The Great Salt Lake (GSL) experienced a significant drop of 0.87 m in mean water surface elevation (WSE) since 1988. A particular concern, not addressed in past studies, is the possibility the response of the GSL WSE during periods of drought may be increasing in severity over time as diversions increase. Statistical tests performed on the GSL WSE time series detected a distinct change point in 2001. This study compared the pre-change (1980-1999) and the post-change (2000-2018) time periods in terms of lake WSE declines and quantified the hydroclimate, and urban development of the contributing tributaries to investigate possible factors that triggered the lake WSE declines. Further, a multi-model approach using Stepwise Regression, Multivariate Linear Regression, Multivariate Adaptive Regression Spline, Principal Component Regression, and Partial Least Square Regression algorithms investigated the importance of drought indices and urban development during both time periods. The results reveal lake WSE sensitivity to drought severity increasing with urban development. Under the most critical condition of extreme drought, the model indicates the higher development condition causes an increase in lake WSE reduction of 1.4 m and 3.3 m compared to the medium development and lower development conditions, respectively. The results of this paper provide information to management policies for the Great Salt Lake contributing areas considering urban development and drought resilience.
