A Functional Flows Framework for the Terminal Great Salt Lake Basin: Can We Have Our Lake and Drink It Too?

ABSTRACT Terminal basins provide unique aquatic environments that are often highly sensitive to streamflow contributions, making them a focal point for environmental water management. However, the water needs for terminal lake, wetland, and river ecosystems, and how they relate, remain a fundamental knowledge gap that constrains our ability to efficiently manage these globally critical and imperiled systems. Recent efforts to increase inflows to Great Salt Lake (GSL) and reverse lake decline underscore the need to simultaneously consider environmental water needs for contributing rivers and peripheral wetlands, so water dedicated and delivered to GSL can achieve additional ecological benefits to the larger basin as a whole. This paper introduces a functional flows framework for the GSL basin, USA. Functional flows are specific components of the annual hydrograph and interannual hydrologic variability that are critical to aquatic ecosystem health. We conceptually characterize functional flows and associated hydrologic metrics for GSL basin's rivers and wetlands and then quantify functional flow metrics for reference stream gages on rivers across the basin. Finally, we discuss how a functional flows approach could help address persistent environmental water management challenges in the GSL basin related to coordination, adaptive management, and resource constraints. Functional flows provide a framework for consistently and transparently quantifying when, where and how much water is needed to achieve critical environmental functions in upland rivers and wetlands as well as GSL itself.