PROJ00538

• Contract/PO #: C153581
• Contractor Name: Minnesota Canal and Reservoir Company
• Water District: 0
• County: Gunnison
• Bill Number: XB 99-999
• Loan Projects - Doc Type: Feasibility Study

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TABLE 6.1
STORM EVENTS
Precipitation (inches)
Recurrence Storm Duration
Interval
(Years) 6 Hours 24 Hours
50 1.8 2.6
100 2.0 2.8
Reference: (NOAA, 1973)

The Probable Maximum Precipitation (PMP) for the project site has been estimated using
analytical methods proposed by the National Oceanic and Atmospheric Administration (NOAA,
1986). PMP calculations were performed for the project site drainage basin for the months July,
August, and September. These three months represent the summer months where maximization
of the PMP is most likely. The" general storm" PMP (convergence PMP and orographic PMP)
Cor various durations is presented in Table 6.2. Derivation of PMP estimates are provided in
Appendix e.

TABLE 6.2
GENERAL STORM PMP (SEPTEMBER)
Duration (hrs) 6 12 18 24 48 72
PMP (in) 4.6 6.6 8.1 9.3 12.6 14.1

The time sequenced "local storm" PMP, as which may be generated during localized
thunderstorm events, is provided in Tables 6.3 and 6.4.

TABLE 6.3
THUNDERSTORM INCREMENTAL PMP
Duration (min) 15 30 45 60
Incremental PMP (in) 4.8 1.2 0.5 0.4

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