Condensed Table 5.3. Information Considered in Determining Annual Releases from Flaming Gorge Dam to benefit endangered fishes

in the Green River at Jensen

Begin Spring Peak Flow

Magnitude of Spring Peak Flow

Duration of Spring Peak Flow

Begin Summer–Winter

Base Flow

Magnitude of Summer–Winter

Base Flow • Forecasted and actual inflow to Flaming Gorge • Forecasted and actual flows in the Yampa River • Water elevation of Flaming Gorge • Presence of adult razorback sucker congregations on spawning bars • Initial appearance of larval suckers in established reference sites in Reach 2 (e.g., Cliff Creek) • Existing habitat conditions (e.g., condition of razorback sucker spawning sites in Reach 2)

• Forecasted and actual inflow to Flaming Gorge • Forecasted and actual flow in the Yampa River • Desired areal extent of overbank flooding in Reaches 2 and 3 • Flow conditions and extent of overbank flooding in Reaches 2 and 3 in previous year • Existing habitat conditions

• Forecasted and actual inflow to Flaming Gorge • Forecasted and actual flow in the Yampa River • Desired duration of overbank flooding in Reaches 2 and 3 • Existing habitat conditions • Desired base-flow magnitude • Presence of razorback sucker larvae in the Green River

• Forecasted and actual inflow to Flaming Gorge • Forecasted and actual flow in the Yampa River • Temperature of water released from the dam • Temperature differences between the Green and Yampa Rivers at their confluence • Initial appearance of drifting Colorado pikeminnow larvae in the Yampa River

• Forecasted and actual inflow to Flaming Gorge • Forecasted and actual flow in the Yampa River • Elevation of sand bars in nursery areas • Temperature of water released from the dam • Temperature differences between the Green and Yampa Rivers at their confluence

Condensed Table 5.5.—Flow and temperature recommendations by hydrologic condition for Reach 2 (Yampa River to White River) to benefit endangered fishes in the Green River downstream of Flaming Gorge Dam.a

Hydrologic Condition b

Wet (0 to 10%

Exceedance)

Moderately Wet (10 to 30% Exceedance

Average (30 to 70%

Exceedance)

Moderately Dry (70 to 90%

Exceedance)

Dry (90 to 100% Exceedance)

SPRING PEAK FLOW Magnitude ≥ 26,400 cfs ≥ 20,300 cfs ≥ 18,600 cfs

in 1 of 2 avr yrs; ≥ 8,300 cfs in other avr yrs

≥ 8,300 cfs

Duration >22,700 cfs 2 weeks +, and >18,600 cfs >4 weeks

>18,600 cfs for 2 weeks or more

>18,600 cfs at least 2 weeks in 1 of 4 avr yrs.

at least 1 week.

2 days or more except in dry years (≥ 98% exceedance)

Timing Peak flows should coincide with peak flows in the Yampa River Hydrologic Condition b

Wet (0 to 10%

Exceedance)

Moderately Wet (10 to 30% Exceedance

Average (30 to 70%

Exceedance)

Moderately Dry (70 to 90%

Exceedance)

Dry (90 to 100% Exceedance)

SUMMER THROUGH WINTER BASE FLOW Mean flow 2,800 - 3,000 cfs 2,400 - 2,800 cfs 1,500 - 2,400 cfs 1,100 - 1,500 cfs 900 - 1,100 cfs Approximate period

Aug 15 to Mar 1 Aug 15 to Mar 1 Aug 15 to Mar 1 Aug 15 to Mar 1 Aug 15 to Mar 1

1 day peak

2 wks @ 22,700 cfs

Base flow 2,800 - 3,000 cfs

18,500 cfs for 2 weeks

1,500

- 2,400 cfs

8,300 cfs 2 to 7 days

900 to 1,100 cfs

Base flow target 1975 cfs

2008

AVR

Research request for 5 consecutive days but got 21 days above 15,000 cfs

CRRP requested 5 days above 15,000 for backwaters. In 2009 there were 13 days above.

2009

Base flow Target 1,700 cfs

Peak flow target 15,000 cfs

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