Why does Mono Lake need saving? An Exploration of Climate and Anthropogenic Impacts on the Mono Lake Water Balance

Abstract

Water levels on Mono Lake (California) declined rapidly from the late 1940s to the early 1980s during a period of increased anthropogenic diversions. Water levels have remained chronically low despite implementation of management plans limiting diversions starting in 1994. Restoring Mono Lake water levels requires a differentiation and understanding of historical drivers of hydrologic variability, and a propagation of that understanding into scenario-based water level management plans. We address this need by first reconstructing Mono Lake's historical water balance using a novel Bayesian inference model. We then use our new water balance component estimates to evaluate four climate change and water diversion scenarios. We find that neither climate change nor diversions alone are solely responsible for the persistent low water levels on Mono Lake. Our results, including our new historical record and scenario analysis framework, provide important guidance to water resource management planners on why Mono Lake still needs saving, and what strategies could be employed to ensure its water levels are restored in the future.