FLOOD08202

• County: Statewide
• Basin: Statewide
• Title: Western Colorado Flood Potential
• Date: 9/25/1997
• Prepared For: CWCB
• Prepared By: USGS
• Floodplain - Doc Type: Flood Documentation Report

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Above 7,500 feet, rainfall runoff has not produced substantial out-of-bank
flooding. Rainfall runoff, like NW Colorado areas, is limited to localized
summer thunderstorms, however, larger rainfall amounts and larger peak
discharges have been documented (e.g., Sweetwater Creek in 1976; -7,400
ft3/s from about 4.5 mi2).

3. SOUTHWEST COLORADO (SW) This area covers the San Juan, Animas, and
Dolores River basins (figure 1) I have included the headwaters of the Rio
Grande basin, which historically has had rainstorms and flooding similar to
the San Juan basin (e.g., 1911). The San Juans are subject to major flow
of moist air in the summer and fall. This area differs from the NW and W
Colorado areas because of moisture enter the area that can and have produce
major, widespread rainfall in the late summer and fall, but at a much lower
intensity (e.g., 1911 and 1970). Major widespread flooding has occurred on
several occasions in the past 100 years. Localized convective rainstorms
also occur and have produced localized flash flooding, but smaller peak
discharges than in western Colorado. Some of the largest 24-hour
precipitation amounts in southwestern Colorado have occurred as snowfall in
the higher mountains such as at Wolf Creek Pass; the largest are labeled as
snow-water equivalent on figure 2.

Figures are being faxed separately. If you have any questions, let me know
(303-236-6447). I will out of the office 9/29 through 10/2

best regards,

Bob Jarrett

Robert D Jarrett
"capt'n flood"
U.S. Geological Survey
Box 25046, MS 412
Denver, CO 80225

Phone: [phone]
Fax: [phone]
Internet: [e-mail]

Printed for r'arrett@servrcolkr (Bob Jarrett)

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