FLOOD05505

• County: Gunnison
• Community: Gunnison County
• Stream Name: Gunnison River, Tomachi Creek
• Basin: Gunnison
• Title: Floodplain Information Report
• Date: 12/1/1976
• Prepared For: Gunnison County
• Prepared By: ECI
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

I
I
I
I
I
I
I
I
I

Characteristics of Different Reaches

I
I
I
I
I

The study reaches for Gunnison River and Tomichi Creek are

shown on the Index Map, (Plate '2). The Gunnison River reach extends

from the bridge across Gunnison River on Colorado Highway 135 to McCabe

Bridge located approximately 1.6 miles downstream from Tomichi Creek

confluence with Gunnison River. The Tomichi Creek reach extends from

the point of its confluence with Gunnison River to its upper limits

represented by a point approximately 500 feet downstream from New Mexico

Principal Meridian. The lengths of the two reaches are approximately

7.6 and 4.9 miles for Gunnison River and Tomichi Creek, respectively.

The stream valleys in the study reach are generally charac-

terized by broad plains extending between hills. These plains vary in

width, and are in excess of 2 miles wide at certain locations. Alluvial

lands on the flood plains along streams consist primarily of material

recently deposited by streams. The texture is widely variable and

commonly has very cobbly or stony areas interspersed throughout. These

lands are subject to erosion from floods and changes in stream channels.

The streams have the tendency to meander, especially Tomichi Creek.

Future floods are likely to shift the river channel as it has in the

past.

I
I
I
I
I

The historical use of the flood plain has been for range and

wildlife with limited improvements confined to dwellings and other

structures supporting ranching activities. Irrigated pastures on these

plains have good plant cover and support meadow vegetation, willows and

narrow leaf cottonwood. Small areas within the floodplain are flooded

annually and support little or no vegetattion. The growth of Gunnison

in recent years has forced greater development in the flood plain par-

ticularly along Gunnison River in the western part of the city and in

the vicinity of Dos Rios Island. With this increased encroachment of

development in the floodplain, the flood hazard to the community is

increased and will continue in the future unless adequate measures are

adopted to keep the development outside the flood hazard areas.

Obstructions to floodflows within the study reach include both

natural obstructions such as vegetation growth, fallen trees, ice jams,

12