Glen Canyon Dam Air Injection

Testing September 2023 

Clarence Fullard 

WQG, AMWQ Division, UC Region 
 

 

 

 

 

Background: Low DO in Glen Canyon 

• Dissolved Oxygen concentrations: 

• 2.4 mg/L September 14, 2022 

• 2.9 mg/L September 19, 2023 

• Low levels stress fish and cause 

mortality 

• Reclamation and the GCDAMP is 

concerned about effects in Glen 

Canyon 2022 

2023 

Image courtesy of Bridget Deemer and Ted Kennedy 
Treatment: Air Injection 

Turbine air injection blower at Canyon Ferry Powerplant 

• Augment DO via air injected into 

draft tubes as it passes through 

GCD 

• Successfully implemented by 

Reclamation at Canyon Ferry 

Dam, MT 

• Increased mean downstream DO 

from 4.6 to 6.0 mg/L 

• GCD has service air system that is 

plumbed to draft tubes 

• No physical modifications needed 

for testing 
 

 

 

Air Injection Testing 

• Coordinated with GCD Operations in fall 2023 to test existing service 

air system for draft tube injection. 

• Two short experiments 

• September 14, 9:30-10:15 am 

• September 18, 8:00-9:00 am 

• Injected air into a single draft tube at a rate of ~1700 CFM 

• Possible changes in DO monitored by sondes located: 

• Draft Tube 2 (baseline) 

• Draft Tube 8 (experiment) 

• Below Dam (USGS 09379901) 

• -8 mile in Glen Canyon 
Testing Goals: 

• Does this method measurably increase DO? 
 

 

Results – September 14th 9:30-10:15 

Minor increase in DO 

immediately below dam 

during test period, but 

also an increase in Draft 

Tube 8 (DT8) preceding 

start of test. 
 

 

Results – September 14th 9:30-10:15 

At time of test, observed a 

concurrent increase in 

Specific Conductance and 

decrease in Temperature 

Due to this uncertainty, 

scheduled a second test for 

Sept. 18th 
Results – September 18th 8:00-9:00 

For this test, we see an 

increase above the 

baseline DO measured in 

DT2 and DT8 during the 

period of testing. 
 

Results – September 18th 8:00-9:00 

Other WQ parameters stay 

more stable during test, 

giving more evidence to air 

injection increasing DO 

immediately below dam 
Results – September 18th 8:00-9:00 

Increase does not 

propagate 

No measurable increase in 

DO recorded downstream 

in Glen Canyon. 
Test Period 

Extreme amount of noise 

in DT2 DO sensor during 

nighttime/lower flow 

periods, likely due to 

differing flow rates 

between draft tubes 
 

 

 

Test Period 

Removing DT2 for clarity -

possible increases in DO 

below dam do not register 

downstream. 
Testing Goals: 

• Does this method measurably increase DO? 

• Yes...but also no 

• Did not create a measurable increase in DO downstream. 
 

 

 

 

Takeaways 

• In spite of ideal testing conditions (low flows, low starting DO, max 

possible air injection), we did not see any meaningful increase in 

dissolved oxygen propagate downstream. 

• Air injection with existing equipment at GCD is not suitable for 

resolving low dissolved oxygen issues. 
 

 

 

Potential next steps: 

• Need to augment current system if we want more air or a longer 

test 

• Dedicated blower system. 

• Modify air lines in GCD for blower and to monitor flow rate. 

• Understand effects at higher discharges. 

• Understand effects on hydropower: 

• Estimated by staff to be marginal, but need dedicated monitoring. 

• What are the DO dynamics downstream? 

• How does DO increase? 

• Preferred DO levels? 

• Marginal increase in survival for trout? Decision framework for initiating 

costly mitigation? 
Acknowledgements 

• Glen Canyon Dam 

• Kato Miyagishima 

• Gus Levy 

• Bob Martin 

• Ray Ripka 

• Power Office 

• Nick Williams 

• GCMRC 

• Tom Sabol 

• Bridget Deemer 

• Bryce Mihalevich 

• Charles Yackulic 
Clarence Fullard 

cfullard@usbr.gov