FLOOD04244

• County: Ouray
• Stream Name: Uncompahgre River
• Basin: Gunnison
• Title: Hydrology Addendum to FIS Ouray County Unincorporated Areas
• Date: 7/3/1985
• Prepared For: Ouray County
• Prepared By: Montgomery Watson
• Floodplain - Doc Type: Floodplain Report/Masterplan

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drains the east side of the basin, Dallas Creek confluences with the Uncompahgre River just
north of the community of Dallas while the Cow Creek confluence is located approximately 5
miles farther north, Pleasant Valley Creek is a tributary to Dallas Creek with the confluence
point being near the intersection of County Roads 1 and 24, approximately 3 miles northwest of
Ridgway,

Floodin!!: Problems and Floodin!!: Historv
The 1985 PIS concludes that floodflows on the Uncompahgre River are typically the result of
snowmelt between the months of May and early July, The snowmelt is occasionally augmented
by rainfalL Streams tributary to the Uncompahgre River within the County are subject to
cloudburst-type flooding but all drain relatively small basins not large enough to significantly
impact peak flows on the Uncompahgre,

USGS gaging stations along the Uncompahgre River have intermittent records from 1903 to the
present. The highest peak flows recorded on the river in that period occurred in early June of
1921 when a flow of 2,000 cfs was recorded at Ouray, 2,400 cfs below Ouray and 4,080 cfs at
Colona near the Montrose.Ouray County line, Other major flooding events reported in the 1985
PIS that resulted in damage in and near the Town of Ouray occurred in August 1909, July 1927,
July 1929, July 1965 and July 1973,

The largest flood recorded on Dallas Creek occurred in July of 1999, The recorded discharge of
3,960 cfs was approximately 3,5 times greater than the previous maximum discharge recorded in
1923, The flood event of 1999 caused significant damage upstream of the Town of Ridgway.

Discharge records exist for Cow Creek but are limited to 18 years between 1956 and 1973, The
highest peak flow recorded during that time frame was 1,360 cfs in June of 1957. Flows close to
this in magnitude also occurred in June of 1968 and 1973, The extent of damage that resulted
from these events, if any, is unknown,

Previous Studies
The July 3, 1985 PIS is the first flood insurance study canied out for Ouray County, Colorado
and has not been revised since its issuance,

Community Response to the CWCR Desi!!:nation and Approval Process
A letter from the CWCB was transmitted to Ouray County regarding the Board's proposed action
for designation and approval of the Ouray County PIS, The County was receptive to the Board's
proposed designation action and provided information on deficiencies and needs relative to the
effective PIS,

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