GCMRC Update – status of resources 

and sediment conditions

Jack Schmidt and Scott VanderKooi

Southwest Biological Science Center

Grand Canyon Monitoring and Research Center
Mainstem flow

Mainstem flow and sediment

Tributary flow and sediment

Sediment budget reach

RM 0-30 – upper Marble Canyon

RM 30-61 – lower Marble Canyon

RM 61-87 – eastern Grand Canyon

RM 87-166 – central Grand Canyon

RM 166-225 – western Grand Canyon

Between July 1 and November 17, 2012, ...

between 550,000 and 760,000 metric 

tons accumulated in upper Marble 

Canyon

617,000 – 769,000 metric tons entered Colorado 

River from the Paria River

between 32,000 and 60,000 mt accumulated 

in lower Marble Canyon

32,000 mt accumulated in 

eastern Grand Canyon
Immediately before the 2012 HFE, sand bars in Marble Canyon 

were as small as they had been since monitoring began in 1990; 

bars were larger in Grand Canyon
Although the median trend in Marble Canyon is 

negative, there are sites that have increased since 1990
Although the median trend in Marble Canyon is 

negative, there are sites that have increased since 1990
Although the median trend in Marble Canyon is 

negative, there are sites that have increased since 1990

?

surveyed

fall 2013 
5 sandbars surveyed immediately after the 2012 HFE 

all increased in volume

?

surveyed

fall 2013 
5 sandbars surveyed immediately after the 2012 HFE 

all increased in volume

?

surveyed

fall 2013 
Most sandbars constructed by the 2012 HFE 

were subsequently eroded

• Response immediately after HFE

– Substantial Gain (deposition): 18 sandbars (55% of sites)

– No substantial change: 12 sandbars (36% of sites)

– Substantial Loss (erosion): 3 sandbars (9% of sites)

• Sandbar condition in May 2013 (before summer fluctuations 

peaking at 18,000 ft3/s)

– Still somewhat larger (8 sites)

– About the same as pre-HFE size (14 sites)

– Smaller than pre-HFE (7 sites)

Preliminary data based on analysis of time lapse cameras
(Preliminary Data from 

Korman and Yard 2013. 

Do Not Cite.)

Pre & Post HFE: Rainbow 

trout populations very 

high in the upstream third 

of Marble Canyon, but 

very low where humpback 

chub live

Home of 

rainbow trout

Home of 

humpback 

chub
Rainbow Trout Abundance Estimates:

Glen Canyon Dam – Below LCR

(Preliminary Data from Korman and Yard 2013, Do Not Cite)

Overall decline in rainbow 

trout abundance over 

course of study
0%

10%

20%

30%

40%

50%

60%

70%

80%

-4.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Proportion

Miles Moved Upstream Downstream

N = 273

Age-0 Rainbow Trout Movement in Glen Canyon:

October to December 2012

90% recaptured 

within 0.25 mi of 

release location

(Preliminary Data from Korman and Yard 2013, Do Not Cite)
Rainbow Trout Length Frequency :

Below Little Colorado 

River Reach - July 2013

(Preliminary Data from Korman

and Yard 2013, Do Not Cite)

About 1/3 of RBT < 100 mm; 

suggests emigration from 

Lees Ferry OR production in 

Marble Canyon
Rainbow Trout Length Frequency :

Below Little Colorado 

River Reach - July 2012

(Preliminary Data from Korman

and Yard 2013, Do Not Cite)

Catches dominated by 

larger fish (> 200 mm)
-3.5 19 39 61 63.5 -3.5 19 39 61 63.5

-3.5 19 39 61 63.5 -3.5 19 39 61 63.5

River Mile

April 2012 July 2012

September 2012 January 2013

Midge Drift

Concentration (#∙m-3

) Concentration (#∙m-3

)

(Preliminary Data from Kennedy 

2013, Do Not Cite)

