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Author ORCID Identifier


Open Access Dissertation

Document Type


Degree Name

Doctor of Philosophy (PhD)

Degree Program


Year Degree Awarded


Month Degree Awarded


First Advisor

Piper Gaubatz

Second Advisor

Richard Wilkie

Third Advisor

Thomas Stevens

Subject Categories

Earth Sciences | Environmental Sciences | Environmental Studies | Forest Biology | Forest Management | Forest Sciences | Geomorphology | Human Geography | Hydrology | Natural Resources and Conservation | Natural Resources Management and Policy | Nature and Society Relations | Physical and Environmental Geography | Physical Sciences and Mathematics | Public History | Social History | Sustainability | Water Resource Management


Despite its “natural” appearance and the Organic Act 1916 mandate for preservation of the natural environment in National Parks, the Virgin River as it flows through Zion National Park’s Zion Canyon was transformed through massive flood control re-engineering projects in the 1930s. The armoring of the river has had significant impacts on riparian vegetation, particularly on the stands of native Fremont Cottonwood trees that once filled the narrow valley. What was the motivation for this massive flood control project carried out in an arid region with less than 15 inches of rain per year?

This dissertation explores the motivations which contributed to the decision to armor the river in the 1930s, and the ongoing consequences of that decision on the ecology of Zion Canyon. This exploration is carried out with a mixed-methods research approach which combines analysis of historical documents, such as reports of flooding by early Mormon pioneers and correspondence between key actors in the management of ZNP, and scientific data (drawn from scientific publications, USGS databases, and National Park and Union Pacific Railroad archives), interviews with ZNP staff, and the author’s personal observations and analysis which began in 2000 while she was a Zion National Park ranger.

Key findings include the discovery that (1) an unusually wet period (pluvial) in the early 20th Century led to misperceptions of the local climate and (2) armoring the river was a result not only of those perceptions, but also of a concern with preserving and adding to the flatlands at the base of Zion Canyon to facilitate construction of visitor infrastructure in the new Zion National Park. The impacts of the armoring of the river remain severe and threaten the future of the native Fremont Cottonwood riparian forest. The dissertation also finds that restoration of the river’s natural course would be consistent with the 1916 Organic Act preservation mandate and is necessary to restore Zion Canyon’s ecosystem. Such restoration might well be key to preserving Zion National Park’s riparian environment for the 21st Century.


Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.