WSP12249

• File Number: 8240.200.10.B
• Description: UCRBRIP - Riverine Fish Flow Investigations
• Basin: Colorado Mainstem
• Date: 6/1/2004
• Author: CDOW
• Title: Riverine Fish Flow Investigations 2004
• Water Supply Pro - Doc Type: Publication

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2000

g 1200
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2001.
832 cfs

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2002~~ _ ,oo~
466 cIs
I 2003.
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2000 -
1026 cIs

800

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Median -
_831 cis

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Excedence frequency

Figure 10. Exceedencc frequency curve for annual minimnm flows IDr the Gunnison River
(Delta and Uncompahgre gages summed) for the period of record (19771.02003).

Dolores River

The Bedrock Gilge was located about 34 miles downstream of the study site in Big
Gypsum Valley, The highest annual peak recorded at Bedrock was 8,150 cfs in 1973. The
top five highest peak flows were all above 5,000 cfs and occurred prior to 1984 (Figure II),
Since 1984 the spring hydrograph of the Dolores River has been highly modified by McPhee
Reservoir which has a storage capacity of 381,000 acre feel. The median annual peak flow
for the 32-year Bedrock Gage history was 3,095 cfs. The annual peak in 1999 was 3, toO and
1,170 cfs in 2000 (Figure II). The annual peak was 522 cfs in 200 I, 388 cfs in 2002 and 323
in 2003, the lowest for the period of record.

Annual minimum flows recorded at the Bedrock Gage for 1999, 2000, 200 I, 2002
and 2003 were 32 cfs, 25 cfs, 24 cfs, 1.4 cfs and 6.4 cis respectively. The 32 year median
minimum flow was 22.5 cfs (Figure 12). The 40-day low-flows for 1999,2000,2001,2002
and 2003 were 48 cfs, 37 cfs, 39 cfs, 2.1 cfs and 14 cfs respectively.

A noticeable change appears in the hydro graph for pre- and post-McPhee Reservoir.
The median peak flow prior to 1984 was 3,660 cfs (18 years of records) and 2,060 for the
period 1984 to 2003 (19 years of records). The base flows have improved in the post period.
Prior to 1984 the median annual minimum flow was 4.3 cfs and the mean 40tlllowest mean
daily was 11,5 cfs. The median annual minimum from 1984 to the present was 32 cfs and 45
cfs for the mean 40th lowest daily flow.

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