Using Repeat Photography to Document Dam 

Operation Effects on Sand Supply, Aeolian 

Landscapes, and Terrestrial Ecology in the 

Colorado River Ecosystem

GCDAMP Annual Reporting Meeting

January 21, 2021

Helen C. Fairley

USGS Grand Canyon Monitoring and Research Center

U.S. Department of the Interior

U.S. Geological Survey
Project Background

 FY18-20 TWP: Project D 

 quantifies geomorphic effects of ongoing and experimental dam operations, 

as well as the geomorphic effects of riparian vegetation expansion and 

management, focusing on effects to the supply of sediment to cultural sites, 

dunefields, and terraces.

 FY15-17 TWP

 Project 4.1 (sub-element 2) – “ascertain the degree to which environmental conditions at or near cultural sites 

have changed during the past >50 years . . . using qualitative visual comparisons 

of historical oblique imagery and current surface conditions”

 Project 12

– “ . . . how and in what respects have cultural resource values associated with the 

riparian landscape been altered, and how do perceptions of change vary across 

the different cultures that place value on these resources?”
LTEMP: Definition and Goals

 CRE Definition: “[T]he area potentially affected by implementation of the LTEMP 

primarily encompasses the Colorado River Ecosystem, which includes the Colorado River 

mainstream corridor and interacting resources in associated riparian and terrace zones, 

located primarily from the forebay of Glen Canyon Dam to the western boundary of Grand 

Canyon National Park (GCNP).]

 LTEMP Goals

 1. Archaeological and Cultural Resources. Maintain the integrity of potentially affected 

NRHP-eligible or listed historic properties in place, where possible, with preservation 

methods employed on a site-specific basis.

 2. Natural Processes. Restore, to the extent practicable, ecological patterns and 

processes within their range of natural variability, including the natural abundance, 

diversity, and genetic and ecological integrity of the plant and animal species native to 

those ecosystems.

 6. Recreational Experience. Maintain and improve the quality of recreational experiences 

for the users of the Colorado River Ecosystem. Recreation includes, but is not limited to, 

flatwater and whitewater boating, river corridor camping, and angling in Glen Canyon.

 7. Sediment. Increase and retain fine sediment volume, area, and distribution in the Glen, 

Marble, and Grand Canyon reaches above the elevation of the average base flow for 

ecological, cultural, and recreational purposes.

 8. Tribal Resources. Maintain the diverse values and resources of traditionally associated 

Tribes along the Colorado River corridor through Glen, Marble, and Grand Canyons.

 11. Riparian Vegetation. Maintain native vegetation and wildlife habitat, in various stages 

of maturity, such that they are diverse, healthy, productive, selfsustaining, and ecologically appropriate.
250+ archaeological sites are located 

in/on ancient & historic flood deposits
Wind-blown sand formerly covered many 

flood deposits and archeological sites
Reduced post-dam sediment budget and reduced 

flow magnitude and variability has disrupted sand 

supply, both in-channel and on-shore

pre-dam post-dam

Glen 

Canyon 

Dam

Pre-Dam

Sand Supply

4-6% of 

predam 

supply

10-15% of predam supply

Post-Dam

Sand Supply
Regulated flows, lack of scouring floods, allowed 

riparian vegetation to colonize bare sand areas

Former camp at RM 74.7

Vegetation cover blocks 

wind, covers bare sand, 

reduces aeolian transport

1973

2007
What does aeolian sand have to do with dam operations?

Wind

River

Fluvial-aeolian sediment connectivity affects 

upland dune fields and archaeological sites
Landscape processes are directly 

affected by aeolian sand replenishment

 Aeolian dunes without modern sand supply are less 

active, develop more biologic soil crust; once gullies 

form in this crust, they are likely to keep expanding

 Sites receiving river-derived sand (fluvial and aeolian) 

more resilient; annealing of small gullies can occur
Repeat Photography has a rich history in 

Grand Canyon and the Natural Sciences!
Repeat Photography, FY16-20

 Relies on unpaid volunteers (photographer and riparian 

ecologist), personal equipment

 All work performed in conjunction with other project elements 

and permitted river trips

 ~200 matches so far

 Focus on matching photos

from 1923 USGS trip

 Matches not evenly distributed 

 Each panorama match requires 7 digital images 

 1-3 hours required to complete each match

 For each match, we also collect detailed info on plants in photo 

view (previous vs. present) plus any other visible changes 

0

5

10

15

20

Frequency

River Miles

Match Distribution
Some 1923 photos were matched in 1990s, 

allowing study of MLLF effects*

Stake 1091, RM 11.5 R, Soap Creek

E. C. La Rue

08/02/1923

E. Hymans

Ca. 1991

A. H. Fairley

05/06/2017

* Asterisk denotes photo match at or near a Project D monitoring site
Current digital images have very high 

resolution, allowing detailed analyses

Mouth of Little Colorado River from right side of Colorado River
Exact matches vs. “pseudo-matches”

RM 98.7 L, Crystal Camp

Stake 2056, true match

E. C. La Rue

08/30/1923

A.H. Fairley

05/06/2018

S2056x, pseudo match
Every match shows vegetation increase!

