FLOOD08558

• County: Eagle
• Community: Gypsum
• Stream Name: Eagle River
• Basin: Colorado Mainstem
• Title: Hydrology Addendum FIS - Town of Gypsum, Eagle County
• Date: 10/1/2002
• Prepared For: CWCB
• Prepared By: Montgomery Watson Harza
• Floodplain - Doc Type: Floodplain Report/Masterplan

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STUDY AREA DESCRIPTION

Community Description
The Town of Gypsum is located in Eagle County in west central Colorado. The corporate limits
have an area of approximately 350 acres. Eagle County is bordered by Routt and Grand Counties
on the north, Garfield County on the west, Pitkin and Lake Counties on the south and Summit
County on the east. Elevations range from 6,300 feet to the northeast and 6,600 feet to the
southwest of the town limits. The Colorado Division of Local Government Demography Section
estimated the population of the Town of Gypsum as 3,654 while the population of Eagle County
is approximately 41,659. It is situated 7 miles west of the Town of Eagle and 6 miles east of the
confluence of the Eagle and the Colorado Rivers. Four streams are included in this designation:
Eagle River, Gypsum Creek, Hardscrabble Gulch, and an unnamed tributary to Gypsum Creek

Watershed Description
In Gypsum, the Eagle River is a large braided channel approximately 5 feet deep and 80 feet
wide. The slope is approximately 25 feet per mile. The floodplain, which is covered with
cottonwood trees and pasture lands, ranges in width from 250 to 1000 feet.

Gypsum Creek flows north from the mountains around Cottonwood Pass into the Eagle River at
U.S. Highways 6 & 24. At Gypsum, the channel is steep and shallow, with a slope of
approximately 100 feet per mile. It has a width of approximately 10 feet, and its depth is
generally between I and 2 feet. The streambed is silty and fairly straight with a few meanders in
the upper reaches of the study. The shallow floodplain, which is well defined in the upper
reaches, ranges in width from 100 to 400 feet. It is covered with thick brush and cottonwood
trees for most of the study area, with scattered brush and grass in the upper reaches. There are a
few residential dwellings in the floodplain upstream of the Denver and Rio Grande Western
Railroad and upstream of Trail Gulch Road

Hardscrabble Gulch includes a six square mile basin south of the Town of Gypsum. The origin
of the water body is adjacent to North Hardscrabble mountain located 5 Y, miles southeast of
town, Hardscrabble Gulch meanders to the northwest through a well defined channel for two-
fifths of its run. The downstream end of the gulch bottom is spread out in a large field before it
confluences with Gypsum Creek

The Unnamed Tributary to Gypsum Creek flows intermittently from the hills just west of
Gypsum, across a field and into Gypsum Creek. The narrow, deep channel is well defined in the
mountains and in the area just upstream from Gypsum Creek However, it is undefined through
the field.

(Note: Information for all water bodies, except Hardscrabble Gulch, from 1983 Flood Insurance
Study)

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