GCDAMP- HFE 2016

High Flow Experiment- 2016

2016 High Flow Experiment Snapshot

• HFE 2016 represents the 4th controlled high flow release conducted under the HFE Protocol.
• Sediment in the system: 962,000 metric tons

Schedule & Duration

• Nov. 7 - 6 a.m. begin upramp to powerplant capacity ( ~21,000 cfs)
• Nov. 7 - 10:00 a.m. open bypass tubes, reach full bypass at 12:00 p.m.
• Nov. 11 - 12:00 p.m. end of bypass
• Nov. 12 - 3:00 a.m. end of HFE
• Total duration: 5 days & 5 hours; 96 hours at peak release

Ramp Rates

• Ramp up: 4,000 cfs/hr from 6,500 - 21,000 cfs, then 3,750 cfs/hr to peak (36,000 cfs)
• Ramp down: 1,875 cfs/hr from 36,000 - 21,000 cfs, then 1,500 cfs/hr to 9,000 cfs

HFE Release Details

• Maximum total release: 36,000 cfs
• Powerplant capacity: 21,000 cfs
• River outlet tubes: 15,000 cfs
• Hydropower generation units available: 6
• River outlet tubes: 4

Releases and Lake Elevation

• Releases will range from 6,500 - 9,000 cfs prior to and after the HFE
• Lake elevation is projected to decrease by approximately 2.5 feet during the 5-day period
• Estimated acre feet of water bypassed during HFE: 125 kaf
• November volume = 745 kaf

Costs

• Estimated costs to hydropower: $1.4 million
• Actual costs to hydropower: TBD
• Direct expenses for removal of concession assets: TBD

SUPPORTING DOCUMENTS

• Fall 2016 HFE Planning

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Dear DOI Glen Canyon Leadership Team,

Please find attached for your consideration the High Flow Experiment (HFE) Technical Team's final conditional recommendation to implement a fall 2016 HFE at Glen Canyon Dam. I am pleased to report the HFE Technical Team's unanimous support of the attached report and recommendation.

In summary, the HFE Technical Team conditionally recommends that an HFE at Glen Canyon Dam be conducted beginning November 7, 2016 with a peak magnitude of approximately 36,000 cubic feet per second for 96 hours, as explained in the attached report, after:

1. By Friday, October 21, GCMRC and NPS personnel confirm ammonia has provided effective treatment for green sunfish in the upper pond in Glen Canyon, and
2. DOI commits to prioritizing the development and implementation of non-native species monitoring and mitigation to be in place within the next year.

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CONCERNS

• Angler's concerns regarding a Fall 2016 High flow experiment
• Re-emergence of green sunfish in the -12 Mile Slough
• Increase in brown trout spawning and the increased prevalence of adult brown trout in the Lees Ferry reach since the beginning of the HFE Protocol

ADDITIONAL

• Downstream Flow Arrival Timing Map
• Glen Canyon Dam Possible HFE Release Pattern

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