Date of Award:


Document Type:


Degree Name:

Master of Science (MS)




Tammy M Rittenour


Semi-arid valleys in northern Utah are home to the majority of the state population and are dependent upon winter snowpack in surrounding mountains for water for irrigation, hydropower and municipal use. Water is delivered to the urban areas in the spring as discharge in rivers draining the mountains. Understanding the natural variability and cycles of wet and dry periods enables water managers to make informed water allocations. However, the complex regional climate teleconnections are not well understood and the shortness of the instrumental period does not allow for a full understanding of natural variability. Paleo proxies can be used to extend the instrumental record and better capture natural variability. This study uses dendrochronology to reconstruct streamflows of the Logan River in northern Utah over the last several centuries to provide water managers with a better understanding of natural variability. This reconstruction involved sampling and creating three Douglas-fir, one limber pine and two Rocky Mountain juniper chronologies in northern Utah. Combined with existing chronologies, three flow reconstructions of the Logan River were created: one using only within basin chronologies, one using all considered chronologies and one long chronology. Employing regional chronologies resulted in the most robust models, similar to other findings. Results indicate that the last several centuries exhibited greater variability and slightly higher mean annual flows than in the instrumental record (1922-2011). These reconstructions were created using species well established within the dendroclimatology literature such as of Douglas-fir and limber pine and the lesser used Rocky Mountain juniper. The success of Rocky Mountain juniper suggests that it can be a useful species for dendroclimatology in other areas lacking more widely recognized species in semi-arid climates (e.g., pinyon pine).

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