No difference 

in midge 

concentrations 

in the drift pre 

& post HFE:
-3.5 19 39 61 63.5 -3.5 19 39 61 63.5

-3.5 19 39 61 63.5 -3.5 19 39 61 63.5

River Mile

April 2012 July 2012

September 2012 January 2013

Blackfly Drift

Concentration (#∙m-3

) Concentration (#∙m-3

)

(Preliminary Data from Kennedy 

2013, Do Not Cite)

Increase in 

blackfly 

concentrations 

in the drift in 

Glen Canyon 

post HFE:
Juvenile Chub Monitoring: 

Total Catch of Humpback Chub (40 - 100 mm)

2013 catches lower 

than 2012, but higher 

than those observed 

during the NSE project

(Preliminary Data from Korman and Yard 2013, Do Not Cite)
(Preliminary Data from VanHaverbeke 2013, Do Not Cite)

2013 spring abundance 

estimate of 150-199 mm 

HBC = 1583 

(95% CI: 1234-1933)

Spring abundance estimates of humpback chub in the Little 

Colorado River remain well above the Biological Opinion trigger
Temperature of HFE release will be ~11.5C

Release temperatures have increased greatly since August

(Preliminary Data from Vernieu 2013, Do Not Cite)
Glen Canyon 

Dam Forebay

Water Quality 

Conditions:

Sept. 16, 2013

(Preliminary Data from Vernieu

2013, Do Not Cite)
+ 110,000 mt

+ 190,000 mt

- 150,000 mt

Sand mass balance 

July 1, 2012, to June 30, 2013

A small amount of the sand 

delivered to the Colorado 

River during the 2012 fall 

sediment accounting season 

remained in Marble Canyon 

at the beginning of the 

2013 accounting season
Paria inputs

July 1 – September 30, 2013
1.9 million metric tons

July 1 – September 30, 2013

Paria inputs
The amount of sand supplied in late summer and fall 2013 is a large amount in 

relation to the long-term median sand delivery

Annual Sand Delivery from 

the Paria River to the 

Colorado River
Colorado River at River 

Mile 30

Discharge

Suspended 

Sand Load

July 1 – September 27, 2013
What came in

(Paria River)

What went out

River Mile 30

1.9 million metric tons

0.13 million metric tons
Upper Marble Canyon (July 1 to September 23)

+ 1,500,000 metric tons

+ 2,400,000 metric tons

(+ 1,900,000 metric tons) 
Mainstem flow

Mainstem flow and sediment

Tributary flow and sediment

Sediment budget reach

RM 0-30 – upper Marble Canyon

RM 30-61 – lower Marble Canyon

RM 61-87 – eastern Grand Canyon

RM 87-166 – central Grand Canyon

RM 166-225 – western Grand Canyon

Between July 1 and September 27, 2013, ...

126,000 metric tons were transported past the RM 30 gage

1,900,000 mt entered 

Colorado River from the 

Paria River

369,000 metric tons were transported past the RM 87 gage

85,000 metric tons were transported past the RM 60 gage

200,000 mt entered Colorado River from the Little Colorado 

River
Mainstem flow

Mainstem flow and sediment

Tributary flow and sediment

Sediment budget reach

RM 0-30 – upper Marble Canyon

RM 30-61 – lower Marble Canyon

RM 61-87 – eastern Grand Canyon

RM 87-166 – central Grand Canyon

RM 166-225 – western Grand Canyon

Between July 1 and September 27, 2013, ...

Between 1,500,000 and 

2,400,000 mt

accumulated in upper 

Marble Canyon

84,000 mt accumulated in lower 

Marble Canyon

40,000 mt was eroded from 

eastern Grand Canyon

Upper Marble Canyon mass balance prior to other HFEs

July 1 to November 19, 2004: 350,000 – 560,000 mt

July 1, 2006 to March 3, 2008: 890,000 – 1,700,000 mt

July 1 to November 17, 2012: 550,000 – 760,000 mt