Toward Sustainable Restoration of Utah Lake: A Synthesis of the Existing Literature with New Active Dust Sampling Data and Analyses

Utah Lake is a large, shallow, highly eutrophic system that is naturally rich in phosphorus (P) and is prone to harmful algal blooms (HABs). While ongoing regulatory efforts often focus on reducing external anthropogenic P loads, particularly from wastewater treatment plants (WWTPs), accumulating evidence suggests that internal sediment P cycling and atmospheric deposition (AD) govern water column P concentrations and are the primary drivers of the lake’s trophic state. We synthesize the existing literature and present new data to demonstrate that (1) the lake’s P-rich, geologic sediments buffer the water column, rendering it largely insensitive to major changes in anthropogenic P inputs due to sorption dynamics, and (2) AD alone provides sufficient P to sustain the lake’s eutrophic status. New analyses on previous AD measurements combined with new active dust sampling data reinforce these conclusions by demonstrating no attenuation of dust deposition to the interior of Utah Lake. We conclude that efforts focused solely on limiting P inputs will have minimal impact on lowering the water column P concentration or improving the lake’s water quality, and that alternative physical and biological restoration methods, such as carp removal and shoreline restoration, are likely to be far more effective.