FLOOD10395 ‎(2)‎

• County: Montezuma
• Community: Dolores
• Stream Name: Dolores River
• Title: Dolores River near Dolores, Colorado, Flood Insurance Study
• Date: 5/1/2004
• Prepared For: Dolores
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Floodplain Report/Masterplan

Mountain, 13,232 feet, in the La Plata Mountains on the southern rim. See Plate 2 for locations

and Plate 3 for stream profiles.

5.3 Geology and Soils. The Dolores River is a tributary ofthe Colorado River Basin. Its

headwaters are in the San Miguel and La Plata mountains of the San Juan Range. The basin is

located in the east-central portion ofthe Colorado Plateau physiographic province. The area is

characterized by northwest trending linear features (the Paradox fold and Dolores anticline),

which are deeply dissected by tributaries ofthe Colorado River.

The stratigraphy of the Colorado Plateau consists of a Precambrian basement of igneous

and metamorphic rocks, followed by a moderately thick sedimentary sequence of marine and

continental sandstones, shales, mudstones, and evaporates ranging in age from Cambrian to

Cretaceous, igneous rocks of Tertiary Age, and unconsolidated sediments of Quaternary Age.

5.4 Climate. The Dolores River Basin area. is semiarid, and is characterized by low

precipitation and humidity, abundant sunshine, a f'a;irly wide daily temperature range, and

moderate south to southwest winds. Typically, clear skies and relatively high elevation of the

area result in warm days and cool nights during the spring, winter, and fall. Maximum daytime

temperatures vary from about 32-40 degrees Fahrenheit in January to 80-90 degrees in July, with

corresponding nighttime minimums ranging from below 0 degrees to around 50 degrees. See

Table 1 below for a tabulation of average monthly temperatures.

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