Dissolved Oxygen Dynamics in Lake 

Powell and in the Glen Canyon Tailwater

Glen Canyon Dam Adaptive Management Program 

Annual Reporting Meeting, January 24, 2023

Bridget R Deemer, US Geological Survey, Southwest 

Biological Science Center, Grand Canyon Monitoring and 

Research Center- bdeemer@usgs.gov

This information is preliminary and is subject to revision. It is being provided to meet the 

need for timely best science. The information is provided on the condition that neither 

the U.S. Geological Survey nor the U.S. Government shall be held liable for any 

damages resulting from the authorized or unauthorized use of the information. 
Lake Powell Appendix

 Project Elements and Objectives

 USGS Ecosystems Mission Area “Forecasting Fish Population 

Responses to Drought”

 Special statement of work: “Leveraging Existing Data and Improving 

Existing Models to Better Bound Possible Water Quality Futures for Lake 

Powell and Its Tailwater” 

 Lake Powell Water Quality Monitoring Program

 Funding amount and source: 

 $100k (USGS Ecosystems Mission Area over 2 yrs)

 $60K (BOR Statement Of Work-AMWG Directive)

 $200K (BOR Interagency Agreement)

 Cooperators: Bureau of Reclamation

 LTEMP Resource goals: Natural Processes
Low Reservoir Water Levels= 

New Era of Water Quality

Preliminary Information- Subject to Revision. Not for Citation or Distribution

Maximum temp of ~21 C 

in Sep 2022 

Minimum DO of 2.5 mg/L 

in Sep 2022

Higher than average 

winter and spring 

conductivity– indicative 

of lake turnover
Low Reservoir Water Levels= 

New Era of Water Quality

Maximum temp of ~21 C 

in Sep 2022 

Minimum DO of 2.5 mg/L 

in Sep 2022

Higher than average 

winter and spring 

conductivity– indicative 

of lake turnover

Preliminary Information- Subject to Revision. Not for Citation or Distribution
Dissolved Oxygen in Lake Powell

Video Courtesy of Robert Radtke

Preliminary Information- Subject to Revision. Not for Citation or Distribution
Metalimnion Low Dissolved Oxygen Events

2017 2018 2019 2020? 2021 2022

Wahweap

Plot Courtesy of Bryce Mihalevich

Preliminary Information- Subject to Revision. Not for Citation or Distribution
Inflow Dynamics are Important

Colorado River Inflow

San Juan River Inflow
Inflow Dynamics 

are Important

GIF courtesy of Dr. 

Joe Mason at UW 

Madison
DO concentrations 

in inflowing water 

based on:

Elevation DO

Discharge DO

Temperature DO

Dissolved Oxygen in Inflows

Preliminary Information- Subject to Revision. Not for Citation or Distribution
Dissolved Oxygen in Inflows

Internal “Decay” of 

DO

Temperature DO

Preliminary Information- Subject to Revision. Not for Citation or Distribution
Observations of low metalimnion DO

 Yrs w/ mean summer metalimnion DO <5.5 mg/L

2005

2011

2019

2022

1973 2008

1985

1972 2015

Preliminary Information- Subject to Revision. Not for Citation or Distribution
Observations of low metalimnion DO

 Low lake elevation + large spring inflow 

2005

2011

2019

2022

1973 2008

1985

1972 2015

2021

Preliminary Information- Subject to Revision. Not for Citation or Distribution
Research Questions

 What are the best predictors of metalimnion 

low dissolved oxygen at Wahweap?

 Lake Elevation

 Spring Inflow 

 Sediment remobilization 

 Water Temperature

 Monsoon Activity (proxy– Escalante, San Rafael, Dirty 

Devil, and Paria) 

 Time Since Reservoir Filling

 Interaction– Elevation X Time Since Filling
Metalimnion Low Dissolved 

Oxygen Events

Quantified the mean 

DO concentration

In metalimnion 

(between 23 and 

164 feet deep) 

Focused on the 

summer and fall 

(July-October)

Did not use 2020 

given limited data

Plot courtesy of Bryce Mihalevich

Preliminary Information- Subject to Revision. Not for Citation or Distribution
Lake Powell Dissolved Oxygen Data

 593 DO profiles at Wahweap from 1966-2022

 Subset to look at July-October= 171 profiles

 Part of a larger dataset on ScienceBase: 

 https://doi.org/10.5066/P9ZIKVYW.

 Data paper published online today: 

https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol

2.10310

Check out Caitlin 

Andrews’ Lake 

Powell Data Viz 

Poster this 

Evening!
General Linear Modeling (1966-2022) 

 DO ~ Spring Inflow + Years Since Filling +

Elevation * Years Since Filling

 Strongest effect is the interaction between 

the lake elevation and the time since filling
General Linear Modeling (1980-2022) 

 DO ~ Years Since Filling + Spring Inflow + 

Elevation * Years Since Filling + Monsoon 

Inflows

 Same top model as with longer term dataset

 Monsoon inflows do not emerge as a significant 

predictor
Dissolved Oxygen in Inflows

DO concentrations at dam:

Elevation 

+ DO 

Time since

dam

Volume of DO

Spring Inflow

Preliminary Information- Subject to Revision. Not for Citation or Distribution
Recent Elevation vs. DO Relationship

Preliminary Information- Subject to Revision. Not for Citation or Distribution
What does this mean for the Glen 

Canyon Tailwater?

 The dam turbines “run rough” at low lake elevation

 Low dissolved oxygen at Wahweap did not translate 

to as low of downstream DO as we thought

Wahweap Below Glen Canyon Dam

Preliminary Information- Subject to Revision. Not for Citation or Distribution
Higher GPP with Warmer Temperatures

Glen Canyon

Preliminary Information- Subject to Revision. Not for Citation or Distribution

Check out Lindsay 

Hansen’s GPP 

Poster this 

Evening!
Elevated Oxygen at Lees Ferry

Daily average

DO ~1 mg/L 

higher at 

Lees Ferry 

than at Dam

Preliminary Information- Subject to Revision. Not for Citation or Distribution
DO Departure Largest During Day

Preliminary Information- Subject to Revision. Not for Citation or Distribution
Global Context

Modified from Blaszczak et al. 2022 L&O Letters
Acknowledgements

 Charles Yackulic

 Caitlin Andrews

 Bryce Mihalevich

 Jeremiah Drewel

 Tom Sabol 

 Nick Voichick

 Robert Radtke

 Funding from the Bureau of 

Reclamation and the USGS 

Ecosystems Mission Area 

Lower reaches of Cataract Canyon, July 2017
Questions