Atmospheric deposition to Utah Lake: science panel subgroup splits between ~32 metric tons TP (majority) and much higher estimates (minority); modeling team to跑

The Utah Lake Water Quality Study’s atmospheric deposition (AD) subgroup presented analyses and a documented split over how to interpret field AD data and which numerical AD inputs to supply to the nutrient model.

Process and datasets: Samuel Wallace summarized subgroup methods and data sources, including a Williams compilation (2017–2020) and a Wood/Miller dataset. The subgroup met multiple times to scrub units, screen for contamination, and develop an approach to gap‑fill and map shoreline fluxes. The subgroup used a decision tree that favored screened samplers and unscreened samples with metadata indicating no contamination; unscreened samples lacking metadata were excluded from the primary analysis.

Majority recommendation: Mike Brett, representing the majority perspective, said the subgroup’s transparent process identified a small number of extreme samples (notably six Saratoga Springs samples reported to contain sweat bees) that dramatically inflated median fluxes. Brett summarized the majority load recommendation for model inputs as roughly 32 metric tons of TP per…