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Scientific Investigations Report 2008–5115

Prepared in cooperation with Bureau of Land Management

An Aerial-Photographic Assessment of Reenacted Handcart Treks on a Section of the Mormon Pioneer National Historic Trail, Fremont County, Wyoming

By Robert R. McDougal, Robert G. Waltermire, Cameron L. Aldridge, Stephen S. Germaine, Scott E. Nielsen, Charlene C. Nielsen, Leanne Hanson, and Zachary H. Bowen


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Reenactments of historical pioneer emigrations have increased in popularity since the celebration of these events during the United States bicentennial in 1976. From 1999 to 2006, approximately 70,000 Mormon trekkers traveled the Mormon Pioneer National Historic Trail (hereinafter referred to as the Trail) segment between Sixth Crossing and Rock Creek Hollow in Fremont County, Wyoming. Recent elevated levels of use have raised concerns over potential recreation-related damage to this particularly scenic segment of the Trail.

In 2006, the Bureau of Land Management (BLM) contracted the U.S. Geological Survey (USGS) to conduct an aerial-photographic assessment of the condition of the Trail between Sixth Crossing and Rock Creek Hollow. Specifically, the USGS was to assess trail conditions for this segment as influenced by handcart use (low, medium, and high intensity of use) and concentrated activities associated with trekking (toilet, rest, and camp sites).

Based on these results, there are identifiable management considerations. Toilet and rest sites need to be carefully located relative to where sensitive vegetation or soils occur. The analyses presented here indicate that limiting motorized vehicle use needs to be a priority over that of adjusting the number of trekkers. Additionally, monitoring of the Trail from Sixth Crossing to Rock Creek Hollow segment needs to consider explicit management targets, such as minimum acceptable levels of bare ground or trail width, and the establishment of permanent monitoring plots to evaluate targets and measure responses to altered management activities.

Version 1.0

Posted August 2008

Suggested citation:

McDougal, R.R., Waltermire, R.G., Aldridge, C.L., Germaine, S.S., Nielsen, S.E., Nielsen, C.C., Hanson, Leanne, and Bowen, Z.H., 2008, An aerial-photographic assessment of reenacted handcart treks on a section of the Mormon Pioneer National Historic Trail, Fremont County, Wyoming: U.S. Geological Survey Scientific Investigations Report 2008–5115, 70 p.




Purpose and Scope

Study Area

Physical Setting

Geologic Setting

Methods of Investigation

Photo Acquisition and Orthorectification

Delineation of Historic Trail and Trekker-Use Area

Classification of Imagery to Bare-Ground Estimates

Trail-Use Data

Sampling Design and Analyses


Trekker-Use Data

Depiction of Trail and Other Spatial Data

Effects of Trekkers on Bare Ground

Patterns in Trail Width by Trekkers

Patterns of Bare Ground On and Off the Trail by Mormon Handcart-Use Intensity

Patterns of Bare Ground by Concentrated-Use Areas


Study Limitations

Management Considerations



References Cited

Appendix 1. Aerial Photograph Acquisition and Ground-Control GPS Details

Appendix 2. Orthorectification and External Orientation Standard Operating Procedures

Appendix 3. Photo Orthorectification: Bundle Adjustment, Color Balance, Mosaicking

Appendix 4. Delineation of the Trail and Trekker-Use Areas

Appendix 5. Classification of Imagery to Bare-Ground Estimates

Appendix 6. Details of Datasets and Statistical Analyses


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