Recent urbanization of Utah Valley, Utah, has highlighted the impacts of anthropogenically-driven eutrophication of Utah Lake, which may lead to more frequent harmful algal blooms. To examine changes in trophic state, three freeze cores were taken from Utah Lake (Goshen Bay, Provo Bay, and near the Provo Boat Harbor) to examine the extent of eutrophication since European settlement. 210Pb and 137Cs chronologies were constructed for all three cores, although due to low supported 210Pb in the Provo Boat Harbor core, an additional pollen analysis was performed. Lower juniper pollen counts in addition to higher POACEAE (grasses and cereals) counts above 27 cm suggests that land clearance was taking place and horizons above this depth are post-1850s, when Utah Valley was settled. Chronologies in Goshen Bay and Provo Bay show that horizons above 40 cm are post-1950s. Hydrogen index (HI) values derived from RockEval pyrolysis were used to characterize the organic matter in the cores. Material from all three cores show an up-section increase in HI, consistent with the increasing deposition of algal matter. δ15NATM and δ13CVPDB isotope ratios were also measured for organic matter in the cores. 15N shows enrichments upward in the cores, combined with a depletion in 13C across all three. δ15NATM values suggest increasing anthropogenic influence with time that may contribute to algal blooms and eutrophication. δ13CVPDB ratios become depleted towards the top of the core showing a change in the lake’s ecology which may be due to the introduction of invasive Phragmites. X-Ray diffraction (XRD) analysis was used to analyze mineralogical differences. Eastern Utah Lake and Goshen Bay cores contain 70-80 % calcite, 10-15% quartz and 10% dolomite. Provo Bay samples contain 50-60% calcite, 20-30% quartz, and 10% dolomite. The dominance of calcite suggests that the sediment is dominated by endogenic minerals, albeit with a greater contribution of detrital minerals in Provo Bay. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used for elemental analysis. Concentrations of phosphorous and trace metals increase in the younger sediment of all three cores, suggesting greater anthropogenic influence on lake water with time. Overall, the rise in HI, P, trace metals, and 15N since European settlement suggests that the lake has become more eutrophic and anthropogenically-impacted in the last 170 years. This highlights the importance of understanding human impacts on water quality to help mitigate any future damage to Utah Lake’s ecology and waterways.



College and Department

Physical and Mathematical Sciences; Geological Sciences



Date Submitted


Document Type





Utah Lake, eutrophication, algal blooms, modern sediment