Impact of Jordanelle Dam on sedimentological and ecohydrological regimes of the Provo River, Utah, USA

ABSTRACT

The impact of large dams primarily built in the 1950s and 1960s has been extensively studied; more recent dam construction often occurs alongside habitat restoration activities, which have the potential to mitigate impacts. Jordanelle Dam on the Provo River, constructed in 1992, is economically and ecologically important to the region. This study aims to elucidate the effects of the dam on the sediment distribution and mobility of the river to inform future management of the system. Due to decreased flows, gravels (D₁₆, D₅₀) downstream of the dam are generally larger and subsurface grains are significantly coarser (p < 0.05), than those upstream of the dam. Further, the flow required to mobilize sediment is larger downstream of the dam and occurs rarely, leading to less mobile sediment and a more stable channel. The reduced mobility of sediment below the dam has decreased channel complexity. Much of the mobile sediment below the dam may be supplied from an unaltered river reach, rather than upstream mobilization. This sediment is vital to trout habitat, an important aspect of the recreation economy of the region. Monitoring changes in grain size distribution below the dam is necessary to prevent the loss of this valuable resource through diminished spawning habitat.

KEYWORDS:

• Dam impacts
• sediment distribution
• hydrology
• Provo River

Acknowledgements

The authors thank Mark Holden and Paula Trater from the Utah Reclamation Mitigation and Conservation Commission for collaborative assistance with permitting and fieldwork, Matt Eastman with Victory Ranch Outfitters for access to the river, and our hardworking undergraduate students who braved wildly variable conditions in the field, especially Jeremy Andreini and Cindy Tumen.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by a 2014 iUtah Research Catalyst Grant a sub-award of the NSF EPSCoR [grant number OIA 1208732] awarded to Utah State University, as part of the State of Utah EPSCoR Research Infrastructure Improvement Award.