Project A: Streamflow, Water Quality, and Sediment 

Transport and Budgeting in the Colorado River Ecosystem 

Project A collects the physical data that directly link dam operations to all 

resources in the downstream Colorado River; data inform 10 LTEMP goals 

• Element 1: Stream gaging 

– Stage 

– Discharge 

• Element 2: Water quality 

– Water temperature 

– Salinity (specific conductance) 

– Turbidity 

– Dissolved Oxygen 

• Element 3: Sediment transport and budgeting 

– Suspended- and bed-sediment data 

– Sediment loads (silt and clay loads and sand loads) 

– User-interactive sand budgets in 6 reaches from Lees Ferry to Lake Mead 

• All elements 

– Database and website (currently UNSUPPORTED) 
 

 

 

 

 

 

 

 

 

 

 

Major risk to GCDAMP remains 

unresolved 

• Despite adequate GCDAMP funding, Project A’s 

database and website have not had stable 

Computer Science support since 2019 

• >30 million dollars of GCDAMP funding since 

1990s for data that mostly exist only in this 

database and are available only through this 

website 

• Database and website are breaking down 

• Risk is loss of ability to relate resource changes to 

dam operations, inability to plan and evaluate 

HFEs, and loss of pre-dam and early syn-dam 

context (1921–1990s data are only available 

through website) 
 

 

 

 

 

 

Only minimal QW data have been 

processed since June 2023 

• We have still not backfilled Project A’s water-quality specialist (Nick 

Voichick retired last June) 

• Only water temperature and specific conductance at Lees Ferry and 

water temperature in three tributaries are QA/QCed and posted at: 

https://www.gcmrc.gov/discharge_qw_sediment/ 

• Good news is on the 

horizon, though... 
~1.5 million metric tons 

 

 

 

Flows at Lees Ferry and sand export 

past Diamond Creek during FY 2023 

of sand export during HFE 

~1.5 million metric tons 

of sand export ~580,000 metric tons 

of sand export 

High “balancing” flows that bracketed the HFE exported 

~2.1 million metric tons of sand to the Lake Mead Delta 

Data from USGS (2024a) 
 

 

 

 

 

 

 

Evaluation of LTEMP sand management 

David J. Topping1 

Paul E. Grams1 

Ronald E. Griffiths1 

Matt Kaplinski1 

Joel A. Unema2 

David J. Dean1 

Katie A. Chapman1 

1U.S. Geological Survey 2U.S. Geological Survey 

Southwest Biological Science Center Arizona Water Science Center 

Grand Canyon Monitoring and Research Center 

The information in several of these slides 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. 
 

 

 

 

 

Basics of sand management 

•

• Keep dam releases low for 

part to much of the year to 

accumulate sand OR 

• Episodic short-duration 

Sand supply is <5% of natural 

artificial floods (HFEs) to Randle and others (2007) 

rebuild sandbars 

• Avoid sustained high releases (e.g., equalization) that greatly 

exceed the sand supply and result in widespread erosion 
 

 

 

8,000 ft3/s 

25,000 ft3/s 

15,000 ft3/s 

45,000 ft3/s 

High-elevation sand 

Figure modified from Hazel and others (USGS-PP, 2022) 

• ~30–50% of the sand stored in sandbars is relict “pre-dam” sand (Chapman and 

others, GSA Bulletin, 2020) 

• Stratigraphic and ground-penetrating-radar data indicate pre-dam sand at depth in 

at least some sandbars (Barnhardt and others, USGS-OFR, 2001) 
 

 

 

 

 

 

 

Downward spiral has likely occurred in long-term sand mass balance... 

and reflected in at least some of the sandbars 

>28 million metric tons of sand eroded since 1963, mostly during 3–4 periods of high dam 

releases (Topping and others, JGR, 2021) 

~12 million metric tons eroded in late 1990s alone (6 from Marble and 6 from Grand) 

*~5.5 million Mg 

sand erosion 

measured but 

not predicted in 

1965 

*>2 million Mg 

sand erosion 

measured but 

not predicted in 

1965 

* 

* 

Figures from Topping and others (JGR, 2021) Preliminary figures from Gushue, Weber, Grams, Hazel (do not cite) 
Sustainable management of sand under the LTEMP sediment goal 

thus requires neutral to positive trends in both the sand mass 

balance (i.e., the bank account) and the high-elevation sandbar 

volume (i.e., your expenditures) over decades 

 

Not sustainable 

Bank account mined to 

deposit sandbars 

“Living on credit” 

Scenario 2 

Sustainable 

“Living 

within your 

means” 

Scenario 3 

Not sustainable 

Paria 

HFE 

Paria 

HFE 

Scenario 1 
 

Metrics Example: The Bank Account 

POSSIBLE SUCCESS! Sustainable in 

Lower Marble Canyon if highelevation sandbar volume is positive 

during this period. 

POSSIBLE FAILURE Not sustainable in 

Eastern Grand Canyon regardless of 

whether high-elevation sandbar 

volume is positive during this period. 