E. C. La Rue

08/02/1923

Stake 672

RM 10.6 L 

A. H. Fairley

05/05/2017
Even bedrock shorelines have increased 

vegetation

E. C. La Rue

09/29/1923

Stake 5315

RM 214.1 L 

A. H. Fairley

09/05/2017
Vegetation increase is densest on bare sand

E. C. La Rue

09/30/1923

RM 217.9 L

Stake 703

A.H. Fairley

05/18/2017
In addition to covering bare sand, vegetation 

encroachment is leading to channel narrowing 

in some areas . . . .

E. C. La Rue

09/27/1923

Stake 1802

RM 204.5 R 

A. H. Fairley

05/11/2018
Matches from early 1990s show less 

shoreline vegetation than today

Stake 1707a, RM 66.0 L 

E. C. La Rue

08/14/1923

E. Hymans

02/24/1993

A. H. Fairley

05/10/2017
Another Example . . .

Stake 2237, River Mile 150.9 L

E.C. La Rue

09/13 /1923

E. Hymans, 

Ca. 1991

A.H. Fairley,

5/16/2017
Many 1923 sand bar camps (aeolian sand sources) are 

unavailable today due to vegetation encroachment

The original President Harding Camp

E. C. La Rue

08/10/1923

Stake 678

RM 43.9 L 

A.H. Fairley

05/06/2019
Repeat photographs of RM 43.9 L, stake 677

E. C. La Rue

08/10/1923

Stake 677

RM 43.9 L 

A. H. Fairley

08/26/2017
More 1923 camps . . . .

22-Mile Camp

Stake 714: RM 22.1 R 

Top: E. C. La Rue, 08/06/1923

Below: A. H. Fairley, 05/06/2017

Top of Hance Rapid

Stake 715: RM 77.1

Top: L. Freeman, 08/1923

Below: A. H. Fairley, 05/10/2019
Another 1923 camp . . .

Stake 2839, RM 197 L 

E. C. La Rue

09/25/1923

A. H. Fairley

05/17/2017

TRUE

MATCH
Same camp, slightly different view

Stake 2839x, RM 197 L 

A. H. Fairley

05/12/2016

E. C. La Rue

09/25/1923
Loss of aeolian sand has affected large portions of the 

bio-cultural landscape of the Colorado River ecosystem

Lower Unkar, RM 73.9 L. Top, S1575, looking upstream; Below, S1574, DS 

view. Left: R. B. Stanton, 01/24/1890; Right: A. H. Fairley, 08/23/2017
With loss of sand supply, dunes have 

become less active, more vegetated*

River Mile 24.7 L 

Left: R.B. Stanton 

07/14/1889, 

Right: A.H.Fairley, 

05/07/2017 

River Mile 125.6 L 

Left: R.B. Stanton 

02/21/1890, 

Right: A.H. Fairley, 

08/31/2017 
Loss of fluvial-aeolian connectivity impacts

area and quality of campsites as well as 

archaeological site integrity*

122 Mile Camp (Project D Study Site)

Top: Borden-Weeden photos, July 1973

Bottom: A. H. Fairley, May 12, 2019

1973

2018
Bass Camp: an example of how aeolian 

sand contributes to camp site area . . .

RM 109 R, Bass Camp, upper half (Stake 1580)

R. B. Stanton, 02/17/1890 A.H. Fairley, 05/11/2019
. . . and quality! As aeolian sand deflates and 

is not replenished, rocky substrate becomes 

increasingly exposed

Bass Camp, River Mile 108.9

July 1973

May 2019

Upper camp Middle camp
Loss of aeolian sand has implications for the plants and 

animals that need or prefer aeolian sand habitats*

Lower Granite Camp, River mile 93.9 L

This photo match shows how perennial shrubs (mostly Isocoma acradenia) have 

largely replaced the bunch grasses (mostly Achnatherum hymenoides, a.k.a. Indian 

Rice Grass) which formerly grew abundantly on the dunes at lower Granite Rapids

Border-Weeden photo, July 1973 H.C. Fairley, 06/23/2020
Dam-induced ecological changes affect 

locations of traditional cultural significance, 

not just camps and archaeological sites*

Mouth of Mohawk Canyon

E.C. La Rue

09/18 /1923

Stake 2239x

RM 171.9

A.H. Fairley

05/15/2019
Questions?

Left Photo: Mexican Hat Expeditions boats parked at 

mouth of Mohawk Canyon; river flow ~65,000-70,000 cfs

Tad Nichols, 07/13-14/1958 A. H. Fairley, 05/15/2019