Eutrophication and Connectivity Among Bays of the Great Salt Lake: What Happens in Farmington Bay Doesn’t Stay in Farmington Bay

Document Type

Conference Paper


Spring Runoff Conference

Publication Date



Natural geography and causeways have divided the Great Salt Lake into four bays with limited, but important connections. Most pollutants from cities in Utah flow into Farmington Bay, and to a lesser extent, into Bear River Bay before entering Gilbert Bay. Routine monitoring at the outflows of Farmington and Bear River Bays and synoptic sampling at 34 stations was done in 2006 to understand how these bays may control nutrient loading and the trophic state in Gilbert Bay. Optical brighteners (wastewater treatment plant tracers) were very high in Farmington and sometimes in Bear River Bay, but were low in Gilbert Bay. Nitrogen and phosphorus loadings to Gilbert Bay were dominated by Bear River inflows during spring runoff, but during summer, loading from hypereutrophic Farmington Bay predominated. MODIS satellite imagery documented plumes of phytoplankton-rich water flowing out of Farmington Bay and extending up to 20 km across Gilbert Bay. Isotopic analyses of 13C and 15N indicated, however, that the high algal production in Farmington Bay did not contribute substantially to the diets of brine shrimp in Gilbert Bay, at least during the May, June and November synoptic analyses. The management of nutrient loading and other pollutants in the Great Salt Lake will need to take into account the close coupling of the bays.

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