GCDAMP- HFE 2016

High Flow Experiment- 2016

2016 High Flow Experiment Snapshot

• The 2016 HFE represents the 4th controlled high flow release conducted under the HFE Protocol.
• A preliminary analysis of these images indicates that sandbar size increased at 55% of sites, remained unchanged and 30% of sites, and decreased at 15% of sites, a response similar to those observed during each of the 2012-2014 HFEs.
• Before and after images from the November 2016 HFE from each of the 45 sandbar sites monitored with remotely deployed digital cameras are available here.

Sediment Conditions

Fall Accounting Period

• Paria input (Jul 1 - Nov 6): 845,000
• Accumulated in Upper Marble Canyon (Jul 1 - Nov 6, lower bound) = 373,000
• Accumulated in Lower Marble Canyon (Jul 1 - Nov 6, lower bound) = 72,000
• Available for HFE: 373,000 + 72,000 = 445,000

HFE Transport

• Paria input (Nov 7 - 12): 1,000
• Evacuated from Upper Marble Canyon (Nov 7 - 12, lower bound) = -492,000
• Evacuated from Lower Marble Canyon (Nov 7 - 12, lower bound) = -184,000
• Left over in Marble Canyon after HFE (Nov 7 - 12): 445,000 + 1,000 - 492,000 - 184,000 = -230,000

Winter Accounting Period

• Paria input (Dec 1 to Apr 1): 160,000
• Evacuated from Upper Marble Canyon (Dec 1 to Apr 1, lower bound) = -241,000
• Evacuated from Lower Marble Canyon (Dec 1 to Apr 1, lower bound) = -81,000
• Available for spring HFE: 160,000 - 241,000 - 81,000 = -162,000

HFE Details

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
• Technical Team Memo: Final Recommendation to Implement a Fall 2016 High Flow Experiment at Glen Canyon Dam
• Leadership Team Memo: Approval of Recommendation for Experimental High-Flow release from Glen Canyon Dam, November 7-12, 2016

COMPLIANCE

• HFE Protocol

CONCERNS

• Grand Canyon Private Boater's Association (GCPBA) letter requesting slower downramp rates following the Fall 2016 High flow experiment.
• Angler's concerns regarding a Fall 2016 High flow experiment on foodbase, trout condition, and disbursement of green sunfish. Also, noted that a comprehensive written three year review of the first three HFEs has not been provided yet.
• 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.

SEDIMENT

• Sediment in the system: 962,000 metric tons

ADDITIONAL

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

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