITR) and adherence to a quality
control plan (QCP).

2.0 STUDY AREA

Gunnison County is located in the southern central portion of Colorado in a valley surrounded by the
Sawatch Range to the north and east and the San Juan Mountains to the south and west. Blue Mesa
Reservoir is located at the downstream end of the county and the Black Canyon of the Gunnison National
Park is just downstream of Blue Mesa Reservoir. The study area is shown on Figure 2.1 with reaches
shown on Figure 2.2. USGS discharge gages used in this study are also shown on Figure 2.2 and listed
in Table 2.1. Photographs of the study area are included in Appendix E.

The basin extends from an elevation of 7,600 feet in the valley to an elevation of 14,000 feet in the
headwaters. The higher elevations within the watershed receive significant snowfall while the valleys are
semi-arid and receive little precipitation. Climate statistics are summarized in Tables 2.2 through 2.4. Due
to the snowfall-dominated climate, peak flows in the study reaches are influenced primarily by snowmelt
runoff. Data trends indicate there is very little inflow resulting from rainfall events in the valleys.

The Taylor Park Reservoir storage facility is the only major reservoir located in the study area and has a
storage capacity of 106,200 acre-ft at the spillway elevation. This is a Bureau of Reclamation irrigation
storage unit for the Uncompahgre Valley. The dam and reservoir were completed and storage began in
1937.

2