Farmington Bay of Great Salt Lake receives a significant amount of the nutrient-polluted runoff from Salt Lake and Davis Counties, Utah. This nutrient-laden runoff has led to seasonal blooms of blue-green algae, Nodularia spumigena, which produce a toxin called nodularin that has been shown to be toxic to aquatic organisms, birds, and mammals. Nodularia spumigena are the most common algae found in Farmington Bay. This study focused on understanding the physical and chemical factors controlling the growth of Nodularia spumigena in order to improve our knowledge about how nutrients impact algae in the Great Salt Lake. The salinity of the bay ranged from almost fresh water (less than 0.2%) to water twice as salty as the sea (7.0%). Nutrient (nitrogen and phosphorus) levels were high in the bay, and showed patterns of change from south to north. Nodularia spumigena was found in concentrations that greatly exceeded the World Health Organization’s standards for contact recreation. Laboratory studies suggest that nutrients and salinity are significantly correlated with levels of Nodularia spumigena from Farmington Bay. In combination with complex ecosystem interactions, nutrients and salinity in Farmington Bay apparently contribute to the high levels of Nodularia spumigena that we measured.

The influence of human activity on surrounding environments is an important field of research. With respect to aquatic settings, lacustrine deposits provide excellent proxies of environmental change since the sediment accumulates at a relatively constant rate, recording environmental change. This study employs isotopic, mineral, and chemical records from Farmington Bay freeze cores, in particular δ13C, δ15N, and 210Pb isotopes as well as phosphorus level fluctuation and trace metal analysis. In particular, 210Pb isotopes permit estimation of the age of sediment with depth and δ15N, δ13C, and concentration of P provides a record of changing nutrient sources and level of eutrophication. Results from 210Pb isotopes have allowed ages to be assigned to depths along the core dating back roughly 100 years at 30 cm. At this depth, a dramatic shift in the δ15N isotope is observed. Initial δ15N levels indicated a nutrient source related to agriculture. However, beginning around 100 years ago, the δ15N shows the main nutrient source for the bay became wastewater which correlates to the completion of a sewage canal in 1911 that began routing wastewater directly into the bay. Results have also shown a large rise in phosphorus levels beginning around 1970 which may be due to the construction of the automobile causeway that isolated Farmington Bay from the rest of the Great Salt Lake.