STATUS OF SAND SUPPLIES IN THE 

BELOW GLEN CANYON DA

BHBF Discussion: Sediment inputs and S

Planning – technical presentation: 08:45

Presented to the GCD-AMP’s Technical Wo

NOVEMBER 9, 2006
STATUS OF SAND SUPPLIES IN THE 

BELOW GLEN CANYON D

The Panow erecurr

Tributaries Have Delivered 1.7 – 2.6 Million M

Experoppobeach flows

6543210

.01

.1

15

102030507080909599

99.9

99.99

LAST 10 YEARS1924-2006

PARIA RIVER ANNUAL SAND SUPPLY (million metric tons)

% OF YEARS IN WHICH SAND SUPPLY IS EXCEEDED NOW pre-2004 BHBF

OVER 2X PARIA SAND SUPPLY 

OVER 3X LCR SAND SUPPLY

RELATIVE TO PRIOR TO 2004 BHBF TEST

5-YEAR EVENT
Sand Bars are Important Elem

Sand Bars are Important Elem

River Restoration Program Be

River Restoration Program Be

• Geomorphic Framework

–

fundamental part of the pre-dam river

• Terrestrial Habitat – substrate for 

riparian vegetation & assoc. fauna

• Aquatic Habitats – nursery habitats 

that may support native fish

• In-Situ Preservation – most 

archeological sites buried in sand/silt

• Recreational Campsites - for 

boaters and backpackers
Can Colorado River Sand 

Can Colorado River Sand 

Restored/Maintained by Do

Restored/Maintained by Do

Sand Inputs + Managed GC

Sand Inputs + Managed GC

pre-2004 BHBF post-2004 BHB
Taking a Strategic, Science Based Approach to the 

ScientistsCurrentlyRecommend
1996

• Channel was sand-depleted.• Bar growth was minimal or negative.• Not a sustainable plan.
1996

• Channel was sand-depleted.• Bar growth was minimal or negative. • Not a sustainable plan.

Pre-1996 FloodPost-1996 Flood
1996

Channel was depleted.Bar growth was minimal or negative. Not a sustainable plan.

2004

• Channel was moderately enriched.• Bar growth was more substantial.• Promising, but additional sand is needed. (

frequent floods, exploiting bigger inpuor constraining flows between floods.)
1996

Channel was depleted.Bar growth was minimal or negative. Not a sustainable plan.

2004

• Channel was moderately enriched.• Bar growth was more substantial.• Promising, but more sand is needed. (Req

floods, exploiting bigger inputs, adding constraining flows between floods.)

Pre-2004 Flood

Post-2004 Flood
1996

Channel was depleted.Bar growth was minimal or negative. Not a sustainable plan.

2004

Channel was moderately enriched.Bar growth was better.Promising, but more sand is needed. (Req

floods, exploiting bigger inputs, adding sedi

constraining flows between floods.)

2006

• Channel is a factor of 2 to 3 times more sa

2004.

• Potential to increase bar size and suppress 

export, while testing flow-only treatme
Native Fishes Native Fishes

Sand Bars And Backwaters May Benefit Native Fishes, EFloods May Displace Nonnative Fishes
Aquatic Food Base 

Aquatic Food Base 

Riparian Vegetatio

Riparian Vegetatio

• Floods May ‘Clean’ Substrates O

Sediments And Senescent AlgaeAlgal And Invert Growth

• Floods May Limit The Extent Of N

Vegetation

• Floods May also Increase the Re

Tributary Derived Organic Matter
Carbon Inputs to Down

Carbon Inputs to Down

Ecosystem Ecosystem

Source Annual 

Production/(metric tons

Particulate Organic Drift from LF (Kennedy, unpublished data)

10,000

Litter inputs from riparian zone (Ralston, unpublished)

520

Algal Production Downstream (estimated from 

Stevens et al. 1997)

2000

Paria River on Oct 6-7, 2006 (Kennedy, unpublished data)

33,000
1997 1998 1999 2000 2001 2002 

Time (years)

60008000

1000012000140001600018000

Total Campsite Area (m2)

Sand Bar Erosion Linked to Recreation C

Sand Bar Erosion Linked to Recreation 

2004 Test RestoCampable AreasFuture Flows Co
Without Enriched BHBFs Without Enriched BHBFs 

- Archaeo

Archaeo

In The Colorado River Ecosystem C

In The Colorado River Ecosystem C

Deteriorate Owing To Combined E

Deteriorate Owing To Combined E

• Ongoing loss of sediment 

from the system

• Insufficient high elevation 

sediment-replenishment

• Weather-induced erosion, 

and

• Continuing visitor impacts 

(social trails, artifact loss, vegetation damage, soil compaction, etc.) 
Rubin et al., 2002, Eos.

Limited Time To Exploit New San
Summary Summary – Flows and 

Flows and 

Transport Transport

Flow 

Regime Months Volume (TAF) Inputs Expor

5 – 10 9 490 1.6 ± 0.40 0.2 ± 0.07 – 13 18 610 1.3 ± 0.33 0.4 ± 0.0

11 – 18 23 850 1.0 ± 0.25 2.4 ± 0.2

Preliminary data subject to review and revision

Low to moderate volumes/peaks re

High volumes/peaks exported more san

Based on data from 
Potential for Equalization Release

Potential for Equalization Release

• October Inflow Has Increased Probability That W

Release May Include Equalization Flows From Gl• New Sand Supplies Will Be Exported Faster UndFlows Associated With Larger Summer Volumes

• Probability of Equalization Releases in WY 2007 

- 50 % Exceedance [A-J ~ 91 %] Avg Summer Re- 40 % Exceedance [A-J ~ 101%] Avg Summer Re- 30 % Exceedance [A-J ~ 114 %] Avg Summer Re- 20 % Exceedance [A-J ~ 131 %] Avg Summer Re- 10 % Exceedance [A-J ~ 155 %] Avg Summer Re

* may not be achievable due to maintenance
Additional Benefit: Additional Benefit:

Suppression Of Sand Export 

Suppression Of Sand Export 

• Coarsening of the channel bed and lowduring BHBFs can reduce the subsequensand in the Colorado River by about 80% of months (Rubin et al., 1998, Geology; T

2000, WRR; Rubin and Topping, 2001, WTopping et al., in press, Sedimentary Ge

• Sand supplied by tributaries after BHBFthan if no BHBF occurred.
TRIBUTARY SAND INPUTS FOLL

BHBFs ARE RETAINED MUCH LO

1

10

100

1000

5000 10000 15000 20000 25000

JAN 2005 EXAMPLE - 1.5 MONTHS AFTER BHBF

JAN 4 through JAN 10JAN 15 through JAN 31

RIVER-MILE 30 SAND CONCENTRATION (mg/l)

WATER DISCHARGE (ft3/s)

ON JANUARY 11-14,PARIA SUPPLIED 650,000 TO 970,000 METRIC TONS OF SAND

1

10

100

1000

5000 10000 

OCTOBER 2006 

RIVER-MILE 30 SAND CONCENTRATION (mg/l)

WA
CONCLUSION

• Current sand enrichment makes 2007 opportunity to conduct an experiment a

limited sand resources to meet manage• This situation occurs on average once years; the last time this level of tributary input from the Paria River occurred was • Properly timed controlled floods from the only known flow option for sand bar restoration.