9556

• UCREFRP Catalog Number: 9556
• Author: Bestgen, K. R., K. A. Zelasko and C. T. Wilcox.
• Title: Non-native fish removal in the Green River, Lodore and Whirlpool canyons, 2002-2006, and fish community response to altered flow and temperature regimes, and non-native fish expansion.
• USFW Year: 2007.
• USFW - Doc Type: 115,
• Copyright Material: NO

less (e.g., 2002). Mean temperature of releases in the June through August period were 11.9,
12.0, 13.0, 12.7, and 13.8°C, for years 2002 to 2006 respectively.
In lower Lodore Canyon, Green River mean daily water temperature reached 16°C at a
relatively consistent time each year: 31 May, 6 June, 29 May, 17 June, and 5 June, in the years
2002 to 2006, respectively. That 16°C temperature level may be consistent with the onset of
smallmouth bass spawning activities (Carlander 1977, KRB, unpublished Yampa River data).
The relatively low 2005 temperatures that occurred relatively late in the year were consistent
with higher and cooler base flows released from Flaming Gorge Dam. Mean daily water
temperatures for the main June-August fish growing season was 19.4°C in 2002, 19.8°C in 2003,
18.6°C in 2004, 17.6°C in 2005, and 19.7°C in 2006.
Effects of Flaming Gorge Dam on Green River discharge and temperature patterras,
Whirlpool Canyon.-Annual peak flows in the pre-impoundment period (1946-1962) showed a
typical dome-shaped hydrograph, with low late summer, autumn, winter, and early spring base
flows, rising to a peak in later spring and early summer (Fig. 10). Post-Flaming Gorge peak
flows in the 1992 to 1996 and 2002 to 2006 periods were, on average, lower than historical, from
a standpoint of mean daily annual flow, peak flow, and maximum May-June flows (Table 1).
However, peak flows in each of years 2003, 2005, and 2006 were higher than occurred in the
1946-1962 pre-impoundment period, and timing of flow peaks more closely approximated those
that occurred historically (Figs. 11 and 12). Base flows in the period August to February were
typically lower in the pre-impoundment period than post. Mean July-August summer base flows
were lower in 1992 to 1996 than historical flows, and mean July-August base flows in the 2002
to 2006 period approximated historical conditions.
Water temperatures of the Green River in Whirlpool Canyon (Mitten Park station, just
upstream of Whirlpool Canyon), in the 1992 to 1996 were substantially cooler than in the period
2002 to 2006 (Fig. 13). Mean daily temperature of the Green River from June through August at
Mitten Park in 1992 to 1996 was 18.0°C compared to 19.8°C from 2002 to 2006. The primary
difference was a period from mid-May to mid-July, when water temperatures were up to 4°C
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