Quantifying evapotranspiration from the wetlands in the peripheral area between the most downstream stream gages and the open water body of the Great Salt Lake

Study region: The eastern peripheral area between the most downstream stream gages and the open water body of the Great Salt Lake (GSL), located in northern Utah within the semiarid western United States (US). Study focus: As GSL levels decline, the eastern peripheral area is expanding, exposing former lakebed, much of which has transitioned into natural and managed wetlands. Evapotranspiration (ET) from these wetlands consumes water that would otherwise reach the open-water lake body, yet these losses remain poorly quantified and directly affect the GSL water balance. This study compares a water-balance-based ET estimate for the wetlands in the peripheral area with remotely sensed ET estimates to improve understanding of water losses and inform strategies to mitigate continued lake-level decline. New hydrological insights for the region: Wetlands covered between 49% and 57% of the GSL eastern peripheral area during the 2003–2021 analysis period and were associated with ET values ranging from 671.01 to 1036.47 mm, with a mean of 886.41 mm, corresponding to an estimated volume of 0.82 ± 0.26 × 10⁹ m³ yr⁻¹ and resulting in, on average, a 17% reduction of the streamflow between its measurement at the most downstream gages and its entry into the lake. These findings highlight the importance of water losses in the GSL eastern peripheral area on lake inflows.