Holocene hydroclimate variability in the Uinta Mountains, Utah inferred from tree-rings and diatoms

The Uinta Mountains are situated in northeastern Utah, USA and contribute ~ 10% of Colorado River Flow at Lees Ferry. Instrumental data suggest that this region is sensitive to major modes of Pacific Ocean variability as well as North American Monsoon dynamics. This work examines multidecadal hydroclimate variability since circa 13,000 cal yrs BP using diatom species assemblage changes in a lake sediment core. Results are suggestive of a Younger Dryas signal and a relatively wet middle Holocene, perhaps associated with enhanced monsoon activity. Detailed analysis of the last ~ 1,000 years using tree-ring reconstructions for snowpack and flow in the Duchesne River, the largest river draining the southern slope of the Uinta Mountains, indicates statistically significant relationships between hydrology and certain phase combinations of the El Niño Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the Atlantic Multidecadal Oscillation (AMO). However, results also indicate that connections between Uinta Mountains hydrology and major modes of ocean variability are inconsistent over time, suggesting changes in the nature of teleconnections to this region.