FLOOD05425

• County: Delta
• Community: Delta
• Stream Name: Gunnison, Uncompahgre River
• Basin: Gunnison
• Title: City of Delta Confluence Park Project
• Date: 10/1/1989
• Prepared For: Delta
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Floodplain Report/Masterplan

Local interests are concerned about the bank erosion
and channel stability of both the Uncompahgre and Gunnison
Rivers in the vicinity of the Confluence Park. These areas
were evaluated, and alternative stabilization techniques
were presented for local consideration.

An existing stockpiled lime fill material was evaluated
to determine its potential engineering properties and any
potential beneficial uses in the park environs.

Development of a non-motorized boat l,aunch on the
Gunnison River is another feature of the Confluence Park
plan. Questions relating to the most desirable
characteristics of a boat launch facility were addressed,
and the locally pr,aferred site was evaluated.

Development of the commercial portion of the site was
of concern to local planners since a sign~ficant portion of
this feature is within the lOa-year flood 'Plain. Although
the final version of the revised flood plain delineation was
not available during this study, the draft delineations
based on 1983 FEMA hydrology were provided.

4. Flood Problems,

Major floodim, in the City of Delta has been the result
of rapidly melting snow, sometimes augmented by general
rain, between May and August.

Historical references to floods on t:he Gunnison River
extend back to 1884. In that year, earlyhiqh temperatures
in May and June resulted in the largest known snowmelt flood
on this river. At Delta, the Gunnison River was reported to
be 10 feet above bankful stage, with a width of
approximately 0.75 miles.

The earliest reference to a flood on the Uncompahgre
River comes from s,attlers who founded Delt'a in the early
1800's. At that time, the Indian squaw, Chipeta, wife of
the famous Ute Chief Ouray, stated that within her lifetime
of about 50 years, she had seen the Uncompahqre Valley at
Delta "flooded from bluff to bluff,"

The largest nacorded flood on the Gunnison River
occurred on May 23, 1920, with a flow of 3~,700 cfs at
Delta. The 1884 flood is estimated to have been 50,000 cfs.

In 1984, the peak recorded flow in t.he Gunnison River
at Delta was 25,506 cfs, and the peak recorded flow at Delta
on the Uncompahgre River was 5,800 cfs. Both flows exceeded
the 100-year peak discharges (21,200 and 5,000 cfs
respectively) pres'anted in the December 1, 1983, FE~1A Flood
Insurance study for the City of Delta,

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