FLOOD11729

• Designation Number: 118
• County: San Miguel
• Community: San Miguel and Unincorporated Areas
• Basin: Gunnison
• Title: FIS - San Miguel and Unincorporated Areas
• Date: 3/1/1978
• Designation Date: 11/1/1978
• Floodplain - Doc Type: Historic FEMA Regulatory Floodplain Information

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County, and on the west by the State of Utah. The population of the
surrounding areas of Placerville and Sawpit was estimated by the county to
be 240 in 1975 (Reference 1). The total population of San Miguel County has
been estimated to be 3000 (1970 census).

The prime economy of the county depends on mining and agricultural
activities. In the past six years, many changes have occurred within San
Miguel County, certainly not the least of which has been the development of
a major ski resort near the Town of Telluride. In addition, Colorado has
become the center of a new market for mountain homesites usually to be
used as second homes. The county has gradually moved toward a recreation-
based economy.

The annual precipitation in the Telluride area is approximately 27 inches, of
which 10 inches is in the period May through September. In the Placerville
area the- annual precipitation is approximately 16 inches, of which 6 inches is
in the period May through September. The annual mean temperature in the
study area is approximately 40 degrees Fahrenheit (F.) which varies from 20
degrees F. in January to 60 degrees F. in July. Humidity is generally quite
low which allows rapid evaporation (Reference 2). Generally, flooding
occurs during periods of melting snow in June; precipitation is generally
insufficient to cause floods except through cloudbursts.

Soils of the study areas in San Miguel County are Cryoboralfs-Rock Outcrop
Associations which are classified by the SCS as Hydrologic Soil Group D
(high runoff potential). Vegetation in this area consists of approximately 80
percent dense trees and 20 percent bushes which tend to slow down the
runoff potential (Reference 3).

The San Miguel River watershed near Telluride comprises approximately
42.4 square miles in area and consists of high mountainous terrain with steep
to moderately steep slopes. Elevations range from about 8,650 feet to
14,000 feet. The San Miguel River watershed at Placerville covers about
290 square miles. It also consists of high mountainous terrain with steep to
moderately steep slopes. The elevation at Placerville is about 7,300 feet.
The Leopard Creek watershed, which is a tributary of the San Miguel River
at Placerville, covers about 62 square miles and rises to an elevation of
approximately 9,800 feet. The Fall Creek watershed, which is also a
tributary of the San Miguel River near the Town of Sawpit, comprises
approximately 42 square miles and rises to an elevation of approximately
13,300 feet. Leopard Creek and Fall Creek flow through narrow canyons and
their watersheds consist of high mountainous terrain with steep to
moderately steep slopes. The Cornet Creek watershed, which is a tributary
of the San Miguel River, covers approximately 2.4 square miles and rises to
an elevation of approximately 13,300 feet. It consists of high mountainous
terrain with steep to moderately steep slopes.

Principal Flood Problems

The only severe floods in the San Miguel River basin for which definite
information is available before 1948 were those of September 5, 1909, and

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