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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ror three consecutive years (t 997, t 998 and 1999) base flows were very high, They
represented a period when habitat or !lows were clearly not a limiting factor in the IS-Mile
Reach for nati ve fish. Base !low were moderate in 2000 and 200 I, but not considered
ecologically problematic. The year 2002 was the only year when tlows were low for most of
the summer. Base flows were again near nonnal in 2003 (Figure 8). Aberrations in the fish
community during 2003 were generally assumed to be due to the 2002 drought.

1800 ]-.
1600 .
1400
1200
~
~
E 1000
, 8001
E
c
,.
.. 600 r=
,
0
0
"
400 .
200
0
0 0.1 0,2 0.3

AnIlUClI tnmflllmflow PalISade gage, 1991 102003

1999.
435 cis

-1

2UOJ.
209 cts

2000 -
543 cis

2001.
477cfs
1

Media,..
550 cftJ

0.4

0.5

0.6

0,&

0,9

0.7

Exceedence Frequency

rigure 8. Exceedence frequency for annual minimum flows at the Palisade Gage, Colorado
River for the period of record (1991-2003).

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Gunnison River (Delta Gagel Uncompalrgre Gage)

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The USGS Gage at Delta is located about five miles downstrean1 of Austin and below
the Hartland Diversion. Hartland removes about 30 to 50 cfs from the river so flows at
Austin are likely somewhat higher than recorded at Delta, The period of record lor the Delta
Gage is from 1997 to the present. Flows from the Delta and the Uncompahgre River gages
were summed to represent flows for the two sites downstream.

Peak flows have declined significantly in the GUlUlison since the t 950s (~1cAda
2003). The median annual peak at the Whitewater Gage for the 95-year period of record is
11,750 cfs. Prior to completion of the Blue Mesa project in 1965 the median peak !low was

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