FLOOD06561

• County: Montrose
• Basin: San Juan/Dolores
• Title: Hydrology Addendum Montrose County
• Date: 11/1/2000
• Prepared For: Montrose County
• Prepared By: CWCB
• Floodplain - Doc Type: Floodplain Report/Masterplan

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STUDY AREA DESCRIPTION

Community Description
Montrose County is located in southwestern Colorado. The county is bordered by Delta County
on the north, San Miguel and Ouray Counties on the south, Gunnison County on the east and the
state of Utah on the west. Montrose is the County Seat of Montrose County. The population of
Montrose County was estimated at 24,423 in 1990 and 32,407 in 1999, corresponding to a
growth rate of 3.1 percent (Colorado Division of Local Government Demography Section). The
area mapped in the FIRMs includes the entire county except the incorporated communities of
Montrose, OIathe, Nucla and Naturita.

Watershed Description
Montrose County is located on the western slope of the Continental Divide in both the Gunnison
and Dolores River basins. The western portion of the county is within the Dolores River basin,
which includes the San Miguel River sub-basin, while the eastern portion of the county is within
the Gunnison River basin, which includes the Uncompahgre River sub-basin. The basins are
generally separated in the county by the Uncompahgre Plateau.

The Uncompahgre River originates on the northern slopes of the San Juan Mountains. The
Uncompahgre flows north through the central portion of the county, including through Montrose
and OIathe, The Gunnison River originates on the west slope of the Sawatch Range, southern
slopes of the Elk Mountains and the northern slopes of the San Juan Mountains. The Gunnison
River flows southeast to northwest through the northeast comer of the county. The confluence of
the Gunnison and Uncompahgre occurs in Delta County. Elevations of the watersheds range
from approximately over 14,400 feet to approximately 5200 feet as the Uncompahgre leaves the
county. The watershed primarily consists of forested lands in the higher elevations and irrigated
agriculture in the lower elevations along the Uncompahgre. Higher undeveloped areas consist of
scrub oak, sagebrush, cedar and ponderosa pine. Lower undeveloped areas consist of scrub oak
and sagebrush with cedar and cottonwood in drainageways.

The Dolores and San Miguel Rivers originate within Dolores and San Miguel Counties along the
western slopes of the San Juan Mountains. The Dolores River generally flows from south to
north through the western third of Montrose County. The Uncompahgre River flows from
southeast to northwest through the southwestern portion of the county to its confluence with the
Dolores River north of the Paradox Valley. There are several other small tributary streams to the
Dolores River within the County. Elevations of the watershed range from over 14,200 feet in the
San Juans to approximately 4700 feet on the floor of Dolores Canyon as it leaves Montrose
County. Higher elevations in the watershed are primarily undeveloped forested lands consisting
of aspen, lodgepole pine, spruce, grass meadows and steep rock faces, There are also remnants
of mining activities in the area, which primarily occurred in the late 1800's and early 1900's.
Lower elevations of the watershed primarily are primarily undeveloped areas consisting of scrub
oak, pinon, cedar and ponderosa pine, with cottonwood in drainageways. McPhee Reservoir is
located on the Dolores River in Montezuma County, However, according to officials with the
Dolores Water Conservancy District, McPhee Reservoir does not provide flood control storage
for the Dolores River.

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