Data from Topping and others (JGR, 2021); USGS (2024a) 
Upper Marble Canyon 

West-Central Grand Canyon 

Remote-sensing and 

channel-mapping data 

can also inform here 
 

Eastern Grand Canyon? Lower Marble Canyon 

East-Central Grand Canyon 
 

HFE-Protocol/LTEMP Period 

Upper Marble Canyon 

7/1/2012 – 9/30/2023 

2012-07-01 

POSITIVE POSITIVE 

Possibly sustainable 

Data from USGS (2024a, b) 
 

HFE-Protocol/LTEMP Period 

Lower Marble Canyon 

POSITIVE POSITIVE(?) 

2012-07-01 

7/1/2012 – 9/30/2023 

Insufficient HFE magnitude/duration or intervening flows too high 

Data from USGS (2024a, b) 
 

 

HFE-Protocol/LTEMP Period 

Eastern Grand Canyon 

INDETERMINATE POSITIVE(?) 

Large LCR 

inputs 2012-07-01 

7/1/2012 – 9/30/2023 

Intervening flows likely too high (SAVED BY THE LCR) 

Data from USGS (2024a, b) 
 

HFE-Protocol/LTEMP Period 

East-Central Grand Canyon 

POSITIVE POSITIVE(?) 

2012-07-01 

7/1/2012 – 8/30/2023 

Insufficient HFE magnitude/duration or intervening flows too high 

Data from USGS (2024a, b) 
 

HFE-Protocol/LTEMP Period 

West-Central Grand Canyon 

7/1/2012 – 8/30/2023 

2012-07-01 

POSITIVE POSITIVE 

Possibly sustainable 

Data from USGS (2024a, b) 
 

 

 

 

 

• Mean high-elevation normalized sand volume is unchanged between 1990 and 2023 

• High-elevation sand at half of the 12 long-term sandbar monitoring sites in Marble 

Canyon defines a downward spiral between 1990 and 2023 

• High-elevation sand at almost half of these sites defines an upward spiral 

Data from USGS (2024b) 
 

 

 

Conclusions • High risk to GCDAMP of catastrophic data loss and inability to plan HFEs until

computer-science support to Project A’s database gets restored 

• LTEMP sand management seems to be “working” in two segments (Upper Marble 

Canyon and West-Central Grand Canyon) 

• LTEMP sand management may require adjustment in two segments (Lower Marble

Canyon and East-Central Grand Canyon) by increasing HFE magnitude/duration or

by reducing dam releases between HFEs 
 

 

 

 

 

 

 

Conclusions continued • As with the mass balance in Eastern Grand Canyon (Topping and others, JGR, 2021), sandbar 

response in this segment during HFEs seems to be driven largely by LCR activity 

• Because the LCR cannot be easily controlled, LTEMP sand management in the Eastern Grand 

Canyon segment may also require a reduction in dam releases between HFEs 

• Evaluation of only the time series of mean sandbar volume can be misleading because of the 

variation in response among sandbars (this is why we need to examine sandbar response in 

more than one way) 

LCR 
Thank you 
 

 

 

 

 

 

 

 

 

 

 

 

 

References • Barnhardt, W.A., Kayen, R., Rubin, D., and Minasian, D.L., 2001, The internal structure of sand bars on the 

Colorado River, Grand Canyon, as determined by ground-penetrating radar: U.S. Geological Survey OpenFile Report 2001-425, 74 p. https://doi.org/10.3133/ofr01425 

• Chapman, K.A., Best, R.J., Smith, M.E., Mueller, E.R., Grams, P.E., and Parnell, R.A., 2020, Estimating the 

contribution of tributary sand inputs to controlled flood deposits for sandbar restoration using elemental 

tracers, Colorado River, Grand Canyon National Park, Arizona: Geological Society of America Bulletin, v. 

133, p. 1141–1156. https://doi.org/10.1130/B35642.1 

• Hazel, J.E., Jr., Kaplinski, M.A., Hamill, D., Buscombe, D., Mueller, E.R., Ross, R.P., Kohl, K., and Grams, P.E., 

2022, Multi-decadal sandbar response to flow management downstream from a large dam—The Glen 

Canyon Dam on the Colorado River in Marble and Grand Canyons, Arizona: U.S. Geological Survey 

Professional Paper 1873, 104 p., https://doi.org/10.3133/pp1873 

• Topping, D.J., Grams, P.E., Griffiths, R.E., Dean, D.J., Wright, S.A., and Unema, J.A., 2021, Self-limitation of 

sand storage in a bedrock-canyon river arising from the interaction of flow and grain size: Journal of 

Geophysical Research: Earth Surface, v. 126, e2020JF005565. https://doi.org/10.1029/2020JF005565 

• U.S. Geological Survey, 2024a, Discharge, sediment, and water quality monitoring, Grand Canyon 

Monitoring and Research Center: accessed on January 11, 2024, at 

http://www.gcmrc.gov/discharge_qw_sediment/ 

• U.S. Geological Survey, 2024b, Grand Canyon sandbar monitoring, Grand Canyon Monitoring and Research 

Center: accessed on January 11, 2024, at http://www.usgs.gov/apps/sandbar/