Modeling Great Salt Lake water levels and salinities to capture current adaptive management actions

Abstract

Study region

The Great Salt Lake (located in Utah, USA) is the largest saltwater lake in the western hemisphere.

Study focus

The Great Salt Lake is a hypersaline, closed basin lake with an east-west rockfill railroad causeway dividing the lake into north and south arms. Recent record low lake levels, increased salinity and water elevation gradients between the two arms have threatened critical ecologic and economic productivity. In response, recent management efforts have focused on a newly constructed submerged berm within a causeway breach, completed December 2016, that has been altered to control bidirectional flow exchange between the higher salinity north arm and the south arm, which receives all freshwater inflows. In this study, a new 1D analytical model of breach exchange flows has been incorporated into a new open-source multi-layer mass balance model of the Great Salt Lake to predict lake levels and salinity.

New hydrological insights for the region

The applied model considers newly combined and curated salinity data from various entities along with relevant hydrologic data and a sensitivity of groundwater contributions. Water level results validated the model formulation and necessary assumptions, with predictions generally within the range of data uncertainty. Further, salinity predictions in the south arm fell within the 90 % confidence intervals. Through model application, the efficacy of the new submerged berm as an adaptive management tool was confirmed, along with the need for additional lake monitoring.